| 单词 | allo-acid |
| 释义 | > as lemmasallo-acid 2. Chemistry. Prefixed to the name of an organic substance to denote another substance isomeric with it (sometimes with the implication of relative instability, or of a particular structural form), as allocinnamic, allomaleic (acids). Also prefixed to other words, as allo-acid, allo-compound, allo-form.Sometimes printed in italics (often with a hyphen). Cf. iso- comb. form 2. ΚΠ 1886 Jrnl. Chem. Soc. 50 688 It is proposed to use the prefix ‘allo’ for the less stable of two such isomerides: thus fumaric acid might be designated allomaleic acid, or the β-trimethylenecarboxylic acid of Conrad and Guthzeit as alloitaconic acid. 1890 Jrnl. Chem. Soc. 58 1417 Both iso- and allo-cinnamic acids are gradually converted into cinnamic acid on exposure to direct sunlight, but the change takes place less rapidly in the case of the allo-acid. 1894 Jrnl. Chem. Soc. 66 i. 173 The allo-form of cinnamylacrylic acid. 1912 J. J. Sudborough & T. C. James Pract. Org. Chem. xxxii. 302 Almost invariably one of the two stereoisomers is less stable than the other; this is frequently termed the allo-compound. 1949 S. Miall & L. M. Miall New Dict. Chem. (ed. 2) 21/1 With sterols and related substances the prefix allo- should indicate that rings A and B are in the trans position to each other, but allocholesterol is an exception. 1969 Science 24 Jan. 354/3 Since the configuration at the beta-carbon atom was not involved, not an antipod ( d-isoleucine or d-threonine) was formed but a diastereoisomer ( d-alloisoleucine and d-allothreonine). 2009 W. L. F. Armarego & C. L. L. Chai Purification Lab. Chemicals (ed. 6) iv. 264 When the allo-acid (m 68°) is heated at 20° above its melting point in a sealed capillary for 0.5 hours and allowed to cool slowly, Erlenmyer's iso-cinnamic acid m 42° is formed. < as lemmas |
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