The oxidation of organic sulphides is very fast with peracids and very slow with hydrogen peroxide. Thus, addition of an excess of methyl p-tolyl sulphide to a mixture of an organic peracid and hydrogen peroxide results in the formation of methyl p-tolyl sulphoxide equimolar with the peracid. The gas-chromatographic determination of the residual sulphide, or of the produced sulphoxide, affords a quantitative evaluation of the peracid present in the mixture. The method has been applied to the determination of m-chloroperbenzoic acid and peracetic and perpropionic acids.

The one-pot synthesis of the title compounds (1) is achieved by reacting acetophenones and nitrobenzenes in 2-propanol with potassium 2-propoxide. The stereochemistry of the 2-butenes has been determined to be Z from an X-ray analysis. Hydrolysis and reaction with hydrazine are reported as examples of the reactivity of the title compounds.1,4-Diketones are useful starting materials for the synthesis of a number of heterocycles.1 The but-2-ene-l,4dione system and its functionalized derivatives are potentially even more valuable. Their use2 has, however, been limited because of their relatively difficult synthesis.We have developed a very simple, one-pot synthesis leading to l,4-diaryl-2-(arylamino)-but-2-ene-l,4-diones (1, ArC(0)C(NHAr)=CHC(0)Ar). The determination of the configuration around the double bond and examples of the reactivity of 1 are also described in this paper. Results and DiscussionSynthesis of l,4-Diaryl-2-(aryiamino)but-2-ene-l,4diones. Addition of potassium 2-propoxide to a boiling solution of variously substituted acetophenones and nitrobenzenes in 2-propanol gives, after 1-2 h at reflux, compound 1 in fair to good amounts (eq 1

In aqueous alkaline solutions peroxycarboxylic acids oxidise sulphoxides to sulphones much faster than hydrogen peroxide. Accordingly, when an excess of methyl phenyl sulphoxide is added to a 3 + 1 waterethanol solution (apparent pH = 12) containing an organic peracid and hydrogen peroxide, formation of methyl phenyl sulphone, equimolar with the peracid, occurs. Under the experimental conditions adopted, hydrogen peroxide is almost unreactive. Therefore, the gasliquid chromatographic determination of the sulphone produced affords a quantitative measurement of the peracid present.

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