3,4-Dimethoxyphenol

Red Crystal Powder

A substituted alkynyl phenoxy compound as new synergists in pesticidal compositions.

3,4-Dimethoxyphenol is used in the preparation of 5,6-dimethoxy benzofuranone derivatives and multi-target anti Alzheimer compounds. It is also used in the preparation of 3,4-dimethoxyphenyl-beta-D-glucopyranoside and 4-(but-2-enyloxy)-1,2-dimethoxybenzene. Further, it serves as a precursor for 4H-chromenes synthesis.

3,4-Dimethoxyphenol is synthesised using Veratraldehyde as a raw material by chemical reaction. The specific synthesis steps are as follows:
Method (i): To a solution of vertraldehyde (2.11)(5 g,0.03 mole)in glacial acetic acid (30 ml)is added dropwise to a solution of peracetic acid5(15 ml) during 30 min.The temperature of the reaction mixture rises,it is kept at 40-45 by cooling.The reaction mixture is left for 10 hr and then concentrated to about 15 ml in vacuo.The residue is extracted with ether (2 x 20 ml).The ether layer is distilled.The formate ester of 3,4- dimethoxyphenol thus obtained is hydrolysed by refluxing with potassium hydroxide (10 g)in aqueous alcohol (1:4,100 ml)for 1 hr.The reaction mixture is concentrated in vacuo almost to dryness.It is dissolved in water (20 ml),the solution rendered acidic with dilute sulphuric acid and extracted with ether.The ether extract is dried (sodium sulphate)and distilled.The oily residue thus obtained is subjected to column chromatography over silica gel(2 x 30 cm).Elution with benzene gave 3,4-dimethoxyphenol as yellow solid.Yield 3g(65.2%).It is crystallised from  benzene as yellow crystalline needles.M.p.78-80(lit.m.p.78-80).

Method (ii): A mixture of veratraldehyde (2.11)(1.66 g,0.01 mole),hydrogen peroxide (30%,2.6 ml,0.023 mole),p-toluenesulphonic acid (6.88 g, 0.036 mole)and methanol (5 ml)is stirred at room temperature.When the reaction is complete (as monitored by TLC)the reaction mixture is diluted with water (50 ml)and extracted with dichloromethane (5 x 50 ml).The extract is dried (anhydrous sodium sulphate)and purified by column chromatography over silica gel(2 x 30 cm).Elution with benzene gave 3,4. dimethoxyphenol as an yellow solid.Yield 1.16 g (75.3%).M.p.78-80.