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The Hammick reaction, named after Dalziel Hammick, is a chemical reaction in which the thermal decarboxylation of α-picolinic (or related) acids in the presence of carbonyl compounds forms 2-pyridyl-carbinols. [1] [2] [3] The Hammick reaction. Using p-cymene as solvent has been shown to increase yields. [4]
Picolinic acid is a bidentate chelating agent of elements such as chromium, zinc, manganese, copper, iron, and molybdenum in the human body. [5] [6] It is a substrate in the Mitsunobu reaction. In the Hammick reaction, picolinic acid reacts with ketones to give pyridine-2-carbonols: [7] NC 5 H 4 CO 2 H + R 2 C=O → NC 5 H 4 CR 2 (OH) + CO 2
A pyridinecarboxylic acid is any member of a group of organic compounds which are monocarboxylic derivatives of pyridine. Pyridinecarboxylic acid comes in three isomers: Picolinic acid (2-pyridinecarboxylic acid) Nicotinic acid (3-pyridinecarboxylic acid), also known as Niacin; Isonicotinic acid (4-pyridinecarboxylic acid)
He recognized the acid from β–picoline as Nicotinsäure (nicotinic acid or "niacin"), [12] which Weidel had discovered in 1873. [13] When Weidel decarboxylated the carboxylic acid of each isomer – by dry distilling its calcium salt with calcium oxide – the reaction yielded pyridine, thus showing that picoline was a mixture of three ...
The reaction mechanism of the Mitsunobu reaction is fairly complex. The identity of intermediates and the roles they play has been the subject of debate. Initially, the triphenyl phosphine (2) makes a nucleophilic attack upon diethyl azodicarboxylate (1) producing a betaine intermediate 3, which deprotonates the carboxylic acid (4) to form the ion pair 5.
2-Picoline is also a precursor to the agrichemical, nitrapyrin, which prevents loss of ammonia from fertilizers. Oxidation by potassium permanganate affords picolinic acid: [1] Treatment of 2-methylpyridine with butyllithium results in deprotonation of the methyl group: [4] H 3 CC 5 H 4 N + BuLi → LiH 2 CC 5 H 4 N + BuH
A workup step with acid is included to ensure formation of 2-aminopyridine. Reaction progress can be measured by the formation of hydrogen gas and red color from σ-adduct formation. [3] Sodium amide is a handy reagent for the Chichibabin reaction but handling it can be dangerous and caution is advised. [4] σ-adduct (Meisenheimer adduct) formation
Chlorpyrifos is produced from 3,5,6-trichloro-2-pyridinol, which is generated from 3-picoline by way of cyanopyridine. This conversion involves the ammoxidation of 3-methylpyridine: CH 3 C 5 H 4 N + 1.5 O 2 + NH 3 → NCC 5 H 4 N + 3 H 2 O. 3-Cyanopyridine is also a precursor to 3-pyridinecarboxamide, [3] [4] [5] which is a precursor to ...