Methanol → Benzaldehyde, 2-hydroxy-5-nonyl-

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A 2-liter round-bottomed flask was charged with magnesium (24 g, 0.98 mol), methanol (570 ml), toluene (240 ml) and magnesium methoxide (10 ml solution of 7.4% by weight magnesium methoxide in methanol). The reaction mixture was heated to reflux and the magnesium dissolved. Para-nonyl phenol (224 g) was added in one portion to the reaction mixture. The flask was then rigged for a fractional vacuum distillation and an azeotrope of methanol/toluene was distilled off to an internal temperature of 70° C. at a pressure of 350 mm Hg. The mixture was cooled to 25° C. and toluene (300 ml) was added. Anhydrous hydrochloric acid (38 g) was added to the reaction mixture over a period of 1.5 hours. Methanol (200 ml) was then added to the mixture and the pot was rigged for an atmospheric pressure fractional distillation. An azeotrope of methanol/toluene was distilled off to a pot temperature of 100° C. The pot was then cooled to 90° C. and paraformaldehyde (94.8 g, a commercial sample containing 5-7% by weight water) slurried in toluene (200 ml) was added over a 1 hour period. During the addition of paraformaldehyde, volatile reaction by-products were continually removed. The reaction mixture was maintained at a temperature of 90° C. for an additional hour after the paraformaldehyde addition was complete. The reaction temperature was then cooled to 70° C. and sulphuric acid (300 ml, 10% w/w) was added to the reaction mixture, which was then stirred for 30 minutes. After phase separation, the organic phase was washed twice with 200 ml portions of water. The washed organic phase was then separated, dried and rendered free of the solvent to yield crude 5-nonyl salicylaldehyde. A 62% yield was obtained.

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