Harry P. Schullz University of Miami
Coral Gables, Florida
I I
Lecture Demonstration Models of ~ycloakanes
Cheap, sturdy models' that can be easily handled during lectures when conformational aspects of the rommon cycloalkanes are illustrated and discussed have been made from 20 gauge galvanized sheet iron, 2 in. length? of 6/16 in. od copper tubing, in. wooden dowels, and either wood or polystyrene spheres. A scale of 4 in. to 1Angstrom unit was chosen to give a model large enough to be seen from all parts of a large lecture hall; this results in models with approximate C-C distances of 61/s in., and C-H distances of 4l/&in. After each model had been completely assembled, the exterior valence angles were then exactly adjusted as follows: cyclopropane HCH angle, 118'; cyclobutane HCH angle, 114'; cyclopentane and cyclohexane HCH angles, 109.5'. The completed bases were then 1 A description of an excellent type of model, as well as references to other descriptions of models, is given in KENNY,M. E., J. CHEM. EDUC.,39,129(1962).
648 / Journal of Chemical Education
cleaned and sprayed with dull black enamel. Although no attempt was made to skew the cyclobutane or cyclopentane models, care was taken to ensure that all the bonds on the chair conformation of the cyclohexane model were staggered.
Model of tronr-1.2-dibromoiyclohexone
