Summary Castor oil can be effectively dehydrated by non‐conjugated oil‐maleic anhydride adducts to give use‐ful paint or yarnish oils. Castor acids dehydrated in the presence of alumina form diene acids of 60% two double bond conjugation. The glyceride from these acids dries more rapidly to a tack‐free film than conventional dehydrated castor oil. In both of these processes the course of dehydration is believed to be the decomposition of esters of the alcohol groups in ricinoleic acid. Acidic ion exchange resins exert some catalytic effect in the dehydration of castor oil, but the oil so made is inferior in color and film properties.

In view of the fact that 9,lO-dimethylanthracenel often cited in the literature erroneously as 9,lO-dimethyl-9,1O-dihydroanthracene since the discovery of this compound,2 we have undertaken to obtain the real 9,lO-dimethyl-9,1O-dihydroanthracene.9,lO-Dimethylanthracene was reduced with sodium and the desired new compound was obtained, It was found that 9,lO-dimethy1-9,lO-dihydroanthracene on treatment with aluminum chloride is converted to 9,lO-dimethylanthracene.The acetylation of anthracene3 gives 9-, 1-and 2-acetylanthracenes, and the treatment of 9acetylanthracene with aluminum chloride rearranges it into Iand 2-acetyl compounds. Nenit-zescu4 acetylated 9,lO-dihydroanthracene and obtained 9-acetyl-9,lO-dihydroanthracene.Acetylation of 9,lO-dimethylanthracene in the presence of aluminum chloride gave 2-acetyl-9,-10-dimethylanthracene. It was shown from this experiment that the acyl group can enter also directly into the 2-position of the anthracene 'nucleus, and that meso-acylanthracene is not always necessary as an intermediate,In the Friedel-Crafts reaction of 1,2,3,4-tetramethylnaphthalene the substitution takes place only a t the 0-position of the n~c l e u s .~ This fact is probably due to the steric hindrance caused by the methyl groups a t the 1-and 4-positions. The acetylation which takes place exclusively at the 2-position of 9,lO-dimethylanthracene may be attributed to the same steric factor, inasmuch as the free benzene ring in 9,lO-dimethylanthracene as well as in lJ2,3,4-tetramethylnaphthalene is attached to a tetra-substituted nucleus.During this experiment we have experienced a slight skin-eruption, presumably caused by the acetyl compound. This fact may be of interest as compared with the similar poisoning effect of benzanthrone in view of the chemical constitution. Experimental6 9,10-Dimethyl-9,10-dihydroanthracene.-Into a boiling suspension of 0.62 g. of 9,lO-dimethylanthracene in 6 g. of ethyl alcohol was added 2.5 g. of metallic sodium in small portions. On addition of sodium the yellow crystals disappeared and a colorless solution resulted, which,

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Increasing use of bis-(p-chIorophenyl)methyIcarbinol (DMC or Dimite) as a miticide has made it desirable to publish analytical procedures. The technical material may contain 4,4'-dichlorobenzophenone, the compound from which it is made, and 1,1bis-(p-chloropheny 1) ethylene, the dehydration product of bis-(p-chlompheny])methylcarbinol. For estimating the composition of mixtures with either one of these impurities, melting point-composition data are given. For mixtures which also contain the 2,4'-isomers, a quantitative dehydration to the