Reaktion #1359750

Reaktionsgleichung

chlorocyclohexane

resorcinol dimethyl ether

trimethyl borate

chlorocyclohexane

HCl

lithium

→

2,6-dimethoxyphenylboronic acid

Ausbeute 91.3%

Lösungsmittel

water

THF

cyclohexane

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONare added dropwise at the same temperature over a period of 15 minutes
2. 2
   workup.DISTILLATIONare distilled off at 35° C. under reduced pressure
3. 3
   workup.ADDITION25 ml of methylcyclohexane are added to the product suspension
4. 4
   Filtrationthe colorless product is filtered off with suction
5. 5
   Waschenis washed once with 25 ml of cold methylcyclohexane and once with 25 ml of cold water
6. 6
   SonstigeAfter drying

Vorschrift

A mixture of 20.88 g of chlorocyclohexane (0.176 mol) and 22.1 g of resorcinol dimethyl ether (0.16 mol) is added dropwise to a suspension of 2.35 g of lithium granules (0.34 mol) in 300 g of THF at −50° C., with an addition time of 2 hours being selected. After a conversion of the chlorocyclohexane of >97% determined by GC (total of 9 h), 16.6 g of trimethyl borate (0.16 mol) are added dropwise at the same temperature over a period of 15 minutes. After stirring for another 30 minutes at −50° C., the reaction mixture is poured into 120 g of water, the pH is adjusted to 6.3 by means of 37% HCl, and THF and cyclohexane are distilled off at 35° C. under reduced pressure. 25 ml of methylcyclohexane are added to the product suspension, the colorless product is filtered off with suction and is washed once with 25 ml of cold methylcyclohexane and once with 25 ml of cold water. After drying, 26.5 g of 2,6-dimethoxyphenylboronic acid (0.146 mol, 91%, melting point: 104–107° C.) are obtained in the form of colorless crystals, HPLC purity >99% a/a.

Quelle