Epoxides, reaction with ammonium hydroxide

The increase in alkylation efficiency of HEC with quaternary ammonium hydroxide is not limited to DPGE. Experiments were conducted in which HEC was alkylated with 1-bromohexadecane (cetyl bromide), 3-n-pentadecenyl phenyl glycidyl ether (PDPGE)14, or 1,2-epoxyhexadecane (C]6 a-olefin epoxide) in the presence of either sodium hydroxide or benzyltrimethylammonium hydroxide. As before, the molar A/HEC ratio was 0.50, and the water content of the diluent in the benzyltrimethylammonium hydroxide experiment was decreased to compensate for the higher water content of the base so that the final water content of both reactions was the same (14.4%). The hexadecyl content of the polymers was measured by gas chromatography. The sodium hydroxide mediated reaction of 1-bromohexadecane yielded a hexadecyl alkylation efficiency of 0.5%, while the benzyltrimethylammonium hydroxide reaction yielded a hexadecyl alkylation efficiency of 6.2%. A twelve-fold increase in the hexadecyl alkylation efficiency was observed in the reaction conducted with the quaternary ammonium hydroxide. 

The reaction between epoxides and ammonia (or ammonium hydroxide) is a general and useful method for the preparation of (3-hydroxyamines. With epoxide derived from terminal alkenes, the reaction with ammonia gives largely the primary amine, but secondary and tertiary amine products are possible from the appropriate epoxide. The reaction of 121 with ammonium hydroxide with microwave irradiation, for example, gave 122. Ethanolamines, which are useful solvents... 

METAPHOSPHORIC ACID (7664-38-2) A medium-strong acid. Violent reaction with strong bases. Violent reaction if water is added to concentrated acid. To dilute, always add acid to water heat will be generated. Reacts violently with solutions containing ammonia or bleach, azo compounds, epoxides, and other polymerizable compounds. Reacts, possibly violently, with amines, aldehydes, alkanolamines, alcohols, alkylene oxides, amides, ammonia, ammonium hydroxide, calcium oxide, cyanides, epichlorohydrin, esters, halogenated... 

Phase transfer catalysis, which proved extremely useful in classical ylid reactions with both phosphonium and sulfonium salts (Ref, 8, 42-45), was first used with a polymer by Farrall, Durst and Frechet in 1978 (Ref, 15) according to scheme 4. In this reaction, the polymeric sulfonium salt (IX), which is suspended in a dichloromethane solution of the carbonyl compound, is treated with aqueous sodium hydroxide in the presence of tetrabutyl ammonium hydroxide to give over 95% yield of the desired epoxide together with a polymeric by-product (X) which can be recycled and reused repeatedly without any loss of activity. In contrast, the same polymeric reagent (IX) used under classical conditions affords lower yields of epoxides and loses its activity rapidly on repeated recycling. This last observation shows clearly that phase transfer catalysis may contribute significantly to the prevention of side reactions in some modifications of polymers. 

In 1994, Mansuy and coworkers found that a simple ammonium salt, like ammonium acetate alone, is a very efficient cocatalyst for the metalloporphyrin-catalyzed epoxidation of simple alkenes by hydrogen peroxide ". Bases like sodium carbonate, sodium acetate or tetrabutylammonium hydroxide turned out to promote the porphyrin-catalyzed epoxidation without any other additive. Adducts of hydrogen peroxide (with Na2C03, urea, MesNO, PhsPO), which turned out to be particularly useful for reactions in which the concentration of H2O2 in solution needs to be controlled at a fixed level, have been employed by Johnstone and coworkers. 

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