Preparation of Pencycuron

4-Chlorobenzyl chloride (I) was added to a mixture of cyclopentylamine (II) and NaOH aqueous solution to give 4-chlorobenzyl-N-cyclopetylamine (III), which was isolated as a colorless oil (bp 109-110 °C/20 Pa). 

Phenylisocyanate (IV) was then added to a solution of (III) in toluene, furnishing N-4-chlorobenzyl-N-cyclopentyl-N -phenylurea (pencycuron) as a white solid (mp 129-134 °C). 

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