Lists
Lists
Frazer, Malcolm John (1955) Interaction of esters of hydroxy-acids with inorganic non-metallic halides. Doctoral thesis, Northern Polytechnic.
The interactions of hydroxy-esters and certain inorganic non-metal halides, e.g. thionyl bromide and boron trichloride, are described. During the work with thionyl bromide unexpected complications arose. Pyridinium polyhalides (C5H5NH+X3-) are formed by the reaction of thionyl halides with pyridine hydro- halides; consequently when thionyl bromide is added to a mixture of a di-alkyl sulphite and pyridine hydrobromide, the reaction sequence is even more complex than hitherto believed. It was necessary to digress in order to study the polyhalide ions in detail and to examine their behaviour in systems involving simple alcohols.
The polyhalides, (e.g. C5H5NH Br2Cl), react with di-alkyl sulphites (e.g. di-1-butyl sulphite) forming a mixture of the alkyl chloride and bromide. Certain interesting reactions with pyridinium tribromide were investigated, (e.g. allyl alcohol quietly yielded di-2:3-bromopropan-1-ol).
A satisfactory procedure for the replacement of nydroxyl by bromine using thionyl bromide is described. Experiments with (+) octan-2-ol and with a number of unsaturated alcohols illustrate the complication of pyridinium tribromide formation.
Passage of hydrogen chloride through ethyl glycollate or ethyl lactate results in decomposition, and after removal of the gas only 50% of the hydroxy-ester is recovered. Ethyl lactate and hydrogen chloride, in a sealed tube at 60º for 6 days, yielded only 10% of ethyl 1-chloro-propionate.
It is shown that boron trichloride forms addition compounds with carboxylic esters and these decompose on heating to give the acyl chloride and the alkyl dichloroboronite. Because of this reaction the dichloroboronites ROBC12 of hydoxy-esters cannot be prepared. However, using the hydroxy-ester (3 mols.) (ethyl glycollate, ethyl 2-hydroxypropionate, ethyl lactate and ethyl malate) and boron trichloride (1 mol.) the four borates were obtained.
 |
View Item |