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Brain, Edward George (1957) A study of the properties of some C-acetylpyrazolecarboxylic acids. Doctoral thesis, Northern Polytechnic.
Some of the properties of the C-acetyl substituted pyrazole ring have been studied, including its methylation. An N-methyl compound previously obtained was shown to be the sole product of methylation under certain conditions, and its orientation has been established.
The route to pyrazolylacetic acids via the Willgerodt reaction has been investigated, and was found to be successful wherever pure intermediates could be isolated. The intermediates obtained were thionacetmorpholides or, in some cases, their hydrochlorides.
Acetylpyrazoles have been condensed with esters to give diketones, and with benzaldehyde to give benzylideneacetylpyrazoles. Both types of product have been used to synthesise dipyrazolyls; 3:5’-,3:3'-, and, and 5:5'-dipyrazolyls were obtained and, in most cases, the orientations were proved.
The behaviour of silver salts of pyrazolylcarboxylic acids when treated with bromine under anhydrous conditions has been investigated. In the cases examined, it has been found that the 4- and 5- carboxylates undergo degradative bromination (Hunsdiecker reaction), but the salts of the 3-carboxylic acids were unaffected by the reagent. In ii connection with this work, the structure of 4-bromo- l-(p-bromophenyl)-pyrazole was established and its formation on brominating 4-bromo-1-phenylpyrazole was demonstrated.
The following new compounds have been prepared and characterised:
3-acetyl-l:4-dimethylpyrazole,
1:4-dimethylpyrazolyl-3:5-dicarboxylic acid,
5-carbethoxy-4-methylpyrazolyl(3-thioacetmorpholide)hydro- chloride,
5-carboxy-4-methylpyrazolyl-3-acetic acid,
5-carboxy-4-methylpyrazoly1-3-thioacetmorpholide,
5-carboxy-1:4-dimethylpyrazolyl-3-thioacetmorpholide,
5-carboxy-1:4-dimethylpyrazolyl-3-acetic acid,
1:4-dimethylpyrazolyl(3-thioacetmorpholide)hydrochloride,
1:4-dimethylpyrazolyl-3-acetic acid,
methyl 5-carboxy-1:4-dimethylpyrazolyl-3-acetate,
4-methylpyrazolyl(3-thioacetmorpholide)hydrochloride,
4-methylpyrazolyl-3-acetic acid,
3-carboxy-1:4-dimethylpyrazolyl-5-acetic acid,
3-acetoacetyl-1:4-dimethylpyrazolyl-5-carboxylic acid,
1:4:3’-trimethyl-3:5'-dipyrazolyl-5-carboxylic acid,
5-carboxy-1'-phenyl-1:4:3’-trimethyl-3:5’-dipyrazolyl,
4'-bromo-5-carboxy-l'-phenyl-1:4:3'-trimsthyl-3:5’-dipyrazolyl,
3-benzoylacetyl-5-carbethoxy-l:4-dimethylpyrazole,
1:4-dimethyl-1’:3’-diphenyl-3:5'-dipyrazoly1-5-carboxyllic acid,
1:4-dimethyl-1':5’-diphenyl-3:3'-dipyrazolyl-5-carboxylic acid,
4'-bromo-1:4-dimethyl-1:3'-diphenyl-3:5'-dipyrazolyl-5- carboxylic acid,
3-benzylideneacetyl-1:4-dimethylpyrazolyl-5-carboxylic acid,
3-benzylideneacetyl-1:4-dimethylpyrazole,
3'(1:4-dimethyl-3-pyrazolyl)-1':5'-diphenyl-2-pyrazoline,
1:4-dimethyl-1':5'-diphenyl-3:3'-dipyrazoly1,
methyl 3-benzylideneacetyl-l:4-dimethylpyrazolyl-5-carboxylate,
3'(5-carbmethoxy-1:4-dimethyl-3-pyrazolyl)-1':5'-diphenyl-2’pyrazoline,
3-acetoacetyl-5-carbethoxy-4-methylpyrazole,
4:3'-dimethyl-1'-phenyl-3:5'-dipyrazolyl-5-carboxylic acid,
1'-phenyl-1:4:3'-trimethyl-5:5'-dipyrazolyl-3-carboxylie acid,
3-benzylideneacetyl-4-methylpyrazolyl-5-carboxylic acid,
1':5'-diphenyl-4-methyl-3:3'-dipyrazolyl-5-carboxylic acid,
4-bromo-l:5-diphenylpyrazolyl-3-carboxylic acid,
4:5-dibromo-l:3-dimethylpyrazole
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