Coming from ALKENES
=Addition or Elimination Involving Asymmetrical Alkenes= When you go through the nodes on addition reactions of alkenes, or elimination of alcohols/haloalkanes to form alkenes you may find a problem: If I added water (H-OH) to an alkene such as propene, is the product propan-1-ol, or propan-2-ol? If I did an elimination reaction with 2-chlorobutane (with alcoholic KOH), would I form but-1-ene or but-2-ene? =Markovnikov= Be aware that in NCEA you must not state "Markovnikov's rule" as an explanation for the formation of major and minor products. A Russian chemist, Markovnikov, came up with some predictable rules for reactions involving asymmetrical alkenes. His major rule can be simplified down to ==="The rich get richer" or "the poor get poorer"=== Basically, if a reaction involves the gain of atoms (addition) where a hydrogen atom and another group are added, the carbon with the most hydrogen atoms attached initially will receive the hydrogen atom (and get 'richer' in H atoms). Alternatively, in an elimination reaction, the carbon with the least amount of hydrogen atoms will be the other carbon involved in the new double bond. The reasoning behind this comes down to the way the reactions occur, and the fact that during these reactions there is an intermediate step where a carbon is left without a 4th bond. The most stable carbons in this situation are those that are tertiary, followed by secondary, and lastly the most unstable are primary. =Major and Minor Products= Out of the two possible products, the product formed following Markovnikov's rule is said to be the major product. This product will be formed 70-95% of the time. The alternative product is known as the minor product.
Credit: Megan Fowler