Bandil (Hive Bee)
11-29-02 22:22
No 384660
      Methylation w/ dimethylsulfate - better solvent?  Bookmark   

Hi!

With some dimethylsulfate at hand swim was about to make the ether of methylhydroquinone. PiKHAL and the STP entry at rhodium suggests the use of NaOH in water. The methylation on ../rhodium/chemistry /pseudodillapiole.html (step two) uses far less solvent and less reaction time.

Which of these schemes would be better for swims compound?

Thanks!

Regards
Bandil
 
 
 
 
    Rhodium
(Chief Bee)
11-30-02 00:56
No 384694
      2,5-Dimethoxytoluene from toluhydroquinone  Bookmark   

I definitely think that the reaction would work all right in acetone.

2,5-Dimethoxytoluene Patent US5656648

A mixture of 12 g of methylhydroquinone, 45 g of potassium carbonate and 45 g of dimethyl sulphate in 300 ml of anhydrous acetone is heated to reflux for 4 days. After cooling, the reaction mixture is filtered and the filtrate is evaporated under vacuum. The residue is taken up in 150 ml of concentrated aqueous ammonia, the mixture is left stirring for 2 hours, diluted with water and extracted with DCM, the organic phase is dried over magnesium sulphate and the solvent is evaporated off under vacuum. The residue is chromatographed on silica H, eluting with a heptane/DCM (50:50; v/v) mixture. 12g (55%) of the expected product is obtained.

2,5-Dimethoxytoluene Patent US4975463

To a well-stirred solution of NaOH (44 g, 1.1 mole), and Na2S2O4 (8.7 g, 50 mmol) in water (500 mL) under N2, was added methyl-hydroquinone (62.07g, 0.50 mole). To the homogeneous solution Me2SO4 (99.4 mL, 1.05 mole) was added and the mixture stirred for 0.5 hour. (If the solution did not remain basic, more NaOH was added, and the mixture stirred for 0.5 hour more). The aqueous layer was extracted with ether (2x200 mL), and the ether layer was washed with 1N NaOH (200 mL). The ether layer was dried (MgSO4), filtered, and the solvent was removed. After vacuum distillation, and the solvent was removed. After vacuum distillation, the yield was 54.9g (69%).

 
 
 
 
    hest
(Hive Adickt)
12-01-02 17:29
No 385171
      Methylation  Bookmark   

Use KOH as the base, usual much better yeald. DMF and potasiumcarbonat is also a good system, usual it runs at 25C for 12 houers. Last time I methylated methylhydroquinon i used water as the solvent works greath (yeald in the 80's))) can't remember iff I posted a synth at the hive, but it's straight ahead, disolve 1,1 mole KOH in wather, add mole methylhydroquinon. Cool with external ice, add 1,1 mole DMS, then boil some houers (1-5) pour out on ice and seperate the TM from the wather xtract the wather with ether, dry, evaporate and distilate. I always get's a red oil afther the destilation but asume it's posible to get a white one.