Vinyl Alcohol: a Stable Gas Phase Species?

Abstract

DURING a study (unpublished results) using a mass spectrometer of the oxidation of dideuteroacetylene at 280° and 330° C in a ‘Pyrex’ reaction vessel, which had previously been used in the oxidation of acetylene, the products were found to contain a mixture of perdeuterated and monoprotonated acetaldehyde, acetic acid and methanol. Except in the case of methanol, the concentration of the monoprotonated substance was greater in the initial stages, but as the reaction progressed the proportion of the fully deuterated compound increased (Fig. 1) The 4 per cent C₂HD impurity cannot account for the hydrogen atoms which must therefore have originated on the walls of the reaction vessel, either as a part of a polymeric substance or in the form of absorbed water, the latter source being favoured because water is an important product of the oxidation and, as the reaction proceeds, D₂O will be absorbed on the walls and cause the increase in the proportion of fully deuterated products. To test this, water was added to the oxidation of dideuteroacetylene and mass numbers 48, corresponding to CD₃CDO⁺, and 47, corresponding to C₂D₃HO⁺, were monitored; in accordance with this suggestion, mass number 48 was suppressed while 47 was, at least initially, unaffected (Fig. 2).