"Synthesis of Pthalamide from pthalic anhydride"

 

Experiment No. 1

Synthesis of orthochlorobenzoic acid from pthalic anhydride:

Organic Synthesis: 

It is a Special branch of synthesis and Concerned with the international-construction of organic compounds. It Can ocurr in many Steps. Above synthesis of o-Chloro benzoic acid occur in following Steps:

Step I:

Synthesis of Pthalamide from phalic anhydride

Step II:

Anthanilic acid from Pthalamide

Step III:

Ortho chlorobenzoic acid from anthranilic acid

 

Step I

Synthesis of Pthalamide from pthalic anhydride

Chemicals required:

1. phthalic anhydride 10 gm
2. Ammonium Carhonate 10 equivalent quantity

Theory: 

The most important Synthesis of Pthalamide is dehydrative Condensation of Phthalic anhydride at high temperature with primary amines ((NH₄)₂CO₃), when amine is not readily availible, the direct of N-alkylation of Pthalimides with the alcohols and of Potasium Pthalamide with alkyl halide are Popular to protect Phthalamines. This synthesis occurs in the absence of solvent. The two moles of CO₂ gas and water molecules evolved in this process.

Chemical Equation:

Mechanism:

 

Procedure:

I mixed thoroughly Phthalic anhydride and 10g ammonium Carbonate in morter and Pistle. Then I placed the mixture in 200ml round bottom flask. Then, I fixed this flask in sand bath and I heated with frequently shaking for 1-2 hours until the reaction mixture got fused. I stopped heating when I observed shiny crystals. The hot reaction was poured into porcelain and allowed to Cool and finally broken into pieces and powdered.

Observations:

Melting Point:

Melting point of Substance is the temperature at which it Changes state from solid to liquid at atmospheric pressure. The melting point of Pthalamide is 234^oC

 

Calculations:

Mass of pthalic anhydride = 10g

Molecular mass of pthalic anhydride = 148 g/mol

Moles of pthalic anhydride = x m/M

                    10g÷148g/mol = 0.06756 moles

Moles of pthalic anhydride = 0.06756 moles

Mass of ammonium carbonates = 10g

Molecular mass of ammonium carbonates = 96g/mol

Moles of ammonium carbonates = x m/M

                       10g÷96g/mol = 0.1042 moles

Moles of ammonium carbonates = 0.1042 moles

From chemical equation;

1eq of pthalic anhydride = 1eq of ammonium carbonates = 1eq of pthalimide

So,

0.6756 moles of pthalic anhydride=0.06756 moles of ammonium carbonates=0.06756

moles of pthalimide

Molecular mass of pthalimide = 147 g/moles

Moles of pthalimide = 0.6756 moles

Mass of pthalimide = n×M

                                (0.6756mol)(147 g/mol) = 9.92g

Theoretical yield = 9.92g

Actual yield = 7g

%age yield   =     Actual yield ÷ Theoretical yield ×100

                                                      7/9.92×100 = 70.56%

%age yield of pthalimide = 70.56%

Yield:

The Calculated amount of product is theoretical yield. The amount of product actually obtained is actual yield and when actual yield is divided by theoretical give obtained yield.

It would give expected product yield.