0-Alkylation alkyl sulfate-alkali method

A better method for studying the alkali metal cation-soap anion interaction on the surface, according to Weil (58), is to assume a similarity between surface behavior and solution behavior and to use the activity coefficient of the solute in the solution as the parameter to account for surface behavior. By plotting activity coefficients as a function of the molality for the salts of the alkali metals (7, 26), the resulting order of the curves of the weak acids (formates, acetates, hydroxides) is the reverse of that found for the strong acids (chlorides, bromides, nitrates, chlorates, sulfates). The activity curves of the acetate salts can be used as the counterparts for the long-chain fatty acid salts, while those for the chlorides can be the analogs of the alkyl sulfates. The scheme is speculative in that the fatty acid and alkyl sulfate salts micellize, and acetate and chloride do not. 

Treatment of alkylating agents with metal cyanides should in principle be the method of choice for preparing isocyanides (equation 25). But as the cyanide ion again represents an ambident nucleophile, the well-known problems already discussed will arise (Section 1.8.2.1.i). It remains to be stated that simple alkylation of alkali metal cyanides with halogen compounds or dialkyl sulfates is not useful for the preparation of isonitriles. The formation of nitriles always prevails and isocyanides are at best obtained in yields of up to 25%. " The prospects are much tetter in the alkylation of heavy metal cyanides, if the reaction is done under conditions which initially give rise to isocyanide-transition metal complexes (equation 26). These will then be transformed into isonitriles by treatment with KCN. Under optimized conditions this technique yielded 55% of ethyl isocyanide. ... 

Sulfates having alkyl groups from methyl to pentyl have been examined. With methyl as an example, the hydrolysis rate of dimethyl sulfate increases with the concentration of the sulfate. Typical rates in neutral water are first order and are 1.66 x 10-4 s-1 at 25°C and 6.14 x 10-4 s-1 at 35°C (46,47). Rates with alkali or acid depend on conditions (42,48). Rates for the monomethyl sulfate [512 42-5] are much slower, and are neady second order in base. Values of the rate constant in dilute solution are 6.5 x 10 5 L/(mol-s) at 100°C and 4.64 x 10-4 L/(mol-s) at 138°C (44). At 138°C, first-order solvolysis is ca 2% of the total. Hydrolysis of the monoester is markedly promoted by increasing acid strength and it is first order. The rate at 80°C is 3.65 x 10-4 s-1 (45). Alkaline solvolysis has been studied by a calorimetric method (49). Heat of hydrolysis of dimethyl sulfate to the monoester under alkaline conditions is 106 kj/mol (25 kcal/mol) (51). 

Ethylenimine is conveniently prepared from ethanolamine by heating the inner salt of the sulfate ester with aqueous alkali (37%). The method has been applied to other /3-amino alcohols to form the C-alkyl homologs of ethylenimine in which one to three of the four hydrogens may be substituted. The general procedure is illustrated by the synthesis of 2,2-dim ethyl ethylenimine (51%). The N-alkyl analogs can be made by treating the N-alkylethanolamine hydrochlorides with chlorosulfonic acid followed by the action of base on the intermediate sulfuric acid esters, as in the preparation of N-ethylethylenimine (70%). ... 

In carbohydrate trityl ethers and the partially acylated carbohydrate derivatives obtained from them, the free hydroxyl groups may be etheri-fied with other alcohols. This method has been used repeatedly, particularly for the preparation of partially methylated compounds. With the alkali resistant trityl ethers, any alkaline alkylation method may be used, for example, dimethyl sulfate and alkali, or methyl iodide and silver oxide. In choosing an alkylation method for partially acylated compounds, one must be selected which does not cause acyl migration or saponification. 

A. Alkylation Methods a. Dimethyl Sulfate and Alkali Haworth)... 

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