Question

The addition of \(\mathrm{HCl}\) to \(3,3,3\) -trichloropropene gives: (a) \(\mathrm{Cl}_{3} \mathrm{CCH}_{2} \mathrm{CH}_{2} \mathrm{Cl}\) (b) \(\mathrm{Cl}_{2} \mathrm{CHCH}(\mathrm{Cl}) \mathrm{CH}_{2} \mathrm{Cl}\) (c) \(\mathrm{Cl}_{2} \mathrm{CHCH}_{2} \mathrm{CHCl}_{2}\) (d) \(\mathrm{Cl}_{3} \mathrm{CCH}_{2} \mathrm{CH}_{2} \mathrm{Cl}\)

Short answer

The product is (a) Cl}_{3} CCH}_{2} CH}_{2} Cl}.

Step-by-step solution

Understand the Reaction

We need to add HCl to the compound 3,3,3-trichloropropene. In this case, HCl will add across the double bond present in the propene group.

Identify Reaction Occurrence

3,3,3-Trichloropropene has a double bond between the second carbon and the third carbon of the chain. HCl will add across this double bond.

Markovnikov's Rule

According to Markovnikov's rule, the hydrogen atom from HCl will attach to the carbon with the most hydrogen atoms already (second carbon, which has none originally), and the chloride ion will attach to the other end of the double bond (third carbon).

Write the Product

The reaction will hence form 3,3,3-trichloro-1-chloropropane, which is Cl}_{3} CCH}_{2} CH}_2 Cl}.

Key concepts

Markovnikov's Rule

Markovnikov's Rule is pivotal in understanding how additions occur in alkene reactions. This rule states that during the addition of an acid, like hydrogen chloride (HCl), to an alkene, the hydrogen atom will attach to the carbon in the double bond that already holds the most hydrogen atoms. In simpler terms, the rich get richer.

When applying this rule to our problem with 3,3,3-trichloropropene, the second carbon has no hydrogen attached, which means the hydrogen from HCl will prefer going there. Meanwhile, the chloride ion will go to the carbon at the other end of the double bond, the third carbon, marking this as a classic example of Markovnikov's addition.

3,3,3-Trichloropropene

The compound 3,3,3-trichloropropene is an organic compound that features prominently in this exercise. It is a type of halogenated alkene, with the name indicating where chlorine atoms are substituting hydrogen. The '3,3,3' notation refers to the positions in the carbon chain where chlorine atoms are attached, specifically on the third carbon.

Its structure comprises a three-carbon chain with a double bond between the second and third carbons. This double bond is where addition reactions, such as the one involving HCl, primarily occur. Knowing the structure of 3,3,3-trichloropropene helps in predicting the outcome of reactions according to Markovnikov's Rule.

Addition Reactions

Addition reactions are fundamental in organic chemistry, involving the addition of atoms or groups to a molecule. For alkenes like 3,3,3-trichloropropene, these reactions typically occur across the double bond. This is due to the electron-rich nature of double bonds that attract reagents like acids or halogens.

In the hydrohalogenation of alkenes, an acid such as HCl is added, and an addition product forms. It involves breaking the pi bond (the second bond of the double bond) and creating two new single bonds. This transformation typically results in more saturated molecules, contributing to the development of various organic products.

Organic Chemistry Reactions

Organic chemistry reactions form the backbone of molecular synthesis, allowing chemists to construct complex molecules from simpler ones. These reactions, like hydrohalogenation, involve the rearrangement or recombination of atoms and typically focus on functional groups, aligning well with specific rules like Markovnikov's.

The mastery of reactions like these not only illuminates the behavior of compounds but also their potential transformations. In practicing these reactions, students gain vital skills in predicting products, managing reactants, and exploring the vast diversity of organic compounds. Fields such as pharmaceuticals, materials science, and agricultural chemistry all draw heavily on these foundational principles.