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Amine
Acetic acid
Acetic anhydride
Diketene
Acetoacetic ester
Salt
N-acylation
distillation
Crystallisation/
salting out
Filtration
Product
H 2 O
CH 3 COOH
C 2 H 5 OH
Solvent
Mother liquor
Figure 2.11: Typical sequence of operations and related waste streams from N-acetylations
2.5.2 Alkylation with alkyl halides
[6, Ullmann, 2001, 15, Köppke, 2000]
Chapter 2
See also Section 4.3.2.2 for environmental issues and treatment of waste streams from
alkylation with alkyl halides.
Alkylations with alkyl halides are important reaction steps in industrial scale chemistry,
predominantly for the synthesis of pharmaceuticals or agricultural chemicals. Some often used
alkyl halides are methyl chloride, methyl iodide, ethyl chloride, isopropyl chloride, tert-butyl
chloride, and benzyl chloride.
Chemical reaction
The following equation shows an example of methylation with methyl chloride:
(1) R – NH2 + 2 CH3Cl + 2 NaOH � R – N(CH3)2 + 2 NaCl + 2 H2O
(2) R – N(CH3)2 + CH3Cl � R – N(CH3)3 + Cl -
Side reactions: The effect of possible side reactions must be considered individually,
but generally the use of lower alkyl halides leads to the formation of a
variety of lower molecular compounds, e.g:
Operations
CH3Cl + NaOH � CH3OH + NaCl
CH3OH � CH3 – O – CH3 + H2O
Because alkylation reactions are diverse in nature, there is no universal method of carrying them
out. The production of each compound needs to be considered individually, taking into account
the chemical, engineering, and economic factors.
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