Case: Alcohols are organic compounds containing one or more hydroxyl groups (-OH) attached to a carbon atom. They are classified into primary, secondary, and tertiary alcohols based on the number of alkyl groups attached to the carbon bearing the hydroxyl group. Alcohols can be prepared by various methods, including hydration of alkenes, reduction of aldehydes and ketones, and from alkyl halides by nucleophilic substitution reactions.
For instance, ethanol (C₂H₅OH) can be synthesized from ethene (C₂H₄) via an acid-catalyzed hydration reaction, where the alkene reacts with water in the presence of a catalyst such as sulfuric acid.
Questions:
Ethanol (C₂H₅OH) is commonly prepared by the hydration of:
The reaction of ethene with water in the presence of sulfuric acid to form ethanol is an example of:
In the preparation of alcohols from alkyl halides, the nucleophilic substitution reaction occurs in the presence of:
Primary alcohols are characterized by having:
Case: Alcohols undergo several important reactions. They can be oxidized to form aldehydes, ketones, and carboxylic acids. The oxidation of primary alcohols results in aldehydes, and further oxidation leads to carboxylic acids. Secondary alcohols, on the other hand, are oxidized to ketones. Tertiary alcohols are generally resistant to oxidation due to the absence of a hydrogen atom attached to the carbon bearing the hydroxyl group.
For example, the oxidation of ethanol (CH₃CH₂OH) with an oxidizing agent like potassium dichromate (K₂Cr₂O₇) results in the formation of ethanal (acetaldehyde, CH₃CHO).
Questions:
The oxidation of ethanol (CH₃CH₂OH) with K₂Cr₂O₇ results in the formation of:
The oxidation of primary alcohols like ethanol produces:
Secondary alcohols are oxidized to form:
Which of the following alcohols cannot be oxidized easily?
Case: Phenols are compounds in which a hydroxyl group (-OH) is directly attached to an aromatic ring. Phenols are more acidic than alcohols due to the ability of the phenoxide ion to stabilize the negative charge through resonance with the aromatic ring. Common examples of phenols include hydroquinone (1,4-dihydroxybenzene), which is used in the manufacture of plastics and as a reducing agent, and salicylic acid, which is the precursor for aspirin.
Phenols undergo electrophilic substitution reactions, such as halogenation, nitration, and sulfonation, where the hydroxyl group increases the electron density on the benzene ring, making it more reactive towards electrophiles.
Questions:
The hydroxyl group in phenols is attached to:
Phenols are more acidic than alcohols because:
The electrophilic substitution reaction of phenol with bromine (Br₂) results in the formation of:
Salicylic acid is the precursor to which of the following drugs?
Case: Ethers are organic compounds in which two alkyl or aryl groups are bonded to an oxygen atom, with the general formula R–O–R'. Ethers are relatively non-reactive but can be used as solvents for reactions involving non-polar substances. One of the most common ethers is diethyl ether (C₂H₅OC₂H₅), which is often used as a solvent in laboratories.
Ethers are relatively resistant to oxidation but undergo cleavage in the presence of strong acids to form alcohols or alkyl halides. For example, when diethyl ether is treated with excess HI, it undergoes cleavage to form ethanol and ethyl iodide.
Questions:
The general formula of an ether is:
Diethyl ether (C₂H₅OC₂H₅) undergoes cleavage with excess HI to form:
Ethers are used as solvents because:
Ethers are relatively resistant to oxidation but undergo cleavage in the presence of:
Case: Alcohols, phenols, and ethers are widely used in various industries. Alcohols like ethanol are used as solvents, fuels, and in the preparation of alcoholic beverages. Ethanol is also used in the production of plastics and pharmaceuticals. Phenols are used in the manufacture of resins, antiseptics, and in the synthesis of dyes. Ethers are primarily used as solvents in laboratories and as anesthetics. For instance, diethyl ether was historically used as a general anesthetic due to its ability to induce unconsciousness.
Questions:
Ethanol is used in the production of:
Which of the following is an industrial use of phenol?
Diethyl ether is commonly used in:
Alcohols, phenols, and ethers are primarily used in industry due to their: