Prelog strain

[1][3] Transannular strain can also be demonstrated in other cyclo-organic molecules, such as lactones, lactams, ethers, cycloalkenes, and cycloalkynes.

Molecular mechanics calculations of strain energy differences ΔSI between a sp2 and sp3 state in cycloalkanes show linear correlations with rates (as

) of many reactions involving the transition between sp2 and sp3 states, such as ketone reduction, alcohol oxidation or nucleophilic substitution, the contribution of transannular strain is below 3%.

Various sized rings, ranging from four to seventeen members, were used to compare the relative rates and better understand the effect of transannular strain on this reaction.

The solvolysis reaction in acetic acid involved the formation of a carbocation as the chloride ion leaves the cyclic molecule.

When water is eliminated from cyclic tertiary alcohols by an E1 route, three major products are formed.

The exact population of each product relative to the others differs considerably depending upon the size of the ring involved.

Illuminati et al. have studied the kinetics of intramolecular ring closing using the simple nucleophilic substitution reaction of ortho-bromoalkoxyphenoxides.

However, by the simple addition of a methylene bridge between the 1 and 6 positions, a stable, flat, aromatic molecule can be made and observed.

Cyclodecane in its lowest energy conformation. The red triangle indicates three hydrogens responsible for transannular strain. There is an identical interaction on the back of the molecule, as well.
Strain increases significantly among medium-sized cycloalkanes.
This S N 1 reaction was studied for n = 4–17. The data is shown in the table. [ 5 ]
Products yielded from the elimination of water from cyclic tertiary alcohols.
In the medium-size ring region, the percent of product is closely correlated with transannular strain.
Addition of a methylene bridge significantly reduces transannular strain.