Syntheses in the epinephrine series. Pt. II. [The formation and properties of some 2:5- and 2:6-substituted pyrazines and their conversion into amino-ketones and imino-diketones] / by Frank Tutin.

  • Tutin, Frank.
Date:
1910
Catalogue details

Licence: Attribution 4.0 International (CC BY 4.0)

Credit: Syntheses in the epinephrine series. Pt. II. [The formation and properties of some 2:5- and 2:6-substituted pyrazines and their conversion into amino-ketones and imino-diketones] / by Frank Tutin. 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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    According to this scheme the action of ammonia on diplienacyl- amine first results in the production of 1: i-dihydro-2 : 6-diphenyl- pyrazine (V), which then passes into 2: 6-diphenylpyrazine by spontaneous oxidation. The change might, however, conceivably take place as follows: If this be the case, the intermediate compound will be 3: 4-di- hydro-2 : 6-diphenylpyrazine (VI). The change which is here shown to occur on heating compounds of the type (R-CO,CH2)2NH with ammonia does not appear to have been observed before, and it therefore seems to afford a new, general method for the production of 2: 6-substituted pyrazines. The interaction of ammonia and w-chloro-p-methoxyacetophenone proceeds similarly to that of cu-chloroacetophenone and ammonia, yielding, as principal products, pp'-dimethoxy-2 : 6-diplienylpyrazine (m. p. 223°) and pp' -dimethoxy-2 : 6-diphenylpyrazine (m. p. 137’5°). The former of these two compounds is of particular interest, as, on fusion, it passes into the “ liquid-crystalline ” state, and this phase persists over an exceptionally large range of temperature, namely, 41'4°. pp'-Dimethoxy-2: 5-diphenylpyrazine therefore represents a new addition to the already considerable list of “ liquid-crystalline p-anisyl derivatives, but it appears to be the first compound of this class in which the anisyl group is attached to a ring. A further interesting property of yp'-dimethoxy-2: 5-diphenylpyrazine is that its solutions exhibit a violet-blue fluorescence, a behaviour which has not previously been observed amongst pyrazine derivatives. Furthermore, on the addition of a drop of concentrated hydrochloric or sulphuric acid to a chloroform solution of this base, a most brilliant green fluorescence is produced, pp1-Dimethoxy-2: 6-di- phenylpyrazine behaves in marked contrast to its 2: 5-substituted. isomeride, as it fluoresces but slightly, and only in neutral solution, and it does not pass into the “ liquid-crystalline ” state. (o-Chloro-mp-dimethoxyacetophenone yielded vara'pp'-tetramethoxy- 2 : 6-diphenylpyrazine (m. p. 208°) and mva! pp'-tetramethoxy-2 : 6-di- phenylpyrazine (m. p. 160°) on treatment with ammonia, neither of which passes into the “ liquid-crystalline ” state. The former compound is, however, strongly fluorescent, but only in neutral solution. It is furthermore shown in the present communication that the series of changes which result respectively in the formation of
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