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Organic Lab Reactions 179

Organic Lab Reactions 179 - CYCLIZATION In an acylation...

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174 THE FORMATION OF CYCLIC KETONES TABLE XIII SOME CYCLIZATIONS BY HEATING THE FREE ACID CHLORIDES Acids Submitted to Cyclization P-Phenylpropionic acid 3,4-methylenedihydroxy- y-PhenylbiUyric acid a-benzyl- 2,4-dimethyl- 3,4-methylenedihydroxy- S-Phenylvaleric acid 3,4-methylenedihydroxy- y-1-Naphthylbutyric acid 4-methoxy-6-methyl- 4-methoxy-5,6,7,8-tetrahydro- 5,6,7,8-tetrahydro- •y-2-NaphthyIbutyric acid 5,6,7,8-tetrahydro- Yields of Ketones («) — (b) 60% (6) 40% ( o ) - Failed (o) 55% (c)(6)65% (d) 50% 88% (6) 67% ( d ) - (b)(e) 83% Reference 86 6 15 86 86 86 234 161 234 60 234 235 59 (o) Phosphorus trichloride used to form the acid chloride. (6) Phosphorus pentachloride used to form the acid chloride. (c) Twelve per cent acid recovered. (d) Thionyl chloride used to form the acid chloride. («) Mixture of ketones (see p. 175). THE INFLUENCE OF THE METHOD ON THE DIRECTION OF CYCLIZATION In an acylation reaction which gives a mixture of isomeric ketones,
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Unformatted text preview: CYCLIZATION In an acylation reaction which gives a mixture of isomeric ketones, the proportion of these isomers can sometimes be altered more or less by changing (a) the solvent, (6) the temperature, and (c) the entire method of acylation. To what extent the proportion of products may be altered, if at all, by such experimental changes cannot be predicted. The influence of the above factors on the course of the reaction has been demonstrated for intermolecular acylation. Changing the solvent from benzene to nitrobenzene in the Friedel-Crafts acetylation of naphthalene makes it possible to obtain principally the /3-isomer instead JM Schroeter, Miiller, and Huang, Ber., 62, 645 (1929). 236 Radcliffe, Sherwood, and Short, J. Chem. Soc., 1931, 2293....
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