3153-97-7

Upstream product

• 50-00-0 formaldehyd 
• 90-05-1 2-methoxy-phenol 
• 2931-90-0 5-formylvanillin 
• 7732-18-5 water 

Downstream Products

• 2931-90-0 5-formylvanillin 
• 50827-57-1 2-methoxy-6-hydroxymethyl-1,4-benzoquinone 
• 28276-05-3 4-formyl-6-hydroxymethylguaiacol 
• 3153-99-9 1-Hydroxy-2-methoxy-4,6-bis-chlormethyl-benzol 
• 3153-98-8 3,4,5-trimethoxybenzyl alcohol 
• 50-00-0 formaldehyd 
• 7732-18-5 water 
• 52607-63-3 3‐methoxy‐5‐(phenyldiazenyl)salicylaldehyde 
• 485-38-1 4,5-dimethoxy-isophthalic acid 
• 3154-01-6 1,2-Dimethoxy-4,6-bis-brommethyl-benzol 
• 3154-00-5 1,2-Dimethoxy-4,6-bis-chlormethyl-benzol 
• 3154-02-7 1,2-Dimethoxy-4,6-bis-carboxymethyl-benzol 
• 3154-06-1 1,2-Dimethoxy-4,6-bis-<2,2-diethoxycarbonyl-2-acetamino-ethyl>-benzol 
• 3327-75-1 1,2-Dimethoxy-4,6-bis-cyanmethyl-benzol 

Relevant academic research and scientific papers

Method for preparing a 4-hydroxybenzaldehyde and derivatives

The present invention concerns a process for the preparation of a 4-hydroxybenzaldehyde and its derivatives. More particularly, the invention concerns the preparation of 3-methoxy-4-hydroxybenzaldehyde and 3-ethoxy-4-hydroxybenzaldehyde, respectively known as vanillin and ethylvanillin. The process for the preparation of a 4-hydroxybenzaldehyde and its derivatives is characterized in that it consists of selectively oxidising, to a carboxy group, the group in the 2 position with respect to the hydroxyl group, present in the phenolic compounds in a mixture comprising at least a phenolic compound (A) carrying formyl and/or hydroxymethyl groups in the 2 and 4 position, a phenolic compound (B) carrying a formyl or hydroxymethyl group in the 4 position, a phenolic compound (C) carrying a formyl or hydroxymethyl group in the 2 position, resulting in a mixture comprising a 3-carboxy-4-hydroxybenzaldehyde, a 4-hydroxybenzaldehyde and a 2-hydroxybenzoic acid, which then undergoes a decarboxylation operation to produce the 4-hydroxybenzaldehyde and a phenol which can optionally be recycled.

Process for the preparation of 3-carboxy-4-hydroxybenzaldehides and derivatives thereof

The present invention concerns a process for the preparation of 3-carboxy-4-hydroxybenzaldehydes and derivatives thereof from phenolic compounds carrying formyl and/or hydroxymethyl groups in the 2 and 4 positions. The invention also concerns the preparation of 4-hydroxybenzaldehydes from 3-carboxy-4-hydroxybenzaldehydes. More particularly, the invention concerns the preparation of 3-methoxy-4-hydroxybenzaldehyde and 3-ethoxy-4-hydroxybenzaldehyde, respectively known as "vanillin" and "ethylvanillin". The process for the preparation of 3-carboxy-4-hydroxybenzaldehyde is characterized in that the group in the 2 position in a phenolic compound carrying formyl and/or hydroxymethyl groups in the 2 and 4 positions is selectively oxidized to a carboxy group, and optionally a hydroxymethyl group in the 4 position is selectively oxidized to a formyl group. A successive decarboxylation step for a 3-carboxy-4-hydroxybenzaldehyde produces a 4-hydroxybenzaldehyde.

ON THE REGIOSELECTIVITY OF THE FREMY'S SALT OXIDATION OF PHENOLS

A detailed study of the regioselectivity of the Fremy's salt oxidation of phenols, including a series of MNDO calculations of the intermediate phenoxy radicals, has been carried out.The analysis of these results has led us to establish a new rule for the para vs. ortho regioselectivity, namely: "C-4 unsubstituted phenols, as well as phenols substituted at C-4 with easy-to-displace groups, undergo oxidation (or oxidative degradation) by the action of Fremy's salt, thus eventually providing the corresponding p-quinones".A similar rule for the ortho vs. ortho' regioselectivity could not be so precisely formulated since now steric effects play a significant major role.