Dimethylformamide → Methylparaben sodium
Reaction equation
[H-].[Na+:2].CN(C)C=O.[CH3:8][O:9][C:10]([C:12]1[CH:13]=[CH:14][C:15]([OH:18])=[CH:16][CH:17]=1)=[O:11].[H][H]>>[C:10]([C:12]1[CH:17]=[CH:16][C:15]([O-:18])=[CH:14][CH:13]=1)([O:9][CH3:8])=[O:11].[Na+:2]Participants
Conditions
- Temperature
- 0 °C
Procedure
To a suspension of sodium hydride (one equivalent, 50% dispersion in mineral oil) in dimethylformamide (DMF) (100 ml per 50 mmole), cooled to 0° C., is added slowly methyl p-hydroxybenzoate (one equivalent). The reaction mixture is stirred under a nitrogen atmosphere until the evolution of hydrogen ceases. To the solution of sodium 4-carbomethoxyphenolate so produced, is added N,N-dimethylthiocarbamoyl chloride [(CH3)2N(CS)Cl] (one equivalent) in one portion. The resulting suspension is heated to 70° C. for 1-3 hours and then is poured into an aqueous solution (1%) of potassium hydroxide (large excess). The suspension is extracted twice with toluene-hexane (4:1 v/v). After drying over MgSO4, the organic extracts are filtered and evaporated to an oil. The oil is purified by chromatography over silica gel using 2% methanol in methylene chloride to give O-(4-carbomethoxyphenyl)dimethylthiocarbamate [p-CH3CO2C6H4O(CS)N(CH3)2 ]. (mp 97°-102° C.). This product is heated under a nitrogen atmosphere at 220° C. for 30-60 min. to give S-(4-carbomethoxyphenyl)-dimethylthiocarbamate [p-CH3CO2C6H4S(CO)N(CH3)2 ] which is crystallized from methanol. To S-(4-carbomethoxyphenyl)dimethylthiocarbamate, dissolved in DMSO, is added 2 equiv. of sodium hydroxide (10% aqueous). The mixture is heated at 65°-85° C., and the alkyl bromide (1equiv.) is added. Heating is continued for 2-4 hours after which the mixture is poured into a large volume of water. Upon acidification, a precipitate forms, which is collected by filtration. The (alkylthio)benzoic acid is crystallized from methanol.
Sources & evidence
- ORD record
- ord-31273d79df454c5d90338eac472f1b49
- Source dataset
- uspto-grants-1981_10
- Patent number
- US04293484
Reaction notes
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