Dimethyl Isosorbide CAS 5306-85-4 DMI

Isosorbide dimethyl ether is synthesized from isosorbide by methylation. The used methylating reagents are dimethyl sulfate (US Patent US4659846 and US4322359), dimethyl carbonate (US Patent US4700871), methyl chloride (US Patent US4435586 and World Patent WO2007096511).

When synthesizing isosorbide dimethyl ether with dimethyl sulfate, the yield can reach more than 70%, and the highest reported in the literature is 83.5%. As we all know, dimethyl sulfate is a highly toxic chemical, a carcinogen, and harmful to the health of operators. When using dimethyl carbonate to synthesize dimethyl isosorbide, the highest conversion rate of isosorbide is only 89%, and the weight ratio of isosorbide dimethyl ether to monomethyl ether in the product is 59:41. Therefore, dimethyl carbonate is not a suitable starting material for the synthesis of dimethyl isosorbide.

When synthesizing isosorbide dimethyl ether, the solvents used include tert-butanol, acetone, dimethyl sulfoxide, etc., these solvents have the disadvantages of lower boiling point, volatile, difficult solvent recovery, environmental pollution and higher cost of use. Fuertes, Patrick improved the solvent in TO2007096511, using the methylated product isosorbide dimethyl ether as the solvent, and the yield was increased to 95%. However, with isosorbide dimethyl ether as solvent, the production cost is relatively high.

An optimized and improved process for synthesizing isosorbide dimethyl ether can not only reduce production cost, but also reduce environmental pollution. It is characterized in that,

Proceed as follows:

1. In reaction vessel, add solvent, isosorbide, alkali and phase transfer catalyst;
2. Stirring, warming up, decompressing and dehydrating;
3. Feed into methyl chloride, complete etherification reaction under certain pressure and temperature;
4. Add acid to neutralize;
5. Filtration desalination;
6. Underpressure distillation, obtain product isosorbide dimethyl ether and reclaim solvent; The alkali used in reaction is selected from sodium hydroxide, potassium hydroxide or sodium methoxide; Described phase transfer catalyst is the phase transfer of quaternary ammonium salts A catalyst, or a quaternary phosphonium salt type phase transfer catalyst; The solvent is an alkyl-terminated low-molecular-weight polyether, and the structural formula of the alkyl-terminated low-molecular-weight polyether is:

In the formula R1, R2 are to select the same or different straight-chain or branched alkyl groups; The alkyl group used contains 1～15 carbon atoms; R3, R4 are hydrogen atoms or methyl groups; m+n is an integer of 4～15 .