From Halogenopyrazines

The preparation of mercaptopyrazines (1) by the reaction of halogenopyrazines with sodium (or potassium) hydrogen sulfide or sodium polysulfide in various solvents (780, 790, 799, 805, 809, 821, 858, 890, 892, 993, 1006-1011), by reaction with phosphorus pentasulfide in pyridine (1013), and by reaction with thiourea in acid (905) and in alcohol followed by alkali (535) has been described in Section V.5G. 

Preparations of mercaptopyrazines from hydroxypyrazines by reaction with phosphorus pentasulfide in boiling pyridine or 3-picoline have been reported in Chapter VI.6B. 

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Many such esters have been made by primary synthesis (see Chapters 1 and 2), from halogenopyrazines by displacement (see Section 4.2.9), or by esterification of pyrazinecarboxylic acids (see Section 8.1.2). The remaining methods are illustrated in the following examples ... 

Examples have been given already of the preparation of isothiocyanatopyrazines from halogenopyrazines (Section 4.4) or from pyrazinamines (Section 7.3.2.4) also of the reaction of isothiocyanatopyrazines with amines to give thioureidopyrazines (Section 7.3.2.4). 

Alkylthiopyrazines may be prepared from halogenopyrazines by reaction with the appropriate sodium (or potassium) alkylthioiate, usually at elevated temperatures. In this way 2-ethylthio- and 2-isopropylthiopyrazine were prepared from... 

The preparation of aminopyrazines and hydrazinopyrazines from halogenopyrazines has been described in Sections V.5B and V.5C, respectively. 

Preparations of aminopyrazine A oxides from halogenopyrazine 7V-oxides have been described in Sections V.7A(1) and V.7B(3). 

Preparations of cyanopyrazines from halogenopyrazines have been described in Section V.5I. 

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