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Substituent effect and rearrangements in the electron-impact spectra of long chain esters of m-and p-methoxybenzoic acid

✍ Scribed by Mitchell A. Winnik; P. Y. Y. Kwong

Publisher
John Wiley and Sons
Year
1975
Tongue
English
Weight
440 KB
Volume
10
Category
Article
ISSN
1076-5174

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✦ Synopsis

Abstract

The mass spectra of eighteen n‐alkyl estars of p‐methoxybenzoic acid are examined. Few differences exist in the spectra of the corresponding para and meta isomers. We describe a new rearrangement, loss of OH from the molecular ion, whichis observed only in the para substituted isomkers. Oxygen‐18 labeling indicates that the oxygen lost in the [MOH]+ ion derives from the carbonyl. No indication is found of hydrogen abstration from the chain by the methoxy group competing withthe benzoate ester rearrangement. We find a substituent effect on that rearrangement, with electron‐donating groups decreasing the values of [ArCO~2~H~2~]^+^/[ArCO~2~H]^+^· ion ratios. this ratio decreases as the ester chain length increases.

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