ChemicalBook CAS DataBase List 2-Methyl-4-nitrobenzoic acid

2-Methyl-4-nitrobenzoic acid synthesis

8synthesis methods

Product Name:2-Methyl-4-nitrobenzoic acid
CAS Number:1975-51-5
Molecular formula:C8H7NO4
Molecular Weight:181.15

99-51-4

1975-51-5

The general procedure for the synthesis of 2-methyl-4-nitrobenzoic acid from 4-nitrophthalic acid is as follows: in a 50 mL three-necked round-bottomed flask equipped with a magnetic stirrer and reflux condenser, 4-nitrophthalic acid (0.15 g, 1 mmol), N-hydroxyphthalimide (NHPI, 0.05 g, 0.3 mmol), 40% nitric acid (1.26 g, 8 mmol), cobalt chloride hexahydrate (CoCl2-6H2O, 7.1 mg, 0.03 mmol), manganese acetate tetrahydrate (Mn(OA)), and cobalt chloride hexahydrate (CoCl2-6H2O). , 8 mmol), cobalt chloride hexahydrate (CoCl2-6H2O, 7.1 mg, 0.03 mmol), manganese acetate tetrahydrate (Mn(OAc)2-4H2O, 7.1 mg, 0.03 mmol), and phase transfer catalyst (0.04 mmol). The reaction mixture was heated to reflux at atmospheric pressure for 12 hours. After completion of the reaction, it was cooled to room temperature and washed with 10 mL of water. The aqueous phase was extracted with ethyl acetate (3 x 5 mL), the organic phases were combined and dried over anhydrous sodium sulfate. Ethyl acetate was removed from the organic phase by rotary evaporation and the crude product was quantified by HPLC analysis based on an internal standard (2,4-dinitrotoluene). The crude product was recrystallized by ethanol/water (3:1) to afford white acicular crystals of 2-methyl-4-nitrobenzoic acid (0.13 g, 72% yield) with melting point 151-152°C. IR (KBr) ν/cm-1 : 1702 (C=O).1H NMR (CDCl3, 500 MHz) δ: 2.79 (s, 3H, CH3), 8.13- 8.17 (m, 2H, Ar-H), 8.21 (d, 1H, J=6.8Hz, Ar-H). The by-product 4-nitrophthalic acid was separated by column chromatography (ethyl acetate/hexane, 1:5) to give light-colored acicular crystals with a melting point of 163°C. IR (KBr) ν/cm-1 : 1730, 1677 (C=O).1H NMR (CDCl3, 500MHz) δ: 7.86 (d, J=8.6Hz, 1H, Ar-H), 8.36 ( dd, J1=8.6Hz, J2=2.0Hz, 1H, Ar-H), 8.42 (d, J=2.0Hz, 1H, Ar-H).

99-51-4
24 suppliers
$13.00/25g

1975-51-5
310 suppliers
$6.00/1g

Yield:1975-51-5 72%

Reaction Conditions:

with N-hydroxyphthalimide;cobalt(II) chloride hexahydrate;nitric acid;manganese (II) acetate tetrahydrate under 760.051 Torr; for 12 h;Reflux;Reagent/catalyst;Concentration;

Steps:

Preparation of 2-methyl-4-nitrobenzoic acid
Preparation of 2-methyl-4-nitrobenzoic acid4-Nitro-o-xylene (0.15 g, 1 mmol), NHPI (0.05 g,0.3 mmol), nitric acid (40 %; 1.26 g, 8 mmol),CoCl2 ·6H2O (7.1 mg, 0.03 mmol), Mn(OAc)2 ·4H2O(7.1 mg, 0.03 mmol) and a phase transfer catalyst(0.04 mmol) were added to a 50 mL three-neckedround bottomed flask equipped with a magnetic stirrerand a reflux condenser. The mixture was heated underreflux for 12 h at normal pressure. After the reactioncompletion the mixture was cooled to room temperatureand washed with 10 mL of water. The aqueousphase was extracted with ethyl acetate (3 × 5 mL)and the obtained organic phase was dried with anhydroussodium sulfate. Ethyl acetate was removedfrom the organic layer by rotary evaporation and thecrude products were determined by the HPLC analysisbased on the internal standard (2,4-dinitrotoluene).The crude products were re-crystallized (EtOH/H2Or = 3 : 1) to give pure 2-methyl-4-nitrobenzoic acid(0.13 g, 72 %) in form of white needle crystals; m.p.:151-152C. IR, ν/cm-1, (KBr): 1702 cm-1.1H NMR(CDCl3, 500 MHz), δ: 2.79 (s, 3H, CH3 ), 8.13-8.17(m, 2H, Ar), 8.21 (d, 1H, J = 6.8 Hz, Ar). Anotherproduct is the 4-nitrophthalic acid which is separatedby column chromatography from ethyl acetate/hexane(r = 1 : 5) in form of light colored needle crystals;m.p.:163C. IR, ν/cm-1, (KBr): 1730 cm-1,1670 cm-1. 1H NMR (CDCl3, 500 MHz), δ: 7.86 (d,J = 8.6 Hz, 1H, Ar), 8.36 (dd, J1 = 8.6Hz, J2 = 2.0Hz,1H, Ar), 8.42 (d, J = 2.0 Hz, 1H, Ar) (Huntress et al.,1936).

References:

Wei, Song-Bo;Tang, Bo;Peng, Xin-Hua [Chemical Papers,2015,vol. 69,# 4,p. 580 - 585]

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