Method for the preparation of α,α, α′,α′-tetrachloro-p-xylene
View Patent ↗A synthesis method of α,α,α′,α′-tetrachloro-p-xylene is disclosed. The method includes reacting terephthaldicarboxaldehyde with a mixture of SOCl 2 and dimethylformamide (DMF) to obtain a product mixture containing α,α,α′,α′-tetrachloro-p-xylene as a major product and 4-dichloromethyl benzaldehyde as a side product, which can be separated by silica column chromatography.
1. A method for synthesizing α,α,α′,α′-tetrachloro-p-xylene, which comprises reacting terephthaldicarboxaldehyde with a mixture of SOCl 2 and dimethylformamide, wherein the reaction is performed at a temperature of 70-95° C.
2. The method as claimed in claim 1 , wherein an amount of SOCl 2 used in the reaction is 2-3 times of that of terephthaldicarboxaldehyde used in the reaction in mole.
3. The method as claimed in claim 1 , wherein an amount of dimethylformamide used in the reaction is 5-25 g per mole of terephthaldicarboxaldehyde used in the reaction.
4. The method as claimed in claim 1 further comprising contacting the resulting product mixture from the reaction with water so that a solid precipitate is formed; removing the solid precipitate from the mixture; introducing said solid precipitate into a silica column and eluting the column with a non-polar solvent; collecting the eluate resulting from the elution; and removing the non-polar solvent contained in the eluate.to obtain a α,α,α′,α′-tetrachloro-p-xylene solid.
5. The method as claimed in claim 4 , wherein the non-polar solvent is n-hexane.
6. The method as claimed in claim 1 comprising performing a first stage reaction by reacting terephthaldicarboxaldehyde with a mixture of SOCl 2 and dimethylformamide to obtain a product mixture including α,α,α′,α′-tetrachloro-p-xylene as a major portion and 4-dichloromethyl benzaldehyde by-product; performing a second stage reaction by adding SOCl 2 and DMF into said product mixture; and contacting the resulting product mixture from the second stage reaction with cooling water to obtain a solid product of α,α,α′,α′-tetrachloro-p-xylene with a purity of 90-99 mole %.
7. The method as claimed in claim 6 further comprising heating and stirring the resulting solid-liquid mixture from said contact to form a dispersion; removing the resulting fine particles of said solid product from said dispersion and drying the fine particles to obtain an α,α,α′,α′-tetrachloro-p-xylene powder having a purity higher than that of said solid product.