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.

    76/1104 page 60
    glycol, formed by the bimolecular reduction of acetone. Its poly- merization by aniline hydrobromide as a catalyst gives methyl rubber used as a rubber substitute during the World War. It is inferior to natural rubber in many respects. The chief product with HBr is Me2C = CMeCH2Br, formed by 1,4-addition. The influence of methyl groups on the polymerization of substituted butadienes has been studied (Whitby, Rep. 1932,113). Pentadiene-1,3, piperylene, CH3CH = CH —CH = CH2, b. 43°, has been obtained by the exhaustive methylation of piperidine, hexahydropyridine. This would be expected to give the 1,4-diene. (EP 637.) l,4-Me2-butadiene-l,3 adds HBr to give MeCH2CHBrCH= CHMe and MeCH2CH = CHCHBrMe in 9 : 1 ratio. Thus the chief addition is 1,2. This may be in- terpreted as indicating that there is less tendency for the group •j; Me — CH2 — CH — CH = CH — Me to undergo the allylic rearrangement to form * Me — CH2 — CH = CH — CH — Me than for * Me — CH — CH = CH2 to change to Me — CH = CH — CH2* as in the 1,4-addition to butadiene. Higher alkylated dienes of the type, Me2C = CHC(Me) = CHR, can be made by dehydrating the product of mesityl oxide with RCH2MgX. The best substitute for isoprene for rubber manufacture is chloroprene, 2-chlorobutadiene-l,3, (p. 98) which polymerizes more readily than isoprene and gives a rubber (Neoprene) superior
    digitised image 1
    digitised image 2
    digitised image 3