Tetraoxaquaterene Synthesis
The acid-catalyzed synthesis of 1,1,6,6,11,11,16,16-odamethyl-21,22,23,24-tetraoquateene (1) from furan and acetone, in the presence and in the absence of lithium perchlorate, has been recommended by Field et al.? as well as by Glidewell3as an organic laboratory experiment illustrating the "template effect2'of appropriate cations in the formation of macroheterocycles such as I in preference to the corresponding acyclic oligomers. However, later painstaking work by Rest et al.4 has shown that added cations (and anions) do not influence the formation of 1via a template effect, but rather by changing the catalytic hydrogen ion activity in the reaction mixture. In fact, as could be expected, 1 does not complex cations as, for instance, the correspondii crown ether (2) which can be obtained by hydrogenation of lf Thus, while the synthesis of 1 still constitutes a valid undergraduate experiment in organic chemistry, it should be made to highlight the present knowledge of its salient features4 rather than the nonexistent "template effect".
'Author to whom correspondence should be addressed. ?Field, K. W.; Glover, A. D.; Moroz, J. S.; Collander, D. J.; Kolb, K. E. J.Chem. Educ. 1919,56,269. Glidewell. C. J.Chem. Educ. 1980.57.236. de Sousa ~ e a l yM.; , Rest, A. J. J. hem Soc., Perkin Trans. 1 1985,973. Kim NOrklfaf and Alexander Sennlngl 4arhus Universitet DK-8000 Arhus C, Denmark
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Journal of Chemical Education
