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6th December 2011 @ 23:02
Product obtained in 75% yield. === Benzoyl protection of glycine using benzoyl chloride in 10% aqueous sodium hydroxide. Prepared according to Org Syn. [b]Reaction Start Time: 10.30 07/12/11[/b] Glycine (12.5 g, 0.17 mol, 1 equiv.) was dissolved in NaOH(aq) (13.3 g in approx 130 mL water, 0.33 mol, 2 equiv.). The flask was placed in a room temperature water bath and benzoyl chloride (21 mL, 0.18 mol, 1.06 equiv.) was added portionwise keeping the temperature below 30 °C. Total addition time approx 60 mins. Stirred for a further hour then cooled in ice. Conc. HCl (approx 20 mL) was added and the mixture stirred for 30 mins. pH 3-4. Copious white precipitate. Filtered and washed with water. The cake was transferred to a beaker and triturated with 100 mL hot DCM for 10 minutes. Filtered and washed with DCM (2 × 20 mL). After air drying (10 mins), dissolved in boiling water (approx 500 mL), hot filtered to remove some residual solid and allowed to crystallise slowly overnight. The crystals were filtered out (room temp.) and washed with water to obtain the product [url=]hippuric acid[/url] as white needles (22.4 g, 75%) after drying under a stream of nitrogen. Mpt. 189-190 °C (water), consistent with literature. [data]912[/data] [b]Solubility:[/b] approx 2 mg/mL in EtOAc: 300 mg sonicated then refluxed in EtOAc (10 mL) for 5 minutes. Allowed to cool to room temperature, filtered and then filtrated concentrated under reduced pressure to obtain white powder (20 mg). Soluble in DMF (very very approx 50 mg/mL). [b]NMR:[/b] [data]946[/data][data]1208[/data] [b]Risk and Hazard Assessment:[/b] [data]904[/data] [b]References:[/b] [url=]J. Chem. Pharm. Res., 2010, 2(4):410-41[/url] Above reference contains procedure with incorrect yield calculation. [url=]Organic Syntheses, Coll. Vol. 2, p.328 (1943); Vol. 12, p.40 (1932)[/url] InChI=1S/C9H9NO3/c11-8(12)6-10-9(13)7-4-2-1-3-5-7/h1-5H,6H2,(H,10,13)(H,11,12)
Attached Files
Reaction Scheme
Risk Assessment
Recrystallised crystals
Re: Synthesis of hippuric acid (PMY 26-1) by OSDD Malaria
23rd January 2014 @ 12:16