Question

Chemistry discussion for baeyer strain theory of alicyclic compounds along with its limitations

Answer 1

The Baeyer strain theory is based on the following assumptions.  ?

• Since carbon atom is tetrahedral in nature with all the four valencies directed towards four corners of a regular tetrahedron, the angle between any two bonds should be 109⁰28′. Thus any deviation from this value would result an internal strain in the molecule.
• All carbon atoms of cycloalkanes ring are planar indicating that cyclopropane ring is an equilateral triangle, cyclobutane ring is square and other cycloalkane rings are regular polygons.
• When an open chain organic compound ,having the normal carbon tetrahedral bond angle of 109⁰28′ is converted into a cyclic compound, a definite distortion of this normal angle takes place leading to a lot of strain in the molecule. This strain ,commonly known as angle strain ,depends upon the extent of deviation of the bond angle from the normal tetrahedral angle value 109⁰28′.
• Thus greater the deviation of the bond angle of the ring from 109⁰28′ ,greater is the strain and consequently more unstable is the ring.
• Baeyer showed that the deviation (d) in cycloalkanes from the normal tetrahedral angle can be calculated as, d =1/2 (109⁰28′ - α) ,Where α,is bond angle in the various cycloalkanes.
• it is important to note that the distortion of bond angle has been assumed to be equally shared between two bonds.