Dulcitol 1,3:4,6-dibenzylidene

The nature of the condensation product derived from any given pair of reactants is frequently independent of the type of catalyst used, but this is not always the case. Haskins, Hann and Hudson, for example, demonstrated that at room temperature hydrogen chloride catalyzes the formation of a 2,3,4,5-dibenzylidene derivative of 1,6-dibenzoyl-dulcitol,... 

The benzylidenation of 1,6-dibenzoyl-dulcitol gives rise to one of two products, depending upon the conditions of the reaction. The use of gaseous hydrogen chloride at room temperature for 12 hours, or of zinc chloride at 60° for 24 hours, results in the formation of a dibenzoyl-dibenzylidene-dulcitol, which melts at 119-120° and which, when treated with sodium methoxide, gives a dibenzylidene-dulcitol melting at 149-1500.1 On the other hand, when the condensation is catalyzed by zinc chloride at room temperature, the main product is an isomeric dibenzoyl-dibenzylidene-dulcitol, which melts at 147-148° and which can be saponified to a dibenzylidene-dulcitol melting at 173-174°. The unstable dibenzoyl-dibenzylidene-dulcitol (m. p. 147-148°) is converted into its stable isomer (m. p. 119-120°) by treatment with zinc chloride and benzaldehyde at 60°, Four independent lines of evidence reveal that,... 

A l,6-ditrityl-2,3,4,5-dibenzylidene-dulcitol (m. p. 233-234°), prepared by Wolfrom, Burke and Waisbrot9 from 1,6-ditrityl-dulcitol and benzaldehyde in the presence of zinc chloride at room temperature, resembled, as might be expected, the ditrityl ether (m. p. 240-242°) derived from the higher-melting (m. p. 173-174°) 2,3,4,5-dibenzylidene-dulcitol reported above. 

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