An efficient process for the synthesis of alkoxy substituted benzaldehydes

A process for the preparation of alkoxy substituted benzaldehydes of Formula I from the corresponding alkoxy benzenes of Formula II,

• wherein:
• R1, R2 and R3 are independent of each other,
• R2 represents alkoxy group —OR, wherein R is a substituted or unsubstituted C1-C4 alkyl group, substituted or unsubstituted C3-C6 cycloalkyl group, or R1 and R2 together jointly form an alkylenedioxy group represented by —O—(CH2)n-O— wherein n is 1, 2, 3 or 4,
• R1 represents H, R or —OR, wherein R is a substituted or unsubstituted C1-C4 alkyl group, substituted or unsubstituted C3-C6 cycloalkyl group, or R1 and R2 together jointly form an alkylenedioxy group represented by —O—(CH2)n-O— wherein n is 1, 2, 3 or 4,
• and R3 is a substituent at any position of aromatic ring other than position 1,3 and 4 and represents H, R, —OR, wherein R is a substituted or unsubstituted C1-C4 alkyl group, or substituted or unsubstituted C3-C6 cycloalkyl group, or R3 represents halogen selected from Cl, Br, I, or nitrogen containing group selected from CN, NO2, NH2, —CONH2, in a straight-through chemical process, said process comprising the steps of:
• a) halomethylation of starting material represented by compound of Formula II in an organic solvent to obtain the compound of Formula VII;
• wherein X is a halogen atom selected from Cl, Br and I;
• b) contacting the resulting reaction mass containing compound of Formula VII with hexamethylenetetramine to obtain a complex of Formula VIII;
• c) decomposing the complex of Formula VIII to produce the compound of Formula I, comprising contacting a reaction mass of step b) with acid, or base or salt or mixtures thereof in biphasic reaction,
• wherein said acid or base or salt or mixture thereof is selected from the group consisting of i) aqueous acetic acid, ii) a mixture of aqueous acetic acid and mineral acids wherein said mineral acid comprises one of phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid and mixtures thereof, iii) a mixture of organic acids selected from the group consisting of acetic acid, chloroacetic acid, a mixture of aqueous acetic acid and iv) alkali metal salts selected from the group consisting of sodium acetate, sodium phosphates, and mixtures thereof, and v) a combination thereof, wherein an initial acid concentration is in a range of about 20% to about 70%
• d) separating an organic solvent layer of a biphasic reaction mass of step c) containing compound of Formula I;
• e) isolating substantially pure compound of Formula I in yield of about 80% comprising recovering the organic solvent from said organic solvent layer of step d) followed by purification of a crude mass by standard purification process.