Question

Match the elements of Column I to elements of Column II. There can be single or multiple matches. Column I (a) Markovnikov addition (b) anti Markovnikov hydration (c) \(\mathrm{OsO}_{4}\) and an alkene (d) Catalytic hydrogenation Column II (p) 1-Butyne and HOCl (q) syn addition (r) Hydroboration-oxidation (s) Addition of HI to but-1-ene in the presence of \(\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COO}\right)_{2}\)

Short answer

Based on the given step-by-step solution: 1. Match the corresponding term of Markovnikov addition from Column II. Answer: (s) addition of HI to but-1-ene in the presence of \(\left(\mathrm{C}_{6}\mathrm{H}_{5}\mathrm{COO}\right)_{2}\)

Step-by-step solution

Understand the terms in Column I

In this step, learn the meaning of the terms given in Column I: (a) Markovnikov addition: A type of regioselective reaction where the addition of a protic reagent to an alkene results in the most stable carbocation intermediate. (b) Anti Markovnikov hydration: A type of regioselective reaction that adds a protic reagent to an alkene in a way that the most stable carbocation intermediate is not formed. (c) \(\mathrm{OsO}_{4}\) and an alkene: OsO4 is osmium tetroxide, which is a catalyst used in the dihydroxylation reaction. When reacting with an alkene, the syn addition of two hydroxyl groups results in a diol. (d) Catalytic hydrogenation: A chemical reaction in which hydrogen is added to a molecule in the presence of a catalyst (usually metal-based) to reduce a double or triple bond in an alkene or alkyne.

Recognize the corresponding terms in Column II

Now that we understand the terms from Column I, let's find the matching elements in Column II: (p) 1-Butyne and HOCl: The reaction of 1-butyne with HOCl results in the formation of an anti Markovnikov product with halogen and(OH) groups, making it related to (b) anti Markovnikov hydration. (q) syn addition: In a syn addition, two substituent groups are added to the same side of a double bond. This reaction corresponds to (c) \(\mathrm{OsO}_{4}\) and an alkene. (r) hydroboration-oxidation: This is a two-step reaction, and it converts alkenes into alcohols. The process occurs by anti Markovnikov hydration, and the final product is an alcohol. Therefore, it corresponds to (b) anti Markovnikov hydration. (s) addition of HI to but-1-ene in the presence of \(\left(\mathrm{C}_{6}\mathrm{H}_{5}\mathrm{COO}\right)_{2}\): In the presence of the \(\left(\mathrm{C}_{6}\mathrm{H}_{5}\mathrm{COO}\right)_{2}\), the reaction proceeds by Markovnikov addition. Thus, it corresponds to (a) Markovnikov addition.

Matching Column I with Column II

After understanding each term and finding the corresponding elements, match the elements of Column I with the elements of Column II: (a) Markovnikov addition -> (s) (b) anti Markovnikov hydration -> (p) & (r) (c) \(\mathrm{OsO}_{4}\) and an alkene -> (q) (d) Catalytic hydrogenation -> (not directly mentioned in Column II) The matching has been done successfully.

Key concepts

Markovnikov Rule

The Markovnikov Rule is a principle used to predict the outcome of certain addition reactions, especially in alkene chemistry. According to this rule, when you add a protic reagent (such as HX, where H is a hydrogen and X is a halogen) to an asymmetric alkene, the hydrogen atom bonds to the less substituted carbon, while the halogen bonds to the more substituted carbon. This results in the formation of the most stable carbocation as an intermediate.
This principle is based on carbocation stability: more substituted carbocations are more stable due to hyperconjugation and inductive effects provided by neighboring carbon atoms.
The Markovnikov Rule helps predict product distribution in reactions and is named after Russian chemist Vladimir Markovnikov. For instance, when HBr is added to propene, the Markovnikov rule suggests the hydrogen will add to the terminal carbon, and the bromine will attach to the central, more substituted carbon, resulting in 2-bromopropane.

Anti Markovnikov Addition

Anti Markovnikov addition is the opposite of the Markovnikov rule, where the protic reagent's hydrogen atom attaches to the more substituted carbon and the anionic part (like a halogen or OH group) attaches to the less substituted carbon.
This kind of addition is favored when radicals, not carbocations, are involved, as in the presence of peroxides. Peroxides facilitate the generation of free radicals that alter the addition pattern.
A classic example of anti Markovnikov addition is the hydroboration-oxidation of alkenes. During hydroboration-oxidation, boron attaches to the less substituted carbon in the hydroboration step, and subsequent oxidation replaces the boron with an OH group, yielding an alcohol. This results in alcohols synthesized via anti Markovnikov addition.

Syn Addition

Syn addition refers to a type of chemical reaction where two substituents are added to the same side of a molecule, typically across a carbon-carbon double bond.
The syn addition mechanism is consequential for specific reactions, like those catalyzed by osmium tetroxide (OsO4). In these reactions, OsO4 facilitates the addition of two hydroxyl groups across an alkene, both added to the same side, resulting in a diol. This is significant for stereochemical outcomes because syn addition preserves the relative configuration of the substituents.
Understanding syn versus anti addition, where the substituents add on opposite sides, is crucial for determining the stereochemistry in the products of organic reactions.

Hydroboration-Oxidation

Hydroboration-oxidation is a two-step reaction sequence that converts alkenes to alcohols. In the first step, hydroboration, an alkene reacts with borane (BH3). Boron attaches to the less substituted carbon, which aligns with the concept of anti Markovnikov addition. This initial reaction involves syn addition, where both hydrogen and boron are added to the same side of the alkene.
In the second step, known as oxidation, the boron is replaced by an OH group through treatment with hydrogen peroxide (H2O2) and a base. This results in an alcohol product. An important aspect of hydroboration-oxidation is its anti Markovnikov nature, which allows formation of alcohols with the OH group on the less substituted carbon.
This reaction is highly practical for synthesizing specific alcohols and is popular in organic synthesis due to its predictable regioselectivity and stereospecificity.