Benzyl 3,5-dinitrobenzoate

Saponification of esters. Aqueous sodium hydroxide method. To hydrolyse an ester of an alcohol, reflux 5-6 g. with 50 ml. of 20 per cent, sodium hydroxide solution for 1-2 hours or until the ester layer disappears. Distil the alkahne mixture and collect about 6 ml. of distillate. This will contain any volatile alcohol formed in the saponification. If the alcohol does not separate, i.e., is water-soluble, saturate the distillate with sohd potassium carbonate an upper layer of alcohol is then usually formed. (The alcohol may be subsequently identified as the 3 5-dinitrobenzoate see Section 111,27,2.) Cool the residual alkahne mixture, and acidify it with dilute sulphuric acid. If no crystalline acid is precipitated, the acid may frequently be isolated by ether extraction, or it may be distilled from the acidified solution and isolated from (or investigated in) the distfllate. (The acid may be subsequently identified, e.g., as the S benzyl wo-thiuronium salt see Section 111,85,2.)... 

On the other hand, 32 was first transformed into the 3,5-dinitrobenzoate 45 which allowed diastereoselective dihydroxylation20 to give 46 after methanolysis and benzylation. 46 afforded the hemiacetal 47 from which L-allose via route A and D-allose via route B were obtained (Scheme 13).16... 

The solvolysis rate constant of 3-indenyl 3,5-dinitrobenzoate 44a was 10 less than that of cyclo-pentenyl dinitrobenzoate 44d and 5 x 10 less than that of indanyl dinitrobenzoate 44b. Methoxy and methyl substituents at the 6-position on the ring in 44a and a methyl substituent at the 1-position on the double bond have accelerating effects expected for benzylic and allylic stabilization, respectively. The cyclopropanated system 44c showed no enhancement of reactivity compared to 44b, and this was taken as evidence for a diminuation in reactivity for 44c by a factor of 10 from that expected for a fully conjugating cyclopropyl group. The rate retardation was ascribed to due to homoantiaromaticity, of the type depicted for 41a. 

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