Efficient Phosphorus-Free Chlorination of Hydroxy Aza-Arenes and Their Application in One-Pot Pharmaceutical Synthesis was written by Wang, Jian;Li, Yan-Hui;Pan, Song-Cheng;Li, Ming-Fang;Du, Wenting;Yin, Hong;Li, Jing-Hua. And the article was included in Organic Process Research & Development in 2020.Application In Synthesis of Pyridin-4-ol This article mentions the following:
The chlorination of hydroxy aza-arenes with bis(trichloromethyl) carbonate (BTC) and SOCl2 has been effectively performed by refluxing with 5 weight % 4-(dimethylamino)pyridine (DMAP) as a catalyst. Various substrates are chlorinated with high yields. The obtained chlorinated aza-arenes can be used directly with simple workup for succedent one-pot synthesis on a large scale. In the experiment, the researchers used many compounds, for example, Pyridin-4-ol (cas: 626-64-2Application In Synthesis of Pyridin-4-ol).
Pyridin-4-ol (cas: 626-64-2) belongs to pyridine derivatives. Pyridine is diamagnetic and has a diamagnetic susceptibility of −48.7 × 10−6 cm3·mol−1.The molecular electric dipole moment is 2.2 debyes. The standard enthalpy of formation is 100.2 kJ·mol−1 in the liquid phase and 140.4 kJ·mol−1 in the gas phase. Many analogues of pyridine are known where N is replaced by other heteroatoms . Substitution of one C–H in pyridine with a second N gives rise to the diazine heterocycles (C4H4N2), with the names pyridazine, pyrimidine, and pyrazine.Application In Synthesis of Pyridin-4-ol