T H E J O l - R , l i A L O F I i V D r S T R I A L A N D EiVGINEERING C H E M I S T R Y
June, 1917
creosote. The toxicity of t h e higher boiling fraction, honever, is slightly greater t h a n t h a t of t h e lower boiling fraction. This is due t o t h e fact t h a t t h e higher boiling frartion contains a greater percentage of phenols (80-S j per cent) t h a n does t h e lower fraction (6j-70 per cent). The lower fraction consists principally of t h e monohydroxy a n d dihydroxy phenols a n d their derivatives, t h e most important being cresol, guaiacol a n d creosol. The higher fraction consists principally of t h e trihydroxy phenols and their derivatives. t h e most important of whirh are t h e dimethyl-ether of pyrogallol a n d its homologues. INYESTIGATIOX I N FOREST PATHOLOGY, BUREAUO F PLANTINDUSTRY IN COOPERATION WITH THE
FOREST PRODUCTS
LABORATORY
MADISON. WISCONSIN
THE DETERMINATION OF PHENOL IN CRUDE CARBOLIC ACID AND TAR OILS By
JOHN
MORRISW E I S S AND c. R. DOWNS Received March 27. 1917
INTRODUCTION
The purpose of this paper is t o describe a method which is capable of giving accurate results for the determination of phenol in mixture with cresols, higher phenols. and neutral oils. Alan? methods for t h e determination of phenol have been proposed. Most of these, however, are designed t o serve as a n assay of pharmaceutical phenol, a n d are of n o value for t h e purposes which this paper is designed t o cover. Leube‘ used a colorimetric method with ferric chloride. Nietsch2 converted t h e phenols into sulfonates, formed t h e barium a n d lead salts a n d made a determination of t h e metal content of these salts. Carre3 converts t h e phenol t o picric acid a n d makes a colorimetric determination. None of these methods are applicable for even a n approximate assay of t h e real content of phenol in a crude acid or t a r oil. m’arnes‘ gives three very empirical methods for testing carbolic acid. T h e results give only t h e melting point of a definite volume percentage fraction of t h e original acid, a n d though comparative between different samples, does not give any real indication of t h e actual amount of t r u e phenol present. Lunge5 gives a table showing t h e lowering of t h e fusing points of mixtures of para-cresol and phenol according t o tests made by Lunge and Zschokke. This table is patently useless for estimation purposes, as, in ordinary cases, meta- and ortho-cresols are also present in varying proportions, and affect t h e melting point t o a very considerable degree. Later, Lunge6 gives a method of examining crude phenols (carbolic acid) for its yield of crystallizable phenol of a melting point from I j . j t o 24‘’ C. This is known as t h e method of Lowe, and was in use among English t a r distillers for some time. The crude acid is fractionally distilled and t h e melting point taken on a definite per cent by volume of the crude acids. Dingier's polylech. J . , Z02, 308. 3
Jahresber. der. chem. tech., 1897, 1036. Compt. rend., 1891, 139.
8
Warnes, “Coal-Tar Distillation.” 1913, 166-7. Lunge. “Coal-Tar and Ammonia,” 5th Ed., 1916, 2 7 i . Ibid., 782.
569
The test is, however, more a specification for quality of crude acids, t h a n a method of analysis. Lunge further states t h a t for t h e purpose of “acquiring good practice in this method” mixtures are made of various content of pure crystallized carbolic acid a n d of cresols (preferably t a r cresols. i. e . , a mixture of t h e three isomers) a n d t h e melting points of these mixtures are previously determined. N o account is taken of variation in melting point due t o variation in t h e interproportion of t h e three cresols. 4 s Lunge himself points out, t h e relative proportions of the three cresols in coal t a r are not constant. N o a t t e m p t was made t o take advantage of t h e differences in specific gravity between phenol and t h e cresols. The method is very crude and vvould give only very approximate results. Stochmeier and Thurnauer’ extract t a r acids from carbolic oil, separate t h e hydrocarbons from the carbolate by steam distillation, liberate t h e t a r acids and fractionate them. They then use Koppeschaar’s bromination method2 on t h e fractions and use special factors for t h e fractions containing t h e cresols. The titration of such mixtures is clearly not allowable as shown b y V a ~ b e l . ~ In 1912 one of t h e authors4 made, perhaps, t h e first published attempt t o develop a rational method for t h e estimation of phenol in crude carbolic acid a n d t a r oils, a n d i t is along the general lines of t h a t method t h a t t h e method given in t h e present paper was developed. The method was fairly accurate, giving results within about I O per cent of t h e phenol present. The range of t h e series of mixtures, however, was not close enough a n d t h e cresols available a t t h a t time were not quite so pure as to-day. Noreover, t h e recent increase in value of phenol has made a more accurate method necessary, whereas in t h e past, t h e close determination of phenol was not of prime importance. I n t h e present method t h e procedure has been considerably changed a n d amplified, and a much more complete series of mixtures of known composition has been prepared a n d studied. Very recently, while this paper was in course of preparation, RenC Masse a n d hl. H. Lerouxj published a method which is in some respect very similar t o t h e method submitted by t h e authors of this paper. We have taken t h e liberty of reproducing t h e determination curve (see Fig. I ) given b y t h e m , in this paper, and plotting on i t points as found in t h e examination of our own series of mixtures. At some points t h e error can be very great. They use solidification point alone for their determination. and with variation of t h e proportion of t h e cresols among themselves, there might be a n error of 2.6 per cent a t t h e 7 j per cent point, of 1.8 per cent a t t h e j o per cent point and of 4.4 per cent a t t h e 6 j per cent point. This will be seen more clearly by a reference t o t h e curve. RIasse and Leroux used a mixture of j o per cent o-cresol a n d 50 per cent of a mixture of 60 : 40 of meta- and para1
Chem.-Zlg., 1893, 119, 131.
* 2. anal. Chem..
1886, 233. s J . p r a k l . Chem., 48, i 4 . 4
J . Franklin Inst., 1912, 683. Usines d Gas,” abstracted in J. Gas Lighling, 136, 5 8 i .
“J.
T H E J O C R N A L OF I N D U S T R I A L A N D E-VGISEERING C H E M I S T R Y
5io
cresols, for t h e basis of t h e determination. I n our work we used a jo : 50 meta-para-cresol mixture (as naturally occurring in our oils) and varied t h e relation of t h e ortho-cresol t o this. I n t h e following table we have shown t h e variation in percentage between their curves a n d ours on t h e mixtures which correspond most closely t o their proportions: TABLEI Per cent Phenol
Per cent o-Cresol
Per cent m50/p50 Cresol
P e r cent Variation
This shows their curve t o be quite correct if t h e proportion of ortho-cresol to meta- and para-cresol
have been 7-ariously given in t h e literature (see Table 11). TABLEI1 Beilstein(a) Xelting Point Boiling Point Specific Gravity Phenol.. . . , 4 2 . 5 t o 43O C. 178.5to184.IoC. 1.0906at0° 0-Cresol.. . , . 30 190.8 1.0578 a t 0' m-Cresol, . , , 3 202.8 1,0498 a t 0' #-Cresol . . , , 36 201.8 1.0522 a t Or Olsen(b) P h e n o l . , . . . . 4 2 . 5 t o 43 182.6 1 . 0 6 i 7 a t 35; o-Cresol.. . . . 30 191 1.0511 a t 35 m-Cresol., , , .3 t o 4 202 I . 0390 a t 3 5 O #-Cresol., , , 36 202 1 . O R 9 0 at s.50 Landolt-Bornstein (c) P h e n o l . , , , , , 4 ? . 5 ' t o 43 181.5 1 ,0489 a t SOo, 4 O o-Creso!. , . . , 30 187.5 t o 188 1.0427 a t 23'/4O m-Cresol, , , , .4bout 4 200.5 1 . 0 3 5 a t 13.6Oj4; p-Creso!. , , , . 36 201.1 1.034 a t l i . i o / 4 (a) Beilsteip. "Hand. d. org. Chem.," 3rd Ed., 1893. ( b ) Olsen, Chem. Annual," 3rd Ed.. 1913. (c) Landolt-Bornstein, "Phys. Chem. Tab.." 4 t h E d . , 1912.
.
There are numerous other single references dealing \vith single properties of these substances but it does
PHENOL IN PERCENT
equal but this is not generally t r u e of t a r oils. Therefore, t h e use of t h e simple solidification point curve is insufficient. I n general, their directions for t h e distillation of t h e liberated acids are fairly complete as is also their description of t h e method for determination of t h e solidifying point of t h e fractions. There are, however, a number of points in t h e handling of t a r acids t o remove neutral oils, on which their directions are not explicit, and here there is considerable chance for the introduction of serious errors. These errors may be further increased in t h e procedure for t h e determination of t h e phenol content of a t a r oil. The physical properties of t h e cresols and of phenol
Vol. 9, NO.6
\,
'. 622%
not seem vTorth while t o collate t h e m here. We have ourselves made a considerable investigation on t h e true solidifying point of pure phenol and find it t o be 4 0 . j ' C. I n this we are confirmed by Eger.lS2 T h e differences i n t h e literature are probably due t o early tests being made on small samples b y t h e capillary t u b e method which might give higher figures t h a n our solidifying point tests taken on a much larger bulk of material. I t is also probable that some of t h e other melting points giren are taken on the same basis although we have not investigated t h e m t o t h e same degree as we have in t h e case of phenol. h comparison 1
Pharm -Zfg. 1903, 210. R e o , 1903, 86.
* Chem - 2 t g .
June, 1917
T H E J O l - R S A L O F I J Y D C S T R I A L d,ITD E N G I S E E R I S G C H E M I S T R Y
of our method for solidifying point (see later) with t h e ordinary capillary t u b e melting point will indicate clearly how such differences might arise. E X P E R I JIE S T A L
T h e authors ha\-e a t t e m p t e d t o give t h e experimental work in chronological order inserting from time t o time t h e conclusions drawn. TT'e have not a t t e m p t e d to give all t h e details of manipulation in t h e single experiments. b u t have collected these together a t t h e end in a description of t h e method. Y e wish t o express a t this point our appreciation of t h e work of H. E. Lloyd and C. J. Downey viho performed most of t h e laboratory work in connection with t h e problem. A-MATERIALS
USED F O R STANDARD M I X T U R E S
TABLE I11 Solidification Specific Gravity Boiling Point Point a t 25' C./25' C. Range 1.0636(a) 180-182O C. Phenol.. , , . . . . . . . . . . 40.4' C. o-Cresol.. . . . . . . . , . . . 2 9 , 0 ° C. 1.0444 , 189-191OC. 199-201O C. 1.0339 m-D-Cresol , . . . . . . , . . Below 0' C. ( a ) Taken a t 4S0/45' C. B-MIXTURE
O F P U R E AIATERIALS
Twenty-one so-called series v-ere made up using from o t o I O O per cent of phenol. each series representing a j per cent phenol increment. In the series themselves t h e relative proportions of t h e o-cresol and t h e m-p-cresol were varied for every even j per cent. This in\-olved making a n d testing a total of 231 mixtures. T h e mixtures were made u p by weight and the accuracy of the weighings was such as t o make a maxim u m possible error in t h e final percentage of t h e ma-
SOUD1FYING P o l N T 3 IN DEGREES C E N T t 6 R . A D E . NOTE: 45 and 407, coincide from 0 to 4.75' C. 35 and 407, coincide from 1 . 7 5 to 3.25' C.
a n o-cresol fraction of high purity. b u t con1 aining some neutral oil a n d naphthalene. I t was dissolved in caustic soda solution, t h e carbolate freed from neutral hydrocarbons b y s t e a m distillation and t h e cresol precipitated again b y dilute sulfuric acid. T h e liberated cresol was separated and fractioned through a 3-bulb LeBel-Henninger column, cutting so as t o give a cresol of a boiling point of about z o C. ( 3 ) Meta-Para-Cresol was prepared in t h e same way as t h e ortho-cresol from another fraction obtained similarly. T h e final material was shown b y t h e Raschig nitration test' t o contain 49.3 per cent metacresol a n d j 0 . 7 per cent para-cresol. T h e three materials as finally used in t h e mixtures showed t h e constants given in Table 111. 1
Z . angew. Chem.. 1900, 760.
( I ) Bulb Distillation-The first few mixtures were submitted t o this test, b u t i t was soon found t h a t sufficiently concordant results could not be obtained. It was necessary t o have accurate readings of percentages distilled every even degree in order t o differentiate between mixtures made over such a close range as these were. There were so many factors, such as barometric pressure, emergent stem corrections, thermometer lag, rate of distillation, effect of air currents, etc., a n y of which could produce a n error as great or nearly as great as I O C., t h a t t h e authors decided it t o be utterly impractical t o use boiling point ranges as a method of differentiation. After a number of tests had indicated t h e hopelessness of this method of attack it was definitely abandoned.
T H E J O U R N A L OF I N D U S T R I A L A N D ELVGILVEERIlVGC H E M I S T R Y TABLEIV-TESTS 0- m-0Phe- Cre- Cre- Sp. Gr. no1 sol sol 25/25' C. SERIES 1 0 0 100 ,0339 0 5 95 ,0344 0 10 90 ,0349 0 15 85 ,0354 0 20 80 ,0359 0 25 75 ,0364 0 30 70 ,0369 0 35 65 ,0374 0 40 60 ,0379 0 45 55 ,0384 0 50 50 ,0394 0 55 45 ,0399 0 60 40 ,0404 0 65 35 ,0409 0 70 30 ,0414 0 75 25 ,0419 0 80 20 0424 0 85 15 ,0429 0 90 10 ,0434 0 95 5 0439 0 100 0 ,0444
Below Below Below Below Below Below Below Below
--i
-7
-7
--i -7
-7 -7 -7 -5.0 -3.0 1.o 4.5 7.2 10.1 12.8 15.8 18.5 21.5 23.9 26.0 29.0
SERIES 2 0 5 10
5 5 5 5
15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
95 1.0347 90 1.0352 85 1.0357 80 1 ,0363 75 1.0370 7 0 1.0377 65 1 ,0384 60 1.0391 55 1 ,0397 50 1 ,0403 45 1.0410 40 1.0416 35 1.0421 30 1 ,0427 25 1 ,0433 20 1 ,0440 15 1 ,0447 10 1.0453 5 1 ,0458 0 1.0464
OF
Solidification Point, C.
Below -7 Below -7 Below -7 Below -7 Below -7 Below --i Below -7 Below -7
PHENOL-CRESOL ~ I I X T U R EPHEKOL S. VARIEOFROM 0 Rei. Ind. 0m-p- Sp. Gr. SolidificEtion 50° C. Phenol Cresol Cresol ! 5 , 2 5 C Point, C. SERIES3 10 0 90 1.0374 Below --T 10 5 85 1 ,0380 Below --i 10 10 1.0388 Below --i 10 15 13 1 ,0394 Below --T 10 20 70 1.0399 Below -7 10 25 65 1 ,0405 Below --i 10 30 60 1.0410 Below --i 10 35 55 1.0415 -4 10 40 50 1.0421 -2 10 45 45 1.0427 1.2 10 50 40 1.0433 3.8 10 55 35 1.0438 7.2 10 60 30 1 ,0444 10.0 10 65 1.04.50 25 12.8 10 70 20 1.0456 15.8 10 75 15 1 ,0462 18.2 10 80 10 1 ,0467 21 .o 10 85 5 1 ,0473 23.6 0 10 90 1.0479 25.8
80
.... .... .... ....
.... ..
-A
0 2.0 5.3 8.3 11.2 14.4 17.4 19.4 22.4 24.7 27.0
.... .... .... .... ..*.
....
....
100 PER C E K T
OF
MIXTURE
0m-p- Sp. Gr. Solidification Phenol Cresol Cresol 25/25' C. Point, C. SERIES5 20 0 80 1.0414 Below -7 20 5 75 1 ,0420 Below --i 20 10 70 1 ,0426 Below -7 20 15 65 1 ,0433 Below --i 20 20 60 1.0438 Below -i 20 25 55 1 ,0443 -5 20 30 50 1,0448 -3 20 35 45 1,0454 -2 20 40 40 1.0461 1.2 20 45 35 1.0467 4.6 20 50 30 1,0473 7.8 20 55 25 1.0479 . 10.4 20 60 20 1.0485 13.4 20 65 15 1.0491 16.2 20 70 10 1 ,0498 18.8 20 75 5 1 ,0504 20.8 20 80 0 1 ,0509 23.8
SERIES6
SERIES4 15 15 15 15 15 15 15 15 15 15 15 I5 15 15 15 15 15 15
TO
T'ol. 9, S O .6
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85
85 80 i5 70 65 60 55 50 45 40 35 30 25 20 15
10 5 0
I ,0393
1.0399 1.0405 1.0411 1.0417 1,0423 1 ,0429 1.0435 1.0441 1 ,0447 1 ,0453 1 ,0459 1.0463 1 ,0469 1.0475 1.0481 I,048i I ,0493
Below Below Below Below Below Below
-7 --i
-7 --i
-7 --i
-6.5 -4 0 2.9 6.2 9.0 11.7 14.8 17.3 19.9 22.6 24.4
25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25
0
75
5 10 15 20 25 30 35 40 45 50
io
55 60 65 70
75
65 60 55 50 45 40 35 30 25 20 15 10 5 0
1.0428 1 ,0435 1 ,0442 1 ,0449 1 ,0455 1 ,0462 1 ,0469 1 ,0476 1 ,0480 1 ,0483 1 ,0490 1 .0498 1 ,0508 1.0512 1.0517 1 ,0524
Below -7 Below -7 Below -7 Below -7 -5 -3 -2 0 4.8 6.6 8.4 12.2 14.9 17.7 20.2 22.6
( 2 ) Refractive Indices-A few preliminary tests plotted curves of all mixtures, where t h e solidifying on t h e components of t h e mixtures showed definitely point is above 0 " C., using t h e solidifying points as t h a t their constants were too close t o enable us t o ordinates and t h e specific gravities as abscissas a n d determine a t all accurately t h e character of a mixture plotting a curve for each j per cent of phenol. It by this means. is evident from a n examination of t h e detailed results ( 3 ) Speci-fic Gravity-This test proved very useful in t h e tables t h a t if a solidifying point of a mixture is a n d was adopted for general use. The details of carry- indeterminate, t h a t is below 0 " C., t h a t t h e specific ing out this test will be given later in connection with gravity alone is not sufficient d a t a for a n exact dethe described testing method. I t was found de- termination. Therefore, for determination of phenol sirable t o use two standard temperatures. The mix- by this method i t is first necessary t o concentrate t h e tures having a solidifying point less t h a n 2 j" C. phenol into a fraction containing only phenol a n d were taken a t z j" C. compared t o water a t z j" C. cresols of such a nature t h a t t h e solidifying point is Above this point t h e specific gravities were taken a t above 0 " C. I t will be further noted in Fig. I1 t h a t , from o 4j" C. compared t o water a t 45" C. Occasionally a mixture test will be found where t h e solidifying t o 30 per cent of phenol. t h e curves are well separated point is z j o C. or a trifle higher a n d still t h e specific and t h e constants of a mixture will serve for exact gravities given as of 2 5 " C.--for all these cases t h e quantitative determination. From 30 t o 7 0 per cent specific gravity was never taken i n t h e solid state or phenol, t h e curves cross each other irregularly a n d b y correction from a higher temperature, b u t repre- points in this area are indeterminate and, therefore, sents a n actual determination in t h e supercooled liquid. not susceptible of exact determination. From 7 0 t o (4) Solidijyiag Poiat-The old method used ordi- I O O per cent phenol t h e curves are well separated a n d narily for phenol, in which t h e thermometer is used this area can be considered as determinate. The two as t h e stirring rod in t h e test tube, was given a thor- determinate areas are shown on a larger scale in Figs. ough trial and proved t o be too inaccurate, in so far I11 and IT'. I t is, therefore, evident t h a t t o deas checks by different operators were concerned, t o termine phenol, it will be necessary t o bring i t into a be used for t h e present purposes. Accordingly a fraction containing only phenol and cresols of such modified method was devised, t h e details of which are composition t h a t its physical constants will plot t o given later under t h e testing method. This modifica- a point within one or t h e other of t h e determinate tion of t h e method was used throughout t h e work areas shown. The first portion of t h e remaining problem was, therefore. t o develop a method of fracpresented in this paper. (j) Detailed Tests-These are shown in Table IT'. tional distillation which would separate all t h e phenol T h e curves in Figs. 11, I11 and IV bring out graphically from a crude acid with only cresols as an impurity. I t is evident t h a t with such a fraction, if its constants important features of these tests. (6) Caizsideratioa of Results-In Fig. I1 there are do not throw it into t h e determinate area, t h a t a mix-
June, 1917
T H E J O U R N A L OF I N D U S T R I A L AND E-YGISEERIYG C H E M I S T R Y
573
TABLEIV-((Concluded) 0m - p - SPECIFIC GRAVITYSolidifiPhe- Cre- Cre- 25 25' 45145O cation 0m-p- Sp. Gr. Solidification no1 sol sol C.(a) C.(b) Point. O C . Phenol Cresol Cresol 2 5 , 25' C. Point, C. SERIES14 SERIES10 Below -7 ,0507 3.4 65 0 35 45 0 ,0590 .... 17.6 55 Below -7 ,0514 3.6 65 5 30 .... ,0595 18.0 45 5 50 Below -7 ,052 1 4.7 65 10 25 ,0604 45 45 10 .... 18.6 -4 ,0528 5.6 65 15 20 45 15 ,0608 19.1 40 .... -3 ,0534 15 ,0617 19.2 35 45 20 .... 6.2 65 20 -1 ,0541 i .4 65 25 30 45 25 ,0622 19.4 .... 0.3 ,0548 8.5 65 30 l: ,0630 19.6 45 30 .... 25 1.6 ,0555 9.4 65 35 0 ,0636 45 35 .... 20.4 20 5.0 ,0562 45 40 15 12.2 SERIES15 8.i 14.6 ,0569 45 45 10 70 0 30 ,0608 22.0 ,0520 11.6 ,0576 45 50 5 17.2 70 5 25 0525 22.2 ,0614 14.2 ,0583 0 55 45 19.6 70 in 20 0530 22.4 ,0623 16.8 SERIESI1 i0 15 15 22.5 ,0530 ,0632 i.1 ,052i 19 3 50 0 50 20 10 70 22.6 ,0540 ,0638 ,0534 21.; 50 5 45 i.9 70 25 5 ,054; 22.8 ,0644 ,0541 50 10 40 8.6 70 30 0 ,0554 23.2 ,0650 SERIES8 9.1 ,0548 50 15 35 35 0 65 ,0466 Below-7 SERIES16 ,0555 9.8 50 20 30 35 5 60 ,0473 -4 2 5.4 75 25 . . . . ,0536 ,0562 10.3 50 25 25 -1 35 10 55 .0480 75 25.4 20 .... ,0542 11.2 .0569 50 30 20 0.5 35 15 50 ,0486 7 5 10 1 5 ,0547 . . . . 2 5 ,0575 11.7 50 35 15 -,>- 15 10 . . . . ,0553 2 5..68 0.2 45 ,0493 35 20 ,0583 14.4 50 40 10 1.4 40 ,0500 35 25 ,> 20 5 0560 25.9 .... ,0589 17.0 50 45 5 3.0 35 30 35 ,0506 75 25 0 0566 26.0 .... .0596 19.2 50 50 0 4.2 35 35 30 ,0513 SERIES12 SERIES17 7.4 35 40 25 ,0520 ,0546 45 11.5 80 0 20 0556 28.6 55 0 . . . . 10.4 35 45 20 ,0527 ,0553 11.9 80 5 5 40 15 0563 29.0 55 .... 13.2 35 50 15 ,0534 ,0560 12.2 80 10 55 10 35 10 ,0570 29.0 . . . . 15.8 10 ,054 1 35 55 ,0567 12.4 80 15 55 15 30 5 . . . . ,0576 29.0 5 18.2 35 60 ,0548 .0574 12.7 80 20 55 20 25 ,0583 29.0 0 .... 0 20.6 35 65 ,0555 ,0580 55 25 20 12.9 SERIES 18 13.6 .0587 SERIES9 55 30 15 85 15 .... ,0572 31.8 -1 40 0 60 1.0487 55 35 10 ,0594 32.0 14.2 85 10 .... ,0579 1 ,0493 0 40 5 55 16.6 ,0599 5 55 40 32.2 5 . . . . 0587 85 10 40 10 \ . 0500 0 . 8 0 50 19.2 ,0605 55 45 ,0594 32.2 85 15 0 . . . . 45 40 15 1 ,0507 2.4 SERIES 13 SERIES 19 40 40 20 1.0565 1 5 . 2 1.0514 3.4 60 0 40 90 0 10 , ,,, 1,0596 34.6 4.6 35 40 25 15.6 1.0574 1.0521 60 5 35 5 , ... 1.0603 34.6 5 90 60 10 40 30 30 1.0581 1.0528 4.8 15.8 30 0 , . . , 1.0607 34.6 90 10 16.0 40 35 25 1.0585 1 .0535 6.9 60 15 25 16.2 SERIES 20 1.0542 40 40 20 1.0592 9.8 60 20 20 5 . . . . 1.0617 3 7 . 2 16.4 95 0 12.4 1.0549 40 45 60 25 15 1.0598 15 0 . , . . 1.0623 37.2 5 40 50 17.0 95 15.1 10 1.0555 60 30 10 1 ,0606 17.6 1.0561 40 55 60 35 5 5 1.0615 17.4 SERIES21 40 60 0 20.0 1.0567 60 40 0 1.0621 19.2 100 0 0 . . . . 1.0636 4 0 . 4 ( a ) T h e values for t h e specific gravity given in this column are plotted on Fig. IV. (,b) These values are plotted on Fig. I1 because if plotted a t 45/4S0 C. the curve for 7 0 per cent phenol would interfere with the other curves i n this figure.
0m-0- Sp. Gr. Phenol Cresol Cresol 2 5 / 2 5 O C. SERIES7 30 0 70 ,0448 30 5 65 ,0454 60 30 10 ,046 1 30 15 55 ,0467 30 20 ,0473 50 45 30 25 ,0479 40 30 30 ,0486 35 30 35 ,0493 40 30 30 ,0500 30 45 25 ,0506 ,0513 50 30 20 ,0520 30 55 15 30 60 10 ,0527 5 30 65 ,0534 0 ,0541 70 30
Solidification Point, C.
~~
:
-_
:
t u r e of t h e fraction with a known amount of p u r e phenol can be made, which mixtures can be made t o fall in one of t h e determinate areas. T h e percentage of phenol can be readily determined in t h e mixture a n d from t h e knowledge of t h e amount of phenol added, t h e percentage of phenol in t h e original fraction can be readily deduced. With this then as a basis. work was commenced on known mixtures of phenol, cresols, higher acids a n d oils t o perfect t h e manipulative details necessary t o bring phenol, no matter what its form, quantitatively into a fraction in which i t was accompanied by cresols alone. C-WORK
ON
KXOWN
MIXTURES
TO
PERFECT
THE
DETAILS O F T H E METHOD
The preliminary tests involved a comparison of the Hempel a n d t h e LeBel-Henninger fractioning tubes. The Hempel t u b e was of t h e standard Barrett t y p e ( A . H. T. Cat. S o . 20496) a n d t h e LeBel, t h e 3-bulb variety: 6-bulb LeBels were tried b u t those obtainable were not of sufficiently good workmanship t o withstand t h e required temperature without cracking. For these preliminary tests i t was necessary t o prepare some phenol-free acids of a boiling point above cresols. This was done b y taking ordinary crude acids, removing t h e oil a n d naphthalene, a n d fractioning, taking for use t h e fraction distilling above z o o o C. I t was shown by careful test t o be free of phenol. I n these preliminary tests t h e acids (free of oil a n d naphthalene) were fractioned and cut a t 190 and 2 0 2 ' . The [ 9 0 - 2 0 2 ~ fraction was redistilled and cut a t 197' C. The total fraction below 197' C.
was compared with t h e curves and t h e phenol content estimated. If necessary a suitable mixture was made with pure phenol so as t o bring t h e mixture into t h e determinative range. Xeedless t o say, all details of t h e distillation were gravimetrically quantitative. Tests I t o 7 may be tabulated as follows: Error in Per cent Per cent Per cent MIXTURE-PERCENTAGES Higher Phenol of Phenol Recovered Present Test KO. Phenol o-Cresol m-$-Cresol -4cids 33.3 .,, ..., 66.7 32.2 -3.3 20.0 20.0 20.0 40.0 16.0 -20.0 20.0 20.0 20.0 40.0 19.2 -4.0 3 4 . . . . . . 10.0 15.0 15.0 60.0 10.4 +4.0 5 50.0 10.0 10.0 30.0 48.0 -4.0 25.0 24.2 -3.2 6 25.0 25.0 25.0 7 ...... 30.0 5.0 5.0 60.0 29.5 -1.7 ( a ) I n this test the Hempel column was used, in all others t h e 1,eBel was used.
.
......
After these tests we decided t o abandon t h e Henipel distillation for this purpose and until otherwise noted all tests were run using t h e LeBel 3-bulb column. A comparison of t h e bulb distillations of t h e "to 19;''' fraction of Tests 2 and 3 shows why Test 2 was so much further off t h a n Test 3. BULB DISTILLATIONSO F TESTS2 A N D 3 ZOO0 187' 190' 195O Test 2 . . . . . , , .,, 2 22 81 94 47 90 98 Test 3 . . ....., . . . . . . 1
..
t , .
Dryat 205' C. 203OC.
T h e Hempel h a d not removed xylenols as well as h a d t h e LeBel. The effect of xylenols would be t o lower t h e specific gravity without proportionally lowering t h e solidifying point, thus giving a lower phenol indication than t h e t r u t h . This is t r u e t o a lesser degree in t h e LeBel tests and is doubtless t h e cause of t h e somewhat low results obtained in a number of t h e tests. In fact, on Tests I t o 7, t h e only
5 74
T H E J O U R N A L OF I N D U S T R I A L -1iV D E N G I N E E R I N G C H E M I S T R Y
Vol. 9, No. 6
June,
1 9 1j
T H E J O C R N A L OF I N D L S T R I A L A N D ENGINEERING CHEMISTRY
57.5
ones where bulb distillations were made on t h e “ t o 197’” fraction, all showed some residue ab0T.e 2 0 1 ’ C. It has not been thought worth while to record these distillations in detail as all t h e essential information is given in t h e t w o already shon-n. 9 t this point of t h e inTestigation we decided t h a t t h e fractioning method n as fairly accurate, though not entirely satisfactory. I t was considered adrisable now t o proceed t o oil mixtures t o determine t h e points in this phase of t h e investigation which required our attention. T E S T 8-For this test n e prepared R quantity of acid-free oil b y c ompletelj extracting ordinary creosote oil with caustic soda. X mixture was made b y using 8 j per cent of thiy oil and I j per cent of acids
benzol xashings were agitated with I O O cc. of m-ater in t w o j o cc. portions. These were added t o the carbolate. which was then boiled gently t o expel a n y benzol present. The sulfate liquor, after acidification, was not washed for recovery of acids. T h e general method of fractioning, which vias adhered t o except where otherwise noted, mas t o distil t o I ~ o ’ .separate acids from water in t h e distillate a n d return the former t o t h e distilling flask. Fractions were then taken t o 190’ C. T h e second fraction &-as redistilled collecting t o 1 9 j ’ C. and combining all acid distillates up t o 197’ for test. T h e recovery of phenol showed a loss of 2 2 . 1 per cent of t h e phenol present. T E S T I G - I ~ this test no change was made in t h e
containing 2 0 per cent phenol. T h e acids were extracted b y caustic soda solution from a portion of this mixture. T h e carbolate was steam-distilled t o remove neutral oils and naphthalene, t h e acids libera t e d b y dilute sulfuric acid and carefully separated from t h e sodium sulfate layer. The test n-as t h e n carried on in t h e usual way. taking care t o separate all water from t h e “ t o 19 j ”’ fraction. T h e phenol rerovered showed a n error amounting t o -20 per cent of t h e phenol present. TEST 9-Here we used 80 per cent of oil and 2 0 per cent of acids containing 2 0 per cent of phenol. T h e carbolate vias formed as in Test 8, and mashed with 600 cc. of benzol in three zoo-cc. portions. T h e united
relative proportions of t h e acids and neutral oil. The carbolate mas steam-distilled. T h e S a O H solution vias added in three 210-cc. portions. The iulfate liquor was washed with I j o cc. of benzol in three jo-cc. portions a n d these washings were added t o t h e liberated acids. The mixture used was t h e same as in Test 9. T h e error amounted t o a loss of 21.; per cent of the phenol. T h e residual acids after fractionation were combined a n d tested for phenol, but none was found. I n this test t h e benzol was separated from the acids in t h e fractionation. The benzol recovered h a d an acid odor, b u t only a trace of acids could be recovered b y solution in NaOH.
T H E JOCRLVAL OF I N D C S T R I A L A N D ESGIAVEERING C H E M I S T R Y
576
T h e results of Tests 9 and I O showed t h a t t h e t a r oils and naphthalene in t h e carbolate may be removed with benzol, instead of steam distillation. T E S T 11-In this test t h e acid-oil mixture was approximately t h e s a m e as in t h e previous tests. The method of procedure was t h e same as in t h e previous test, except t h a t t h e liberated acids were washed with zoo cc. of a saturated KaC1 solution for removal of sulfate liquor. The solidifying point of t h e acid mixt u r e made on fractionation of t h e acids was so low t h a t no further d a t a were t a k e n . T E S T 12-This t,est in conjunction with Test 11was made in order t o determine t h e loss due t o solution of acids in t h e sulfate liquor. I n t h e light of further tests, however, i t does not indicate much. This is due t o other greater losses which h a d not been discoi-ered at this time. No neutral oil was used in t h e mixture. T h e carbolate was formed using I z j per cent of t h e theoretical N a O H necessary. T h e acids were liberated with j o per cent H2S04. The sulfate liquor was washed with I jo cc. benzol in 50-cc. portions a n d t h e recovered acids fractionated. An acid containing 20 per cent of t h e phenol was taken. The error amounted t o - 8 . j per cent of t h e phenol present. T E S T 13-In this test t h e new modifications were t h e weakening of t h e H2SO4 t o 331/3 per cent a n d t h e washing of t h e extracted oil with a n additional I O O cc. of N a O H solution (making a total of 140 per cent). Benzol was used t o wash t h e carbolate. T h e sulfate liquor was agitated with 1 2 5 cc. of benzol and t h e washings added t o t h e main quantity of acids. The acids were fractionated in t h e LeBel-Henninger column. The same mixture was used as in Test 1 2 . The error found was -13.2 per cent of t h e phenol present. T E S T 14 was made in order t o compare t h e loss of phenol with t h e loss in Test 1 2 , where a carbolate was made a n d t h e acids liberated. The mixture contained no oil a n d was simply fractionated in t h e LeBel column. Here t h e error was -8 per cent of t h e phenol present. T h e results of this test would indicate t h a t t h e loss in recovery from a carbolate was not much. TEST I j was made in order t o check t h e curve with a mixture containing 20 per cent of phenol.
.......................... 20.15 6 . . . . . . 40.05 g. . . . . . 40.05 g. Pure P h e n o l . , .................... Mixture No. 2 Solidification Point of Mixture No. 2 . .. . , 28.8' C. Specific Gravity (45/45' C . ) of Mixture h-0. 2 . . . . . . . . . . . . . 1 . 0 5 7 Phenol in Mixture No. 2 . . . . . . . . . . . . . . . . Phenol in Mixture No. 1 . . . . . . . . . . . . . . . . Mixture No. 1
i{'
Pure Phenol.. Pure o-Cresol
,,,
,,,,,,,,,
,,,
,
This shows t h e curves t o be correct at this point. 16-In view of t h e results of tests t o this point i t was thought t h a t a considerable part of our losses was due . t o fractionation and t h a t a change in t h e temperature a t which t h e fractions \\.ere cut might help in t h e phenol recovery. Accordingly a mixture of acids was made a n d fractionated using t h e LeBelHenninger column as in previous tests. The first fraction collected was t o 190' C., the second between 190 a n d 2 0 5 ' C. This second fraction was redistilled until a temperature of 198' C. was reached. T h e first a n d redistilled fractions were collected in t h e same TEST
v01. 9, NO. 6
flask as in previous test. Using t h e usual 20 per cent phenol acid, a n error of -16. j per cent of the phenol present was obtained. TEST 17-In this test t h e temperature of fractionation was again changed. T h e first fraction collected was t h a t coming over t o 190' C.; t h e second between 190 a n d 204' C. This fraction was redistilled up t o 1 9 j ' C. With the same mixture as in Test 16 we showed a n error of -10.1 per cent of t h e phenol present. Changing t h e temperature of fractionation did not increase t h e amount of phenol recovered. We then concluded t h a t t h e column used in fractionation should be changed. T E S T IS-We then decided t o t r y t h e 12-pear column. T o determine t h e efficiency of this apparatus as a fractioning device, we made a mixture of pure acids as in previous tests, a n d fractionated t h e mixture using t h e original temperature, i. e . , t o 190' C. (190-202' C.) and redistillation t o 197' C. The error here amounted t o only t i . 1 per cent of t h e phenol present. Results of this test showed t h a t t h e losses due t o faulty fractionation h a d been overcome. F r o m this point on, our tests were made with a view t o overcoming t h e losses which occur on formation of carbolate a n d subsequent liberation of t h e acids. This involved t h e proper strength and amount of H2S04, t h e temperature of acidification, the washing of carbolate a n d recovery of t h e acids dissolved in t h e sulfate liquors. T E S T 19-In this test we attempted t o recover all of t h e phenol in a pure acid mixture after converting t h e acids t o a carbolate. The acids were agitated with I 2 j per cent of t h e theoretical amount of NaOH necessary. The acids were then liberated with 2 j per cent solution of H 2 S 0 4 ,using a very slight excess of acid (about I O cc.). The sulfate liquor was washed with I O O cc. of ether in two jo-cc. portions a n d t h e washings added t o t h e main quantity of acids. The acids were then fractionated with t h e 12-pear column. It was impossible t o make a clear separation of t h e ether and acid distillates. The ether and water t h a t came over were agitated with a n K a O H solution a n d t h e acids recovered. They amounted t o about 4 cc. However, they were not added t o t h e acid distillate a n d so were lost, Better results were obtained here by reducing t h e strength of t h e sulfuric acid t o 2 j per cent. There was a cleaner separation, t h e acids were lighter colored and there was no gas formation. T h e error here per cent of t h e phenol present. was -2.1 The results of this test indicated t h a t t h e phenol in a mixture of pure acids could be recovered substantially quantitatively from a carbolate. T E S T ao-In this case I j o per cent of the theoretical quantity of N a O H was used to form t h e carbolate. The sulfate liquors were washed with benzol. Any acid mas recovered from t h e benzol b y washing with caustic soda as described previously. This acid was added t o t h e main bulk of acids. The recovery of phenol showed a very low error, only 0.2 per cent of t h a t present. TEST 2 1 was made using a mixture of 2 0 per cent of pure phenol with crude cresols a n d higher acids, instead of t h e purified acids, as in Tests 19 and 20.
T H E J O C R - V d L O F I S D C S T R I A L AiVD E S G I S E E R I - V G C H E M I S T R Y
June. 1917
I 2 j per cent of t h e theoretical amount of S a O H was used. T h e carbolate was washed with joo cc. benzol in 125-cc. portions. T h e acids were recovered from t h e sulfate liquor as in Test 2 0 . T h e error was -1.3 per cent of t h e phenol present. T E S T 2 2 was a check on Test 2 0 , t h e samc procedure being used in each test. T h e error here v,-as -0.8 per cent of t h e phenol present. After running Tests 2 0 . 2 1 and 2 2 , we concluded t h a t t h e phenol present in a mixture of acids with small amounts of oil could be recovered with b u t slight loss. Our next a t t e m p t was t o recover t h e phenol from a n acid-oil mixture which contained a large amount of neutral oil. T E S T 23-111 this test we added enough neutral oil t o t h e acids t o make it So per cent of t h e total mixture a n d a t t e m p t e d t o recover t h e phenol. T h e acids were extracted from the mixture with ~ j per o cent of t h e theoretical amount of a 2 0 per cent N a O H solution: 800 cc. of t h e N a O H solution were used in three zoo-cc. a n d t w o 100-cc. portions. T h e carbolate was washed with joo cc. of benzol in 100-cc. portions. T h e sulfate liquor was washed with ether, a n d t h e dissolved acids recovered from ethereal solution with a \Teak NaOH solution a n d added, after liberating with H2S04, t o t h e main q u a n t i t y ; 9.2 grams were recovered. This method of recovery a n d separation from t h e solvent is a new a n d important step in t h e process. T h e acids were fractionated as before.
..
Phenol. . , , . , . . o-Cresol. . . . . . m-0-Cresol. ... , . Higher Acids. , , .
h-eutral Oil.. , . , . . . . . ,
. . ....... , , .
59.85 59.80 59.80 119.30 1212.50
grams grams grams grams grams
20% 20% 20Y0 40%
80 per cent
I n t h e above mixture t h e acids, with t h e exception of t h e phenol, were crude. T h e loss of phenol in this test (-16 per cent of the phenol present) was very high (due t o imperfect technique, as will be seen later), a n d i t was decided t o make tests using smaller quantities of neutral oil. F r o m this point on, t h e general method of recovery of t h e acids was t h e same, i. e., formation of a carbolate with NaOH ( 2 0 per cent strength) washing of t h e carbolate with pure benzol, washing t h e benzol solution of carbolate with watert boiling of t h e carbolate, liberation of t h e acids with z j per cent H2S01)washing t h e sulfate liquors with benzol a n d recovery of t h e dissolved acid with weak ( I O per cent) solution of NaOH. -411 fractionations were made with t h e pear column. T h e essential results of Tests 24 t o 3 j inclusive are shown in t h e following table: Grams Test hTo. 24 25 26 27
28 29 30 31 32 33 34 35
Grams Phenol 59.75 59.20 60.00 60.00 58.55 29.65 29.40 14.65 15.05 88.55 149.90 15.05
0-
Cresol 60.00 59 75 60.10 59.61 60.00 70,oo 70.30 7 5 00 76
no
44.90 30 0 5 7 4 85
Grams
m-p-
Cresol 60.35 59.85 60.00 59.70 59.60 70.00 69, 7 0 74.80 74.80 15.10 29.65 75 50
Grams Higher Acids 119.90 119,io 119.60 119.10 119.iO 129.30 129.30 134,70 335.15
119.io Y O . 15 134.80
Grams Error in Grams Phenol 5% Phenol Oil Recovered Present 101.75 55.83 -6.6 58.08 -1.8 10.10 63.10 t5.1 10.30 30.00 60.08 -0.13 -0.8 58.10 120.00 . . . . 31.20 - 5 , z .... 29.80 +1.,6 .... 1 4 . 0 5 -4.1 T7.0 15.90 .... .... 82.30 -7.0 149.20 -0.5 12oo:oo 14.73 -2.1
I n Test 3 3 , a ltnom-n loss occurred in manipulation, so t h a t this result is natural. T h e tests seemed t o us t o be accurate enough for all practical purposes, a n d
577
checks should be obtained t o 0.8 gram of phenol if t h e work is carried on carefully a n d conscientiously. Up t o this point we had succeeded in t h e recovery of t h e phenol from its mixtures with other pure acids, with unpurified acids in varying portions, a n d with neutral oil in varying proportions. T o determine t h e reliability of t h e test, when applied t o crude carbolic acid, we first determined t h e percentage of phenol in a sample of ordinary crude acids, and next in these acids t o which we had added a known amount of pure phenol. T E S T 36-Determiiiatioii of the phetiol iiz ordinary c r u d e carbolic acid: T h e acids contained j . 3 2 per cent (by weight) of water and h a d a specific gravity a t I j . j " C. of 1 . 0 7 2 . K e first tried t o wash a carbolate made with t h e crude acids as obtained, b u t there was not a clean separation of t h e benzol a n d carbolate layers. We found it necessary t o distil t h e acids first. T h e crude acids were distilled, after weighing, directly into a 2 0 0 0 cc. separatory funnel. Weight of acids distilled., . , , , . , . . . . . . . . . . . . . 301.5 grams Weight of distillate (by difference) ... , , . . . , . . . 271 . 3 grams-YO Black pitch residue. , , . , , . , , , , , , , , . , , , , , , , , , 3 0 . 2 grams
per cent
T h e carbolate was now formed as in previous tests, and washed with benzol. T h e recovery of t h e acids and t h e fractionation were carried out as in t h e previous tests. TTe found t h e phenol content b y weight t o be 16 per cent on t h e dry acids or I j.14 per cent on t h e wet acids. T E S T 3;-In this test vie added a known amount of pure phenol t o t h e crude acids tested above Crude acids ..... . .. . . . . . . . . . . . . . , 3 0 1 . 1 5 grams Pure phenol a d d e d . , , . , , , . , , , , , , 15.85 grams
.
On determination of t h e phenol we found t h a t of t h e phenol added we had recovered 99.2 per cent. The better results in t h e later tests were due t o constant improvements in t h e technique with experience. I n t h e following description, we believe, we have given t h a t technique with sufficient wealth of detail t o enable a n y operator following directions carefully, t o obtain consistent, accurate results. D-STASDARD
lCETHOD F O R D E T E R M I N A T I O X O F P H E S O L
IS C R U D E C A R B O L I C A C I D A S D T A R O I L S I. PREFACE-In this test extreme care a n d faithful attention t o details are necessary t o secure accurate results. All instructions given are t h e epitomized result of considerable experience and are not gil-en arbitrarily, b u t with a purpose. The test has been a difficult one t o develop and requires greater care and skill t h a n do t h e ordinary tar-testing methods. Even a slight deviation from t h e directions can cause serious discrepancies. 11. P R E P A R A T I O S O F T H E oIL-If t h e oil is a t all dirty, so t h a t t h e subsequent separation of the carbolate will not be clean, it must be distilled. This shall be accomplished b y weighing a suitable quantity of oil into a clean copper tar-still and taking t h e total distillate from t h e s t a r t of distillation t o coking. T h e amount of total distillate b y weight shall be noted so t h a t results may be figured back t o t h e original oil if desirable. If a n y foaming-over occurs during t h e
-
578
T H E J O U R N A L O F I N D C ' S T R I d L AiVD E N G I N E E R I N G C H E M I S T R Y
distillation, t h e run must be rejected a n d a new one undertaken. 111. E X T R A C T I O X O F T H E A C I D S F R O M THE on-The approximate percentage of t a r acids in t h e oil should be determined by a rough test. A weight of oil which contains between 300 a n d 350 g. of acids shall be placed in a separatory funnel and treated with 300 cc. (approximate) of 20 per cent caustic soda solution; this caustic soda solution may be made from commercial caustic soda. The oil a n d caustic soda shall be given a thorough mixing by shaking, care being taken t o prevent mechanical loss. The mass shall now be allowed t o s t a n d until t h e carbolate settles completely a n d a sharp line of division appears between t h e oil a n d t h e carbolate. With a properly distilled oil, from 1 5 t o 30 minutes should suffice. If t h e oil contains solids, i t shall be warmed before extraction t o a temperature sufficient t o keep solids in solution, and while settling be suspended in a b a t h of like temperature. After settling is complete, t h e carbolate shall be separated and brought into another separatory funnel. T h e oil shall be washed successively with three more portions of zoo cc. each of t h e same caustic soda solution, observing t h e same precautions as t o agitation, settling and separation. These separated soda solutions are t o be added t o t h e first carbolate. On t h e last separation it is better t o run a few drops of oil along with t h e carbolate, rather t h a n leave a few drops of carbolate in t h e oil. .4fter this treatment t h e oil shall be tested t o determine if it is free from t a r acids a n d if so, it may be discarded. KOTE-If crude acids, not oil, are t o be tested, 300 t o 3 j o g. of t h e crude acid shall be taken in a separatory funnel a n d dissolved in 800 cc. of 2 0 per cent caustic soda solution. The treatment from this point on is t h e same as with carbolate extracted from oil. If t h e crude acids are t a r r y i t is advisable t o distil t h e m quantitatively before dissolving them in caustic soda. carbolate I V . P U R I F I C A T I O N O F T H E CARBOLATE-The in a separatory funnel shall be extracted five times successively with 100-cc. portions of pure benzol. The manipulation shall be: Add t h e benzol t o t h e carbolate, mix thoroughly b y shaking a n d allow t o settle. Draw t h e carbolate into another separatory funnel and draw t h e benzol into a third separatory funnel. Repeat t h e agitation with fresh benzol four times more, using t h e two original separatory funnels for this purpose. Finally, after running t h e washed carbolate into a beaker, rinse each of t h e funnels which contained carbolate, twice, with 2 j cc. each of water. a n d a d d t h e water t o t h e carbolate in t h e beaker. Take t h e third separatory funnel, which contains t h e combined benzol, and wash twice with j o cc. of water, adding this water also t o t h e carbolate in t h e beaker. Bring t h e carbolate in t h e beaker t o a gentle boil until t h e odor of benzol disappears. N o odor of creosote shall be evident in t h e carbolate a t this point. If such odor appears, t h e washing has not been properly carried o u t a n d must be repeated. The carbolate purified of oil is ready for acidification after cooling. The benzol used for extraction may be discarded. v. ACIDIFICATIO~-~he purified carbolate shall be
1701. 9 ,
NO. 6
placed in a separatory funnel a n d acidified with sulfuricacidof 2 j p e r cent strength(sp.gr.1.21 a t ~ j . j ~ C , ) . The beaker containing t h e carbolate shall be rinsed with water and t h e rinsings added t o t h e carbolate in the funnel. During acidification t h e mass m u s t be kept below 40' C. b y immersion in a b a t h of cold water. Test for acidity should be made from time t o time with litmus paper. More LhaiL a very slight excess of acid ( j t o I O cc.) must not be added after litmus shows a red color. When acidification is complete, t h e funnel shall be allowed t o stand until complete separation has taken place and t h e lower layer of sodium sulfate solution is perfectly clear or a t most shows a slight opalescence. This settling requires from 3 t o 4 hours. After settling is complete t h e sulfate layer shall be drawn off and kept for further treatment. The carefully separated acid layer shall be drawn down into a weighed joo cc. round-bottomed short ring neck flask a n d kept there until further I treatment. VI. T R E A T M E S T O F T H E S U L F A T E soLuTIox-This shall be returned t o t h e separatory funnel which contained t h e separated t a r acids, which still has a t h i n film of t a r acids adhering t o t h e walls. The sulfate liquor shall be extracted three times with successive portions of IOO cc. each of pure benzol a n d t h e benzol extracts combined in a separatory funnel of about joo cc. capacity. The benzol extract shall now be extracted with two successive portions of 2 5 cc. each of 20 per cent caustic soda solution, or until t h e soda solution separates nearly colorless. The benzol can then be discarded. The caustic soda solution shall then be warmed until all odor of benzol disappears a n d acidified with enough z j per cent sulfuric acid t o make slightly acid. This shall be allowed t o settle completely, t h e lower layer of sulfate drawn off a n d discarded, and t h e upper layer of acids added t o t h e flask containing t h e main amount of t h e separated acid, This flask shall non7 be weighed a n d t h e weight of w e t crude acids recorded. VII. P R A C T I O X A L DISTILLATIOS-A. Column-This shall be t h e standard I 2-pear still head (Eimer & Amend catalogue NO. 71 j 6 ) . B . Flask--This shall be a short neck flask as described under l-. C. Coizdepiser-This shall be t h e regular Barrett trough type with a 24-in. t u b e ( A . H. T. catalogue NO. 20432). D . Theriizorneter'-This shall conform t o t h e following specifications: ( I ) I t shall be graduated from 1 7 0 to 2 2 j o C. in 1//50 C. and shall be accurate at total immersion t o 1 / / 6 0 C. ( 2 ) I t shall be well annealed and shall conform t o t h e following dimensions: Total length-less t h a n 380 mm. j mm. Bulb length-2c-s I;OO mark t o bottom of bulb--jo-80 mm. Scale length 1 7 0 - 2 2 j o - z ~ o - 2 8 0 mm. Stem diameter- j-7 mm. Bulb diameter-4j.j mm. E . Setting zip dpparutus-The flask shall be supported over a burner on a 6 in. square of ' / 4 in. asbestos 1
This thermometer can be obtained from the Taylor Instrument Co.
June, 1917
T H E J O U R N A L 0 F I S D US T R I A L A -I'D E LVGI N E E RI IVG C H E J f I S T R Y
board with a n opening in t h e center 3 . j in. in diameter. It shall be surrounded b y a circular asbestos shield about 31t'? in. high a n d of such diameter as t o enclose t h e flask. A piece of asbestos with a hole cut for t h e neck of t h e flask forms t h e t o p of t h e shield. The pear column shall be connected t o t h e flask by a tightfitting cork, a n d t h e condenser t o t h e side t u b e of t h e pear column. The thermometer shall be inserted into t h e t o p of t h e pear column b y means of a well-fitting cork in such manner t h a t t h e t o p of t h e thermometer bulb is opposite t h e middle of t h e off-take of the column. The condenser trough shall be kept full of cold water. F . Method of Copiductiiig the Distillutioiz--The app a r a t u s shall be set u p as described a n d t h e distillation started a n d continued a t t h e rate of one drop per second. T h e distillate shall be first caught in a 100-cc. separatory funnel until t h e temperature has reached 170' C. The distillation shall then be interrupted and sufficient salt added t o t h e contents of theseparatory funnel t o cause a n y acids coming over with t h e water t o rise t o t h e surface. T h e aqueous layer is removed a n d t h e acids returned t o t h e distillation flask, a n d t h e flask with contents weighed. Thereby t h e weight of d r y acids is recorded. The distillation shall be again started and t h e first few drops of acid a n d water coming over collected in a small, dry separatory funnel. When t h e last drop of water is over, a fraction t o 190" C. is collected in a weighed flask, which shall be closed b y a cork as soon as t h e distillation is completed. T h e few drops of acid a n d water which have been collected i n t h e small funnel shall be separated a n d the acid layer added t o t h e distillate t o 190' C. X second fraction from 190 t o 202' shall be collected in a z jo-cc. round-bottom, short ring-neck flask, which need not be weighed. The distillation shall be discontinued a t 2 0 2 ' C. a n d t h e flask containing t h e 190-202' fraction shall be substituted for t h e first flask. which contained t h e crude acids. This fraction IS now redistilled after drying t h e condenser tube. using t h e weighed flask containing t h e -190' fraction from t h e first distillate as a receiver. The distillation shall be carried t o 197' C. The receiver which now contains t h e combined fraction u p t o 197' shall be weighed, t h e weight of t h e fraction recorded, and t h e receiver kept tightly stoppered. G. Testiizg the Fraction-The fraction shall be tested for specific gravity a n d solidifying point :is follows: ( I ) SoZidiJying Point: A test t u b e I in. inside diameter (this dimension bears no deviation) and j in. t o 6 in. long is held by a clamp in a vertical position with 3 in. of its lower end immersed in a joo-600-cc. beaker full of water. A standard 0-80' melting point thermometer (A. H. T. Cat. No. 20476), calibrated t o a n accuracy of at least 0.1' C., is fastened rigidly by another clamp in t h e center of t h e test tube with t h e bottom of t h e bulb 0 . 5 in. f r o m t h e bottom of t h e test tube. ;In agitator. composed of a n iron washer a t tached t o a wire a n d arranged t o work freely up and down t h e test t u b e around t h e thermometer, completes t h e outfit. The fraction t o be tested for solidifying point shall be poured into t h e t u b e t o a depth of 2 in. and a n
5i9
approximate solidifying point taken. The contents of t h e tube shall be again liquefied a n d t h e outside b a t h adjusted t o a temperature 4. j t o j.j ' C. below t h e approximate solidifying point. The temperature relation is very important. The sample is now allowed t o cool with constant stirring. The temperature of t h e sample falls, b u t when crystals begin t o separate a rise is noted which soon reaches a maximum where i t remains constant for a varying period of time. This maximum temperature shall be taken as t h e solidifying point. Two successive tests must give identical results and care must be taken t o keep t h e relation between solidifying point and b a t h temperature within t h e 4 . j t o j . j oC. range. ( 2 ) Specijic Granity-If t h e solidifying point is z j ' C. or less, this shall be taken a t z j / z j o C.; if greater t h a n 2 j ' C , t h e specific gravity shall be taken a t .+j 45' C. The specific gravities shall be taken with a Westphal balance. Most of t h e instruments supplied in t h e United States are standardized for I j.j o C. T h e balance is set u p a n d t h e plummet should exactly counterpoise t h e a r m when swinging freely in air. It must be first adjusted t o this condition b y means of t h e leveling screw on t h e base of t h e column of t h e balance. The plummet is then immersed in freshly boiled distilled water a t I j . j" C. and if t h e balance and weights are properly made a reading of 1.000 should be obtained. Next, a reading is taken in boiled distilled water a t either 2 j or 4 j O C., depending on t h e temperature desired. After t h e first adjustment of t h e balance, t h e reading in water a t I s. j o C. may be dispensed with. b u t care should be taken t o see t h a t t h e balance in air is correct before readings are made. After t h e water standard a t 2 j or 4j0 C. is established, a reading is taken in t h e acid fraction a t t h e same temperature. h simple division gives t h e specific gravity. Precautions t o be observed are: keep t h e balance clean a n d d r y ; see t h a t t h e plummet is properly cleaned and dried when changing from one liquid to another; keep t h e point t o which t h e wire holding t h e plummet is immersed constant; control the temperature carefully; a n d see t h a t t h e plummet swings freely a n d does not touch t h e sides of the vessel containing t h e liquid. ( 3 ) Comparisoii z'ith Curves-After t h e solidifying point a n d specific gravity of t h e fraction are determined, compare t h e m with t h e phenol determination curves and see whether t h e point plotted b y t h e constants falls well within a determination area. If it does not or if it is very close t o t h e limit. it is best t o proceed t o make a mixture of t h e fraction with pure phenol. (4) W i x t u v e with Phem--Phenol for this purpose must possess a solidifying point of a t least 40.3' C., tested on t h e thoroughly dry material. A little judgment is required in making t h e mixture so as t o use t h e least amount of phenol which will bring t h e test? of t h e mixture well within one or t h e other of t h e determinate ranges. Seedless t o say. t h e mixture must be strictly quantitative. and must be made in perfectly dry containers. The mixtures are made up until one susceptible of determination is obtained.
T H E JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
580
T h e specific gravities a n d solidifying points are taken exactly as described previously. H . Interpretation of Results-After t h e tests show t h e point t o be within t h e determinative areas t h e method of interpolation is as follows: If t h e plotted point occurs in t h e lower set of curves a line is drawn through t h e point normal t o t h e curves between which it lies. The distance from curve t o curve is measured accurately along this line a n d t h e fractional distance of t h e point is interpolated into per cent phenol. If t h e point occurs in t h e upper set of curves, t h e line is drawn through t h e point parallel t o t h e nearest of t h e d o t t e d converging lines, t h e linear distance measured a n d t h e percentage interpolated as before. If mixtures are made, t h e calculations are somewhat complicated a n d t h e following formula may be used: Let A = per cent phenol found in mixture B = Grams " t o 197'" fraction taken C = Grams pure phenol taken X = per cent phenol in "to 197"' fraction
x=
~
( B +~c)--_IPsc B
The per centphenolinthe"t0 19; '"fraction multiplied by t h e weight of t h e fraction gives t h e weight of total phenol in t h e oil or crude acid taken. A specimen test on acid with t h e recorded d a t a may be shown as follows: TAKEN:Crude Acid, 300 g. Distilled 170-190;. ...................... 60.65 g. 190-202 ....................... l i 8 . 0 5 g. 190-202° redistilled t o 197'. ........................ 78.05 g. Total under 1 9 i 0 . ,...................... 138.7 g. = 4 6 . 2 per cent 1.0$02 Sp. gr. a t 25/25' C . . Solidifying point.. ......................... 20.4 These constants are indeterminate. t o 197' fraction.. . . . . . . . . . . . . . 25 g. MIXTURE Pure phenol.. . . . . . . . . . . . . . . . 25 g. Sp. gr. a t 45/45' C . . 1.0576 31.7' C. Solidifying point., ......................... Phenol in fraction mixture (from curve). . . . . . . . . . . . . . 84.75 per cent PHENOL IN ORIGINAL ACIDS(calculated). . . . . . . . . . . . . . 32.2 per cent
.......................
{
.......................
The method requires about two days t o complete a test b u t several can be run simultaneously. The keynote of success in this work is extremely careful and accurate attention t o t h e details of manipulation. This test has been in use in our laboratories since t h e early part of 1916, and has given very satisfactory results. RESEARCH DEPARTMENT, THE BARRETTCOMPANY 17 BATTERYPLACE,NEN YORK CITY
A NOTE ON SILICON-COATED METAL By W, E. VAUTER Received February 10, 1917
T h e resistance of silicon t o t h e corrosive action of acids a n d alkalies is taken advantage of in chemical industry b y using apparatus constructed of iron which contains a large percentage of silicon. However, t h e high silicon castings have small tensile or compressive strength a n d breakage is high. It was therefore thought t h a t , if iron could be satisfactorily coated with silicon, a great saving could be effected. Coating iron b y dipping into molten silicon is unsatisfactory, since t h e melting points of t h e metals are similar and iron is soluble in fused silicon.
V O ~9, . SO.6
The object of a study made by t h e author was t o investigate a process for coating a metal, preferably iron, with silicon, so t h a t t h e non-resisting metal would be amply protected from a n y corrosive chemical, a n d a t t h e same time s t a n d u p under severe handling, without injury t o t h e object or t h e protective coating. Samples of iron were heated t o temperatures of l o o to 600' C. in a n atmosphere of silicon hydride,' in order t o ascertain whether t h e gas would decompose a n d form a coating of silicon upon t h e surface of t h e iron. E X P E R I Y E NT A L
I-Iron wire was heated t o j50' C. in a current of dry silicon hydride for one hour. Small patches of silicon formed over t h e surface of t h e wire, b u t when t h e sample was placed in a normal solution of sodium chloride, corrosion immediately started where no silicon was present, totally undermining t h e silicon coating after two weeks' immersion. 2-A repetition of Experiment I . I n this experiment t h e silicon did not appear t o be undermined; t h e coating of silicon remained after two weeks' immersion, although corrosion h a d taken place rapidly a t all other places. 3-This sample was heated t o joo' C. for two hours. A thin film of silicon was deposited on t h e wire a n d t h e wire became badly pitted where there was no coating of silicon. The silicon coat was intact after two weeks' immersion. 4-This sample was heated for 3l/2 hrs. a t 550' C. Very little silicon adhered t o t h e wire, a n d t h a t which deposited was in scales a n d could easily be removed. j-This sample was first pickled in acid and then heated in a current of silicon hydride a t j j o ' C. for 2 hrs. T h e resulting coating was smooth a n d uniform in color, a n d t h e treated iron remained in salt solution four days before a n y corrosion was noticed; this was a t t h e end where t h e wire h a d been cut a n d had no silicon protection. 6-The sample was first heated t o 7 0 0 ' C. a n d then allowed t o cool t o 550' C. before exposing t o t h e gas. While a n excellent coat was obtained, which stood up well in t h e salt solution, no advantage in preheating could be observed. ;-This sample, after running two hours at j jo' C., was further heated for j minutes a t 700' C. Ten days' immersion in salt solution completely removed t h e coat. I t was expected t h a t t h e silicon would attach itself more firmly t o t h e iron by t h e heat treatment, b u t t h e after-heating probably broke t h e coat a t some place and allowed corrosion t o set in. 8-An exact duplicate of Experiment 5 with similar results. 9--A piece of wire, which h a d been pickled, washed, dried a n d exposed t o t h e air for several hours, until 1 T h e silicon hydride used in these experlments was prepared by treating an alloy of magnesium and silicon with a dilute solution of hydrochloric acid. T h e evolved gas consisted of about 5 per cent of sllicon hydride and 95 per cent of hydrogen. T h e alloy was pcepared b y intimately mlxtng one part of powdered silicon with two parts of powdered magnesium and heating the mixture for two hours a t 600° C. in an atmosphere of hydrogen This alloy has the composition approximately represented by the formula SiMgz.
