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(3) After 155 g (969 mMol) of 25% sodium hydroxide aqueous solution was added in the reaction product (the reaction liquid) obtained by the above-mentioned process (1) to make the liquid alkali (pH 12), 700 g of toluene was added and the extraction treatment of the reaction liquid was conducted under stirring. After being separated and recovered from water phase, the organic phase was washed with 600 g of water and separated. Then, the washed organic phase was concentrated under reduced pressure and 536 g of crude para-menthane-3,8-diol was obtained. Next, said crude para-menthane-3,8-diol was distilled and375.8 g of purified para-menthane-3,8-diol (a mixture of cis form and trans form) was obtained.
2-[2,6-dimethyl-5-heptenyl]-4,4,8-trimethylhexahydro-1,3-benzodioxine[ No CAS ]
[ 42822-86-6 ]
[ 89-79-2 ]
Yield
Reaction Conditions
Operation in experiment
With sulfuric acid;cetyltrimethylammonim bromide; In water; at 35℃; for 5.0h;
A method for carrying out this invention is as indicated below. The actual detail of the processing will be known to those skilled in the art:1. A solution of hexadecyltrimethylammonium bromide (0.05%) in 5% sulphuric was charged into a reactor and vigorously stirred. Citronellal in an amount equivalent to 33.32.% of the total charge was fed into the reactor over a five hour period with the temperature being maintained at or below 350C. Stirring was continued for a further three hours.2. The stirring was stopped and the two phases were allowed to separate. The lower aqueous acid solution was run off to be used in further batches. The temperature should be maintained above 30C for ease of separation. <n="15"/>3. The organic layer was washed with a solution of mild alkali such as sodium carbonate or sodium bicarbonate to remove residual acid until an aliquot shaken with water showed a pH of 5.0 - 8.0. The product was filtered through a lOOmuM filter to remove residual water and any suspended solids.4. The resultant product is a clear or slightly opaque almost colourless, moderately viscous liquid with a slight pleasant floral odour quite unlike that of the starting material.Analysis of the product of the above process shows a typical composition: PMD-citronellal acetal 5-12%Isopulegole 7-14%/?alphara-menthane-3,8-diol remainder