Case: Haloalkanes are organic compounds where halogens (chlorine, bromine, iodine, or fluorine) are bonded to alkyl groups. These compounds undergo a variety of reactions, including nucleophilic substitution and elimination reactions. One of the most common nucleophilic substitution reactions is the conversion of an alkyl halide to an alcohol in the presence of a strong base, such as sodium hydroxide.
For example, in the reaction of methyl chloride (CH₃Cl) with aqueous NaOH, the chloride ion (Cl⁻) is replaced by a hydroxyl group (OH⁻), resulting in the formation of methyl alcohol (CH₃OH). The mechanism of this substitution can follow either an SN1 or SN2 pathway depending on the structure of the haloalkane.
Questions:
In the nucleophilic substitution reaction of methyl chloride (CH₃Cl) with NaOH, the product formed is:
The nucleophilic substitution reaction of methyl chloride (CH₃Cl) with NaOH proceeds via:
Which of the following factors does NOT affect the rate of nucleophilic substitution in haloalkanes?
In an SN2 reaction, the transition state involves:
Case: Haloalkanes can also undergo elimination reactions, where a small molecule (like HX) is removed from the molecule, leading to the formation of an alkene. One example is the reaction of chloroethane (C₂H₅Cl) with alcoholic potassium hydroxide (KOH), which results in the formation of ethene (C₂H₄). This type of reaction follows the E2 mechanism, where the base abstracts a proton from a β-carbon, leading to the simultaneous elimination of the halide ion and the formation of a double bond.
Questions:
In the reaction of chloroethane (C₂H₅Cl) with alcoholic KOH, the product formed is:
The reaction of chloroethane (C₂H₅Cl) with alcoholic KOH is an example of:
The E2 mechanism of elimination is characterized by:
The major product of the elimination reaction of chloroethane with KOH is determined by:
Case: Haloalkanes can be prepared through several methods, including the halogenation of alkanes, alcohols, and the reaction of alkyl groups with halogens. One of the most common methods is the halogenation of alkanes, which occurs via a free radical mechanism. For example, methane (CH₄) reacts with chlorine (Cl₂) in the presence of ultraviolet light to form methyl chloride (CH₃Cl) along with hydrogen chloride (HCl). This reaction follows a free radical substitution mechanism, where the chlorine molecule is homolytically cleaved, forming chlorine radicals that attack methane.
Questions:
The preparation of methyl chloride (CH₃Cl) from methane (CH₄) and chlorine (Cl₂) is an example of:
The reaction between methane and chlorine occurs in the presence of ultraviolet light to:
Which of the following is the correct order of reactivity in the halogenation of alkanes?
The halogenation of methane with chlorine follows a mechanism known as:
Case: Haloarenes are aromatic compounds that contain halogen atoms attached to an aromatic ring. These compounds are known for their stability and are widely used in pharmaceuticals, pesticides, and as intermediates in organic synthesis. The reactivity of haloarenes is generally lower than that of haloalkanes, due to the electron-withdrawing nature of the halogen, which deactivates the aromatic ring towards nucleophilic substitution reactions.
An important feature of haloarenes is their tendency to undergo electrophilic substitution reactions rather than nucleophilic substitution. For example, chlorobenzene (C₆H₅Cl) reacts with an electrophile like nitric acid (HNO₃) in the presence of sulfuric acid (H₂SO₄) to form 1,2-dichlorobenzene (ortho product) or 1,4-dichlorobenzene (para product), depending on the conditions.
Questions:
In haloarenes, the halogen atom deactivates the benzene ring towards:
The product formed when chlorobenzene reacts with HNO₃ in the presence of H₂SO₄ is:
In the electrophilic substitution reaction of chlorobenzene, the halogen:
Haloarenes are less reactive in nucleophilic substitution reactions because:
Case: Haloalkanes and haloarenes are widely used in various industries. For example, methyl chloride (CH₃Cl) is used as a refrigerant, in the production of silicones, and as a solvent. Chlorobenzene (C₆H₅Cl) is primarily used in the synthesis of phenol, pesticides, and in the production of other chemicals such as DDT. Both types of compounds also serve as intermediates in the synthesis of drugs and other organic materials.
Questions:
Methyl chloride (CH₃Cl) is commonly used as a:
Chlorobenzene is mainly used in the synthesis of:
Which of the following is a major industrial use of haloalkanes and haloarenes?
DDT (dichlorodiphenyltrichloroethane) is an example of a pesticide derived from: