Alkali cellulose was treated with meso-dichlorosuccinic acid (DCS) in water or in isopropanol to obtain cellulose monoether of chloromalic acid. By alkaline hydrolysis, the product was further converted to the disodium salt of cellulose monoether of tartaric acid (Cell-TA), water soluble white powder. The effects of the amount of DCS on the degree of ether formation and the amount of sodium hydroxide on the yield of Cell-TA have been clarified. The results indicated that the concentration of the sodium hydroxide solution had to be more than 45% and its molar ratio to cellulose, more than 6.4. The degree of etherification fell within a narrow range, 0.380.43, when tested at molar ratios of DCS to cellulose varying from 1.0 to 2.0.
As continuation of our previous studies, the carboxylation of potassium phenoxide in a liquid state was investigated under higher carbon dioxide pressure. Particularly, attempts have been made to elucidate the effects of the physical and chemical properties of the solvents on the yields and on the isomer distributions of the hydroxy carboxylic acids. Even in water-insoluble aprotic solvents, the reaction proceeded in a manner similar to that of gas-solid state carboxylation. Apparently, high-boiling solvents, such as biphenyl ether, kerosene, and light oil, etc. improved the yields of the acids. Best solvents were found among water-miscible aprotic-polar solvents, DMF, DMA, NMP, and HMPA. The results were not analogous to that obtained in gassolid state reactions. A few other protonic solvents were also found to be effective. The yields of the acids show rough correlations with the physical properties of the solvents, but the ratios of the p-isomer/o-isomer do not, except for the above mentioned acid amide solvents.
Reduction of a variety of haloalkanes with organosilicon hydrides was carried out under homolytic conditions. While the fluorides and iodides employed were found to be quite inert, the bromides and chlorides could be readily reduced. The mode of the reduction is consistent with a radical chain mechanism previously proposed. The apparent reactivities (Br>Cl>>F, I) can be reasonably understood by applying the Hirschfelder rules to the halogen atom abstraction step in the presence of the organosilyl radicals. The vicinal dibromide underwent radical debromination rather than bromine-hydrogen exchange, presumably due to the reversible addition of bromine atoms to olefins. Simple alkyl bromides, however, are less reactive than carbon tetrachloride. This seems to imply that the polar factor is also important in determining the relative rates of the halogen atom abstraction.
Relative rates of chlorine atom abstraction by organosilyl radicals were determined by allowing six different polychloroalkanes to compete in pairs for an insufficient amount of triethylsilane, phenyldimethylsilane, diphenylmethylsilane and ethyldichlorosilane at 80°C in the presence of benzoyl peroxide. Relative reactivities per chlorine atom of the trichloromethyl groups in X-CCl3 towards the four organosilyl radicals are satisfactorily correlated with the Taft σ values of the substituents X. These relationships can be interpreted in terms of the polar factor which is important in determining the reactivities of the chlorine atoms in this class of substrates. In the absence of solvent, the Hammett ρ values for the reactions of triethylsilyl, phenyldimethylsilyl, diphenylmethylsilyl and ethyldichlorosilyl radicals are 0.29, 0.27, 0.29 and 0.29, respectively. It was also found that the selectivity of the reaciton in methyl ethyl ketone or methyl acetate was somewhat greater than that in cyclohexane, benzene and chlorobenzene.
The automated peptide synthesizer as developed based on the solid phase synthetic method of Merrifield has been improved. The automatic synthesizer developed in the present study is less expensive, and can be operated automatically as well as manually. Thus, the reaction conditions and the reaction sequences, etc. can easily be changed. A heptapeptide, Gly-Pro-Gly-Phe-Gly-Pro-Gly, was synthesized rapidly and in a good yield.