Preparation of substituted benzaldehydes by reacting substituted benzene with carbon monoxide in the presence of metal halides and acids.Patent US6080892
EXAMPLE 1
100.0 g of aluminum chloride (mol. wt. 133.34; 750 mmol) was poured over about 484.55 g of chlorotoluene in a 2 liter Paar.RTM.-brand stainless steel reaction vessel. Five drops of aqueous hydrochloric acid (concentrated) were then added and the vessel was sealed and purged two times with nitrogen at 60 psi. Then about 67.6 g of o-xylene (mol. wt. 106.17; 625 mmol) were charged to the vessel. The reactor was then purged three times with carbon monoxide at a pressure of about 110 psi. After the final purging, the vessel was vented and a final introduction of CO was made at a final pressure of about 110 psig, the pressure at which the reaction was maintained for the total reaction time of about 18 hours (the reaction temperature was maintained at about 5 DEG C. for the duration as well). After that time, the resultant mixture (exhibiting a dark orange color) was purged three times with nitrogen and poured into about 570 g of ice water (which turned the solution a dark purple), to which was then added 500 mL of cyclohexane (which turned the color to grey and produced a two-phase mixture). The top, organic layer was removed and washed three times with water using a separatory funnel and dried over magnesium sulfate. The residual organic phase was then distilled under a vacuum to remove o-xylene, cyclohexane, and chlorotoluene, and left about 74.36 g of the 3,4-dimethylbenzaldehyde target product (554 mmol; yield of approximately 88.7%).
EXAMPLE 2
99.4 g of aluminum chloride (mol. wt. 133.34; 745 mmol) and about 74.0 g of o-xylene (mol. wt. 106.17; 697 mmol) were charged to a 2 liter Paar.RTM.-brand stainless steel reaction vessel with about 150 mL of o-dichlorobenzene. The vessel was sealed, purged two times with nitrogen at 50 psi, then once with carbon monoxide at a pressure of 100 psi. After the final purging, the vessel was vented and a final introduction of CO was made at a final pressure of about 40 psig, the pressure at which the reaction was maintained for the total reaction time of about 14 hours (the reaction temperature was maintained at about 18-200 DEG C. for the duration as well). Once the reaction was complete, the resultant mixture was poured into about 600 g of ice water to produce about 900 mL of a two-phase mixture. The top, organic layer was removed and washed three times with water using a separatory funnel and dried over magnesium sulfate. The residual organic phase was then decolorized with activated charcoal and subsequently distilled under a vacuum to remove o-xylene (which has a boiling point of about 143-145 DEG C.), then o-dichlorobenzene (which has a boiling point of from about 174 to 180 DEG C.), and left about 50 g of the 3,4-dimethylbenzaldehyde target product (372.5 mmol; yield of approximately 50%).
Synthesis of aldehydes using the Gattermann-Koch reaction without activators.Golubev, G. S.; Simonova, T. A.; Aleksandrov, V. N.; Gitis, S. S.
Zh. Prikl. Khim. (Leningrad) (1979), 52(4), 954-5.
ISSN: 0044-4618. Journal in Russian. CAN 91:56544
Abstract
Gattermann-Koch formylation of RC6H4Me (R = H, 2- and 3-Me) in C6H6 contg. AlCl3, HCO2H and SOCl2 or PCl5 gave 56.4-68.4% x,4-RMeC6H3CHO. (This article is on its way)
MethylbenzaldehydesPatent JP54157534
Abstract
Methylbenzaldehydes were prepd. by liq.-phase autoxidn. of polymethylbenzenes having 2-4 Me groups in the presence of sol. Br compds. over >0.005 mol equiv sol. Co salts in 1.0 mol equiv. satd. fatty acids or their anhydrides as solvents at <85° to a point of <95% conversion. Thus, a liq. mixt. of 1:12.5:0.3:0.03 M 1,3,5-Me3C6H3, HOAc, Co(OAc)2.4H2O, and Br was heated 30 min at 49-51° with introduction of O to give dimethylbenzaldehydes with 61% selectivity and 59% conversion, vs. 23 and 58%, resp., without Br. Similarly oxidized were 1,2,4,5-Me4C6H2, o-, m-, and p-xylene, and 1,2,4-Me3C6H3.
Process for the preparation of substituted benzaldehydes Patent US4622429
This is the traditional gattermann-koch reaction which requires high pressure(~1000psi) HCL and CO.
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