The Vespiary
The Hive => Novel Discourse => Topic started by: Rhodium on August 09, 2002, 01:57:00 PM
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2,5-Dimethoxy-4-ethylbenzaldehyde
2,5-Dimethoxyethylbenzene (66.4 g, 0.4 mol) was dissolved in 250 ml of dry CH2Cl2 and cooled to 10°C and 208 g (0.8 mol) of anhydrous SnCl4 was added. Cl2CHOCH3 (45.9 g, 0.4 mol) was then added over 40 min, maintaining the temperature at 5-10°C. The solution was allowed to warm to room temperature over 45 min, heated under reflux for 1 hr, cooled, and poured over 500 g of ice-H2O. The aqueous layer was discarded. The CH2Cl2 layer was washed with 3 N HCl and H2O and dried (Na2SO4). After removal of the solvent the residue was triturated with saturated NaHSO3 solution. The addition product was dissolved in H2O; the aqueous solution was washed with Et2O and then decomposed with Na2CO2 solution. On cooling, the aldehyde solidified, was collected by filtration, and recrystallized from MeOH-H2O: yield 42g (54%); mp 46-47°C.
1-(2,5-Dimethoxy-4-ethylphenyl)-2-nitropropene
This nitrostyrene was prepared by condensation of the above aldehyde with EtNO2 in AcOH containing NH4OAc. The yellow product was recrystallized from MeOH: yield 60.8%; mp 63-64°C.
1-(2,5-Dimethoxy-4-ethylphenyl)-2-propanone
This substituted phenylacetone was prepared by Fe-HCl reduction of the above nitro compound: yield 60%; by 131-132°C (0.1mm); oxime, mp 79.5-80.5°C
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Cl2CHOCH3 (45.9 g, 0.4 mol) was then added
This is not a typo? This is not supposed to be bis(chloromethyl)ether e.g. (CH2Cl)2O ?
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Definitely not, the sought after compound is dichloromethyl methyl ether, which together with a mild Lewis acid is a common way of introducing a formyl function to an aromatic ring, especially moderately activated ones.
It is a simple friedel-crafts alkylation (using a masked formyl equivalent), the intermediate product being Ph-CHCl-OMe, which upon aqueous hydrolysis splits off HCl and MeOH, giving PhCHO (benzaldehyde).