Essay Preparation of 4-Bromoaniline

Essay Preparation of 4-Bromoaniline

Preparation of 4–bromoaniline

Introduction

Aromatic compounds tend to undergo electrophilic aromatic substitutions rather than addition reactions. Substitution of a new group for a hydrogen atom takes place via a resonance–stabilized carbocation. As the benzene ring is quite electron–rich, it almost always behaves as a nucleophile in a reaction which means the substitution on benzene occurs by the addition of an electrophile. Substituted benzenes tend to react at predictable positions. Alkyl groups and other electron–donating substituents enhance substitution and direct it toward the ortho and para positions. Electron–withdrawing substituents slow the substitution and direct it toward the meta positions.

Aromatic compounds also undergo ... Show more content on Helpwriting.net ...Aniline 93.1 10 0.107 Yes

Ethanoic anhydride 102.1 12 0.118 No

Glacial ethanoic acid 60.1 25 0.416 No



No. moles produced by aniline = 0.107 moles

Theoretical mass of N–phenylethanamide = n*MR = 0.107 × 135 = 14.44g

Percentage yield = actual yield (g)/theoretical yield (g) × 100 = (11.9/14.44) × 100 = 82%

For preparation of N–(4–bromophenyl) ethanamide:

Product RMM Volume used/ g Volume used/ mL Moles used Limiting reagent?

N–phenylethanamide 135.2 5 0.0370 No

Bromine 159.8 2.1 0.0131 Yes



No. moles produced by bromine = 0.0131 moles

Theoretical mass of N–(4–bromophenyl) ethanamide = n*MR = 0.0131 × 159.8 = 2.10 g

Percentage yield = actual yield (g)/theoretical yield (g) × 100 = (5.00/2.10) × 100 = 238%

For preparation of 4–bromoaniline:

Product RMM Volume used/ g Volume used/ mL Moles used Limiting reagent?

N–(4–bromophenyl) ethanamide 214.1 5 0.0234 Yes

Hydrochloric acid 36 50 5.00 No



No. moles produced by N–(4–bromophenyl) ethanamide = 0.0234 moles

Theoretical mass of 4–bromoaniline= n*MR = 0.0234 × 214.1 = 5.01 g

Percentage yield = actual yield (g)/theoretical yield (g) × 100 = (1.60/5.01) × 100 = 32%



Discussion

The preparation of N–phenylethanamide from aniline was the first step of the experiment.

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