Hydroquinone dibenzoate

Preparation by Fries rearrangement of hydroquinone dibenzoate with aluminium chloride [249,250], (good OH yield) [251], at 140° for 1 h (33%) [252], at 190-200° for 1 h 30 min (50%) [253] or at 200° for 20 min [20]. Preparation by oxidation of 5-(benzoyloxy)-2,3-diphenyl-benzofuran with chromium trioxide in boiling acetic acid for 2 h, followed by saponification of the keto ester formed with boiling 8% sodium hydroxide in ethanol [254]. 

Also obtained by photo-Fries rearrangement of hydroquinone dibenzoate in benzene for 8 h under nitrogen (10%) [843]. 

The polyester made by reacting hydroquinone with terephthalic acid also melted above 500°C. That from bis-phenol A and 4,4 -(2,2-butylidene)dibenzoic acid is said to be stable in nitrogen to above 400°C. 

Polymeric pseudocrown ether networks have been generated in situ by the photopolymerization of poly(ethylene glycol) diacrylate transition metal complexes <00CM633>, and the effect of metal ion templation was evaluated. The 1,6,13,18-tetraoxa[6.6]paracyclophane-3,15-diyne (termed pyxophanes) was prepared from hydroquinone and l,4-dichlorobut-2-yne it forms size-selective 7i-complexes with alkali metal cations <00CC2377>. Dibenzo[ ]crown-m have been used in numerous elegant studies in which they were the needles that were threaded by diverse reagents the resultant... 

The allyl group in the allylphenols can be oxidized, after protecting the hydroxyl group, to yield substituted phenylacetaldehydes 78 - 76 76 and phenylacetic acids. Thus, homogentisic acid LXIII is prepared readily by ozonizing the dibenzoate of allylhydroqumone LXIV, which is obtained by rearrangement of the allyl ether of hydroquinone mono-... 

Instead of attaching a large substituent, phenyl, to the hydroquinone molecule to reduce the high melting points of hydroquinone terephthalate polyesters, flexible aliphatic components can be incorporated in the polymer chain. In our earlier paper,we noted that the polyester of 4,4 -(ethylenedioxy)dibenzoic acid and hydroquinone (II, n=2, R=H) melted at... 

Also obtained by hydrolysis of quinbenzophenone monobenzoate—5-(benzoyloxy)-2-hydroxy-benzophenone—(easily obtained by Fries rearrangement of hydroquinone mono or dibenzoate), with concentrated sulfuric acid at r.t. for overnight [252] or with 85% sulfuric acid [253]. 

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