Diethylamine.hydrobromide

An amount of 40 g. of 2,3,4,6-tetra-O-acetyl-a-D-glucosyl bromide is warmed with 12 g. of diethylamine in 20 ml. of dry benzene at 60° until dissolved. (Benzene is often replaced by chloroform, and the initial warming is often omitted.) After 32 hours at room temperature, the reaction mixture is extracted with dry ether, and the diethylamine hydrobromide is removed by filtration. The filtrate is washed once with dilute sulfuric acid and twice with water and is dried over calcium chloride. After evaporation of the ether under diminished pressure, the residue is dissolved in the least possible amount of hot alcohol. Crystallization occurs after the addition, with stirring, of petroleum ether to the cooled solution. Yield of crude 2,3,4,6-tetra-0-acetyl-(2-hy-droxy-D-glucal), 17 g. (51% of the theoretical). Itecrystallization is effected from hot water or from ethanol with the addition of water to turbidity.1 2... 

Deprotection. The neopentyl protected sulfonyl group in 40 (4.57 g) is cleaved with an A-methylpyrrolidone solution (40 ml) of diethylamine hydrobromide (5.45 g, 35.4mmol) at 120 °C for 48 h to obtain 41, the acid form of the copolymer 40. After cooling to room temperature, the dark brown viscous reaction solution is poured into diethyl ether. Insoluble material is collected by... 

The spectra of Fig. 3-21 present the remarkable structure of p, of solid diethylamine hydrochloride and hydrobromide. All of the features in the spectral region 1600-2500 cm" are iapparently associated with p Not a single feature in this richly structured band is lost on cooling the sample to 4°K. 

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