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ChemicalBook CAS DataBase List 5-Fluoro-2-hydroxypyridine
51173-05-8

5-Fluoro-2-hydroxypyridine synthesis

2synthesis methods
5-Fluoro-2-hydroxypyridine is synthesised using 5-fluoro-2-methoxypyridine as a raw material by chemical reaction. The specific synthesis steps are as follows:
A total of 4.6 L of toluene solution containing 3-80 was placed in several sealed tubes and treated with 900 ml of 35percent HCl at 145° C. for 2 hr. LC/MS showed no starting material, only 4. The toluene solution was decanted and discarded. The aqueous phase was washed with EtOAc and concentrated down to remove volatiles to afford a brown solid containing the desired fluoro-hydroxypyridine 4-80. [1488] A total of 244 g of this solid was collected and taken to next step as is (it was not completely dry). [1489] Note: We have subsequently run this by decanting the toluene layer first prior to heating to reduce volumes. Same reaction was carried out using HBr (48percent in H2O) at 100° C. for 6 h with similar result to the literature procedure 49percent yield. [1490] Ref: J. Heterocyclic Chem., 10, 779, 1973 (for above Reactions, Including Analytical Data).
5-Fluoro-2-hydroxypyridine synthesis
-

Yield:51173-05-8 49%

Reaction Conditions:

with hydrogen bromide in water at 100; for 6 h;

Steps:


A total of 4.6 L of toluene solution containing 3-80 was placed in several sealed tubes and treated with 900 ml of 35% HCl at 145° C. for 2 hr. LC/MS showed no starting material, only 4. The toluene solution was decanted and discarded. The aqueous phase was washed with EtOAc and concentrated down to remove volatiles to afford a brown solid containing the desired fluoro-hydroxypyridine 4-80. [1488] A total of 244 g of this solid was collected and taken to next step as is (it was not completely dry). [1489] Note: We have subsequently run this by decanting the toluene layer first prior to heating to reduce volumes. Same reaction was carried out using HBr (48% in H2O) at 100° C. for 6 h with similar result to the literature procedure 49% yield. [1490] Ref: J. Heterocyclic Chem., 10, 779, 1973 (for above Reactions, Including Analytical Data)

References:

Wang, Tao;Zhang, Zhongxing;Meanwell, Nicholas A.;Kadow, John F.;Yin, Zhiwei;Xue, Qiufen May;Regueiro-Ren, Alicia;Matiskella, John D.;Ueda, Yasutsugu US2004/110785, 2004, A1 Location in patent:Page 211

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