Die Angewandte Makromolekulare Chemie 255 (1998) 23–28 (Nr. 4438) 23 Ó 1998, Hu ¨thig & Wepf Verlag, Zug CCC 0003-3146/98/$12.00 Study on the synthesis of p-tert-butylcalixarenes and p-isopropenylcalixarenes P. Novakov 1 , S. Miloshev 1 , P. Tuleshkov 1 , I. Gitsov 2 , M. Georgieva 1 * 1 University of Chemical Technology and Metallurgy, Kliment Ohridski Ave. 8, Sofia 1756, Bulgaria 2 College of Environmental Science and Forestry, New York State University at Syracuse, USA (Received 7 April 1997) SUMMARY: A new method for one-step synthesis of calixarenes has been developed. Ethylene glycol was used as the medium, and sodium tetraborate-decahydrate as the catalyst. For the first time p-isopropenyl- calix[6]arene and p-isopropenylcalix[8]arene were obtained. A parallel investigation of polycondensation and cyclization of p-tert-butylphenol and p-isopropenylphenol was performed. The influence of the quantities of the catalyst and formaldehyde on the composition of the reaction products and the yield of cyclic oligo- mers were investigated. The conditions ensuring the highest yield of p-isopropenylcalixarenes were found. ZUSAMMENFASSUNG: Eine neue einstufige Synthese fu ¨r Calixarene wurde entwickelt, die mit Natrium- tetraborat-decahydrat und Ethylenglykol als Katalysator bzw. Lo ¨sungsmittel zu ho ¨heren Ausbeuten fu ¨hrt. p- Isopropenylcalix[6]aren und p-Isopropenylcalix[8]aren wurden erstmals synthetisiert. Der Verlauf des Poly- kondensationsprozesses und der Cyclisierung von p-tert-Butylphenol und p-Isopropenylphenol wurden ver- folgt. Der Einfluß der Konzentrationen von Katalysator und Formaldehyd auf Ausbeute und Zusammensetzung der Produkte wurde untersucht. Die Bedingungen fu ¨r die Synthese der p-Isopropenylcali- xarene wurden optimiert. 1. Introduction In the last fifteen years a lot of papers on the synthesis and the properties of the cyclic phenol-formaldehyde oli- gomers (so called calixarenes) have been published 1–10) . The reasons for such a high interest are: the relatively low price, the easy preparation and the high selectivity as chelate agents and polymer carriers of these com- pounds 1–3) . Their selectivity could be modified to a desired direction by synthesis of calixarenes containing different number of phenolic units, by esterification or ether formation of the phenolic hydroxy groups (so called lower rim functionalisation) or by including different functional groups into the p-positions of the aromatic rings (so called upper rim functionalisation). Usually the upper rim functionalisation is carried out in two steps. The first step is an elimination of the alkyl-groups of the p-tert-butylcalixarenes by Lewis-acid-catalysis 4) . The second step is an electrophilic substitution of the p-posi- tion hydrogen atoms by treatment of the dealkylated calixarene with some of the following reagents: sulfuric acid 5) , N-bromosuccinimide 6) , dialkylamine and formal- dehyde 7) , octyl chloromethyl ether and stannous tetra- chlorides 8) , etc. After introducing the functional group, a new modification of already functionalized calixarene could be carried out easily if necessary. Unfortunately this widespread scheme has some disad- vantages: low yields of entirely functionalized calixar- enes in first two steps, a necessity of expensive or hardly accessible reagents, inhomogeneous composition of the obtained products, etc. As a result of such a modification the main advantage of the calixarenes – their low price – is lost. The purpose of our research was to investigate the pos- sibility for direct synthesis of calixarenes with phenols containing functional groups in p-position, and particu- larly the synthesis of p-isopropenylcalixarenes. 2 Experimental part 2.1 Materials The p-isopropenylphenol was prepared according to Verch- ovskaja 11) and purified using a method developed by us 12) . The p-tert-butylphenol (CHIMSNAB-Bulgaria product) was purified by recrystallization in CH 3 OH/H 2 O (1 : 2, v/v). Para- formaldehyde, dioxane (Merck products), THF (Fluka), ethy- lene glycol (Polfa-Poland product), sodium tetraborate- decahydrate and hydrochloric acid (CHIMSNAB products) were put in use without purification. Calixarene standards were Aldrich products. * Correspondence author.