ChemicalBook CAS DataBase List 2,4-Dimethoxybenzoic acid

2,4-Dimethoxybenzoic acid synthesis

11synthesis methods

Product Name:2,4-Dimethoxybenzoic acid
CAS Number:91-52-1
Molecular formula:C9H10O4
Molecular Weight:182.17

17715-69-4
307 suppliers
$9.00/10g

124-38-9
722 suppliers
$175.00/23402

91-52-1
238 suppliers
$10.60/1gm:

Yield:91-52-1 91%

Reaction Conditions:

Stage #1:1-Bromo-2,4-dimethoxybenzene with n-butyllithium in tetrahydrofuran at -78; for 0.5 h;Inert atmosphere;
Stage #2:carbon dioxide in tetrahydrofuran at -78; for 0.75 h;

Steps:

4.1.4. 2,4-Dimethoxybenzoic acid (9)²²
n-BuLi (2.5 M in THF, 3.3 mL, 8.3 mmol) was added drop wise to a stirred solution of 1-bromo-2,4-dimethoxybenzene (7) (1.5 g, 6.9 mmol) in THF (15 mL) at -78 °C under N₂ atmosphere. After 30 min, CO₂ gas was passed through the solution during 45 min of time and the mixture was allowed to warm up to room temperature. THF was removed in vacuum and the mixture was treated with saturated NaHCO₃ solution (40 mL). The water layer was washed with ethyl acetate (2*20 mL) and then acidified with conc. HCl. The mixture was extracted with ethyl acetate (2*75 mL). The organic layer was washed with water (2*30 mL), brine (30 mL), dried (Na₂SO₄), filtered and concentrated. Recrystallization from ethyl acetate produced 9 (1.15 g, 91%) as white solid. R_f 0.3 (1:1 ethyl acetate:hexane); mp 103-105 °C (lit.²² 107-109 °C); ¹H NMR (CDCl₃, 500MHz): δ 8.10 (d, 1H, J=9.0Hz, C6-H), 6.61 (dd, 1H, J=9.0, 2.0Hz, C5-H), 6.50 (d, 1H, J=2.0Hz, C3-H), 4.01 (s, 3H, OMe), 3.86 (s, 3H, OMe); ¹³C NMR (CDCl₃, 125MHz): δ 179.9 (C), 165.2 (C), 160.2 (C), 135.2 (CH), 110.1 (C), 106.2 (CH), 98.5 (CH), 56.4 (CH₃), 55.7 (CH₃).

References:

Pahari, Pallab;Saikia, Ujwal Pratim;Das, Trinath Prasad;Damodaran, Chendil;Rohr, Jürgen [Tetrahedron,2016,vol. 72,# 23,p. 3324 - 3334] Location in patent:supporting information

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