T H E JOLiHNAL OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
Nov., 1916
Exp. No. 15 18 17 32 13 12 14 16 23 27 30 31 4 I 5 6 10 2 3 7 8 9
YIELDS OF TRINITROTOLUENE BY DIFPERENTTREATMENTS KINDS A C I D MIXTURE-PERCENTAGES EXCESS Ratio Acid PER CENT CRYSTALLIZED O F ACIDSUSED Sulfuric Nitric NITRICACID Mixture to CRUDE TRINITROTOLUENE Sulfuric Nitric Water Acid Acid Per cent Mononitrotoluene T. N. T. Per cent M. P. 1.52 2 86 12 32 9.5 : 1 85.1 63.4 79.2' 98% 9.5 :.1 1.52 2 82 16 75 80.8 .... .... 98% 78 6 : I 1 .52 2 20 31 77.3 47.0 75.0 98% 2 80 7.5 : 1 73.6 1.52 18 49 .... 98% 16 2 82 8 : 1 80.8 1.52 32 98% 7 86 1.52 12 81.4 9.5 : 1 31 .... 98% 79.1 II 1.52 13 9.5 : 1 .... .... 2 87 98% 2 82 16 1.52 85.9 75 10 : 1 77.0 80.0 98% 16 75 1.52 2 82 9.5 : 1 .... 79.4 72.8 98% 16 1.52 75 2 82 9.5 : 1 87.1 80.3 76.0 12 27 2 1.52 86 9.5 : 1 80.3 79.2 57.3 33 13 1.52 2 85 9.5 : 1 .... I . . . 81.5 43 1.50 1 77 23 5.5 81.0 .... 100% 24 43 1.50 1 75 81.6 5.5 : 1 100% 51 25 1.52 0 75 77.6 ",.. .... 5.5 : 1 64 26 1.52 0 74 6 : I 80.3 .... .... 12 1.45 6 82 ~33 10 : 1 62.2 79.7 83.3 1.50 1 74 25 57 5.5 : 1 .... 72.9 100% 1.50 1 77 22 43 5.5 : 1 .... 75.7 100% 4 83 1.52 10 : 1 13 51 .... .... 70.6 95% 1.52 18 1 81 8 : 1 62.2 79.8 53 75.4 98% 1 .45 10 : 1 12 33 80.8 6 82 59.8 7S.8 98% 4 : I 36 lOO7, with 100 62.5 44.0 7 (sod 52 a1 some 15% oleum 7 (SOa) 54 36 100 4 : 1 53 65.5 46.0
.... ....
!!$ yij
EXPERINENTAL
I t may be pointed out t h a t in Experiment I t h e proportions recommended b y Langenscheidt a n d b y Escales were taken. 'The mononitrotoluene used in these experiments reported in t h e accompanying table was made in a small Dopp kettle i n t h e usual manner. Tolnene(a) . . , , . , . , . . . . , . . . . . . . . . . , . . . . . . 47.5 lbs. 2 0 . 0 lbs. Nitrating Sulfuric Acid, sp. pr. 1.84 Mixture Sulfuric Acid, sp. gr. 1.84.. . . . . . . . . , . . . . . . 5 0 . 0 lbs.
.I
Nitric Acid, sp. gr. 1.42 (12 per cent excess) J 2 . 0 lbs.
Xitrating temperature 22' C., finally raised to 95' C. PRODUCT-68 lbs. (96 per cent of theoretical) crude mononitrotoluene, sp. gr. 1.163 a t 22' C. ( a ) T h e purity of the toluene was confirmed b y slowly distilling 0.5 liter through a three-bulb Glinsky distilling tube: Distillate below 108.8", 6 per cent: 108.8' t o 109.6', YO per cent; 109.6 t o ill", 3 per cent.
After nitrating t o t h e trinitro product, t h e cooled nitrating mixt.ure was added t o five volumes of ice water!' filtered. washed with very dilute sodium bicarbonate solution a n d recrystallized from alcohol containing I O per cent b y volume of benzene. I n conclusion, t h e author desires t o express his indebtedness t o Dr. B. ?'. Brooks, for suggestions given during t h e course of t h e work. INSTITUTE O F IXDlXTRI.4L RESEARCH PITTSBURG.H
REAGENTS FOR USE IN GAS ANALYSIS-V THE RELATIVE ADVANTAGES OF THE USE OF SODIUM AND POTASSIUM HY.DROXIDES IN THE PREPARATION OF ALKALINE PYROGALLOL B y R. P. ANDERSON Received September 15, 1916
The compositios of alkaline pyrogallol prepared with potassium hydroxide a n d t h e behavior of this reagent in various pipettes has recently been studied 1
MAXIMUM TEMPERATURE C. Hrs.
....
120-125
....
in t h e purification of t h e crude T. N. T., a n d t h e value of t h e final prodiict will largely determine what conditions of nitratin,g are t h e most economical, t h e following d a t a show t h a t better yields of pure T. S . T. are obtained. b y operating at a somewhat lower temperature t h a n 140°, as prescribed b y Langenscheidt, a n d employing sulfuric acid (98 per cent HgSOd) instead of t h e Io0 per cent acid,and maintaining t h e final nitrating mixture at I 20-1 2 j O for a longer time, namely about hrs. The proportion of acids a n d toluene are so chosen t h a t t h e concentration of water in t h e final ,mixture is about 4.4 per cent. I n view of t h e general interest in this subject a t t h e present time these d a t a are here briefly presented.
brELLON
999
Cf. McHutchison and Wright, J . SOC.Ckem. I n d . , 34 (l@l5), 781.
130- 135 130-135 140-145 140-145 140-. 145 140- 145 145-150 125-120 100-105
3 2.5 1.5 3.5 1.5 1.5 2 1.5 1.o
2.5 3 2.5 2 0.5 3 0.5 0.7 0.5 0.5 0.5 1
2 2 2.5
b y t h e author.' More recently, Shipley2 has made a s t u d y of t h e effect of t h e substitution of sodium hydroxide for potassium hydroxide in alkaline pyrogallol a n d has made comparisons between t h e t w o reagents. While admitting freely t h e importance of Shipley's work, t h e author is not entirely satisfied with t h e comparisons drawn b y him and presents herewith a careful comparison of t h e two reagents based upon t h e information i n t h e references t h a t have been cited. The points t h a t have been considered are: ease of preparation, time required for analysis, convenience of manipulation, specific absorption, a n d t h e cost of materials. The relevant information has been correlated under each heading for t h e convenience of t h e chemist who may wish t o become familiar with t h e advantages a n d disadvantages of each of t h e two varieties of alkaline pyrogallol. EASE O F PREPARATIOX
Each solution can be prepared b y dissolving pyrogallol in a solution of t h e proper alkali in water, so t h a t t h e preparation of either is a matter of little difficulty. T o prevent caking of t h e pyrogallol, Shipley recommends t h e addition of a little water t o it before t h e addition of t h e solution of sodium hydroxide. T I M E R E Q U I R E D FOR A N A L Y S I S
The time required for t h e determination of oxygen with either of t h e reagents is dependent upon t h e time consumed in obtaining complete absorption, since t h e other operations incident t o t h e analysis require about t h e same amount of time in each case. Shipley has adopted a 4-minute interval3 for complete absorption with t h e sodium reagent, while I-minute contact is sufficient for t h e potassium reagent. Assuming t h a t t h e 4-minute interval includes t h e time necessary for t h e initial passage of t h e gas into t h e pipette a n d for t h e final passage of t h e gas out of t h e pipette, t h e corresponding time for t h e potassium reagent, allowing 1 5 seconds4 for each passage of t h e gas, would be 1'/2 minutes. This means a saving of z1/2 minutes on each determination where t h e potassium reagent is employed in place of t h e sodium reagent. Anderson, THISJOVRKAI,, 7 (1Y15), 587; 8 (1916), 131, 133. Shipley, J . A m . Chem. Soc., 38 (1916), 1687. 3 Reagents 3 and 4 on p. 1691 of Shipley's article Kive complete absorption in 2 min., but elsewhere 4 min. is the minimum time recommended. 4 See THISJ O I - R X ~ L , 8 (1916), 131. 1
2
1000
T H E J O C R S d L O F I X D U S T B I A L AA’D E S G I T E E R I A V G C H E X I S T R Y
v01. 8,XO. T I
cc. of solution) contains 0 . 2 1 2 g. of pyrogallol and 0.666 g. of potassium hydroxide pcr cc. With pyrogallol a t $2.8j per lb. and potassium hydroxide a t yo cents per lb., and assuming t h a t t h e potassium hydroxide is yo per cent pure, this reagent costs o 28 cent per cc. (pyrogallol 0.133 cent, potassium hydroxide o 147 cent), and with a specific absorption of 36, I cc. of oxygen can be absorbed for 0 . 0 0 8 cent. -It prices current during July, I g~$,’-pyrogallol a t $ I 40 per lb., 60 per cent sodium hydroxide a t I . 5; cents per Ib., potassium hydroxide a t j cents per 1b.t h e sodium reagent costs 0 . I j2 cent per cc. (pyrogallol 0.1; cent, sodium hydroxide 0 . 0 0 2 cent); and t h c potassium reagent, 0 . 0 7 4 cent per cc. (pyrogallol S P E C I F I C A B S0R P T I 0N o 066 cent, potassium hydroxide 0.008 cent). T h e From d a t a given b y Shipley, pp. 1693 and Ijoo. cost per cc. of oxygen in normal times is t h u s o OOI j t h e specific absorption3 within the 4-minute interval cent for t h e sodium reagent and 0 . 0 0 2 cent for the of the best sodium reagent (No. 9) employed a t room potassium reagent. temperature in a pipette of Shipley’s design on jo S U M UARY cc. samples of air is 102, and the specific absorption On t h e basis of the information t h a t has been preof t h e potassium reagent recommended b y t h e author sented, the best sodium reagent is superior t o the best for use in t h e Hempel double pipette for liquid re.potassium reagent as regards specific absorption and agents under t h e same conditions is 20, t h e sodium cost of materials and inferior as regards t h e time for reagent thus having more t h a n j times t h e specific complete absorption and t h e convenience of manipulaabsorption of t h e potassium reagent. T h e author tion. The relative importance of the first three of these has found t h a t t h e specific absorption of the same points of superiority and inferiority can best be shown by potassium reagent for I-minute contact employed computing the saving in expense t h a t could be effected a t room temperature in t h e usual form of the Orsat b y using t h e slower reagent and comparing it with pipette on IOO cc. samples of air is 2 2 . In especially t h e saving of time t h a t could be effected by the use constructed pipettes, a higher concentration of pyroof the more expensive reagent. For example. Ijo cc. gallol can be employed and t h e specific absorption of sodium reagent S o . 9 can be employed for the abof t h e solution employed in these pipettes was found sorption of I j.3 liters of oxygen a t a cost of 3 cents t o be 36, for t h e same temperature, procedure and per liter, or $0.46. T o absorb the same amount of source of oxygen as with t h e Orsat pipette. Thus the oxygen with t h e potassium reagent will cost 8 cents ratio of the specific absorptions of the best sodium per liter, or $I zz-$o. 76 in excess of t h e cost of the and potassium reagents is about 3 t o I , rather t h a n sodium reagent. I n normal times, using the priccs j t o I. I t is somewhat confusing t o note t h a t under current during July, 1914, as a basis, 15.3 liters of t h e topical heading in Shipley’s article, “Specific oxygen can be absorbed b y the sodium reagent for 2 3 Absorption of Reagents,” t h e values given are ob- cents a n d by the potassium reagent for 30 cents. T o tained b y a method closely resembling t h a t of Hemcounterbalance the increased cost of using t h e potaspel4 for “analytical absorbing power,” a t e r m repre- sium reagent, me have t h e saving of lime effected by senting something entirely different from specific its use, a factor t h a t is influenced b y t h e percentage absorption. of oxygen in t h e gases t h a t are analyzed. Assuming .C 0 IiV E KI E K C E 0 P 11.1 K I P U LA T I 0 S
Three or four transfers of t h e gas sample t o t h e pipette and return within t h e 4-minute limit are recommended b y Shipley for the sodium reagent. This is perhaps a more convenient method of effecting t h e absorption of oxygen t h a n shaking for I minute, a procedure t h a t is recommended for t h e Hempel double pipette for liquid reagents in the article of t h e author’s t o which Shipley made reference.’ In subsequent articlesZ 1-minute contact is recommended for t h e potassium reagent employed in pipettes containing glass tubes. This latter procedure is obviously more convenient than making three or four transfers of t h e gas as recommended b y Shipley for t h e sodium reagent.
T H E COST O F MATERIALS
Shipley’s sodium reagent S o . 9 (IO g. of pyrogallol, 7.36 g. of sodium hydroxide, 11.62 g. of water, sp. gr. I. 40 j) contains 0 . 4 8 j g. of pyrogallol and 0 . 3 js g . of sodium hydroxide per cc. With pyrogallol a t $ ~ . 8 per j lb. and 74 per cent sodium hydroxide a t 4 cents per lb.,6 this sodium reagent costs 0 . 3 0 9 cent per cc. (pyrogallol 0 . 3 0 j cent, sodium hydroxide 0 . 0 0 4 cent); and with a specific absorption of 1 0 2 , I cc. of oxygen can be absorbed for 0.003 cent. Similarly, Anderson’s potassium reagent (21,2 g. of pyrogallol and 6 6 . 6 g. of potassium hydroxide t o IOO THISJOURNAL, 7
(1915), 587. I h i d . , 8 (1916). 131, 133. 3 Anderson, I b i d , , 7 (191.51, 587. “Gasanalytische Methoden,” 4th Ed., p. 128. 6 Wholesale prices in the S e w York market, Aug. 2 1 , 19 16, THISJOURN A L , 8 ( 1 9 1 6 ) , 866. 1
2
IOO cc. samples of 2 0 per cent oxygen, 765 analyses would be required in t h e absorption of I j.3 liters of oxygen. With a saving of z1/2 minutes on each analysis, t h e total saving of time during 7 6 j analyses becomes 31~18hrs. From this must be subtracted t h c time required for the two extra fillings of t h e pipette with t h e potassium reagent necessitated b y its smaller specific absorption, for which might be allowed the excess over 30 hrs. With a choice between 30 hrs. of time and a n expenditure of $ 0 . 76 ( $ 0 . 0 7 in normal times) i t is difficult t o concur with t h e following statements from Shipley’s article. (The italics are the author’s.) “Such a reagent as No. g should replace in technical gas analysis the use of the more expensive and less e,flicient potassium solution. T h e saviirg o j t i m e aFrd 1 THISJOURNAL,
6 (19141, 704
Nov., 1916
T H E J O l i R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
trouble in using a reagent lasting five times1 as long should alone decide i n i t s favor.” I t is hoped t h a t these figures will show t h a t , as long as potassium hydroxide is obtainable even a t prices many times t h e present extraordinary one, t r u e economy dictates t h a t i t should be employed in preference t o sodium hydroxide for t h e preparation of alkaline pyrogallol. , . ..... IN D E F E N S E O F T H E H E M P E L P I P E T T E
During t h e reading of Shipley’s article for t h e preparation of t h e compariisons in t h e preceding pages, t h e author noted a paragraph of criticism of t h e Hempel pipette upon which he desires t o make brief comment. The paragraph i n question follows: “It is hard to understand why the Hempel pipette should be longer used for any but very special work. I t is difficult to fill with any reagent and especially so if the reagent is somewhat viscous. The long bent Capillary is a source of weakness in structure and of irregularity in use. The enormous friction of the liquid in the capillary requires, even with comparatively fluid reagents, a considerable excess of pressure to overcome and prohibits entirely the use of many concentrated reagents because of their viscosity. Moreover, the pipette requires a special and expensive stand while shaking has to be resorted to in order t o obtain efficient absorption. Should the pipette be broken anywhere only an experienced glass-blower can repair it.” Relative t o sentence two, i t should be mentioned t h a t a n opening2 between t h e second a n d third bulbs of t h e Hempel double pipette for t h e insertion of a funnel renders t h e filling of t h e pipette with a n y reagent a simple matter, even if t h e reagent is somewhat viscous. As regards sentence three, t h e eliminations of t h e unnecessary U-tube of t h e original Hempel pipette increases t h e strength of t h e apparatus a n d facilitates its manipulation. With t h e V-tube removed from t h e p:ipette, t h e pressure required t o force viscous liquids such as alkaline pyrogallol through capillary of I mm. bora is not unduly large (see sentence four). As t o whether shaking has t o be resorted t o (sentence five) depends upon t h e style of pipette t h a t is employed. A special form of t h e Hempel double pipette4 for solid a n d liquid reagents is especially adapted for the absorption of oxygen on I-minute contact with alkaline pyrogallol. A properly constructed frame for t:hese pipettes is extremely longlived a n d has proven a n economy on account of t h e protection which it affords t h e pipette. CORKELL L-NIVERSITY, I’CHACA, NEW YORK
RAPID VOLUMETRIC DETERMINATION OF INDIGO By SAMt-EL h%. JONESA N D WALTER SPAANS Received July 3, 1916
Of t h e various met:hods proposed for t h e determination of indigo, t h e one which depends upon t h e reduc1 Reagent S o , 9 has about 5 times the specific absorption of the potassium reagent recommeniied for use in t h e Hempel double pipette for liquid reagents to which Shipley refers. This reagent contains 0.136 g . of pyrogallol and 0.715 g. of potassium hydroxide per cc. and, a t the present time, costs 0.242 cent per cc. Using 20 as the specific absorption of this solution-Shipley’s value--the cost of absorbing 1 cc. of oxygen is 0.012 cent. T h e cost of absorbing 15.3 liters is then in this case $1.84, an excess of $1.38 over the cost with the sodium reagent. Four extra fillings would be required with this reagent, so t h a t the saving in time might be estimated a t 28 hrs. 2 This construction is shown on a special pipette for use with cuprous chloride, designed by the United Gas Improvement Co., in the catalogs of Eimer and Amend and A. H. Thomas Co. 3 White and Campbell, J. .4m.Chem. SOC.,27 ( 1 9 0 3 , 731; Anderson, Trns JOURNAL, 6 (19141, 237. 4 Anderson, THIS JOURNAL, 8 (1916), 133.
IO01
tion of t h e sulfonated product b y means of a sodium hydrosulfite solution is t h e one i n most general use a t t h e present time. This method, which was first proposed b y A. Muller1 a n d fully described in t h e Badische Indigo Book, was a material improvement over t h e older oxidation methods. Briefly s t a t e d , i t consists i n comparing t h e sample with a n indigo of known strength b y titrating t h e sulfonated product with a solution of sodium hydrosulfite, also of known concentration, until t h e solution becomes colorless. By comparing t h e results, t h e relative value of t h e indigo in question may be obtained. Although t h e principle involved in this method is correct, there are several factors which render i t not only difficult t o perform b u t in many cases inaccurate. I n t h e first place, indigo white, t h e leuco derivative formed b y reducing indigo, is very unstable, a n d is nearly quantitatively reoxidized t o indigo b y exposure t o air. Muller tried t o overcome this difficulty b y performing t h e titration i n t h e presence of a n inert gas, such as coal gas, b u t , according t o our experience, this is not ’sufficient. I n spite of maintaining a constant atmosphere of coal gas, t h e indigo white reoxidizes very quickly if there is not a n excess of hydrosulfite present. Consequently, i t is impossible t o ascertain t h e a m o u n t of hydrosulfite necessary t o produce t h e endpoint. Moreover, t h e sodium hydrosulfite, however pure, is like t h e indigo white. very susceptible t o oxidation, as conservation trials of a n aqueous solution will readily show. These two factors render t h e method inaccurate. Realizing t h e importance of a rapid accurate method for t h e determination of indigo, especially in t h e textile industries, we have succeeded in devising one which produces t h e desired results. Like t h e method of Muller. our new method is based on t h e reduction of indigo to indigo white. I n stead, however, of working in t h e presence of coal gas, we have found t h a t b y using a current of hydrogen, t h e titration may be carried out the s a m e as any other volumetric titration, without fear of subsequent oxidation. I n other words, working with our a p paratus in a current of hydrogen, only t h e amount of hydrosulfite actually necessary t o produce .the reduction need be used. We have, in addition t o this, substituted formaldehyde sodium sulfoxylate, which is manufactured in a very pure form b y t h e Badische Company under t h e name of Rongalite C, for t h e unstable sodium hydrosulfite. A4queous solutions of formaldehyde sodium sulfoxylate may be conserved for hours or days without suffering t h e slightest decomposition, which makes it especially suitable as a “standard” t o be used for volumetric reduction methods. This very stability, however, especially a t low t e m peratures, a t first presented considerable difficulty, for on running t h e solution of sodium formaldehyde sulfoxylate into t h e sulfonated indigo, no reduction takes place a t ordinary temperatures, a n d only on 1
Amevccan Chemryt 126.
