Synthesis of Benzoic acid

Synthesis of Benzoic acid - Experiment Synthesis of Benzoic...

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Experiment: Synthesis of Benzoic acid Reaction In this lab we investigated the Grignard synthesis of Benzoic acid which is illustrated by the following formula C 6 H 5 Br + Mg/diethyl ether + CO 2 + HCl ----> C 6 H 5 COOH + MgBrCl [ + (C 6 H 5 ) 2 ] Mechanism of the Synthesis In this reaction when bromobenzene reacts with Magnesium it forms an intermediate which has a highly polarized covalent bond. This intermediate is called the Grignard reagent which acts both as a strong base as well as a nucleophile. We want the reagent to act as a nucleophile in its reaction with CO2 therefore there should not be any water available in the reaction mixture(it acts as a base with water)
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Table of reagents Compound Formula M.W. Grams OR mL used Moles used mp ( o C) bp ( o C) Density (g/mL) Solubility Bromo- benzene C 6 H 5 Br 157.02 2.0ml 0.01899 -31 156 1.491 al, eth, bz, w Carbon Dioxide CO 2 44.01 12g 0.2726 -56.6 -78.5 1.977 al, ace Magnesium Mg 24.31 0.6g 0.0247 648.8 1090 ---- ---- Diethyl ether (CH 3 CH 2 ) 2 O 74.12 40ml 0.3853 -116.2 34.51 0.714 ace, chl Conc. Hydrochloric Acid 12M HCl (aq) ---- 5ml 60 ---- ---- ---- ---- water H 2 O 18.01 N/A N/A 0 100 1.000 ---- 5% Sodium Hydroxide 5% NaOH (aq) ---- N/A N/A ---- ---- ---- ---- Theoretical Yield Benzoic Acid C 6 H 5 COOH 122.13 23.2g .01899 122.4 249 1.266 al, eth, bz, ace, chl biphenyl (C 6 H 5 ) 2 154.21 N/A N/A 69-72 255 0.992 al, eth, bz, Procedure and Observations The glassware and the magnesium for this preparation were obtained from the ovens in the lab. The pre-weighed, (0.60 g), dry magnesium from the vial was put into the 500mL flask along with a medium sized magnetic stir bar and the apparatus set up. The water hoses were attached to the condenser and the cooling water turned on. Procedure for Preparation of Phenylmagnesium Bromide: Oven-dried (and subsequently cooled) graduated cylinders were used to measure 2.0 mL of bromobenzene and about 30 mL of anhydrous ether. About 10 mL of the anhydrous ether and 1 mL of the previously measured bromobenzene were added to the reaction
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Synthesis of Benzoic acid - Experiment Synthesis of Benzoic...

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