Adolf von Baeyer suggested that, since carbon prefers to have tetrahedral geometry with bond angles of approximately 109^@, ring sizes other than five and six may be too strained to exist. Baeyer based his hypothesis on the simple geometrical notion that a three-membered ring (cyclopropane) should be an equilateral triangle with bond angles to 60^@, a four membered ring (cyclobutane) should be a square with bond angles of 90^@ and so on. According to Baeyer's analysis, cyclopropane, with a bond angle compression of 109^@ - 60^@ = 49^@, should have a large amount of angle strain and must therefore be highly reactive. Cyclohexane becomes puckered to releave its strain. The angular derivation of cycloalkane is (-11^@). Greater is the angular deviation more is the torsional strain. The tendency of cyclopropane (I), cyclopropane (II) and cyclopropane (III) to form addition compounds is in the order