Ammonium esters, structural properties

The carbon-chain structure of the sugar obtained from hamameli-tannin was established by the classical method of Kiliani,26 which is based on the reduction, with hydrogen iodide, of polyhydroxy acids to fatty acids. Treatment of the calcium salt of hamamelonic acid under these conditions led to inconclusive results. The reduction of the corresponding, crystalline ammonium salt, however, furnished 3.5 to 5% of 2-methylvaleric acid, which was identified by the properties of its crystalline p-iodophenacyl ester. Thus, it was proved that the sugar must have structure XIV. 

Gas hydrate inhibitors. Gas hydrates, solid water clathrates containing small hydrocarbons, are problematic for oil and gas production because they can precipitate and cause line blockage. Simple cationic surfactants containing at least two butyl groups were previously developed to inhibit formation of gas hydrate precipitates in gas production lines [87]. However, similar to the situation with cationic drag reduction additives, poor toxicity profiles prevent widespread commercial acceptance. Ester quaternaries with structures somewhat similar to those used in fabric care have been claimed as hydrate inhibitors [88 ]. Additionally, certain alkylether quaternary compounds, e.g. C12-C14 alkyl polyethoxy oxypropyl tributyl ammonium bromide, were shown to have hydrate inhibition properties [89]. 

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