24
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
tion of t h e solvent t h e residue 'was made t o crystallize without difficulty. The crystals obtained softened a t 60' a n d melted a t 67-68'. By repeated crystallization from ethyl acetate t h e compound finally melted at 72-72.5'. The crystals obtained from t h e fraction boiling a t 172-174' contained a greater amount of dipentene dihydrochloride t h a n t h e fraction boiling at I 70-1 7 1 '. T h e sylvestrene regenerated from t h e purified dihydrochloride gave a beautiful, deep blue color with acetic anhydride a n d concentrated sulfuric acid. A 3.21 per cent ethereal solution of t h e sylvestrene dihydrochloride h a d t h e rotation CxD240 1.9'. L I M O N E N E A N D DIPEKTENE-Dipentene tetrabromide having t h e melting point I 24-1 24.j ' was obtained from a fraction boiling at 174-174.5'. Ten grams of a fraction having t h e boiling point I 75-176', aDZ4o +56.34', a n d dlSo 0.8536 a f t e r t r e a t m e n t with bromine a n d standing in t h e cold 2 4 hrs. gave 0.87 g. of crystalline tetrabromide. By fractional crystallization i t was possible t o obtain two tetrabromides melting a t 123.5 a n d 113'. The original mother liquor, on s t a n d ing, deposited a n additional 2.4 g . of crystals t h a t were richer in limonene tetrabromide since t h e first fraction on fractional crystallization melted at 1 1 j-116 ' after three additional crystallizations from ethyl acetate. T h e behavior of t h e tetrabromides shows t h e presence of both limonene a n d dipentene The total sylvestrene, limonene, a n d dipentene fractions amounted t o 269.5 g. (53.9p e r . c e n t ) . BoRNEoL-The fraction boiling a t 200-23 j ' after saponification yielded a n oil having a ~ 2 8 0-12.32. O B y means of t h e phthalic ester an oil was obtained h a v ing a strong odor of borneol. On oxidation camphor melting a t 173-174' was obtained. ACETIC ~ c r ~ - T h e oil decomposed t o some extent above 177' during distillation, a strong odor of acetic acid being produced. The presence of this acid was confirmed b y analysis of t h e silver salt as follows:
+
0 2218 g silver salt g a \ e 0 1427 g Ag = 64.34 per cent Ag Silver acetate, CHJ COO4g, requlres 64 63 per cent Ag.
T h e acids obtained b y saponification of t h e esters contained a second acid, t w o fractions of whose silver salt contained 39.32 per cent a n d 39.13 per cent .4g. T h e precipitates probably consist of silver caprinate with a small amount of silver acetate. SESQUITERPEKE-After removal Of t h e esters 3 2.8 g. of oil distilled between 2 5 0 - 2 8 0 ' a n d I O g. of a deep green oil between 2 8 0 a n d 310'. T h e fraction boiling at 250-280' contained a sesquiterpene having t h e properties: b. p., 260-280'; dmo, 0.9292;nmoo, 1.4994; o ( ~ 16.4'. ~ ~ ~ The , fraction yielded a hydrochloride crystallizing from ethyl acetate in t h i n plates a n d melting a t 132-133'. This sesquiterpene has not been identified with a n y of t h e sesquiterpenes recorded in t h e literature a n d has been tentatively called "libocedrene." Lack of material prevented further study. BARK
OIL
T h e bark oil had t h e following properties: Color, faint greenish yellow; da0, 0.8621;flD15e, 1.4716;Q I D Z O O , +I.IO'; acid No., 0.60;ester No., 3.22; ester No. after acetylation, 9. j3; yield of oil, 0.14 per cent. The sample consisting of 179 g. distilled as follows:
Temperature. Per cent
......
...
157-160 55.0
160-165 27.0
V O ~8. , NO. I
170-190 9.5
190-250 3.5
250-290 3.0
FURFURAL-This aldehyde was qualitatively detected in t h e fraction boiling a t 157-1 j8". a-PINEKE-The total oil boiling below 168' amounted t o 90 grams. This distilled almost entirely between 156' a n d 160'. A small portion distilling between 16-168" was examined for 0-pinene with negative results. Ten grams of a fraction boiling a t 156-1;7', 0 1 ~ 1 8 0 +1.46', dlso 0.8630,gave 4 g. of pinene nitrosochloride. The pinene nitrolpiperidine melted a t I I 7118'.
DIPENTENE--Nine grams ( 5 per cent) of oil distilled between 168-173' a n d h a d ( ~ ~ -1.46'. ~ 0 0 Dissolved in dry ether a n d saturated with dry HCl gas a dihydrochloride melting a t 48-49 ' was obtained. A L C O H O L FRACTIOK-The ester fraction boiling a t 190-z35" amounted t o 2.6 g. a n d was not further examined, owing t o t h e small quantity. The free alcohol a n d ester content hav$ been calculated as borneol a n d bornyl acetate. " G R E E N OIL"-A greenish yellow oil weighing j . j g. (3 per cent) was obtained between 2 5 0 - 2 9 0 ' . When a drop was dissolved in acetic anhydride a n d a drop of concentrated H2S04 added, a dark green color changing t o greenish yellow was obtained. When t h e oil was dissolved in glacial acetic acid and bromine vapors added t h e pink color a t first obtained changed t o purple, finally becoming deep blue. An ethereal solution of oil when saturated with HCl gas became deep crimson a n d yielded no solid hydrochloride. SCMMARY
The leaf and twig, a n d bark oils of incense cedar have approximately t h e following percentage composition : CONSTITUEKTS PRESENT Furfural.. . . . . . . . . . . . . 1-=-Pinene, , , . . , , , , , , . d-Sylvestrene, . . . . . . . . . . . . . . . . . . . . . . . . . . .
.......................
Dipentene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bornyl acetate.. . . . . . . . . . . . . . . . . . . . . . . . . Free borneol.. . . . . . . . . . . . . . . . . . . . . . . . . . . "Libocedrene" . . . . . . . . . . . . . . . . . . . . . . . . . . "Green oil". . . . . . . . . . . . . . . . . . . . . . . . . . . . . Losses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
LEAP TWIG ARD OIL Trace 12-16
BARKOIL Trace 75-85
54-58 8 4 6- 7 2 6
...
5-6 1 2
... 3 6
FOREST PRODUCTSLABORATORY FOREST SERVICE U. s. DEPARTMENT O F AGRICULTURE (In cooperation with the University of Wisconsin) MADISON,WISCONSIN
REAGENTS FOR USE IN GAS ANALYSIS 11. CHROMOUS CHLORlDE B y R. P, ANDERSONAKD J. RIFFE Received July 31, 1915
Chromous chloride seems to have been first prepared by Llobergl a n d b y Peligot2 working independently, t h e latter making special reference in his description of this substance t o t h e avidity with which i t unites with free oxygen. Otto von der Pfordten3 proposed t h a t t h e compound be used as a n absorbent for oxygen, with particular reference t o its removal from hydrogen sulfide. In his method of preparing t h e reagent, chromous acetate was first made b y a method essen1
Jour prakt. Chem., 29 (1843), 175; 44 (1848), 322 36 (1845). 27; Ann. rhim. p h y s , [3] 12 (1848),528 Ann. der C h e m , 228 (1885), 112.
* Ibid., 3
Jan., 1916
T H E J O U R N A L O F I N D U S T R I A L A.VD E N G I N E E R I N G C H E M I S T R Y
tially t h a t of hiloissanl a n d t h e n decomposed b y hydrochloric acid with t h e formation of t h e chloride. Jannasch a n d MeyerZ used chromous chloride with excellent results for t h e removal of oxygen from nitrogen in connection with t h e combustion of organic substances containing t h e latter element. They purchased chromous acetate in paste form a n d treated it with hydrochloric acid for t h e production of chromous chloride. They found t h a t t h e reagent decomposes with t h e evolution of hydrogen if a n excess of acid is employed, a n d therefore recommend t h a t a small a m o u n t of undecomposed chromous acetate be allowed t o remain in t h e solution. Berthelots found t h a t hydrogen is always obtained from a solution of chromous chloride in water unless t h e preparation is pure a n d free from a n y trace of acid. Peters4 states t h a t acid solutions of chromous chloride liberate hydrogen. Dorings substantiated t h e results obtained b y Berthelot. Chromous chloride has found b u t little application as a reagent in gas analysis. Some text books on t h e subject include i t among t h e absorbents for oxygen a n d one communication6 was found in which chromous chloride is suggested as a reagent for t h e determination of oxygen in flue gases in t h e presence of carbon dioxide a n d hydrogen sulfide; b u t nothing seems t o have been accomplished i n t h e way of t h e proper composition of t h e reagent or t h e proper method of its, use. T h e following experiments were performed t o obtain information on these points. E X P E RI ME pi T A L W 0R K
I t seemed desirable t o p,repare t h e reagent first according t o t h e method used b y Otto von der Pfordten a n d b y Jannasch a n d Meyer. Chromous acetate in paste form was not available on t h e market a t t h e time t h a t these experiments were performed a n d accordingly a considerable quantity of this material was prepared for conversion t o chromous chloride as needed. Three hundred grams 'of green chromic chloride were dissolved in a minimum amount of water a n d t h e solution transferred t o a large Erlenmeyer flask fitted with a rubber stopper carrying a n inlet t u b e , a separatory funnel, a n d a n outlet t u b e long enough t o reach t o t h e bottom of t h e flask. T h e chromic chloride was reduced t o chromous chloride b y nascent hydrogen prepared from zinc a n d hydrochloric acid, about twice t h e theoretical amount of zinc being placed in the flask a n d t h e hydrochloric acid added from time t o time in small amounts from t h e separatory funnel. During this operation t h e inlet t u b e was kept closed a n d t h e hydrogen which escaped oxidation in t h e flask was allowed t o pass through t h e outlet t u b e , t h e lower end of which was raised above t h e level of t h e solution. After complete reduction of t h e chromic chloride h a d been obtained, a s evidenced b y t h e appearance of t h e characteristic blue color of chromous chloride in solution, t h e end of t h e outlet t u b e was lowered below t h e 1 2 3 4
6 6
Compt. rend., 82 (18811, 792; Ann. chim. Dhys., [ 5 ] 26 (1882). 401. A n n . der Chem., 293 (1886), 375. Compt. vend., 127 (1898), 24. Z. physik. Chem., 26 (1898). 193. Jour. pvakt. Chem., [ Z ] 66 (1902), 65. Anonymous, Zeit. f. Chem. Apparalenkunde. 8 (1908), 315.
25
surface of t h e solution, a n d carbon dioxide admitted t o t h e flask through t h e inlet tube, t h u s forcing t h e solution through t h e outlet tube, a n d through a glasswool filtering device, into a 5-liter bottle containing t h e theoretical amount of sodium acetate. These auxiliary portions of t h e apparatus h a d previously been freed from air b y t h e waste hydrogen from t h e Erlenmeyer flask. A red precipitate of chromous acetate was formed, which was washed repeatedly b y decantation, first with dilute acetic acid, saturated with carbon dioxide, t o dissolve a n y basic zinc carbonate t h a t may have been thrown down, a n d finally with distilled water saturated with t h e same gas. These operations were performed in a n atmosphere of carbon dioxide and t h e resulting paste of chromous acetate was k e p t in t h e same bottle, tightly stoppered, with carbon dioxide above it. T o prepare t h e reagent, t h e desired amount of chromous acetate was transferred t o a 300 cc. Erlenmeyer flask. A rubber stopper carrying a n inlet tube, a separatory funnel, a n d a n outlet t u b e was placed in t h e neck of t h e flask, the air was displaced from it b y a current of carbon dioxide, a n d dilute hydrochloric acid was added through t h e separatory funnel t o effect t h e decomposition of t h e acetate. The solution of chromous chloride t h u s obtained was t h e n forced into a Hempel double pipette for liquid reagents' until it was filled t o t h e proper point, a n d finally water was placed in t h e t r a p in t h e usual fashion. Solutions were prepared using varying amounts of hydrochloric acid in proportion t o t h e chromous acetate, b u t none of t h e m was found t o be stable. When sufficient acid was employed t o decompose all of t h e chromous acetate, decomposition took place rapidly; when some undecomposed acetate was left in t h e solution, i t was found, contrary t o t h e statements of Jannasch a n d Meyer,z t h a t minute bubbles of gas formed in t h e reagent a n d collected in t h e upper portion of t h e pipette, from 30 t o 50 cc. being t h u s obtained during t h e first week. T h e gas was analyzed a n d found t o consist largely of hydrogen, some carbon dioxide being present a s a result of t h e saturation of t h e reagent with this gas during i t s preparation. Several a t t e m p t s were made t o prepare a stable solution of chromous chloride b y decomposing chromous acetate with insufficient hydrochloric acid, using two different preparations of t h e paste of chromous acetate, b u t none of t h e a t t e m p t s was successful. I t t h u s appears t h a t t h e statement of Berthelot2 a n d others concerning t h e effect of acid upon chromous chloride is correct a n d t h a t t h e acetic acid formed on t h e decomposition of chromous acetate b y hydrochloric acid is responsible for t h e instability of chromous chloride t h u s prepared. Accordingly t h e a t t e m p t t o prepare t h e reagent b y this method was abandoned. Chromous chloride was next prepared b y t h e reduction of violet chromic chloride in a current of hydrogen. A piece of Jena glass tubing was filled with violet chromic chloride a n d heated t o 400- j o o o C. in a combustion furnace. A current of hydrogen, 1
A modified form wademployed.
2
LOC.
cit.
See THISJOURNAL, 6 (1914), 237.
T H E JOCR,VAL O F I.VDl-STRIAL A N D E N G I N E E R I N G C H E M I S T R Y
26
freed from oxygen b y alkaline pyrogallol and from water vapor by strong sulfuric acid, each in a Friedrichs \Trashing bottle, was passed through the chromic chloride, t h e hydrogen chloride resulting from t h e reduction being absorbed in water in a .third Friedrichs washing bottle. The reduction was carried on until t h e contents of t h e tube took on t h e yellowish white color of chromous chloride. I n the preparation of the reagent, the desired amount of the product of t h e reduction was rapidly transferred t o a 300 cc. Erlenmeyer flask fitted with a rubber stopper carrying a n inlet tube, a separatory funnel, and a n outlet tube. Treatment of the material with water and t h e transfer of t h e resulting solution t o a pipette mas carried out in a fashion similar t o the procedure described for the preparation of the reagent from chromous acetate, except t h a t instead of carbon dioxide, hydrogen mas employed throughout t o a r o i d the difficulties due t o the high solubility of the forrner gas. T h e product of t h e reduction of chromium chloride with hydrogen is not entirely soluble’ in water a n d it was found t h a t if the solution was transferred t o t h e pipette without filtering, hydrogen was gradually liberated in small amounts; on t h e other hand, if the solution was filtered through glass wool during t h e passage from t h e Erlenmeyer flask t o t h e pipette, it was found t o be stable. On treating the filtered reagent with samples of air, t h e greater portion of t h e oxygen was absorbed during t h e first few seconds of shaking, but t h e absorption was not complete even after several minutes’ shaking, t h e decrease amounting in most cases t o 20.4 t o 2 o . j per cent. Four solutions prepared b y t h e above method were examined with t h e same result in each case. T h a t t h e absorption of oxygen was actually incomplete was demonstrated by treating the residual gas with alkaline pyrogallol, a procedure which resulted in a slight decrease in volume in every case a n d which gave the correct percentage of oxygen in airs2 S L-11MAR Y
I-The preparation of chromous chloride according t o t h e method followed b y Otto von der Pfordten and b y Jannasch a n d Meyer does not result in a stable solution a n d hence the reagent t h u s prepared is unsatisfactory for gas-analytical work. 11-The preparation of chromous chloride b y t h e reduction of violet chromic chloride b y means of hydrogen results in a solution which, when properly filtered, is stable, b u t the absorption of oxygen, although rapid, is not complete, and therefore t h e reagent thus prepared is unsatisfactory for gas-analytical work. While t h e foregoing results are unfavorable as regards t h e possible wider application of chromous chloride as a n absorbent for oxygen, nevertheless they should not be construed‘ as necessarily indicating t h a t a solution of this substance which shall be suitable for gas-analytical work can not be prepared. It is not likely, however, in view of t h e high cost of the maAccording t o Moberg, some metallic chromium is formed. 2 The departure of the junior author from the University prevented further investigation of this problem under the present joint authorship. 1
Yol. 8, NO.
I
terials a n d the probable inconvenience of preparation, t h a t chromous chloride will ever be widely used except in cases, such as t h e absorption of oxygen in t h e presence of carbon dioxide and hydrogen sulfide, where other reagents can not be employed. C O R X E LUKIVERSITY, L ITHACA, KEWYORK
A RAPID CONTROL METHOD FOR THE DETERMINATION OF SULFUR IN PYRITES CINDER By H. C. M O O R E Received August 26, 1915
Many methods for the determination of sulfur in pyrites, blendes a n d cinders have been proposed, b u t apparently no one of the methods thus far reported has been generally adopted. Some methods require costly apparatus, the expense of which is hardly justified in many laboratories; others require one or more standard solutions, which are hardly worth while for many analysts t o prepare, owing t o t h e few determinations t o be made. There have been proposed a few rapid methods requiring no expensive apparatus, and if standard solutions. only those found in every laboratory, b u t , for various reasons, no one of these methods has come into general use. The so-called rapid control methods may be divided into five classes as follows: I-Dry oxidation by fusion and subsequent precipitation as barium sulfate. 2-Dry reduction by heating with powdered metal, such as iron or aluminum or a mixture of the two, with the subsequent determination of sulfur by expelling as hydrogen sulfide and determining the latter volumetrically. 3-Direct combustion of cinder at high temperature, preferably in an electric tube furnace, collecting the sulfur as su!fur dioxide in standard alkali.’ 4-Heating the cinder with sodium bicarbonate of known alkalimetric value, leaching, filtering and determining the excess of bicarbonate.a j-Heating the cinder with a mixture of sodium carbonate and some oxide, such as zinc oxide, leaching and filtering, determining the sulfur gravimetrically as barium sulfate; or by precipitating in neutral solution with standard barium chloride, determining the excess of barium chloride by titration against standard sodium carbonate, using phenolphthalein as indicator.4 There are a few methods which will not fall in these classes, b u t in referring t o some of them, Lunge says on page 74, “Sulfuric Acid and Alkali,” Vol. I , P a r t I , “expeditious assays of pyrites have been proposed in many ways b u t none of t h e m are sufficiently accurate t o be employed for estimating t h e sulfur in fresh pyrites and some of t h e m are not even accurate enough t o test sulfur remaining in burnt ore.” T h e number of determinations t o be made, a n d t h e time permitted for a n analysis are t h e important factors in selecting t h e method t o be used. If a result is desired in t h e shortest possible time, probably t h e method of Nitchie, a n d its modification b y C o m e r stand preeminent. These methods, however, require a n 1
9 3
4
Nitchie. THIS JOURNAL, 4 (1912). 30. C o m e r , Ibid.. 6 (1913), 399. Lunge’s “Technical Chemists’ Handbook,” p. 113. Chem. Zlg., 37 (1913), 11Oi.
