Further syntheses of p-hydroxyphenylethylamine / by George Barger and George Stanley Walpole.

  • Barger, George, 1878-1939.
Date:
1909
Catalogue details

Licence: Attribution 4.0 International (CC BY 4.0)

Credit: Further syntheses of p-hydroxyphenylethylamine / by George Barger and George Stanley Walpole. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    interest of the substance, other syntheses were attempted, and two of these form the subject of the present paper. In the first place, the introduction of a phenolic hydroxyl group into phenylethylamine was attempted. By nitrating benzoyl- phenylethylamine, a 2>nitro-derivative was readily obtained, and this yielded by successive reduction and diazotisation the A-benzoyl derivative of the desired substance, which was readily converted into p-hyclroxyphenylethylamine itself by heating with acids. Instead of benzoylation, we also used acetylation as a means of protecting the amino-group, but in this case the p-nitro-derivative is not so readily separated from its isomerides. Phenylethylamine can also be nitrated in the form of its benzylidene derivative when dissolved in concentrated sulphuric acid, but the mixture of nitro- compounds, which results on dilution with water, cannot be separated except by acetylation or benzoylation. The second synthesis to be described starts from anisaldehyde, which was converted into p-methoxyphenylpropionic acid. This acid, first prepared by W. H. Perkin, sen. (Trans., 1877, 31, 411), is more readily obtained by the method given by Perkin, jun., and Robinson for 3: 4-dimethoxyphenylpropionic acid (Trans., 1907, 91, 1071). The amide of this acid, MeO'CcH^CHo’CHo’CO’NH^ yielded by Hofmann’s reaction p-methoxyphenylethylamine, MeO-CGH.1*CH2‘CII2-NPI2, from which the methyl group was finally removed by heating with hydrobromic acid. Experimental. I.—Synthesis of y-Ilydroxyphenylcthylamine from Phenylethylamine. Benzoyl-'p-nitrophenylethylamine, N02*C6H4*CH2,CH2,NHBz, was prepared by slowly adding benzoylphenylethylamine (8 grams) to fuming nitric acid (40 grams), the temperature being kept below 5°. After pouring on snow, the product solidified. On crystal- lisation from alcohol, 3 4 grams of the para-compound separated in long needles; the mother liquor contains isomeric nitro-compounds, which are much more soluble. Benzoyl-p-nitrophenylethylamine was obtained pure by a second crystallisation from alcohol, and then melted at 162°. It is moderately soluble in boiling alcohol, but only sparingly so in cold alcohol: 0-2573 gave 22‘2 c.c. N2 (moist) at 11° and 748 mm. N = 10-0. C15ITi403fc2 requires N = 10'4 per cent.