2-Amino-5-nitrothiazole

The reaction of 2-amino-5-nitrothiazole with (3-chloroethyl isocyanate gives the corresponding thiazolyl urea (137) (Scheme 90) (298). Other examples are given in Section V.l.B, where the preparation of thiazolyl-thioureas is discussed,... 

That numerous 2-amino-5-nitrothiazole derivatives exhibit antiamebic, antihistomonal, antitrichomonal, and antischistosomal properties (see Section VI.2) explains the large number of nitration reactions reported. Nitration in a mixture of concentrated nitric and concentrated sulfuric acids IS among the most common experimental methods (16, 27, 58, 374-377). 

Amino-5-nitrothiazole, on treatment with arenesulfonyl halides and dimethylformamide at 140 C, gives (5-nitro-2-thiazolyl)amidme (274) (Scheme 168) (507, 508). The condensation products of the reaction of 2-aminothiazole derivatives with various aldehydes are grouped in Tables... 

Nitraminothiazole. treated for 12 hr with 96% sulfuric acid, gives 2-amino-5-nitrothiazole (194). The mechanism of this rearrangement is not yet quite resolved even for nitraminobenzene derivatives (617). The series of kinetic determinations and appropriate labeling performed by Toth et al. provide, however, precious hints for this difficult problem (1578. 1579). 

Some 2-halogeno-5-nitrothiazoles and 2-nitro-5-halogenothiazoles are known. 2-Halogeno-5-nitrothiazoles can be prepared by a Sandmeyer reaction from 2-amino-5-nitrothiazole (1, 85), while 2-nitro-5-halo-genothiazoles can be analogously prepared by decomposition of dia-zonium salts arising from 2-amino-5-halogenothiazoles in presence of nitrite anion (82, 84). 

One of the earliest diazo components of this type to be introduced was 2-amino-5-nitrothiazole (4.81), prepared by condensation of thiourea with chloroacetaldehyde and nitration of the resultant 2-aminothiazole (Scheme 4.32). This component yields bright dischargeable blues, such as Cl Disperse Blue 82 (4.82), which have outstanding build-up, very high extinction coefficients and good fastness to burnt gas fumes. Use of diazo component 4.81 with coupling component 4.83 yields a greenish blue dye. 

Niridazole Niridazole, l-(5-nitro-2-thiazolyl)-2-imidazolidinone (38.1.11), is made by reacting 2-amino-5-nitrothiazol with 2-chloroethylisocyanate to make the disubstituted urea (38.1.10). Heating this compound results in an intramolecular N-alkylation reaction to form the desired imidazolidine derivative, niridazole [7-11]. 

Amino-2,5-dinitrotoluene, 2783 2-Amino-5-nitrothiazole, 1117 6-Aminopenicillanic acid 5-oxide, 3010... 

Amino-2-nitrophenol 2-Amino-5-nitrothiazole 2-Amino-9A-pyrido[2,3-i]indole (see A-a-C)... 

Aminothiazoles and derivs 1 A263—A264 2-amino-5-nitrothiazole 1 A263... 

Enheptin see 2-Amino-5-nitrothiazole 1 A263 ENIAC 5 E101 Ennayaku 5 E101... 

Derivatives of 2-amino-5-nitrothiazole have antiparasitic activity. Niridazole (253) is used in the treatment of schistosomiasis, but its side-effects make it unattractive for treating other diseases, e.g. amoebiasis, for which safer drugs are available. The nitroimidazole metronidazole (254) is particularly useful in amoebiasis and trichomoniasis, and the latter disease may also be treated with nimorazole, l-morpholinoethyl-5-nitroimidazole. 

Among the earlier examples are dyes based on 2-aminobenzothiazole (B-52MI11203), which on diazotization and coupling with iV,N-dialkylanilines gives rise to red dyes (71 Mil 1201), and 2-amino-5-nitrothiazole (68USP3380990), which on similar treatment gives reddish blues. 

Dyes from 2-amino-5-nitrothiazole, such as (48) e.g. 53USP2659719), have high extinction coefficients and are reddish-blues to blues depending upon the substitution pattern in the coupler, a subject which has recently received attention (e.g. 79MI11202). 

Amino-5-nitrothiazole is prepared (59JOC187, 55JOC499) by the reaction between 2-chloroacetaldehyde and thiourea followed by nitration of the free amine. It has been shown that the nitration proceeds by the N-nitration of the 2-amino group followed by rearrangement. Several other derivatives of 2-aminothiazole have been described in patents but none have reached any commercial significance. 

Energies, Activation. See Activation Energies A100-R A101-L Enheptin. See 2-Amino-5-nitrothiazole A263-R... 

Developments in the field of heteroaromatic amines as diazo components started with the finding that 2-amino-5-nitrothiazole [121-66-4] [17] gave bright blue shades of reasonable fastness in azo dyes for cellulose acetate (e.g., 3) [18], [19], Because of their good dischargeability but limited fastness properties, these dyes were also used on polyester. The importance of this class of dyes has diminished since some of them have been found to have sensitizing properties (see Chapter 8). 

In this respect, the syntheses of a wide series of 2-amino-5-nitrothiazole 572 complexes with various metal(II) salts are representative. These reactions were carried out in methanol medium and led to adducts of type 573 [12] (3.13) ... 

To a solution of 1 kg (7 moles) of 2-amino-5-nitrothiazole in 5 L of pyridine (dried with potassium hydroxide) was added dropwise for 2-3 hours 8.5 moles of 2-thienoylchloride. N-(5-Nitro-2-thiazolyl)-2-thiophenecarboxamide was prepared as a yellow crystals with melting point 255-256°C. 

Isolation of the carbinolamine intermediate (66) is possible in the reaction of 2-amino-5-nitrothiazole with acetaldehyde (Scheme 46) (216). 

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