Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Extranuclear Halogenation

Note This process is seldom satisfactory for alkylpyrazines but it can be useful for arylpyrazines. [Pg.120]

5-Dimethylpyrazine (270, R = H) gave 2,5-bis(bromoethyl)pyrazine (270, R = Br) (Br2, K2C03, Bz202, hv, CC14, reflux, h 7.5% after separation from several other products).513 [Pg.120]

Note Even with careful control of reactant ratios and conditions, this route invariably gives two or more products that involve chromatographic or other separatory processes.513 [Pg.120]

2-Methylpyrazine gave 2-chloromethylpyrazine (272) ((V-chlorosuccinimide, Bz202, A, CC14, reflux, 24 h 89% after purification by TLC).205 cf428 674938  [Pg.121]

2-Benzylpyrazine gave 2-(a-bromobenzyl)pyrazine (273) (NBS, Bz202, CC14, 20°C, h 32% after chromatography).366 2,3,5,6-Tetramethylpyrazine gave 2,3,5,6-tetrakis(dibromomethyl)pyrazine (274) (NBS, CC14, hv, h 70%).33 [Pg.121]

2-Benzylpyrazine gave 2-(a-bromobenzyl)pyrazine (273) (NBS, BZ2O2, CCI4, 20°C, h 32% after chromatography).  [Pg.121]

6-Tetramethylpyrazine gave 2,3,5,6-tetrakis(dibromomethyl)pyrazine (274) (NBS, CCI4, hv, 1 h  [Pg.121]


Many halogenocinnolines, especially those with halogeno substituents on the carbocyclic ring or at extranuclear positions, have been made by primary syntheses (see Chapter 1), and some extranuclear halogenocinnolines have been made by passenger alkylations (see Section 2.2.1) or by direct halogenation (see Section 2.2.2). Other important preparative procedures are illustrated in the following examples. [Pg.45]

The formation of extranuclear halogenophthalazines by halogenation of alkyl- or arylphthalazines has been covered in Section 9.2.2. Other routes to such halogeno derivatives are illustrated in the following examples. [Pg.208]


See other pages where Extranuclear Halogenation is mentioned: [Pg.139]    [Pg.139]    [Pg.120]    [Pg.139]    [Pg.120]    [Pg.139]    [Pg.139]    [Pg.120]    [Pg.139]    [Pg.120]    [Pg.120]    [Pg.120]    [Pg.178]    [Pg.265]    [Pg.87]   


SEARCH



Extranuclear

© 2024 chempedia.info