A Simple Way To Draw the Chair and Boat Conformations of Cyclohexane Undergraduate students in chemistry and biochemistry have difficulty in rcprcsenting uyeluhexane according to the mamconfarmatrnns knownas thechairformrFig. ljand the boat form(F~g.2,.Somemcrhodsolreadge~st',but students requirc a good memory to use these if the molecular models arc not in front orthem. We have sucrrssfullp tested the following construction, schematized a t the right:
1.Employing the sawhorse view, draw two molecules of ethane without showing the atoms, either with a staggered conformation, or with an eclipsed conformation, so that they are symmetric with regard ta avertical 2 I olane. 2. Then combine the two pictures sothat they meet a t Figure 1. Chair form: all C bonds staggered. the bonds marked a and b. 3. Finally, to complete the figures, draw the substituents of the central carbons so that they are staggered with their nearest neighbors. This method allows us to place the axial and equatorial substituentsvery quickly and clearly, thus showing that for the "chair form" all suhstituents are staggered, but this is not the case for the "boat form". 1 2 '(a) Mc M u r r y , J . Fundamentals of Organic Chemistry; BrooksICole: Montemy CA, 1986; p 5 6 5 8 . (b) Wingrove, A. S.; Figure 2. Boat form: 12 C bonds eclipsed Caret, S. L.; 0rQankChemistry;HarperandRow: NewYork, 1981; ~
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p112-113.
Pierre Leriverend Departement de Chimie Universite de Caen F-14032 CAEN Cedex
Volume 68 Number 11
November 1991
957
