• Journal of the Korean Chemical Society
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• v.32 no.6
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• pp.557-566
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• 1988

The causes of failure in the deketalization of rigid ${\beta}$-aminoketals were separately investigated by examining the deketalization of 3 ketals, 2-ethylenedioxy-l-acenaphthenylamine (2), N-(2-ethylenedioxy-l-acenaphthenyl)acetamide(13) and trimethyl-2-ethylenedioxy-1-acenaphthenylammonium iodide(14), and by examining the deketalization of non-rigid ${\beta}$-aminoketal, 2-amino-l-ethylenedioxyacetophenone(19) and non-rigid aliphatic acetals, dimethylaminoformaldehyde dimethylacetal (20) and 2-aminoactaldehyde dimethyl acetal(21). While compounds 2 and 14 were not able to be hydrolyzed in the various acidic conditions 13 was easily deketalized. The result indicated the importance of electrostatic repulsion in the possible dicationic intermediates as a factor of failure in the deketalization. The observations of easy deketalization of compounds 19, 20 and 21 indicated that the structural characters of rigid $\beta-aminoketals$ are also important factors in the hydrolysis of ${\beta}$-aminoketals.

• Korean Journal of Food Science and Technology
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• v.20 no.2
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• pp.176-187
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• 1988

Volatile flavor components in the Chinese quince fruits were trapped by simultaneous steam distillation-extraction method, and these were fractionated into the neutral, the basic, the phenolic and the acidic fraction. In the identification of carboxylic acids, the acidic fraction was methylated with diazomethane. Volatile flavor components in these fractions were analyzed by the high-resolution GC and GC-MS equipped with a fused silica capillary column. The total of one hundred and forty-five compounds from the steam volatile concentrate of the Chinese quince fruits were identified: they were 3 aliphatic hydrocarbons, 1 cyclic hydrocarbon, 4 aromatic hydrocarbons, 9 terpene hydrocarbons, 17 alcohols, 3 terpene alcohols, 6 phenols, 21 aldehydes, 7 ketones, 28 esters, 27 acids, 3 furans, 2 thiazoles, 2 acetals, 3 lactones and 9 miscellaneous ones. The greater part of the components except for carboxylic acids were identified from the neutral fraction. The neutral fraction gave a much higher yield than others and was assumed to be indispensable for the reproduction of the aroma of the Chinese quince fruits in a sensory evaluation. According to the results of the GC-sniff evaluation, 1-hexanal, cis-3-hexenal, trans-2-hexenal, 2-methyl-2-hepten-6-one, 1-hexanol, cis-3-hexenol, trans, trans-2, 4-hexadienal and trans-2-hexenol were considered to be the key compounds of grassy odor. On the other hand, esters seemed to be the main constituents of a fruity aroma in the Chinese quince fruits.