4-Amino-5-ethylsulfonyl-2-methoxybenzoic acid synthesis

4synthesis methods

Product Name:4-Amino-5-ethylsulfonyl-2-methoxybenzoic acid
CAS Number:71675-87-1
Molecular formula:C10H13NO5S
Molecular Weight:259.28

methyl 4-amino-5-(ethylthio)-2-methoxybenzoate

1119455-01-4

71675-87-1

The general procedure for the synthesis of 4-amino-5-(ethylsulfonyl)-2-methoxybenzoic acid using amisulpride impurity 4 as a starting material was as follows: 30% hydrogen peroxide was slowly added to isopropanol (4.84 L) at ambient temperature containing a catalytic amount of sodium tungstate (0.0082 kg) in 4-amino-2-methoxy-5-ethylthiomethyl benzoate (X) (1.21 kg) solution. The reaction mixture was stirred at 40-45 °C for 3-4 hours and subsequently cooled to 5-10 °C. To the reaction mixture, 5% sodium thiosulfate solution (0.06 kg dissolved in 18.15 L of water) was added and stirring was continued for 60 min to produce methyl 2-methoxy-4-amino-5-ethylsulfonylbenzoate (XI) in situ. Subsequently, sodium hydroxide (1.00 kg dissolved in 10 L of water) was added to the reaction mixture, warmed to 60-65 °C and stirred for 2-3 hours. Upon completion of the reaction, the reaction material was cooled and the pH was adjusted to 4.0-4.5 with dilute hydrochloric acid (1:10). the product was isolated by diafiltration in 82% yield and 99% purity.

1119455-01-4
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71675-87-1
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Yield:71675-87-1 82%

Reaction Conditions:

Stage #1:methyl 4-amino-5-(ethylthio)-2-methoxybenzoate with dihydrogen peroxide;sodium tungstate in isopropyl alcohol at 40 - 45;Industry scale;
Stage #2: with water;sodium hydroxide in isopropyl alcohol at 60 - 65;Industry scale;
Stage #3: with hydrogenchloride in water;isopropyl alcohol; pH=4 - 4.5Industry scale;

Steps:

6
30% Hydrogen peroxide was slowly added to a solution of the 4-amino-2-methoxy-5- ethylthio methyl benzoate (X) (1.21 Kg) in isopropyl alcohol (4.84 Lit.) containing sodium tungstate (0.0082 Kg) as a catalytic amount at ambient temperature. The mixture was stirred at 40-45°C for 3-4 hrs then cooled to 5-10°C. 5% sodium thiosulphate solution (0.06 Kg in 18.15 lit. water) was added to reaction mixture. Reaction mass was stirred for 60 min and 2- methoxy-4-amino-5-ethyl-sulfonyl methyl benzoate (XI) was obtained in situ. To the reaction mixture was added sodium hydroxide (1.00 Kg, in 10 lit. water). The temperature was raised up to 60-65 °C and stirred the reaction mixture for 2-3 hrs. The reaction mass was cooled and adjusted pH 4.0 - 4.5 by using diluted hydrochloric acid (1 : 10). The product was isolated by filtration under suction.Yield : 82%Purity: 99%

References:

LUPIN LIMITED;PAGHDAR, Dinesh, Jayntibhai;KOLEKAR, Mahesh, Ramkumar;DESHPANDE, Tushar, Nandkumar;PATIL, Suryaprakash, Pandurang;CHAVAN, Yuvraj, Atmaram;RAY, Purna, Chandra;SINGH, Girij, Pal WO2011/158084, 2011, A1 Location in patent:Page/Page column 12

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27492-84-8 Synthesis