2-Amino-4,5-dimethoxybenzoic acid

Brown Solid

48.13 g (0.729 mol) of KOH pellets (w=85percent) are dissolved in 250 ml of ice water. 50 g (0.207 mol) methyl-4, 5-dimethoxy-2-nitro-benzoate (1) are added to the clear solution and the resulting green suspension is heated to 70° C. During the heating a dark red solution is formed. Once the reaction has ended (monitored by HPLC) the solution is cooled to ambient temperature and adjusted to pH 6.6 with 34.6 g (0.570 mol) glacial acetic acid. The resulting red suspension is hydrogenated with 1 g of 10percent Pd/C at 50° C. and 3.5 bar until the reaction comes to a standstill. Then the hydrogenation solution is filtered off and adjusted to pH 5.1 with 31.82 g (0.525 mol) glacial acetic acid under an inert gas. The light green suspension is stirred for 30 min at RT, then cooled to 5° C. and stirred for another 30 min.The product (2) is filtered off, washed in two batches with a total of 250 ml of ice water and then dried at 55° C. for 12 h in a vacuum drying cupboard.This reaction yielded 35.18 g (0.173 mol, 83percent of theory) of light grey crystals.Compound 3 (10 g, 44.02 mmol), Pd/C (0.5 g) and 200 mL methanol were added to the 500 mLhigh pressure reactor, the air in the reactor was replaced by H2 (0.1 MPa) three times and shut downthe vent valve. The mixture was stirred at 45 C and 0.4 MPa of H2 for 2 h, after the reaction was over, Pd/C was filtered out and the solution was distilled under vacuum as soon as possible. The resultingresidue was filtered and washed to give a yellow solid 7.2 g with a yield of 83.7percent, m.p. 170.4–172.0 °C.A solution of 2-nitro-4, 5-dimethoxybenaoic acid (8 g, 35.2 mmol) in EtOH (50 mL) was added with ammonium formate(8.8 g, 139.7 mmol) and 5percent Pd-C (0.19 g) and wad heated to refluxfor 6 h. The reaction was cooled to rt and filtered off the solid. Thesolution was concentrated to dryness that was then purified bysilica gel column to give 2-amino-4, 5-dimethoxy benzoic acid (5a)as a white solid (6 g, yield 65percent). mp 156-157 °C; 1H NMR (CDCl3, ppm): δ 7.36 (s, 1H), 6.17 (s, 1H), 3.91 (s, 3H), 3.86 (s, 3H).Intermediate 1 (1 g, 4.40 mmol) was dissolved in 20 ml of absolute ethanol at 80 ° C and dissolved in 20 ml.Water and ammonium chloride (0.47 g, 8.80 mmol) were heated to 100 ° C to add reduced iron powder (1 g, 17.86 mmol) in portions.The reaction was completed by TLC reaction for 3 hours. After the completion of the reaction, the mixture was filtered with hot water, and then filtered and evaporated to ethyl acetate. The silica gel column gave 0.3 g of an off-white solid, yield 34.6percent.In a 500 mL reaction flask equipped with a stirrer, 16 g of 2-nitro-4, 5-dimethoxybenzoic acid was added to the solvent150 mL of methanol, then hydrated hydrazine 105 g and Raney nickel 0.4 g, Nitrogen protection reaction system, heated to 50 ° C reaction, reactionAfter 5 h, the TLC monitors the reaction of the starting material completely, filters the reaction solution, and removes the solvent methanol to give 2-amino-4, 5-dimethoxybenzoic acid11g.

Used as an intermediate in organic synthesis

Molecular Weight:197.19
XLogP3:1.3
Hydrogen Bond Donor Count:2
Hydrogen Bond Acceptor Count:5
Rotatable Bond Count:3
Exact Mass:197.06880783
Monoisotopic Mass:197.06880783
Topological Polar Surface Area:81.8
Heavy Atom Count:14
Complexity:209
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes