O-Benzylbenzoic acid

As much as 67 g. of 7 2-naphthylbutyric acid, using 500 g. of hydrogen fluoride, has been cyclized at one time.186 The yield of pure ketone was 94%. The method also is applicable to the cyclization of o-benzylbenzoic acids to anthrones.129... 

The excellent method for cyclizing o-benzylbenzoic acids to anthranol acetates, by heating the acid in- a mixture of acetic acid, and anhydride with zinc chloride as a catalyst,228 has been used also in the preparation of cyclic ketones of the tetralone type. In this way 7-3-acenaphthylbuty-ric acid has been cyclized in 78% yield 224 Y-2-phenanthrylbutyric acid48 and the 9,10-dihydro derivative97 in 51% and 59% yields respectively and a,j8-dimethyl-Y-2-naphthylbutyric acid in 90% yield.186... 

Another reagent, fused zinc chloride, which has been more commonly used for the ring closure of o-benzylbenzoic acids, was applied to the cyclization of 7-3-pyrenylbutyric acid (Table IY, example 2). The reaction was carried out at 180°, and the yield was 16%. 

The only cases of cyclization of 7-2-naphthylbutyric acids in which the ring does not close into the reactive 1-position to form a phenanthrene derivative are those in which either this position is blocked or the 8-position is substituted. The latter clearly seems to be an example of hindrance. An illustration is afforded by the cyclization of 7-8-methyl-2-naphthylbutyric acid (XXXIX) to the linear anthracene derivative XLI instead of the expected ketotetrahydrophenanthrene.26 The orientation influence of the methyl substituent would not be expected to affect the course of the reaction in such a manner. In like manner the tetramethyl derivative XL gave the product of linear ring closure XLII in good yield.27 A similar abnormal course of cyclization 28 has been observed in the benzylbenzoic acid derivative, o-(8-methyl-2-naphthyl- ... 

Figure 6 Effect of contact time on conversion and selectivity in benzyl alcohol oxidation on BaPbo.7Bio.2Cuo.1O3. Reaction temperature 623 K, Po2 132 torr. (A% conversion, benzaldehyde, X toluene, benzoic acid, o benzylbenzoate)...

Tributyl- and triphenyltin esters of 2-benzylbenzoic acid, 90 and 91, are self-assembled supramolecular chains formed by Sn- O secondary bonding (2.675 and 2.880 A, respectively) [246]. 

Such regioselectivities are unique and suggest that redox pillared clays may have broad scope and utility as selective, heterogeneous catalysts for liquid phase oxidations. Indeed, V-PILC also catalyzes the oxidation of benzyl alcohol (to a mixture of benzoic acid and benzylbenzoate) whilst a-methyl benzylalcohol is left completely untouched.71 Similarly, p-substituted benzyl alcohols are oxidized whilst o-substituted benzyl alcohols are inert.71... 

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