June 1, 1914.] 



THE INDIA RUBBER WORLD 



481 



WHAT THE RUBBER CHEMISTS ARE DOING. 



[Exti'acts from recent articles on the Chemistry of Rubber which 

 have appeared in some of the foreign publications.] 



JELUTONG AND THE METHODS FOR SEPARATING ITS RESINS. 

 IN "Le Caoutchouc et la Guttapercha," No. 114, G. Noyer 

 * makes a contribution on "Jelutong and the Methods for 

 the Separation of Its Resins." According to Dubosc, a 

 previous investigator of this subject, trt-ating crude Jelutong 

 with acetone and ether, a product is obtained which after 

 repeated crystallization can be shown to consist of two sub- 

 stances. These substances differ (1) in their melting points, 

 which are respectively 80 degs. and 105 degs. C; (2) in their 

 boiling points, which are 255 degs. and 280 degs. C; (3) in 

 their solubility in acetone and chloral; (4) in their reaction 

 with nitric acid; (5) in their reaction with sulphuric acid. 

 These resins are completely unsaponifiabic and produce a 

 high optical rotation. The author believes that there is a 

 simple relationship between Cholesterin and the purified 

 Jelutong resins. The latter he regards as isomers of Phytos- 

 terin or Plant-Cholesterin. Cholesterin gives a characteristic 

 reaction with propionic anhydride, the so-called Cloez re- 

 action. By the action of this reagent on Cholesterin, a blue 

 color is obtained which turns green, orange and finally red. 

 On treating a sample of Jelutong resin, which has been puri- 

 fied by successive recr>'stallizations, with propionic anhydride 

 on the reflu.x condenser, the mass first of all becomes blue, 

 subsequently turns green, then orange and finally red. With 

 acetic anhydride a violet color is obtained which subsequently 

 turns black. The resulting resin propionate has a melting 

 point between 98 degs. and 100 degs. C. Cholesterin pro- 

 pionate melts at 98 degs. C. The resin acetate melts at 110 

 degs. to 112 degs. C. Cholesterin acetate melts at 113 degs. C. 

 The resin acetate, just as the Cholesterin acetate, is saponi- 

 fiable with boiling water, in the former case, the original resin 

 with correct optical rotation being obtained. 



Furthermore, the reactions of Jelutong resin with sulphuric 

 acid are analogous to those of Cholesterin. As a result of 

 these and further analogies between Cholesterin and Jelutong 

 resin, the author suggests a method of separation of the resin 

 from the rubber which is based on the well known properties 

 of Cholesterin with oxidizing agents. Potassium permanga- 

 nate, chromic acid, and sulphuric acid oxidize Cholesterin 

 to acids which are soluble in ammonia. Accordingly it is 

 suggested to take Jelutong and boil for three or four hours 

 with one of the above oxidizing agents. The resin is con- 

 verted into Cholesterin acid, which is easily separated from 

 the rubber by means of ammonia. The physical properties 

 of the residual rubber are claimed to be equal to those of 

 the rubber obtained by acetone extraction. 



If crude Jelutong is fractionally extracted with acetone in 

 a Soxhlet extractor, three distinct^products can be isolated, 

 melting respectively at 141 degs. C, 115 degs. C. and 103 

 degs. C. A mixture of equal parts of these resins melts at 

 82 degs. C. These three bodies are isomers, their chemical 

 composition being in accordance with the formula CmHijO. 



MR. DITMAR'S EXPERIMENTS WITH RUBBER SUBSTITUTES. 

 In the "Gummi Zeitung," Vol. 28, page 998, R. Ditmar pub- 

 lishes an investigation on Factis (rubber substitute). The 

 author describes an apparatus for measuring the elasticity 

 of substitute, the principle of which is as follows : A small 

 cylindrical vessel is charged with the pulverized substitute. 

 A closely fitting metal plate is then inserted into the cylinder 

 so that it lies on top of the substitute. The plate is con- 

 nected by means of a vertical rod with a second horizontal 

 plate, which latter faces a scale. On this top plate a given 

 weight is put, the compression of the substitute being noted 

 on the scale. The weight is then released and tlie return 



again noted. This return is regarded as being proportionate 

 with the elasticity. 



The author carried out a very large number of experiments 

 lor the purpose of determining the nature of the products 

 obtained by varying the amount of sulphur, the length of the 

 period of heating, the state of oxidation of the vegetable oil, 

 and the addition of paraffin wax and mineral oil. 



Considering nonoxidizcd rape seed oil and sulphur, it was 

 found that a product containing 32 per cent, sulphur on the 

 weight of the oil gave the most desirable substitute. If oxi- 

 dized oil is used, it was found that equally good results can 

 be obtained by using much less sulphur, only about 22 per 

 cent, being necessary to give a very good product. The rape 

 seed oil is oxidized by blowing air through the oil for a 

 period of five hours, the oil being heated to 250 degs. C. For 

 the purpose of studying the action of mineral oil on substitute 

 the author worked with a mi.xture containing 100 parts non- 

 o.xidizcd oil, 26 parts of sulphur, and mineral oil in propor- 

 tions from 5 to 10 parts. The samples when freshly prepared 

 did not look very favorable, but on standing for several weeks 

 the products had become sufficiently hard to be available for 

 genera! manufacturing purposes. Using oxidized oil on the 

 contrary, it was found that the addition of mineral oil in 

 amounts in the neighborhood of 5 per cent, yielded products 

 which were sufficiently firm, even immediately after manufac- 

 ture, to be available for manufacturing purposes. 



Another series of experiments was carried out using 28 

 parts of sulphur for 100 parts of oil, and it was again found 

 that in the case of the oxidized oil it was possible to add 

 a larger amount of mineral oil than when nonoxidized oil was 

 used. 



The author finally studied the addition of paraffin wax to 

 substitute made from oxidized and nonoxidized rape seed 

 oil. In this case it was found that the amount of sulphur 

 added to the oil was a determining factor as to whether the 

 addition of paraffin gave satisfactory results or not. Using 

 24 per cent, of sulphur on the weight of the nonoxidized oil, 

 as much as 15 per cent, paraffin was found to give a satisfac- 

 tory substitute, whereas in the case of the oxidized oil this 

 proportion of paraffin was found to be exceedingly unsatis- 

 factory. On the other hand, using 26 per cent, sulphur on 

 the weight of the nonoxidized oil with the addition of 5 per 

 cent, paraffin wax, there resulted very unsatisfactory prod- 

 ucts, whereas the oxidized oil in this case, even with 10 per 

 cent, paraffin wax, gave fairly good results. Similar anomalies 

 were noted in two other series of experiments using 28 per 

 cent, sulphur and 30 per cent, sulphur on the weight of the oil. 



The author also carried out analyses on many of the sub- 

 stitutes which he prepared, determining the loss of sulphur 

 owing to volatilization in the heating process, the total sul- 

 phur in the substitute, the free sulphur and also the free oil. 

 It was found that the volatilization of the sulphur was uni- 

 formly greater in the case of the nonoxidized oils than in 

 the case of the oxidized oils. This is attributed to the higher 

 viscosity of the oxidized oils. The substitutes manufactured 

 from the nonoxidized oils had higher free oil and free sul- 

 phur contents than those products manufactured from the 

 oxidized oils. From the nature of an oxidized oil, one would 

 expect just the reverse to be true regarding the free sulphur 

 content. It is supposed that the oxidation of an oil results 

 in the addition of oxygen to some of the unsaturated double 

 bonds present in the oil. An oxidized oil, therefore, is more 

 saturated than nonoxidized oil and one would therefore 

 expect it to be less capable of adding sulphur. But just the 

 reverse is found to be true. 



VARIOUS SYNTHETIC RUBBER PATENTS. 

 British Patent No. 21,173, 1912, has been granted D. Spence, 

 A. P. Clark and the Diamond Rubber Co. for "Improvements 



