Bond angles angle strain

Cyclopropane. Bond angles, angle strain, and torsional strain. 

The stmcture of DPXN was determined in 1953 from x-ray diffraction studies (22). There is considerable strain energy in the buckled aromatic rings and distorted bond angles. The strain has been experimentally quantified at 130 kj/mol (31 kcal/mol) by careful determination of the formation enthalpy through heat of combustion measurements (23). The release of this strain energy is doubtiess the principal reason for success in the particularly convenient preparation of monomer in the parylene process. 

Bond Lengths, Bond Angles, Ring Strain... 

Mn(HI) electrostatics H-bonding bond stretch angle strain ... 

Number of atoms in the ring Bond angle distortion Strain energy (idmoT )... 

If we assume that there are certain ideal val ues for bond angles bond distances and so on itfol lows that deviations from these ideal values will destabilize a particular structure and increase its po tential energy This increase in potential energy is re ferred to as the strain energy of the structure Other terms for this increase include steric energy and steric strain Arithmetically the total strain energy ( ) of an alkane or cycloalkane can be considered as... 

Wangle bending s the Strain that results from the expansion or contraction of bond angles from the normal values of 109 5° for sp hybridized carbon... 

At Its most basic level separating the total strain of a structure into its components is a qualita tive exercise For example a computer drawn model of the eclipsed conformation of butane using ideal bond angles and bond distances (Figure 3 8) reveals that two pairs of hydrogens are separated by a distance of only 175 pm a value considerably smaller than the sum of their van der Waals radii (2 X 120 pm = 240 pm) Thus this conformation is destabilized not only by the torsional strain associ ated with its eclipsed bonds but also by van der Waals strain... 

Conformational analysis is far simpler m cyclopropane than m any other cycloalkane Cyclopropane s three carbon atoms are of geometric necessity coplanar and rotation about Its carbon-carbon bonds is impossible You saw m Section 3 4 how angle strain m cyclopropane leads to an abnormally large heat of combustion Let s now look at cyclopropane m more detail to see how our orbital hybridization bonding model may be adapted to molecules of unusual geometry... 

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