To solve this question, we need to identify the reagent 'R' in the given chemical reaction sequence.
The sequence involves the following steps:
The starting material is an aniline derivative, which is converted into a diazonium salt using NaNO_2 and HCl at 0 - 5°C. This is a standard procedure to form diazonium salts from aromatic amines.
The diazonium salt can undergo various reactions depending on the reagent used next. Here, we need to identify 'R'. The product shows that a replacement of N_2^+Cl- with hydrogen occurs, typically done using an alcohol.
Given the options, we evaluate their suitability for this task:
CuCN/KCN: Typically used for introducing cyano groups, not suitable here.
H2O: Would result in phenol formation, which is not the observed product.
CH3CH2OH (Ethanol): Commonly used in the reduction of diazonium salts to aryl hydrocarbons (replacing N_2^+Cl- with hydrogen), which fits the product.
HI: Used for converting diazonium groups into iodides, which does not match the product.
Thus, the correct choice is CH3CH2OH, as it successfully reduces the diazonium salt to the corresponding hydrocarbon.
Alcohols are characterized by the presence of the hydroxyl (-OH) functional group, which makes them polar and capable of forming hydrogen bonds. They are typically classified as primary, secondary, or tertiary, depending on the number of alkyl groups attached to the carbon atom bearing the hydroxyl group. Alcohols undergo various chemical reactions, including oxidation, dehydration, and esterification.
Phenols are organic compounds that contain an -OH group attached to an aromatic ring. They are weaker acids than carboxylic acids but stronger acids than alcohols due to the resonance stabilization of the phenoxide ion. Phenols undergo various chemical reactions, including electrophilic substitution and oxidation.
Ethers are organic compounds that contain an oxygen atom bonded to two alkyl or aryl groups. They are characterized by their low boiling points and are often used as solvents. Ethers undergo various chemical reactions, including cleavage of the C-O bond and oxidation.
In summary, alcohols, phenols, and ethers have distinct chemical properties due to the presence of the hydroxyl or ether functional group. Understanding these properties is important for understanding their reactivity and potential applications in various fields, including chemistry, biology, and industry.
