Organic 2 Review Problem 254

Organic 2 Review Problem 254 - 238 PRACTICAL ORGANIC...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
238 PRACTICAL ORGANIC CHEMISTRY tetrachloride slowly from the dried product and then collect the ester as the fraction boiling at 269-272°. Yield, 17 g. Ethyl cinnamate is a colourless liquid of b.p. 271° and d , 1-05; it possesses a pleasant and characteristic odour. i,8-Diphenyloctatetrene. C 6 H 5 CH:CH(CH:CH) 2 CHiCHC 6 H 5 . This reaction illustrates one of the methods by which R. Kuhn synthesised long polyene chains terminated at each end by phenyl groups. When cinnamaldehyde, succinic acid and acetic anhydride are heated in the presence of litharge (PbO), the aldehyde and the succinic acid condense to give the dicarboxylic acid (I), which undergoes decarboxylation to give the pale yellow crystalline i,8-diphenyloctatetrene (II). Kuhn has shown that as the PhCH:CH-CHO + H 2 C CH, + OCH-CH:CHPh I I COOH COOH I PhCH:CH-CH:C C:CH-CH:CHPh I i COOH COOH (I) I PhCH:CH-CH:CH-CH:CH-CH:CHPh (II) length of the polyene chain increases in such compounds, the colour steadily darkens, and becomes red when the chain contains 9 double bonds. Although a compound such as (II) could theoretically exist in a number of
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.

Ask a homework question - tutors are online