Glaxo Group Limited

David W Latham

Andrew Jonathan Whitehead

Michael David Goodyear

Tony G Roberts

Colin B Sidgwick

Steven F Beach

A process for the preparation of the compound of formula (I), a useful intermediate for the preparation of analgesic agents. ##STR1## which comprises reading a compound of formula (II) or an acid addition salt thereof ##STR2## with propionic anhydride and then treating the resultant product with methanol.

Process for preparing a piperidine derivative

1-Hydroxy-2-naphthalene carboxylate (hydroxynaphthoate) salt of 4-hydroxy-a.sup.1 -[[[6-(4-phenylbutoxy)hexyl]-amino]methyl]-1,3-benzendimethanol in the form of spherical accretions of microcrystals, the spherical accretions being free-flowing, friable and micronisable and preferably having a mean particle size of from 70 to 300 mm and a mean surface area from 4 to 12 m.sup.2 g.sup.-1. The hydroxynaphthoate salt in the claimed form may be prepared by quenching a hot organic/aqueous organic solution containing the salt with a cold organic/aqueous organic solvent.

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Ware, United Kingdom

David W Latham