The nucleophile has greater difficulty getting to the Carbon if large groups are attached to the carbon. Therefore, Sn2 reactions are more likely to occur on primary carbons, as there is much less steric hindrance than there is on tertiary carbons. In Sn1 reactions, an intermediate carbocation is created. The most stable carbocations are those that are tertiary carbons. As a result, Sn1 reactions are most likely to occur on tertiary carbons, and are least likely to occur on primary carbons, due to the high instability of primary …show more content…
Elimination reactions can occur instead of substitution reactions. There are two kinds of elimination reactions: E1 and E2. E1 reactions are 2 step; the leaving group will leave, forming a carbocation and a leaving group anion. Then, a hydrogen on a neighboring carbon will leave; the electrons from the C-H will remain on the C, forming a double bond between the two Carbons that had the LG or H leave. The positive Hydrogen that left will bond with the nucleophile. E2 reactions are one step; the leaving group will leave at the same time that the anti-periplanar hydrogen on a neighboring carbon leaves, resulting in a double C=C bond. A leaving group anion and an H-Nu will both form. Nucleophiles that are very polarizable and are slightly basic such as Cl- and H2O will typically undergo substitution reactions. Weakly polarizable nucleophiles that are very basic will typically undergo elimination reactions. The solvent in which the reaction occurs is also important; polar protic solvents can cause Sn1/E1 reactions to occur, due to how the solvent will interact with the