The Pyrolysis of Esters 2419 of the starting material) melting at 100.5-100.7°alone and when mixed with the original material. Summary 1. cis-1,2-Dimethylcyclopentanediol-l ,2 undergoes the pinacol rearrangement with migration of a methyl group and production of 2,2-dimethylcyclopentanone.2. trans -1,2 -Dimethylcyclopentanediof-1,2 when boiled with dilute aqueous acid undergoes resinification. It has not been possible to char-acterize any product from this reaction. It is suggested that dehydration without rearrangement is here occurring, yielding a product which is rapidly polymerized by the acid.3. These observations confirm the conclusion previously reached that in the pinacol rearrangement elimination of a hydroxyl group and the arrival of a migrating radical occur on opposite sides of the same carbon atom.Cambridge, Mass.

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PENTOSE REACTIONS. I 317 was dried over anhydrous sodium sulfate and evaporated under diminished pressure. There was obtained a residue which, when recrystallized from hot water, separated as colorless crystals melting at 144-144.5°, with evolution of gas. The neutral equivalent was found to be 123; that calculated for 2-phenyl-3,6-dicarboxy-5,6-dihydro-l,4-pyran is 124.When the hot alkaline reaction mixture was acidified with hydrochloric acid the product obtained was the mono-carboxylic acid (see below).-Benzoyl-a-hydroxyvaleric Acid (VIII).-One gram of the cyano acid (VII) was heated under a reflux condenser with 60 cc. of a 50% solution of sulfuric acid. After fifteen minutes of^boiling the cyano acid was completely dissolved. The solution darkened rapidly and at the end of an hour dark crystals began to separate. The heating was then discontinued and the reaction mixture was diluted with an equal volume of water. This solution was cooled to 0°and allowed to stand for several hours. The crystals obtained in this way were removed by filtration and recrystallized first from hot water and then from ethyl acetate. The -benzoyl-a-hydroxyvaleric acid thus obtained was shown to be identical with that prepared from the dicarboxylic acid as indicated in the preceding section. It melted at 120-120.5°; the yield was 88% of the theoretical.

Vol. 69 2. Fluorene has similarly been converted to fluorene-9-carboxylic acid.3. The potassium salt of ¿-butyl diphenylacetate, prepared by means of potassium amide, has been benzoylated and acetylated and the resulting /3-keto esters cleaved to a, a-diphenylaceto-phenone and a, -diphenylacetone, respectively.4. Ethyl a, a-diphenylbenzoylacetate, prepared by benzoylating the potassium salt of ethyl diphenylacetate, is stable toward ketonic cleavage. Durham, N. C.

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