| 释义 |
isoprene|ˈaɪsəʊpriːn|
[f. iso-, perh. + propylene.]
a. 2-Methyl-1, 3-butadiene, CH2:C(CH3)CH:CH2, a colourless liquid obtained by the destructive distillation of rubber and from petroleum and used in the manufacture of certain synthetic rubbers.
1860C. G. Williams in Phil. Trans. R. Soc. CL. 244, I have given the substance thus examined the name of isoprene. Ibid. 249 Isoprene combines explosively with bromine. Ibid. 255 The isolation of isoprene, C10H8. 1867Bloxam Chem. 481 Heated in a retort, caoutchouc is decomposed into several hydrocarbons, one of which, called isoprene, boils at about 100°F. 1906Westm. Gaz. 8 Sept. 10/2 In forming caoutchouc from isoprene, the great problem is already practically solved. 1957Technology July 176/3 By the use of Ziegler catalysts..Goodrich-Gulf were able to synthesize from isoprene a polymer almost identical with natural rubber. 1972P. Wiseman Introd. Industr. Org. Chem. vii. 253 More important than high molecular weight homopolymers of isobutene are copolymers with 1·5 to 4·5% of isoprene, known as butyl rubber.
b. attrib., as isoprene rule, the rule that the carbon skeleton of a terpene is made up of isoprene units linked together; isoprene unit, the arrangement of five carbon atoms found in the isoprene molecule (the single or double nature of the bonds between them being disregarded).
1926C. K. Ingold in Proc. Leeds Philos. & Lit. Soc. (Sci. Sect.) I. 11 It is known..that the carbon skeletons of all terpenes of established constitution can empirically be built up from the skeleton of isoprene, the common product of thermal degradation of almost all terpenes. Divisibility into isoprene units may therefore be regarded as a necessary condition to be satisfied by the structure of any plant-synthesised terpene product. 1931J. L. Simonsen Terpenes I. p. xii, An apparent exception to the ‘isoprene rule’, the hydrocarbon, sylvestrene, has been shown not to be a plant product. 1942Fuson & Snyder Org. Chem. xxvii. 358 Caoutchouc is composed of the isoprene unit repeated over and over. Ibid., The occurrence of isoprene units is so general that investigators of the structures of natural products generally consider the most probable formula of an unknown compound to be that which contains the maximum number of isoprene units. 1959L. Ruzicka in Proc. Chem. Soc. 343/2 Up to 1921, the idea that the higher terpenes are structurally composed of isoprene units was not used as an accepted working hypothesis. 1967Nature 18 Nov. 642/2 The occurrence of a series of hydrocarbons, with structures based on the C5H8 isoprene unit, has been invoked as evidence for life-forms in Pre-Cambrian times. 1971J. D. Roberts et. al. Org. Chem. xxix. 779 The empirical isoprene rule resulted from Ruzicka's observation that the majority of the terpene families could be considered as arising from head-to-tail combinations of isoprene units. |