Hydroquinone 7-Hydroxyacetophenone

Darby JM, DG Taylor, DJ Hopper (1987) Hydroquinone as the ring-fission substrate in the catabolism of 4-ethylphenol and 4-hydroxyacetophenone by Pseudomonas putida Dl. J Gen Microbiol 133 2137-2146. 

The above process is applicable to almost all hydroxyalde-hydes in which the hydroxyl and carbonyl groups occupy ortho or para positions relatively to each other 1 in the latter case derivatives of hydroquinone are produced. When the hydroxyl and carbonyl groups occupy the meta position with respect to each other, no reaction takes place, as is also the case with certain ortho and para compounds containing nitro groups and iodine atoms. o-Hydroxyacetophenone and />-hydroxyaceto-phenone are also capable of yielding catechol and hydroquinone respectively under the above conditions. 

Hydroperoxy-2-nitropropane, 256 p-Hydroquinone, 331,393,418 p-Hydroquinone dimethyl ethers, 432 Hydroquinones, 72 Hydrosilylation, 562 Hydroxamic acids, 204 2-Hydroximino-l-phenylpropane, 124 ai-Hydroxyacetophenone, 342 (3-Hydroxyacetylenes, 144-145 a-Hydroxy acids, 492 (5-Hydroxy acids, 301 1-Hydroxyadamantane, 126 a-Hydroxyaldehydes, 342 3o-Hydroxy-5a-androstene-17-one, 227-228... 

The TS-1 catalyzed hydroxylation of phenol to a 1 1 mixUne of catechol and hydroquinone has been commercialized by Enichem. Similarly, the ammoximation of cyclohexanone is being developed commercially as a low-salt alternative to the conventional process for the production of cyclohexanone oxime, the raw material for nylon-6. The reaction involves initial TS-1 catalyzed oxidation of NH3 by HjOj to give NH2OH. The fact that bulky ketones such as cyclododecanone undergo ammoximation is consistent with subsequent reaction of NHjOH with the ketone substrate taking place outside the molecular sieve. The method has been used [49] for the conversion of p-hydroxyacetophenone to the corresponding oxime which is the precursor of the analgesic paracetamol (Reaction 13). 

To prepare 19, we started with 4-hydroxyacetophenone which acted as a masked form of hydroquinone. It was condensi with the tosylate 13 in refluxing toluene with potassium carbonate as base and tetrabutylammonium bromide as phase-transfer catalyst. The intermediate 16 was isolated in over 98% e.e. and in 94% yield. 

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