一二三四区视频,亚洲少妇熟女色,日本久热无码视频网,欧美国产日韩大尺度,亚洲a视频,久久少妇一区二区,日韩999无码视频,刺激久久久久久久,啊啊啊啊不要啊在线

Welcome to chemicalbook!
Chinese English Japanese Germany Korea
010-86108875
Try our best to find the right business for you.
Do not miss inquiry messages Please log in to view all inquiry messages.

Welcome back!

ChemicalBook CAS DataBase List D-Biotin
58-85-5

D-Biotin synthesis

4synthesis methods
-

Yield:58-85-5 95%

Reaction Conditions:

Stage #1: N,N'-dibenzylbiotinwith boron tribromide in dichloromethane at -5 - 50; for 1.16667 h;Inert atmosphere;
Stage #2: with hydrogenchloride in water;Temperature;Solvent;

Steps:

1.1; 1.2; 2.1; 2.2; 3; 3.2; 4; 4.2 (1) Synthesis of crude d-biotin

In an anhydrous reaction vessel,Dissolve bis-benzyl biotin (2.13 g, 5 mmol) in 100 mLIn anhydrous dichloromethane, the air in the system is replaced with argon three times and then argon gas is protected.Instilled in an ice bath at -5 ° C1M solution of boron tribromide in dichloromethane (15 mL, 15 mmol) was reacted for 20 min, and then transferred to 25 ° C for 50 min.After monitoring the reaction completely by HPLC,The reaction system was cooled in an ice bath at 0 ° C, and quenched by adding 213 mL of saturated aqueous sodium carbonate.Rotate to remove organic solvent and addExtract 213 mL of water, 500 mL of ethyl acetate, then extract twice with water, each time 326 mL,The aqueous phase was collected and decolorized with 5 g of activated carbon for 30 min, and adjusted to pH 1-2 with concentrated hydrochloric acid.A white solid precipitated, filtered and washed with water to pH 7.A crude d-biotin was obtained.(2) Purification of crude d-biotinThe above crude product was recrystallized by adding 15 mL of pure water, stirred under reflux for 8 h, cooled, crystallized, filtered,The white crystalline powder obtained by freeze-drying and drying is pure d-biotin.The freeze-drying temperature is ≤ -30 ° C,The degree of vacuum is ≤ -10 Pa and the time is 12 hours.The obtained d-biotin mass was 1.16 g.The yield was 95.0%.

References:

CN109627254,2019,A Location in patent:Paragraph 0037; 0038; 0039; 0040; 0041; 0042; 0043-0060

D-Biotin Related Search:

南江县| 视频| 钦州市| 沁阳市| 夏邑县| 长治市| 滦南县| 县级市| 富宁县| 武乡县| 休宁县| 泽库县| 磐安县| 益阳市| 昌吉市| 西城区| 新河县| 温泉县| 通化市| 云南省| 牟定县| 五峰| 延川县| 阿巴嘎旗| 许昌县| 东阳市| 顺平县| 靖西县| 新干县| 山东| 丹寨县| 武冈市| 五家渠市| 华坪县| 太谷县| 巫溪县| 阿荣旗| 随州市| 喀什市| 兴和县| 社旗县|