clocinizine clocinizine clocinizine is a first-generation antihistamine of the diphenylmethylpiperazine class. it is marketed in spain in combination with phenylpropanolamine under the brand name senioral. clocinizineclinical datatrade namessenioral (with ppa)ahfs/drugs.cominternational drug namesroutes ofadministrationby mouthatc codenoneidentifiers iupac name 1--4-piperazine cas number298-55-5pubchem cid5375618chemspider4525064unii8hqj711kh8chemblchembl2104069chemical and physical dataformulac26h27cln2molar mass402.97 g·mol−13d model (jsmol)interactive image smiles clc1ccc(cc1)c(c2ccccc2)n3ccn(cc3)c\c=c\c4ccccc4 synthesis synthesis: patent: the reduction of 4-chlorobenzophenone (1) with nbh gives 4-chlorobenzhydrol (2). halogenation of the alcohol in muriatic acid afforded 4-chlorobenzhydryl chloride (3). alkylation with one equivalent of piperazine gives 1-(4-chlorobenzhydryl)piperazine (4). alkylation of the remaining nitrogen with cinnamyl bromide (5) completed the synthesis of clocinizine (6).