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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 13, Number 1
JKCSEZ 13(1)
February 20, 1969 

Studies on Tropolones (Ⅰ) The Synthesis of 4-Ethyltropolone from Cyclopentadiene and Its Spectroscopic Characteristics

Tropolone 류에 관한 연구 (Ⅰ) Cyclopentadiene으로부터 4-Ethyltropolone의 합성과 그 분광학적 특성
Jae Hu Shim

4-Ethyltropolone has been prepared in three steps from cyclopentadiene by a dichloroketene process, and at the same time, a comparison has also been made with the case of tropolone synthesis. In the addition reaction of dichloroketene to cyclopentadiene as well as to ethylcyclopentadiene, and also in the separation of cycloadducts from reaction mixture, the best results were given by prevention of the reactants from dimerization. Under these condition, the yields of cycloadducts were around 70% for both. Tropolone and 4-ethyltropolone were obtained in the yield of 51% and 32%, respectively, by hydrolysis of cycloadducts with potassium acetate in aqueous acetic acid. These results revealed that the steric effect of ethylgroup was more sensitive to the hydrolysis than to the cycloaddition reaction. A comparison of UV, IR and NMR spectroscopic results of 4-ethyltropolone with those of tropolone was also made together with a brief discussion of the tropolone ring system and ethylgroup effect.
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