BECKMANN REARRANGEMENT

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BECKMANN REARRANGEMENT

• RUBA AZMI

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TYPE OF CONTANT

• Objectives
• Background
• Reaction and Mechanism
• Application and recent literature
• Conclusion
• references

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Objectives

• My object is to learn about BECKMANN
  REARRANGEMENT and Im try to understand what is
  it ? what is an application and its mechanism?
  .

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Background

• The Beckmann rearrangement, named after the
  German chemist Ernst Otto Beckmann (18531923),
  is an acid-catalyzed rearrangement of an oxime to
  an amide. Cyclic oximes yield lactams.
• This example reaction starting with cyclohexanone
  , forming the reaction intermediate
  cyclohexanonoxime (in the image, the ending ono'
  in the name is missing) and resulting in
  caprolactam is one of the most important
  applications of the Beckmann rearrangement, as
  caprolactam is the feedstock in the production of
  Nylon 6.
• The Beckmann solution consists of acetic acid,
  hydrochloric acid and acetic anhydride, and was
  widely used to catalyze the rearrangement. Other
  acids, such as sulfuric acid or polyphosphoric
  acid, can also be used. sulfuric acid is the most
  commonly used acid for commercial lactam
  production due to its formation of an ammonium
  sulfate by-product when neutralized with ammonia
  . Ammonium sulfate is a common agricultural
  fertilizer providing nitrogen and sulfur
• a chemical reaction that converts oximes into
  acid amides under the influence of acidic
  dehydrating agents (PCl5, H2SO4, oleum, and
  others)
• where R and R are identical or different
  organic radicals (CH3, C2H5, C6H5, and so on).
  The Beckmann rearrangement is used in industry to
  obtain kapron (a stage in the conversion of
  cyclohexanon oxime into ?-caprolactam). The
  Beckmann rearrangement was discovered in 1886 by
  the German chemist E. O. Beckmann.

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Reaction and Mechanism
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Application and recent literature
Two interesting examples utilizing the weak or
low acidity and the shape selectivity of ZSM-5 or
Silicalite zeolite are shown. The first one is a
para-selective dealkylation of cymenes, and the
second one is a vapor phase Beckmann
rearrangement of cyclohexanone oxime into
e-caprolactam. In the para-selective
dealkylation, the para-selectivity was obtained
rather easily by impregnation of MgO, but the
difficulties were how to obtain a high purity of
recovered propylene while keeping a high
conversion of p-cymene, and how to prevent a coke
deposition. For these purposes, three types of
ZSM-5 were found to give good results
MgO/LiZSM-5, MgO/(NaH)ZSM-5, and very high
silicious ZSM-5 or Silicalite with Si/Al ratio
more than 5,000, being impregnated also with
MgO. In the Beckmann rearrangement, the catalytic
activity, the selectivity and also the catalytic
life (time-on-stream) were strongly dependent
upon the Si/Al ratio of ZSM-5, and HSM-5 or
Silicalite with high Si/Al ratio ( 1,000) gave
good results.
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Conclusion

• in Caprolactam Via Gas Phase Beckmann
  Rearrangement the conclusion that there are
  significant potential opportunities for
  improvement that may result in a cost competitive
  process
• The formation of a number of byproducts was
  observed as a result of the dehydration and
  hydrolysis of the reactant cyclohexanone oxime
  and of the reaction product e-caprolactam
• Beckmann rearrangement of cyclohexanone oxime has
  been carried out in vapor phase by means of a
  pulse reactor unit directly coupled to a gas
  chromatograph. The catalysts chosen gave good
  yields of e-caprolactam. Apparent rate constants
  and activation energies were calculated in terms
  of the kinetic model of Bassett and Habgood.
  Selectivity studies, using pulse experiments
  interpreted by OPE curves, led to the conclusion
  that e-caprolactam and 5-cyanopent-1-ene were
  competitive products. A reaction pathway is
  proposed which is in agreement with both the
  observed rates and selectivities

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references

• Takatsuki Research Labo., Sumitomo Chemical
  Company Ltd
• Beckmann, E. (1886). "Zur Kenntniss der
  Isonitrosoverbindungen
• Donaruma, L. G. Heldt, W. Z. (1960).
• Wikipedia