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 1,5-Dibromopentane
111-24-0

1,5-Dibromopentane synthesis

11synthesis methods
1,5-Dibromopentane was obtained by ring-opening bromination of tetrahydropyran. In a 500ml flask, add 250g of 48% hydrobromic acid, 75g of concentrated sulfuric acid, 21.5g of redistilled tetrahydropyran (86.5-87.5°C fraction) in turn to a reflux condenser and heat the brown mixture gently to reflux for 3h. After cooling to room temperature, partition the lower layer of dibromide and wash each with saturated sodium carbonate solution and water once. Dried with anhydrous calcium chloride. Distill under reduced pressure and collect the 104-106°C (2.53 kPa) fraction as 1,5-dibromopentane in 46-47 g yield and 80-82% yield.
1,5-Dibromopentane synthesis route
1,5-Dibromopentane synthesis route
-

Yield:111-24-0 88%

Reaction Conditions:

with hydrogen bromide in octane;water at 148 - 150; for 6 h;Dean-Stark;Temperature;

Steps:

General procedure
General procedure: A one-neck rb flask was charged with diol (1equiv), 48% aq HBr (~3 equiv/OH), octane (~7:1 v/w ratio vs diol), fitted tothe fractionating column/Dean-Stark trap, and heated inan oil bath (145-150 °C) w/rapid magnetic stirring. The aqueous (lower) layer of the initialazeotrope condensate (bp 89-92 °C) was tapped offuntil about half of the theoretical amount of H2O had been collected;the azeotrope temp (still head) then began to rise. The condenser was set to total reflux forseveral h, reopened, and aq material collected for 1h more (head temp 96-100°C). The final volume of aq distillatewas 90-100+% of theory (higher-boiling distillate contained up to 24% HBr). When the (pale tan) octane phase containedboth dibromide and bromoalkanol (6band 6c), washing with cold 85% v/v H2SO4 (10 mL,then 5 mL) removed all color and all bromoalkanol. For all three dibromides (3b, 4b, 6b) the neutralized octane solutionwas stripped of solvent (vigreux column, reduced pressure), and the essentiallypure residue (1H NMR) was kugelrohr distilled. A trace of 4-methyltetrahydropyran was foundin 4b before distillation.

References:

Mekala, Shekar;Hahn, Roger C. [Tetrahedron Letters,2015,vol. 56,# 4,p. 630 - 632] Location in patent:supporting information

FullText

1,5-Dibromopentane Related Search:

梁山县| 剑河县| 海口市| 赣榆县| 常德市| 胶南市| 松溪县| 通江县| 醴陵市| 漠河县| 磴口县| 山阳县| 永吉县| 陇西县| 河东区| 镇远县| 长葛市| 额济纳旗| 赞皇县| 义乌市| 张家口市| 田东县| 湟源县| 马鞍山市| 公安县| 西华县| 建阳市| 哈尔滨市| 深泽县| 浙江省| 通化市| 共和县| 扶沟县| 永清县| 丹寨县| 麻栗坡县| 长泰县| 尉犁县| 新化县| 保定市| 枝江市|