Molbank 2006, M477

Esterification and hydrolysis under microwave irradiation

Krunal G. Desai* and Kishor R. Desai

Department of Chemistry, Synthetic Organic Chemistry Research Laboratory, Veer Narmad South Gujarat University, Surat-395 007 (Gujarat), India.

Tel: (0261) 2258384, Fax: (0261) 2258384 e-mail: [email protected]

*Author to whom correspondence should be addressed

Received: 27 June 2005 / Accepted: 6 September 2005 / Published: 31 March 2006

Keywords: esterification, ammonolysis, microwave effect.

p-methoxy benzoicacid 1 (1.67 g, 0.01 mole) and catalytic amount of conc. H₂SO₄ (2-3 drops) in absolute methanol (30 mL) was taken in RBF placed in a microwave oven and irradiated (400w, 61-62^oC) for 2.5 min [1]. Upon completion of reaction (monitored by TLC), using petroleumether-ethylacetate (8:2) as the eluent solvent system. The reaction mixtures was allowed to attain room temperature and treated with cold water. The solid separated was filtered, washed with water and recrystallised from ethanol to furnish compound 2, yield 90%.

Methyl ester of p-methoxy benzoicacid 2 (1.66 g, 0.01 mole) and hydrazine hydrate (0.9 mL, 0.01 mole) in ethanol (20 mL) was taken in RBF placed in a microwave oven and irradiated (450w, 76-78^oC) for 3.5 min [1]. After completion of reaction (monitored by TLC), using petroleumether-ethylacetate (8:2) as the eluent solvent system. The mixture was cooled and the resulting solid was filtered, dried and recrystallized from ethanol to get compound 3, yield 83%.

Melting point: 88^oC 2 and 136^oC 3.

IR (KBr) (cm^-1): 2 1722 (>C=O of ester), 1225, 1044 (C-O-C), 3023 (C-H, aromatic ring), 1510 (C=C, aromatic ring), 2825 (-OCH₃).3 1661 (>C=O of amide), 3355, 3382 (-NHNH₂), 2837 (-OCH₃), 3028, 1522 (C-H, C=C, aromatic ring).

¹H-NMR (CDCl₃-DMSO-d₆) (400 MHz) δ (ppm): 2 6.70-7.90 (4H, m, Ar-H), 4.0 (3H, s, -COOCH₃), 3.87 (3H, s, -OCH₃). 3 6.85-7.96 (4H, m, Ar-H), 4.41 (2H, s, -NH₂), 7.85 (1H, s, -CONH-), 3.89 (3H, s, -OCH₃).

¹³C-NMR (CDCl₃-DMSO-d₆) (62.90 MHz) δ (ppm): 2 56.60 (-OCH₃), 115.29-134.1 (aromatic carbons), 170 (>C=O of ester), 20 (-COOCH₃). 3 57.68 (-OCH₃), 117.31-130.0 (aromatic carbons), 162 (>C=O of amide).

MS (m/z): 2 166 (M⁺) (C₉H₁₀O₃⁺), 135 (C₈H₇O₂⁺), 107 (C₇H₇O⁺), 59 (C₂H₃O₂⁺), 31 (CH₃O⁺). 3 166 (M⁺) (C₈H₁₀O₂N₂⁺), 135 (C₈H₇O₂⁺), 107 (C₇H₇O⁺), 31 (N₂H₃⁺), 16 (NH₂⁺).

Elemental Analysis: Calculated for 2 C₉H₁₀O₃: C 65.06, H 6.02. Found: C 65.10, H 6.00.

Elemental Analysis: Calculated for 3 C₈H₁₀N₂O₂: C 72.18, H 6.02, N 16.86. Found: C 72.20, H 6.04, N, 16.89.

Acknowledgment

The authors thank the Veer Narmad South Gujarat University, Surat for providing research facilities and one of the author (Krunal Desai) is thankful to the Gujarat Council On Science & Technology, Gandhinagar for financial support (Grant No. GUJCOST/200389/MRP/2003-04/10689). Authors are also thankful to CDRI, Lucknow for providing spectral and analytical data of the compounds.

References

1. Desai, K. G.; Desai, K. R. Indian J. Chem. (Sec-B). 2005, (In Press).

Sample Availability: Available from MDPI.