Auwers, K. v.; Breyhan, Th. published the artcile< Further observations on alkylation and acylation of pyrazoles>, COA of Formula: C6H8N2O2, the main research area is .
3(5)- Methyl-5(3)-chloropyrazole with MeBr (8 hrs. at 100) gives 100% of the 1,3-di-Me derivative; CH2N2 gives largely the 1,3-di-Me derivative with some of the 1,5-isomer; the Na salt with Mel gives 100% of the 1,5-isomer. 3(5)- Phenylpyrazole (I) with MeBr (1 day at 100°) gives principally 1-methyl-3-phenylpyrazole, with some of the 5-Ph isomer; the Na salt with MeI yields 100% of the 5-Ph isomer. Excess ClCO2Me gives 1-carbomethoxy-3-phenylpyrazole (II), m. 76°. The Na derivative of BzCH:CHOH and MeO2CNHNH2 in dilute Et4OH give a nearly quant. yield of the carbomethoxyhydrazone of benzoylacetaldehyde, m. 152°; POCl3 in CHCl3 yields the 5-Ph isomer of II, m. 63-4°, with some II. I and SO2Cl2 give 4-chloro-5(3)- phenylpyrazole (III), b11 193°, m. 102°. 1-Methyl-4- chloro-3-phenylpyrazole (IV), pale brown, b9 163-5°; 5-Ph isomer (V), b12 153-6°. III and MeI with Na give about equal quantities of IV and V; Me2SO, in NaOH also give a mixture of the 2 isomers; MeBr gives essentially IV; CH2N2 reacts only slightly with III. II and SO2Cl2 give the 4-Cl derivative (VI), m. 89-90°; the 5-Ph isomer, m. 113-15°. III and ClCO2Me give VI. 3(5)-Methyl-5(3)-phenylpyrazole and MeBr (8 hrs. at 100°) give principally 1,5- dimethyl-3-phenylpyrazole, with some of the isomer; the Na salt with MeI gives the same products. 1-Carbomethoxy-3-phenyl-5-methylpyrazole, m. 74-5°; it is unchanged after heating with MeBr at 100° for 1 day; 4-Cl derivative, m. 107°. The carbomethoxyhydrazone of benzoylacetone, pale yellow, m. 121-2°; POCl3 gives 1-carbomethoxy-3-methyl-5-phenylpyrazole, m. 58-9°; 4-Cl derivative, m. 97°. Me pyrazole-3(5)-carboxylate, m. 139-40°; both MeBr and CH2N2 give principally Me 1-methylpyrazole-5-carboxylate, b9 73°, with a little of the 1,3-isomer, bg 120°. Me 5(3)-methylpyrazole-3(5)-carboxylate and CH2N2 give principally the 1,3-di-Me derivative, with some 1,5-isomer; the Et ester behaved similarly; there was no reaction with MeBr; MeI gives the almost pure 1,5-di- Me derivative; the Na salt with MeI gives principally the 1,3- isomer; EtI gives the 1-ethyl-5-methyl derivative; the salt with AcCl in C6H6 yields the 1-Ac derivative, m. 68.5-9.5°, and with ClCO2Me in Et2O the 1-MeO2C derivative Me 3(5)-phenylpyrazole-5(3)-carboxylate does not react with MeBr; with Mel it yields Me 1-methyl-3-phenylpyrazole 5-carboxylate; the Na salt and Mel in C6H6 give the same compound; the free ester or the Na salt and ClCO2Me yield a N-carbomethoxy derivative, m. 95°; the Et ester also does not react with EtBr; the Na salt and EtI give Et 1-ethyl-3- phenylpyrazole-5-carboxylate; the Na salt does not react with AcCl. 3(5)-Phenylpyrazole-5(3)-carboxylic acid (VII) and ClCO22Me give a N-carbomethoxy derivative, m. 126- 6.5°; with Cl the CO2Me group is split off. The 4-Cl derivative of VII m. 258-61°; it does not yield a CO2Me derivative
Journal fuer Praktische Chemie (Leipzig) published new progress about Acylation. 17827-61-1 belongs to class pyrazoles-derivatives, and the molecular formula is C6H8N2O2, COA of Formula: C6H8N2O2.
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics