T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
75 0
sults from samples Nos. 9, 1 2 a n d 18, Table I , a n d disks Nos. I and 2 , Table 11. This suggests t h e possibility of obtaining considerably larger yields of ethyl alcohol from slabs a n d edgings t h a n from mill-run sawdust. According t o Fischer,' when 0.1 g. of mannose hydrazone is dissolved in I cc. of concentrated cold hydrochloric acid, j cc. of r a t e r immediately added, and t h e solution examined in t h e polariscope using a I dcm. tube, t h e d-compound gives a rotation of I . z " t o t h e left. The crude mannose phenylhydrazone obtained from Pinus lambertiana was recrystallized three times from dilute alcohol. Two different samples of t h e hydrazone purified i n this way, using t h e proportions given b y Fischer, h a d t h e rotations -0.657 O and -0.796". Lindsey a n d Tollens2 found -0.761" for t h e mannose hydrazone obtained from sulfite liquor. 4 portion of t h e practically colorless hydrazone was heated with phenylhydrazine acetate in aqueous solution for I . j hours on t h e steam bath. The yellow osazone obtained, after recrystallization from 60 per cent alcohol, melted at 103-4'.
FIG.
I-MANNAN CONTENT
RADIAL SECTION OF
OF
SUGAR P I N E
A sugar solution obtained by t h e hydrolysis of white spruce was treated with phenylhydrazine acet a t e in t h e manner described above a n d allowed t o stand over night. T h e hydrazone obtained was so very impure t h a t a quantitative estimation of mannose was impossible. T h e hydrazone was dissolved in 7 5 per cent alcohol, t h e solution filtered, a n d allowed t o crystallize. After these operations had been repeated four times t h e crystals melted at 186-8". It is proposed t o extend this investigation t o other species a n d determine if t h e amount of mannan in a given tree actually varies throughout t h e year. T h e statement of Czapek3 t h a t mannans always belong t o t h e reserve hemicelluloses requires confirmation. It is very questionable if t h e mannans, especially those occurring in t h e heartwood of trees, can be considered as reserve food materials. SUMMARY
I-The results of t h e examination of z z different species of Gymnosperms and 6 species of Angiosperms show mannan t o be present in appreciable quantities in all t h e conifers b u t absent from t h e hardwoods. 11-It appears t h a t t h e mannan content of t h e sapwood is generally larger t h a n t h a t of t h e heartwood; mannan decreases from t h e base upwards b u t remains 1
Ber., 23 (1890), 384.
2
Ann., 267 (1892). 350.
a "Biochemie der Pflanzen," Zweite Auflage, p. 657.
Vol. 9 , NO. 8
uniform throughout t h e heartwood i n a radial direction. 111-Mannan is of industrial importance in t h e production of ethyl alcohol f r o m sulfite liquor a n d by t h e hydrolysis of sawdust with catalyzers. FORESTPRODUCTS LABORATORY M A D I S O N , WISCONSIN
THE PREPARATION OF ETHYLENE GLYCOL BY
BENJAMIN
T. BROOKS AND
IRWIN
HUMPHRSY
Received May 15, 1917
The preparation of ethylene glycol has usually been effected through t h e hydrolysis, under different conditions, of ethylene bromide. T h e reason t h a t ethylene bromide has nearly always been employed probably lies in t h e kact t h a t this substance is easily made in t h e laboratory. However, Nef pointed out, long since, t h a t alkyl bromides a n d iodides generally give larger proportions of olefines t h a n t h e chlorides and t h a t t h e latter derivatives invariably give t h e better yields in t h e so-called double decomposition reactions. Aqueous or alcoholic caustic alkali converts ethylene bromide almost quantitatively into vinyl bromide. Very good yields of ethylene glycol, about 7 0 per cent of t h e theoretical, can be obtained, starting with ethylene bromide, b y passing through t h e diacetate, and even higher yields are said t o be obtainable by employing t h e dibromide and aqueous silver carbonate. I n view of t h e relatively high cost of t h e materials (potash salts, bromine, etc.) required b y t h e methods heretofore published, we have developed a method which permits t h e easy preparation of ethylene glycol in large quantities a t low cost. For a starting point, ethylene chloride was selected in preference t o t h e bromide, owing t o t h e cheapness of chlorine and t h e ease with which ethylene, from alcohol or oil gas, may be converted into t h e dichloride.' T h e method which we have developed consists in heating a mixture of ethylene chloride, sodium formate a n d methyl alcohol t o 165' C. in a suitable autoclave. An excess of methyl alcohol, six mols or more, is employed in order t h a t t h e alcoholysis of t h e glycol formate may be very nearly quantitative. -4s contrasted with t h e older methods, i t will be noted t h a t potassium salts have been replaced b y sodium formate, a n d methyl acohol is employed as a solvent. When this alcohol is employed in t h e reaction mixture, t h e isolation of t h e glycol ester is unnecessary since alcoholysis of t h e glycol formate occurs. This is a special development of Henry's2 studies on t h e equilibria in mixtures containing a n organic acid and two alcohols, and was apparently first employed as a preparative method by Nef, who made acetol in this way. The reaction may be carried out in a simple steel, or preferably, copper-lined autoclave. 1 Very pure ethylene chloride can be prepared if the chlorine-ethylene reaction mixture is kept cold. The reaction develops considerable heat and, if not cooled, large proportions of trichlorethane are formed. In a small apparatus, proper cooling can be easily effected by mixing the gases in a glass or metal coil surrounded by cracked ice. The gases should not be dried. A private communication from Mr. K. P . McElroy states that very dry ethylene and chlorine may coexist for a long time without reacting. 2 Bull. acad. roy. mad. belg., 1902, 445.
T H E J O U R N A L O F I N D U S T R I A L A N D E ;VGI N E E RI N G C H E M I S T R Y
A%., 1917 CHzCl ~
CHzCl
-
CHzOzCH
+2HCOsXa+
CHiOzCH
I
CHzOzCH
4- 2CHsOH
I
CHzOzCH CHzOH L O H
+ 2KaC1
(1)
+ 2HCOzCHz
(2)
+
By employing considerable excess methyl alcohol t h e equilibrium is maintained by proportionately more glycol formate being converted t o glycol, which amounts in t h e experiments here noted t o about 8 j per cent conversion. E X P E R I ME N T A L
The experiments tabulated below indicate t h a t t h e conditions for maximum yields are: heating t h e reaction mixture, consisting of one mol of, ethylene chloride in five volumes of methyl alcohol a n d about three mols of sodium .formate, t o a temperature of 1 6 j t o 170' C. for about 7 hrs. At this temperature t h e pressure will vary from about 2 4 0 lbs. at t h e beginning t o 290 lbs. per sq. in. after 7 hrs., and a pressure, when cold, of about j o lbs., which.latter pressure is undoubtedly due t o t h e decomposition of a small amount of sodium formate. When autoclaves of several liters capacity are employed, i t is highly desirable t o stir t h e contents, which is most simply done by slowly rotating t h e autoclave.' Above 1 7 j ' C. large proportions of diglycol are formed as is shown b y Experiments 19 a n d 2 7 . TABLE I-YIELD
GLYCOL BY ACTION OF SODIUM FORMATE A N D METHYL ALCOHOL O N ETHYLENE CHLORIDE KO.O F MOLSUSED TREATMENT PRESSURE YIELD Exp. Ethylene Sodium Methyl Temp. Time Max. Cold Per cent of ,No. Chloride Formate Alcohol Lbs. Lbs. Theoretical C. Hrs. 13.0 105 4 3 45-5 0 5 2.5 13.0 140 8 100 * 5 15 32 16 2.5 165 7 13.0 195 * 5 25 55 7 2.0 165 7 13.0 220 * 10 30 65 10 2.5 250 70 6.5 170 5 4 10 25 17 2.5 12 165 f 5 7 13.0 82 260 10 55 4.0 60 165 f 5 8 29 13.0 .... 40 4.0 60 240 * 10 40 1,O f 5 6 28 13.0 4.0 1 . 5 250 * 10 0 li5 f 5 15 6.5 21 2.5 35 5 4 10 , . 165 6.5 220 23* 2.5 13.0(c) 160 f 5 8 79 2.7 .... .. 24t 175 f 5 7 13.0 2.7 .... ,. 19t .... .. 180 f 10 10 13.0 2.7 27t * 5 grams HgSOd added. t In rotating autoclave. ( a ) 40 grams. ( b ) 300 grams. (c) 1500 cc. ( d ) 18 per cent "diglycol" also obta.ined. (e) 35 per cent "diglycol" of b. p. ;215 to 250' C. also obtained. OF
f
f
f
-
Ex?
T h e general procedure for isolating t h e glycols was as follows: After cooling, t h e slight "cold pressure" was released, t h e methyl alcohol solution poured from t h e crystalline salt and sodium formate mixture, t h e latter washed with a little cold methyl alcohol and t h e combined alcoholic solution distilled. GLYCOL F R O M ETHYLENE CHLORIDE B Y THE ACETATE METHOD TREATMENTPRESSURE GRAMSMATERIALS USED YIELD Temp. Time in Exp. Ethylene Sodium Sol-. Per cent of C. Hrs. Lbs. No.Chloride Acetate vent Theoretical 4 50 115 75(a) 170 f 5 4 150 * 10 32(c) 5 8 175 f 10 34(c) 6 50 115 75(a) 185 7 110 37(d) 8 65 65 110(b) 160 ( a ) Acetic acid. ( b ) Ethylalcohol (sp. gr. 0.83). (c) Diacetate hydrolyzed by alcoholic HCl: see Henry, Chem. Zentr., l ( 1 9 0 7 ) . 1314. ( d ) This method yields the monoacetate: cf. Erlenmeyer, Ann., 192, 244; Demole. A n n . , 173, 117.
TABLE11-YIELD
OF
f
I n some cases t h e methyl alcohol was distilled a t ordinary pressure a n d t h e glycol then distilled in vacuo. I n most cases, however, t h e glycol was distilled a t atmospheric pressure. 1 This keeps the contents well mixed, prevents the formation of a salt cake in the bottom of the apparatus and very materially improves the yield as has already been shown by us in the case of the preparation of amyl acetate from chlorpentane, anhydrous sodium acetate and acetic acid. Cf. U. S. Patent No. 1,197,019.
751
The reaction of ethylene chloride with sodium acet a t e in glacial acetic acid takes place less readily, as is indicated by t h e lower yields in Experiments 4 and 6 in Table 11. A very small fraction boiling between 170' and 180' C. was always obtained, amounting usually t o 8 t o I O per cent of t h e weight of t h e dichloride employed, which consisted of glycol diformate, boiling point 174' C.' Saponification of I O g. of this ester yielded 7 . j g. of glycol, boiling point 190-196' C. MELLON INSTITUTE O F I N D U S T R I A L RESEARCH O F PITTSBURGH, PITTSBURGH, P A . UNIVERSITY
IODOMETRIC DETERMINATION OF CHLORINE I N CHLORIDES By GREGORY TOROSSIAN
Received May 10, 1917
With t h e object in view of determining chlorine in chlorides quickly and accurately and without t h e use of silver nitrate, t h e well-known method for valuation of the available N n O s by iodine was applied. I n t h e determination of t h e available MnOz b y iodine t h e sample is treated with a quantity of hydrochloric acid in a small distilling flask, t h e liberated chlorine is carried through a glass tubing into a solution of potassium iodide and t h e liberated iodine is titrated with a N / I O sodium thiosulfate solution. I n t h e proposed method for t h e determination of chlorine in chlorides t h e sample is mixed with finely powdered manganese dioxide, a n d treated with sulfuric acid ( I : I by vol.) in a distilling apparatus, as in the MnOz determination, and t h e chlorine, produced by t h e interaction of M n 0 2 and t h e HC1 set free from t h e chloride sample by the action of HzS04, is conducted into a K I solution a n d the liberated iodine titrated as usual with N / I O Ka2S2O3. I n this reaction between sulfuric acid and a chloride in t h e presence of l l n O z , t h e chlorine from t h e chloride is all distilled off, t h e spent liquor showing no chlorine when tested with A g S 0 3 . The reaction appears t o be: 2XaC1
+ 2HzS04 + MnOz = NazSOd + MnSOA + 2Hz0 + CL. LIETHOD
I ) Finely ground MnOz (passing Ioo-mesh sieve). ( 2 ) Sulfuric acid ( I : I by vol.) free from nitric, hydrochloric acids, nitrates and nitrous fumes, etc. (3) Potassium iodide solution, 2 j grams per liter. (4) X/IOsodium thiosulfate solution.
T H E R E A G E K T S REQUIRED-(
T H E A P P A R A T U S used is the same as in t h e case of MnOz determination b y distillation with hydrochloric acid and is shown in t h e accompanying sketch
T H E S A X P L I N C in this method is very important. In t h e case of solids t h e sample must be finely powdered t o insure intimate mixing with t h e manganese dioxide. If this is not done, there may occur a loss of chlorine during t h e operation or incomplete decomposition of t h e chloride. I n t h e case of liquids the sample must be measured from a burette if percentage by volume is required or weighed in t h e flask directly without adding any water. The amount of sample to be taken 1
Grimaux. Bw., 1 (1874). 263.
