How do you synthesis Benzocaine?
Synthesis of benzocaine: Into a 100 ml flask, mix 1.25 g of p-aminobenzoic acid hydrochloride, 10 ml of EtOH, and 0.5 ml H2SO4 (conc.). Heat the mixture at reflux for 2 h. After cooling the mixture, neutralize with an aqueous sodium carbonate solution (10%).
How is lidocaine synthesized?
Lidocaine, 2-(diethylamino)-N-(2,6-dimethylphenyl)acetamide (2.2. 2), is synthesized from 2,6-dimethylaniline upon reaction with chloroacetic acid chloride, which gives α-chloro-2,6-dimethylacetanilide (2.1. 1), and its subsequent reaction with diethylamine [11].
How do you recrystallize lidocaine?
Lidocaine is highly soluble in all common organic solvents but it can be recrystallized from warm hexane using 1 mL of solvent per gram of crude product. The product crystallizes in large colorless spars, mp 65–67 °C (lit.
Why is glacial acetic acid used in lidocaine synthesis?
b. Glacial acetic acid is used as solvent in the reaction to dissolve 2,6-dimethylnitrobenzene, which does not dissolve in the strongly ionic aqueous solution.
Why is absolute ethanol used in the synthesis of benzocaine?
By using absolute ethanol, ester becomes acid due to the hydrogen from water. Therefore, absolute ethanol is chosen for this reaction which will lead the reaction to right (Forward reaction), rather than using any forms of diluted ethanol that could only negatively influence reaction for ester formation.
What is the purpose of sodium acetate in lidocaine synthesis?
The addition of sodium acetate causes the anilide to precipitate because the protonated form of the anilide is deprotonated. The xylidinium salt is is not deprotonated under these conditions and remains in solution. d. Any amount of water in the anilide will be detrimental to the formation of lidocaine.
What is role of glacial acetic acid?
Glacial acetic acid is an excellent polar protic solvent, as noted above. It is frequently used as a solvent for recrystallization to purify organic compounds. Acetic acid is used as a solvent in the production of terephthalic acid (TPA), the raw material for polyethylene terephthalate (PET).
What is absolute ethanol and why is it used instead of 95% ethanol?
Absolute ethanol is hygroscopic (it attracts water), so don’t expect it to remain ‘100%’ ethanol for long if it’s left uncapped. Denatured ethanol (either 95% or absolute) contains additives (such as methanol and isopropanol) that render it unsafe to drink, and therefore exempt from certain beverage taxes.
Why do you think absolute ethanol is preferable to 95% ethanol in these reactions?
The most important reason for using absolute ethanol is that the Fischer esterification is an equilibrium reaction with a Keq≈4 . If you use ordinary 95 % ethanol as a reactant, the 5 % water will push the position of equilibrium somewhat to the left and decrease your yield.