T H E J O C R - V A L OF I N D L 7 S T R I a 4 L AAYD ESGI,'\:EERING
820
Boiling point at 760 m m . . . . . . . . . . . . . . . . . . . 217-218' C 1 Sp. pr. at 15". . . . . . . . . . . . . . . . . . . . . . . . . . . . .O,935-0.9401 . 1.480841 Refractivity T L ~ .......................... 35'2 Melting point.. ...........................
The close agreement of the fir oil and especially of the fractions between 218-220' is very marked, with the exception of the melting point, the fir oil solidifying below -40' C. and the fractions between 218-220' a t o o C. This exception is not unusual in the presence of impurities, as i t has been shown by Bouchardat and Voirys that terpineol which will not solidify above -50' C. has a melting point of 30-32'
c.
The conclusion drawn from these tests is that not less than I/s of fir oil consists of terpineol and that fir oil is so closely similar t o pine oil in its properties as to be able to be substituted for the latter in its commercial application. The uses of the latter have become very extensive in the last few years. As a solvent for varnish gums in the cold, for rubber, for nitrocellulose lacquer, in the manufacture of metal polishes and for general use as an essential oil, it is being sold regularly in carload lots. This same market should be open in the future to fir oil for the same or similar uses. LABORATORY OF INDUSTRIAL CHEMISTRY, OF WASHINGTON. UNIVERSITY SEATTLE.
A STUDY OF THE BROMINE AND IODOMETRIC METHODS FOR THE DETERMINATION OF RESORCINOLP B y C . If. PENCE. Received August 2 8 , 1911.
Koppeschaar's (I) modification of Landolt's bromine method for the determination of phenol suggested several years ago that other phenols ( 2 , 3, and. 4) might be estimated b y practically the same procedure. Degener ( 5 ) devised the following bromine method far-resorcinol: A standard solution of free bromine is run into the resorcinol solution as long as a precipitate forms and until solution becomes yellow. Then potassium iodide is added and the liberated iodine titrated with N/IO thiosulphate. Richards (6) proposed an iodometric method similar in procedure t o the bromine method of Degener with the exception that it is necessary t o add some substance like sodium acetate to cause greater completion of the reaction b y uniting with the hydriodic acid formed during the substitution. A study was made of these two methods with the purpose of finding a rapid and yet accurate method for the estimation of resorcinol. Resorcinol of uncorrected m. p. 109-110O C. was recrystallized from distilled water, the crystals were disintegrated and allowed to drain thoroughly, then recrystallized from absolute alcohol free from aldehydes, etc. The crystals thus obtained were broken Gildermeister ahd Hoffman, p. 140. *Liebig's Alan.. 275, p 104. 3 Compf. rend., 104, 996; Ber., 20, 286. Paper read before the Pharmaceutical Division, Indianapolis meeting, Amer. Chem. SOC.. June, 1911.
CHE.IfISTRY.
Nov., 1911
apart, thoroughly drained, desiccated in vacuum desiccator over sulphuric acid, powdered and redesiccated to free from the last traces of alcohol. T'olumetric solutions were prepared from these crystals and an attempt was made to apply the Koppeschaar procedure for the volumetric estimation of phenol as outlined in the U. S. Pharmacopoeia, 1900 ed. This method seemed to have several advantages over that of Degener inasmuch as the Koppeschaarbromine solution is much superior to a standard solution of free bromine in stability and ease of handling. The U. S. P. of Koppeschaar method is briefly as follows: The aqueous phenol solution is measured with a pipette into a 500 cc. receptacle with groundglass stopper. A measured quantity of standard bromine solution sufficient t o give a small excess of bromine is added, then 5 cc. of concentrated HC1. The bottle is shaken and let set 30 minutes. Five cc. of One cc. 20 per cent. K I are added and bottle shaken. of CHC1, is added, bottle again shaken and free iodine titrated with N/IOthiosulphate until chloroform is free from color. Starch was used as an indicator instead of chloroform, which was added merely as a solvent for precipitated phenols, thus increasing the sensitiveness of end point. I t was found that when solution was allowed t o stand 30 minutes after addition of HC1 the results would be much too high. This was attributed t o the formation of tribromresorcinolbrom ( 7 ) which did not readily decompose after the addition of KI. Expts. I and 2 show this tendency, Expt. 2 also showing t h a t short time of standing after addition of K I did not permit the decomposition of the additive compound formed. An attempt was now made t o counteract tendency for formation of this compound by shortening the reaction period of bromine upon resorcinol. Expts. 3, 4 and 5 show much lower results. I n the next experiments (6-14) the reaction period of bromine was kept a t I min. and solution was allowed t o stand after the addition of KI. I t was found that K I caused a reversal whereby the tribromresorcinolbrom was entirely decomposed. Expts. 6 and 71 2 and 14 show this reversal effect of K I and length of time required for complete reversal under the specific experimental conditions used. Expt. 13 shows that heat increases the speed of reversal. Now it was observed dming the course of the above experiments that a pronounced precipitate formed upon the addition of KI. It was thought probable t h a t this precipitate consisted partially of or occluded some tribromresorcinolbrom and prevented a ready reversal. This supposition was verified by Expts. 15-28. By proper dilution the precipitation was prevented. However, it was found that reversal did not cease after breaking down the tribromresorcinolbrom but t h a t some of the tribromresorcinol was decomposed. Chloroform was used, thinking t h a t decomposition might be taking place almost entirely during the titration. This was found t o be untrue (Expts. 2 0 , 24, 2 5 , 26, 27, 2 8 ) . Nevertheless, these experiments did show that amount of reversal was
T H E J O U R N A L OF I N D U S T R I A L A N D ElVGIAiEERING CHElZlISTRY .
Nov., 1911
Resor-
Expt 1 2 3 4 5 6 7 8
9
. . cinol cc. 20 20 20 20 20 10
BrN/10 . cc . 50 50 50 50
50 20 LO 50 50 40
10
LO
12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53
20 50 50 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 25 25 20 20 25 25 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 25 25 20
50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50
54 55 56 57 58 59 60 61 62
25 25 25 25 25 25 25 25 25
50 50 50 50 50 50 50 50 50
10 11
E x p. 63 64 65 66 67 68 69 70 71 72 73
40
20 20 20 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50
Resorcinol cc . 20 20 20 20 20 20 20 20
20 20 20
.
Time H10 . HC1 cc . cc. standing 5 30 min. 50 60 " 5 30 5 5 'I 30 3 30 5 30 5 5 " .. 5 1 1 5 1 ', 5 20 1 " 5 20 10 1 '( 5 5 1 " 10 5 1 'I 20 1 " 20 5 1 " 20 5 5 1 30 5 1 " 30 5 30 1 'I 1 5 30 1 5 30 5 30 2 " 5 5 /' 30 5 '# 5 30 5 30 5 " 5 30 2 " 5 1 " 30 1 5 30 1 l' 5 30 30 1 " 5 30 5 " 5 50 1 5 50 5 1 I' 50 5 2 '( 30 2 " 5 1 '# 50 5 50 1 " 5 30 5 2 30 5 " 5 5 I' 30 5 30 5 5 30 5 5 c' 1 " 30 5 30 5 2 30 5 1 I' 30 5 3 30 5 5 '# 30 5 I 30 5 30 '' 30 30 " 5 5 30 ' 45 " 30 5 15 sec 30 5 1 min 30 5 1 " 30 (IOCC 1 '# 10%) 50 5 1 " 5 1 #' 50 50 5 1 " 50 5 1 5 1 " 50 50 5 1 #' 50 5 1 5 1 #' 50 50 5 1 '#
H2 0 cc .
...
200
...
200
'/
... ...
'/
..
...
('
...
...
... ...
...
...
...
... ...
... ... ...
..
...
... ...
... ...
... ... ...
...
...
...
6l
200 200 200 200 200
... . .
'(
...
...
cg
... ...
...
('
...
...
('
... 200 200 200 200 200 200 200 200
'(
.
'(
I'
.
N/10 I cc . 50 50 50 50 50 50 50 50 50 50
50
NaCH2CO0. Grams.
.. 1
200 200 200 200 200 200 200 200 200
NazHPO Grams. 2
..
..
KI 20 Der cent . Time standing. cc 10 ..... 10 min . 5 10 ..... IO ..... 5 ..... 10 1 hr . 10 2 hrs . 2 " 10 10 2 I' 1 hr . 10 1 " 10 10 30 min . 10 30 '' IO 1 hr . 10 1 " IO ..... 15 ..... 15 ..... 1 hr . 10 10
1
10 10
5 min . 5 'I 5 1 hr . 2 min . 2
10
IO
10 10 10 5
... ...
5
.. ..
...
..
.. ..
0.5 2.0
5 2
..
1
...
...
...
"
.....
.....
..... ..... ..... ..... .....
....
....... ....... ....... ......
.....
1 min .
...... ..... ..... .....
....
Shnok well
1 min
.....
c
.... ....
.... .... ....
...... ......
......
'(
"
"
.... ....
1 min . 1 " '( ('
1
"
....
.... ....
1 min . 1 " 10 I' 45 I' 15 " 1 hr . 1 min.
....... Shook well
1
"
3
"
....
1 min .
3 8 14 5 8 12 15 20
...
.
20 15 30
1 1
... ...
Time standing 5 min. 1 hr. 15 min . at once 30 rnin at once at once at once 3 hrs . 5 min 3 hrs
.
....
Shook well
...
....
1 *' 5 '( 1 hr . 1 min 1 mln . 2 'I 2 'I 2 I' 1 "
...
...
....
....
.......
200 200 200 200 200 200 200 200 200 200
... ...
....
....... .......
... ... ... ...
.....
.... ....
.... ....
...
..... .....
....
....... .......
...
.....
NaHC03. Grams.
..
.... .... ....
200
3 min . 6 'I 5 3 '/ 5 "
5
1
'I
1 hr .
5
...
..
1
...
3
..
"
...
d
... ...
200 150 150 150 150 150 150 150 150 150 250 250 250 250 200 200 200 200 200 200 200 200 200 200 200
T.me standing
....
...
5 5 5 5 5 5 5 5 5 5 IO 10 5 5 5 5 5 5 5 5 5 5
1 1 1
...
'(
1
Procedure.
...
200
1 hr . 1 "
d
...
...
('
10
5 5 5 5 5 5
HzO . cc .
HzO added cc. 200
.
200
200 200 200 200 200 200 200 200 200
" " I'
"
" " "
.
CHCI. . Result . cc . Per cent 5 102.58 .. 102.6 100.13 20 100.15 .. .. 100.1 10 100.3 10 99.9 IO 99.78 99.71 10 10 9989 10 99.94 10 100.39 10 99.82 10 99.99 .. 99.4 .. 99.3 .. 99.41 .. 99.4 .. 99.4 20 99.5 99.6 20 20 99.56 .. 99.59 20 99.5 20 99.76 20 99.74 20 99.74 20 99.76 .. 99.30 .. 99.25 .. 99.95 .. 99.92 .. 99.92 .. 99.49 .. 9945 .. 100.00 .. 100.00 .. 99.96 .. 99.86 .. 100.0 99.86 20 100.05 20 100.1 .. 100.21 .. 100.4 .. 100.03 .. .. 99.93 .. 100.1 100.1 .. .. 99.7 .. 101.04 .. 100.26 .. 99.86
..
.. ..
.. .. .. ..
.. ..
99.95 99.95 99.97 99.95 100.00 100.12 100.04 100.04 99.99
Result. after excess thiosulphate. Result . titrated back .
...
...
99.2 98.6 98.4 99.33 99.33 97.7 98.2
98.94 98.35 98.7 99.15 99.15 97.5 98.3
...
...
...
...
... ...
.
82I
Br N/10 excess
.
.......
.......
....... 1.5 1.7
8.25 8.22 1.42 1.6 1.48 about 12.0 cc
.
34.6~~. 34.9 cc. about 16.0 cc .
Remarks .
Too dark to titrate
Too dark to titrate Too dark to titrate Too dark to titrate
822
T H E J O U 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 .
Nov., 1911
3. Volumetric Estimation of Orthocresol with Bromine. R . Clauser. dependent upon time of standing after dilution. Oeslerr. Chem. Z t g . . 11, 585 (1899): through (Abst. Analyst. 1900, 74). Compare Expts. 15-24 with Expts. 25-28. 4 A New Method for Analysis of Commercial Phenols. S. B . Schrwer. It now remained to ascertain whether or not a J. SOC.Chem. I n d . , 1899, 553. 5. Quant. Estimation of Resorcinol. Degener. J . braklische smaller amount of K I would counteract tendency for Chemie, [Z 1 20,322:through (Abst. Beilstein’s “Organische Chemie.” 2, 916). decomposition of tribromresorcinol and under what 6. Preparation of Iodo Derivatives of Phenols and Determination of conditions such would obtain. ‘ I t was found that Resorcinol. E. Richard. J . Pharm. Chim., [5] 15, 217-22 (1902): through J . SOC.Chem. I n d . , 1902, 423). this decomposition was prevented ; that solution must (Abst. and Tribromresorcinolbrom. Benedikt. 7. Tribromphenolbrom not stand too long after addition of K I before dilu- Berichle. 12, 1005-1006; through (Abst. J. Chem. S O C . ,1879, 36, 717). RESEARCH LABORATOXY, tion; that in diluted condition, time of standing might ELI LILLY& COMPANY, be somewhat prolonged without deleterious results ; INDIANAPOLIS. that after dilution and addition of KI, solution should not stand as long as I hour before titration (Expst. A NEW AND ACCURATE METHOD FOR DETERMINING THE 2 9 and 30-31, 32, 33-34, 3s). TRYPTIC VALUE O F PANCREATIN.‘ Several experiments were run varying the length B Y CLARENCE F. RAMSAY. of time bromine was allowed to react with resorcinol Received August 28,.1911. in order to study the length of time it would take K I At the present time very little attention is being to produce proper reversal under varying conditions. paid to pancreation as regards its proteolytic activity. In general, it may be said that KI should react a t This is probably due to the fact that no satisfactory least as long as bromine is permitted to react with test has been proposed by which it might be ascerresorcinol. Experiments 36, 37, 38, 39, 40, 41, 42, tained just how much proteid a given sample of pan43, 44, 45, 46, 47, 48 and 49. creatin will digest. It was found in Expt. 50 that reaction between broThe tryptic value of pancreatin should be taken mine and resorcinol would not be completed in 1 5 into account for it is more energetic than pepsin. secs.; in Expts. j r and 52 that solution should set a t I n the case of pepsin considerable time is necessary least 5 mins. after addition of K I when excess of bro- for proteid to be converted into peptone while trypsin mine is large; in Expt. 53 that reaction between bro- converts proteids rapidly into proteoses and peptone. mine and resorcinol solutions is much ‘more rapid It has been stated that .trypsin is so energetic that . when strong acid is used. i t will convert proteid beyond the stage of peptone The method of Degener would be open to consider- into leucin, tyrosin, and other amides. able error, due t o formation of the additive compound The U. S. P. method for determining the tryptic and to insufficient time and dilution for its decom- power of pancreatin is very indefinite and uncertain position. because of the manner of testing the end reaction. Richards’ iodometric method has several features It states that by adding a little nitric acid to a portion that condemn i t : Ist, solutions darken upon standing of the peptonized milk no coagulation should occur. so that end point is obscured; 2nd, even upon pro- As regards the word coagulation in this test there ionged standing results are much too low (Expts. is a difference of opinion. If we are to think of co63-73). agulation as the result obtained when adding rennin The following method is suggested for the estima- to milk it would be better to call this separation tion of resorcinol in commercial resorcinol: Its ac- a precipitation. The result depends altogether upon curacy may be noted by reference to Expts. 54-62. the amount of acid added. If a minute quantity Weigh out I ,4563 g. resorcinol. Dissolve in dis- of acid is added, no precipitate is formed, while with tilled water, filter if necessary, and dilute to 5 0 0 cc. more acid there is a decided precipitation. A large in a volumetric flask. Withdraw a 2 5 cc. portion excess of acid generally results in solution of the prewith a pipette and place in a 5 0 0 cc. receptacle wiih cipitate. Acid will cause a precipitation in peptonized ground-glass stopper. Add 50 cc. N/IO bromine solu- milk no matter how long the digestion takes place. tion and 50 cc. dist. water. Add 5 cc. conc. HC1, In view of the importance of trypsin in pancreatin shake .and let set about I minute. Dilute with about the writer wishes to propose a milk test which, if z o o cc. water, add 5 cc. 2 0 per cent. K I , shake vigorcarried out exactly in accordance with directions, ously and let set about 5 minutes. Titrate, using will give very accurate results. In testing the activity starch as indicator. Divide number of cc. of N/IO of enzymes, i t is very important to adhere to certain bromine solution consumed by 0.4 (or multiply by conditions such as temperature, time for digestion, 2. j) for correct percentage of resorcinol. etc. So it is in testing trypsin. This test determines A blank should be run along with the determina- the amount of pancreatin necessary to peptonize tion, using the same pipette and draining in the same a given quantity of milk in fifteen minutes. The end manner in order to obtain an exact duplicate titre of reaction is determined by adding a slightly acidified N/IObromine solution. 7-10 cc. of 2 0 per cent. KI solution of rennin t o a portion of the peptonized should be used instead of 5 cc. as in regular deter- milk and noting if precipitation or coagulation takes place. The final end point of the test is reached when mination. BIBLIOGRAPHY. the milk is just sufficiently peptonized so thatpit 1. Volumetric Estimation of Phenol. W. F. Koppeschaar. Zeitschr. will not be coagulated by the rennin. To determine anal. Chem., 1876, 233-245; through (Abst. Jr. Chem. Soc., 1877, 746). this it is necessary t o test the pancreatin first at wide 2 . Reactions of B r with Phenol and the Cresols, A Process of Calcu-
lating the Composition of Mixtures Thereof. Ditz and Cedivoda. Zeitschr. a m l . Chem.. 1899, 873 and 897: through (Abst. Analyst. 1900, 74).
1 Paper read before the Pharmaceutical Division, June meeting, American Chemical Society.
