Keto acids infrared absorption

Oxodecanoic acid. Dissolve 4.0 g of 3-carboxy-3,4-dibromodecanoic acid in 60 ml of 2m sodium hydroxide solution and heat the solution at 80-90 °C for 2 hours. Cool to room temperature and acidify with dilute sulphuric acid carbon dioxide is evolved and a white precipitate is formed. Filter the precipitated keto acid from the cold solution and recrystallise from light petroleum (b.p. 40-60 °C). 4-Oxodecanoic acid, m.p. 68-69 °C, is obtained the yield is 1.6 g (80%). The infrared spectrum shows absorptions at 3400-2400 cm-1 (OH stretch of COzH) and 1700 cm-1 (0=0). 

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