July, 1922
T H E JOUR,VAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
619
Drying Oils from Petroleum and Other Products, Produced by Chlorination and Dechlorination' By Henry A. Gardner and E. Bielouss INSTITUTEOF PAINTAND VARNISHRESEARCH, 1845 B ST., N.W., WASHINGTON, D. C.
The following investigations were undertaken with the object of developing a commercial process f o r the production of a drying oil from petroleum, which could be used i n place of linseed oil in the manufacture of paints, linoleum, and printing inks, and in similar industries. The investigations, which have covered a long period of time, were successful f r o m a production standpoint, and the product is now being produced on a semicommercial scale f o r experimental use. Its drying value is equal to that of raw linseed oil. I t has, moreover, the peculiar property of polymerization to a solid, elastic mass when heated to high temperatures. It is also susceptible to vulcanization with surfur chloride to f o r m plastic products of interest. I t m a y be compounded with rubber and similar plastic m a t e r i a l . Unfortunately the color is very dark, and until a method is found of eliminating the color, its use i n paints will be Iimited to biack and very dark colors. For the latter purpose its durability has not proved entirely equal to that of linseed oil, when subjected to exterior exposure. I n general, however, good results have been obtained.
HE drying power of linseed oil is largely due to the absorption by the latter of oxygen through the instrumentality of the double carbon bonds. While polymerization of the unsaturated glycerides and coagulation of the oxidized glycerides may also play an important role in this process,2no evidence is a t hand to show that the carboxyl group of the acid or the hydroxyl radical of the glycerol has any bearing on the drying of the oil film. The problem of producing a drying oil from the abundant source of mineral oil could therefore find its solution in the preparation of unsaturated compounds from the natural oil. Theoretically, the following reactions are a t the disposal of the research chemist for this purpose:
T
1-Dehydrogenation, e. g., elimination of hydrogen from a saturated compound by the aid of metals a t high temperature,3 the reaction being a reversible one. 2-Elimination of water from compounds containing a hydroxyl group, as, for example, ethylene from ethyl alcohol. CzHsOH --t CHz=CHz
To this group belongs also the formation of unsaturated aldehydes by condensation of saturated ones, an aldnl being primarily produced, for example: 2CHsCHO
+ CHsCH(0H)CHzCHO
CHsCH=CH.CHO
3-By electrolysis of a dibasic acid, as, for example, ethylene from potassium succinate:
-CHCI-CH2-
---f
CHzCFl-
+ HCI
The first four reactions are possibly not applicable for commercial purposes. The last was first made use of in the process of the De Bataafsche Petroleum Maatschappij .6 CHLORINATION
As a suitable source for the production of unsaturated hydrocarbons, several hundred types were experimented with. While successful results were obtained with a number of these, one of the best was a fraction known as nonviscous neutral oil. In the absence of any definite information as to its chemical composition, it may be assumed that it consists chiefly of the hydrocarbons C1,H36 up to C2BH54,the lower members of this range predominating. A great many publications and patents are available on the subject of chlorination of lower and higher hydrocarbons of petroleum. The reactivity of the chlorine in the chlorinated hydrocarbons attracted the attention of many investigators in their desire to develop synthetic methods for the preparation of a number of industrially important products. Thus, Zilinslri6 chlorinated different fractions of Baku petroleum, subjecting' the products obtained to the Grignard reaction with the object of preparing fatty acids. C. F. Bochringer und Sohne* obtained resins by chlorination of petroleum. As a basis for the production of synthetic rubber, the Badische ilnilin und Soda Fabrikg systematically chlorinated and dechlorinated pentane, with the conversion of the latter into isoprene. Brooks,'O Oberfell, and Boyd1' prepared amyl acetate from chloropentane. Methyl chloride, chloroform, carbon tetrachloride, etc., were prepared by chlorination of natural gas.l2 McElroy13 has taken out a series of patents on the production of ethylene chlorohydrin by chlorination of ethylene. Dakin14 is chlorinating paraffin, using the chlorinated product as a solvent vehicle for chloramine-T. The methods applied for the direct chlorination by chlorine of paraffin hydrocarbons in the above and other processes all call for the aid of some catalytic agent in carrying out the absorption of chlorine. Water,16 sulfur, phosphorus, iodine, carbon tetrachloride; metals or their oxides, as iron;16 actinic 1ight;n porous materials to increase the efficient concentration of chlorine;18 sulfur dioxide, sulfur chloride and sulfuryl chloride,lo and silent electric discharges20 have been used. 'Brit. Patent 23,376,December 1, 1914. angew. Chem., 16 (1903),37. 7 French Patent 326,665,November 25, 1902. 8 D.R. P. 256,856,November 19, 1910; 258,156,December 28,1911. French Patents 435,312,October 14, 1911; and 452,246,December
e 2.
4-The partial cleavage of high molecuiar, saturated hydrocarbons into unsaturated a t high temperature, as in the cracking process for the production of g a ~ o l i n e . ~ &--The cleavage of halogen compounds by different methods into hydrogen halogens and unsaturated residue : Received April 26, 1922. P. Stransky, Z . angew. C h t m . , 84 (1921),8 6 . 8 M. Padra and U. Fabris, J . SOL.Chem. I n d . , 27 (1908),1083. 4 New Oil Refining Process Ltd., Brit. Patent 10,040, April 29, 1912. According to the claims in this patent, the unsaturated hydrocarbons formed can be utilized as siccative oils; see also Gawolowski, Oesterr. chem. tech. Z . , 70 (1910). 1 2
20, 1912 THIS 11
JOURNAL,
10 (1918), 511.
U.S.Patent 1,302,583,May 6, 1919.
Jones, Allison and Meighan, Bur. Mines, Tech. Paper 265. U. S. Patents 1,253,61517; 1,264,535;1,295,339;1,315,229. til J. A m . Med. Assoc., 69 (1917),24. 15 Bedford, U. S. Patent 1,245,553,uses water to remove the hydrachloric acid as fast as it is formed. 18 Ann., 225 (1884),196; 281 (1885),158. 17 U.S. Patent 1,191,916. Bur. Mines, Tech. Paper 265; U. S. Patent 1,380,067. 10 U. S. Patent 1,362,355. 10 U.S. Patent 1,012,149. If
la
THE JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
620
i l l these catalysts were tried out in our investigations. The writers found, however, that in the case of the neutral oils and other high boiling liquid paraffin hydrocarbons, the absorption of chlorine took place so smoothly a t the temperatures employed that no catalyst was required. The reaction involved in the chlorination of saturated hydrocarbons is one of substitution of hydrogen by the halogen, as evidenced by the following formula:
+ mClt
CnHtn+t
+ mHCl
= CnHan+z-mClm
As much chlorine is therefore evolved in the form of hydrogen chloride as is fixed by the hydrocarbon. The following factors have a marked influence on the speed of this reaction: VELOCITY OF CHLORINE-The chlorination is accelerated by the increase of the chlorine velocity up to a certain limit, while the coefficient of efficiency of the chlorine (C1 absorption:Cl input) decreases a t the same time. INFLUENCE OF TEiwERATuRs-With rising temperature the absorption of chlorine is accelerated. This holds true for temperatures up to a certain limit. Above this point another set of reactions comes into play, especially when the chlorination has progressed for some time. The chlorinated hydrocarbon splits off hydrochloric acid, forming an olefin. The olefin would add chlorine, then by splitting off hydrochloric acid would yield a molecule containing conjugated double bonds. This molecule in its turn, by addition of chlorine and subsequent dechlorination, would result in an unsaturated compound of a quite unstable double-allenic structure. The following formulas illustrate this sequence of reactions:
-
-CHr-CHCl-CHz-
a,,
z!
A
!+I
A i+l I
n
l
l
I
n+2
1
: CH-
/
-
I
1
I
n+1
n+2 I
2HC1 = -CH
+ 2C1z
=
11+2
l
l
I
I
i+3
1
n - t l n+2 n + 3
-CHCl-CHCl--CHCl-CHCl-
n
. CH-
: CH-CH
I
n
nSlnf2nf3
n
l
n+3
-CHz-CHCl-CHCl-CHCl-CHCl-CH-
n-1
: CH-
l
n i l n+2
I 1+1
?+2
-CH-CHCl-CHC1-CHz-
-CH:CH-CH
I
n
+ Clz = -CHt-CHCl-CHCl-
: CH-
-CH-CH
HC1 = -CH*-CH
i s 2
I
n+l
n+2
I
nf3
- 4HC1 =
I
n+4 -CH I
n-1
: CH-CII: I
n
I
n+l
C : C : CHI
I
I
n+2n+3n+4
The possibilities of formation of a cyclic compound or isomerization through intramolecular transformation or migration is thereby left out of considera tion. INFLUENCE OF ABSORBED CHLoRiNp-In the first stage when the amount of absorbed chlorine is insufficient to transform the whole of the hydrocarbons into the monochloro derivative, it is the concentration of the hydrocarbon in the monochloro derivative which may influence the further chlorination. If we figure, for the sake of convenience, the mean molecular formula of our hydrocarbon mixture as Cz0H42, about 12.5 per cent increase in weight is necessary for the formation of the monochloro derivative. The numerous experiments of the writers showed that there is no marked change in the rate of absorption of the chlorine up to a 15 per cent absorbed chlorine (15 per cent increase in weight of the hydrocarbon). Above this point the absorption slows down considerably, this lowering of the absorption progressing continually with the increasing concentration of the polychloro derivatives. With progresshg chlorination the velocity of chlorine has to decrease in order to keep the coefficient of chlorine efficiency (chlorine input: chlorine absorption) on the same level.
DECHLORINATION The means for the removal of the hydrochloric acid from a chlorinated hydrocarbon can be divided into the following two main groups: 1-Dechlorination by the action of alkalies (usually in1aqueous or alcoholic solution) on the halogen-containing hydrocarbons,
Vol. 14, No. 7
whereby the liberated hydrochloric acid is absorbed by the alkali. Besides the formation of olefins, this reaction yields ethers and alcohols.21 2-Dechlorination by heating the chlorinated hydrocarbons to a temperature above their dissociation point, usually a number of catalysts being applied to facilitate this dissociation. Th;s SabatierZ2passed the chlorides over divalent metals a t 260 Senderens23used alumina for this purpose. A number of patents based on these methods were taken out by the Badische Anilin und Soda Fabrikz4 for the preparation of isoprene and its homologs.
.
In the course of these investigations it was found by the writers that in the Case of the mixture of high molecular hydrocarbons, which is represented by the so-called neutraI oils, the dissociation point of the polychlorides lies between 1%'0O and 250" C., and that b y heating these chlorinated hydrocarboas up to 25O0C., a practically complete dechlorination can be effected without the aid of a n y other agent. This dissociation of the chlorinated hydrocarbon does not necessarily lead to the formation of olefins. While it hydrorarbon containing 35 to 36 per cent of chlorine should yield after dechlorination (the degree of dechlorination was accurately determined by the titration of a standardized sodium hydroxide solution in which the hydrochloric acid evolved was absorbed) an olefin possessing a Hanus or Hiibl number of 254, the iodine numbers always varied between 70 and 130. This phenonienon is due to the fact that olefins primarily formed undergo a further change in their nascent state, namely, transformation into cyclic compounds by a mutual saturation of their double linkages.25 The unsaturated hydrocarbons obtained by the above process thus consisted of a mixture of open-chain olefins and of cyclic hydrocarbons of a presumably saturated nature. These hydrocarbons were investigated in their behavior toward the following reagents: ACTION OF HzSOd-While the lower hydrocarbons give addition compounds with sulfuric acid, which through hydrolysis yield alcohols, the effect of this acid on our olefins consisted in a practically complete polymerization of the hydrocarbons; no watersoluble fraction could be extracted from the reaction product, The temperature range under which this reaction was tried was from - 5 " to + Z O O C. ACTION OF SzC12-The action of sulfur chloride can be twofold: (1) Addition to the double-linked carbon atoms, and (2) substitution, mainly of the hydrogen, with disengagement of hydrochloric acid. By allowing the sulfur chlorides to act in small portions and keeping the temperature of the reaction mass low, it was possible to add the chloride in amounts of 10 per cent t o 30 per cent of the hydrocarbons, with the formation of hard and brittle products. I n the presence of a t least 10 to 15 per cent of tung oil, rubber-like products were obtained, similar in appearance to certain of the so-called vulcanized oils. ACTION OF "Os-Concentrated nitric acid acts very vigorously on the product, causing the formation of polymerized masses. It was found possible to prepare chloronitro hydrocarbons by slowly adding the chlorinated hydrocarbons to a mixture of 1 part "Os (sp. gr. 1.42) to 4 parts HzS04 (66" BC.) and keeping the temperature fairly low. These chloronitro compounds contained from 3 to 4 per cent nitrogen. * ACTION OF ORGANIC ACIDS-Many unsaturated hydrocarbons are able to fix carboxylic acids a t higher temperatures, with the formation of esters, as represented by the formula: -c = c-
I
H
I
0.CO.R
Ann., 318 (1901), 1. Compt. rend., 138 (1904), 407. 23 Bull. soc. chem., [4] 3 (1908), 827; see also W. F. Faragher and F. H . Garner, J. Am. Chem. Soc., 43 (1921), 1715. 2 4 French Patents 435,312 and 434,586 (1911); D. R . P. 284,473 H and 255,538 (1913); U. S. Patent 1,221,382 (1917). 16 Schaarschmidt and Thiele [Bey., S3B (1920), 2128-431 observed that by dechlorinating a t higher temperatures chlorinated hydrocarbons of high molecular weight, the resulting olefins show a materially lower iodine number than those obtained by the action of alcoholic alkali. 21 22
