Pyridine is an important intermediate in the production of pesticides and pharmaceuticals, as well as an important solvent in the polymer and textile industries. Important derivatives of pyridine include niacin and niacinamide (essential vitamins for human health), chlorophenylpiromin (an antihistamine), cetylpyridine salt (an insecticide and preservative), isoniazid (an important anti-tuberculosis drug), and paraquat (an herbicide).

On the loop structure to connect a methyl pyridine called methyl pyridine or leather, colin and includes polymerization conditions for hexamethylcyclotrisiloxane, 3 - methyl pyridine, and 4 - methyl pyridine. Pyridine and methylpyridine can be obtained as by-products of the coal tar industry or coke production. However, only a small amount of pyridine has been found in coal tar, and the preferred method for obtaining pyridine is catalytic synthesis. Catalytic synthesis is generally through the reaction of ammonia with the catalytic gas of carbonyl compounds such as aldehydes or ketones. However, these catalytic synthesis methods have historically had the disadvantages of low yield and poor selectivity as well as short operation cycle and catalyst life.

Progress in Catalysis (1968) reported the synthesis of pyridine and methylpyridine from formaldehyde, acetaldehyde and ammonia with H-mercerite as catalyst, but the required product selectivity is very low. US4675410 and US4886179 disclosed the synthesis of pyridine and methylpyridine from formaldehyde, acetaldehyde and ammonia as raw materials, in which metal ions of the eighth group of the periodic table modified ZSM-5 zeolite as catalyst. US4220783 discloses the method of synthesizing pyridine and methylpyridine from carbonyl compounds and ammonia as raw materials, in which cadmium metal ion modified ZSM-5 zeolite as catalyst.

The preparation methods of pyridine/methylpyridine all use phosphorous modified molecular sieve as catalyst and ammonia and at least one C1 ~ 5 carbonyl reactant as raw materials. However, they all have the problem of low selectivity and yield of pyridine and methylpyridine products, the high yield of the product is only 70%, which is low.

polymerization conditions for hexamethylcyclotrisiloxane https://www.clentpharma.com/What-are-the-polymerization-conditions-for-hexamethylcyclotrisiloxane.html