The Structure of Hexachlorinated 2,4-Dicarbethoxy-3,5-dimethylpyrrole

Abstract

Notes 2153 chloric acid. The precipitated crystalline atrolactic acid was removed by filtration and sublimed at 70 to 75°; m.p. 91 to 92°. Methyl Phenyl Diketone-3-C14 (II).-This compound was prepared by the treatment of carbonyl-labeled propiophenone with butyl nitrite, followed by acid hydrolysis of the resultant monoxime.Rearrangement of Methyl Phenyl Diketone.-The diketone (II), dissolved in a large volume of ether, was stirred vigorously for 1 hr. with an equal volume of 20% sodium hydroxide solution maintained at 0°. Under these conditions, a yield of about 25% of the desired atrolactic acid (III) could be isolated after neutralization of the aqueous layer.Oxidation of Atrolactic Acid (III).-In a typical degradation, 83 mg. of III was decarboxylated at room temperature by treating with a mixture of 44 mg. of chromium trioxide and 2 ml. of glacial acetic acid in a small flask connected to a barium hydroxide absorption train. The apparatus was swept with nitrogen gas and the evolved carbon dioxide was converted to barium carbonate. The precipitated barium carbonate was washed with water and centrifuged several times before air drying. The residue in the reaction flask was extracted with ether and the ether extract was washed with sodium bicarbonate and then evaporated. The residual acetophenone was converted to the semicarbazone which after two crystallizations from 25% alcohol melted at 198°.Radioactivity Assay of Oxidation Products.-The determination of carbon-14 was conducted by the wet combustion of small samples of the barium carbonate and acetophenone semicarbazide according to the technique of Raaen and Ropp.5 The results are given in Table I. Table I Radioactivity of Carbon 14 in mc./mmole