Fotooxidación sensibilizada de furfural en -media n-butanólico. I. Análisis de los productos de reacción

Abstract

The photosensitized oxidation of furfural in n butano! at 60 ºC was studied. Since a high leve! of radiation is necessary to achieve an acceptable yield of reaction products it is economically not simple to maintain a low reaction temperature using room temperature water for cooling. The nature of the reaction products revea! that the furfural at 60 ºC, not only reacts with singlet oxygen, a minar part of the consumed furfural is transformed through radical oxidation with triplet oxygen. The reaction products can react further with either singlet or triplet oxygen or undergo reactions with the solvent. The qualitative composition of che reaction mixture_in photooxidations with initially added water or without water addition was similar. In both cases , 2,5-dihydro-5-hydroxi-2- furanone (I) and 2,5-dihydro-5-butoxi-2-furanone (II) were the main reaction products. Last compound, a potentially interesting comonomer, was isolated and characterized. The cyclic structure of this compound has proved, by means of NMR, to be stable at the temperature of 120 ºC or less. The possible structure of the volatile reaction products present in the reaction mixture is discussed on the basis of their mass spectra. The qualitative composition of che reaction products mixture is analyzed by means of GC, TLC and GC-MS. The nature of the by-products shows that radical oxidatio4 reactions and butyral forming reactions lower the yield of the products I and II.