多聚甲醛苯酚甲酰化反应

多聚甲醛和甲醇镁进行邻位苯酚甲酰化，一般产率较高，特别适用于对甲氧基苯酚的甲醛化。有些专利上报道，加入吡啶有利于提高产率。

Phenol (37.6 g,0.4 mol) was added to magnesium methoxide (259 g of 8 wt% solution in methanol; 20.7 g, 0.24 mol) and the mixture was heatedto reflux. Approximately half the methanol was distilled off and toluene (300 g) was added to the residue. Theazeotropic mixture of toluene and methanol was removed by fractionaldistillation, until the temperature of the reaction mixture rose to 95 ℃. A slurry ofparaformaldehyde powder (43.2 g,1.44 mol) in toluene (75 g)was added in small portions over 1 h to the reaction mixture at 95 ℃with concurrent removal of volatile materials by distillation. Stirring wascontinued at 95 ℃ for 1h, after which the mixture was cooled to 25 ℃ and added slowly to 10% sulfuricacid (450 g). Theresulting mixture was stirred at 30-40 ℃ for 2 h, after which the aqueouslayer was separated and extracted with toluene (2x100 g). The combined organic layers and extracts werewashed with 10% sulfuric acid (50 g)and water (50 g) andevaporated under pressure to give the aldehyde as a pale yellow oil (48.35 g, 84% w/w by GC and 1H NMRcomparison against a reference standard and against a commercial sample ofknown purity; 83% yield).

Reference: Journalof the Chemical Society Perkins Transactions I, 1823-1831 (1994)

在氯化锡或者氯化亚锡条件下，用多聚甲醛可在苯酚邻位上醛，反应收率较高。

To a four-neck RB flask (2.5 l) eq. with a reflux condenser, mech. stirrer, thermometer,and N2 source was added anhydrous toluene (200 mL) an appr. phenol(1 mol) tributylamine (54 g,0.4 mol) and SnCl4 (26 g,0.1 mol). The mixture was stirred 20 min at RT, then paraform was added (66 g, 2.2 mol). The resulting yellow solutionwas heated at 99~101 oC at 8 hrs. After cooling the RM was pouredinto water (5 L)acidified to pH 2 with 2N HCl and extracted with ether. The ether extract waswashed with satur. brine, dried over Na2SO4 and conc. toleave crude aldehyde. Product was purified by steam distillation and ifnesessary, by subseq. distillation and recryst. from pet. ether. Yields, f.e.from p-methoxy-phenol, 85%, mp 51-52C.

Reference: JCS Perkins I, (1980)1862-1865

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