preparation of 6-methyl-2-pyridinecarboxaldehyde_industrial additives

preparation background of 6-methyl-2-pyridinecarboxaldehyde

6-methyl-2-pyridinecarboxaldehyde is an organic intermediate that can be prepared from 2,6-lutidine through a four-step reaction. 6-methyl-2-pyridinecarboxaldehyde can also be condensed with primary amines to generate schiff bases to generate bidentate chelating ligands, which are similar to 2,2′-bipyridine and 1,10-azophenanthrene. ligands have similar properties to form complexes with transition metals.

preparation of 6-methyl-2-pyridinecarboxaldehyde

synthesis of (1)4b

add 3b36.8g (300mmol), 70ml of glacial acetic acid and 50ml (500mmol) of 30% h₂o₂ into the reaction flask in sequence, stir at 75°c reaction 6h. add 50% h₂o₂ and react at 75°c for another 16 hours [tlc tracking, developing agent: a=v (petroleum ether): v (ethyl acetate) =1:3]. rotary evaporate until half of the solution is removed, add 100 ml of water, and evaporate until no liquid drips out; repeat three times. the residue was adjusted to ph≈10 with saturated na₂co₃ solution, and extracted with chcl₃ (3×100ml). combine the extracts and use dry with anhydrous na₂so₄, rotary evaporate to remove chcl₃, and distill under reduced pressure to obtain yellow transparent oily liquid 4b (yield 78%, rf=0.2).

synthesis of (2)5b

add 60ml of acetic anhydride into the reaction bottle, add 4b35.7g (300mmol) dropwise with stirring, complete the dripping, react at 100°c (micro reflux) for 10h (exothermic is severe, should be heated slowly, tlc tracking, developing agent: a=1:1). distilled under reduced pressure to obtain light yellow slightly mucilage 5b (yield 59%, rf=0.64).

synthesis of (3)6b

add 5b28.0g (170mmol) into the reaction bottle, slowly adjust ph≈14 with naoh saturated solution while stirring (the color deepens from yellow to orange), and reflux the reaction (tlc tracking). cool n, extract with chc sodium bicarbonate 1₃ (3×100ml), combine the organic layers, and dry with anhydrous na₂so₄. rotary evaporate to remove chcl₃ to obtain 6b.

(4) 7b is the synthesis of 6-methyl-2-pyridinecarboxaldehyde

add active mno₂59.6 g (700mmol), chcl₃250 ml and 6b17.7 g (140 mmol) into the reaction flask, stir and reflux the reaction ( tlc tracking). cool n, filter, and evaporate the filtrate to obtain a dark brown liquid, which is decolorized by column chromatography (eluent: a=7:1) to obtain 7b, which is 6-methyl-2-pyridinecarboxaldehyde. 7b: yellow solid, m.p.36℃～38℃, yield 76%, rf=0.80(a=1:2);

¹hnmrδ: 2.67( s,3h, ch3 ), 7.38～7.43( m, 1h, pyh), 7. n-butylboronic acid 77( d,j=6.0 hz, 2h, pyh), 10.05(s, 1h, cho);

irν: 3 408, 3064, 2927, 2827, 2684, 1914,1713, 1677, 1593 cm^-1.