Organic chemistry / by Frank C. Whitmore.

  • Frank C. Whitmore
Date:
1937
Catalogue details

Licence: In copyright

Credit: Organic chemistry / by Frank C. Whitmore. Source: Wellcome Collection.

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    depending on whether one or two mols of the diene react with the quinone (EP 650) (Rep. 1930, 88) (Allen, Ed. 1933). “Die Methoden der Dien-Synthese,” Alder, Berlin, 1933. The Diels-Alder reaction gives a good method for separating dienes from other materials and identifying them since the compounds with maleic anhydride are well crystallized and have characteristic melting points (EP 660). Butadiene-1,3 polymerizes to a rubber-like material. The small amount of it in the butylene fraction of cracked gases from gasoline manufacture offers a possible source for a rubber substi- tute (Brooks). Because of its tendency to gum formation, the determination of butadiene in petroleum gases is important (Tropsch 1934). One type of polymerization of dienes results in the formation of cyclic compounds and probably resembles the Diels-Alder reaction in being a 1,4-addition of the diene to a double bond in another molecule (Vaughan 1932). CH—CH CH = CH / \ / \ ch2 ch2 -> ch2 ch2 \ / CH2 = CH—CH = CH2 CH2—CH—CH = CH2 Isoprene, 2-Methylbutadiene-l,3, b. 37°, is the most important diolefin (EP 153, 635). It can be made by the destructive distillation of natural rubber (caoutchouc). Because it can be polymerized readily to rubber, many processes have been evolved for its preparation. The synthesis of rubber by these processes has not become commercial partly because their threat to the natural rubber industry has stimulated the improvement in the growing of plantation rubber to the point where it has sold as low as five cents per pound. Isoprene has been made by exhaustive methylation of /3- methylpyrrolidine. Some of the more interesting syntheses of isoprene follow: 1. Trimethylethylene, converted to the dichloride and then treated with alkali to remove 2 HC1. A difficulty here is the formation of 2-Me-3-chlorobutene-2 instead of the dichloride.
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