Chemical Properties of Alcohols, Phenols, and Ethers

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Questions and Answers

What defines an alcohol in terms of its functional group?

Contains one or more hydroxyl (OH) groups (correct)

Contains one or more carboxylic groups

Contains ester functional groups

Contains carbonyl groups directly attached to an aromatic system

Which statement correctly describes phenols?

They have hydroxyl groups attached to an aliphatic system.

They are always ionized in solution.

They lack hydroxyl groups.

They have hydroxyl groups directly attached to a carbon atom in an aromatic system. (correct)

What is the product when a hydrogen atom of a hydroxyl group is substituted by an alkyl or aryl group?

Carboxylic acid

Ester

Alcohol

Ether (correct)

Which of the following compounds is an example of an ether?

Dimethyl ether Signup and view all the answers

What structural feature distinguishes ethers from alcohols and phenols?

Substitution of hydrogen from a hydroxyl group Signup and view all the answers

What is the primary characteristic that classifies alcohols?

The hybridisation of the carbon atom to which the -OH group is attached Signup and view all the answers

Which method is NOT used to prepare alcohols?

Substitution of haloarenes Signup and view all the answers

Which of the following statements about the acidity of phenols is correct?

Electron withdrawing groups increase the acidic strength of phenols Signup and view all the answers

What occurs when primary alcohols are oxidized with mild oxidizing agents?

They yield aldehydes Signup and view all the answers

Which of the following is a true statement about tertiary alcohols?

They are resistant to oxidation Signup and view all the answers

Which statement accurately describes the acidity of alcohols compared to water?

Alcohols are weaker acids than water. Signup and view all the answers

What indicates that phenols are stronger acids than both alcohols and water?

Phenol reacts with metals and sodium hydroxide to release protons. Signup and view all the answers

Why are alkoxides considered stronger bases than hydroxide ions?

Alkoxides are better proton acceptors than hydroxide ions. Signup and view all the answers

What characteristic of phenols contributes to their acidic nature?

The electron-withdrawing effect of the sp hybridised carbon in the benzene ring. Signup and view all the answers

In which situation is the proton donation capability of water exemplified?

When water interacts with an alkoxide. Signup and view all the answers

Which compound is the weakest acid among the following?

Ethanol Signup and view all the answers

What is the order of increasing acid strength for the compounds: Propan-1-ol, 4-Methylphenol, Phenol?

Propan-1-ol, 4-Methylphenol, Phenol Signup and view all the answers

Which of the following statements regarding pKa values is true?

p-Cresol has a lower pKa value than ethanol. Signup and view all the answers

In terms of acidity, which of the following compounds is likely to be the most acidic?

2,4,6-Trinitrophenol Signup and view all the answers

What is the primary reaction that occurs between alcohols or phenols and carboxylic acids?

Esterification Signup and view all the answers

Which bond is stronger between O–CH3 and O–C6H5?

O–C6H5 Signup and view all the answers

What product is formed when the O–CH3 bond is broken by iodide ion (I–)?

CH3I Signup and view all the answers

Why do phenols not react further to give halides?

The sp hybridized carbon cannot undergo nucleophilic substitution. Signup and view all the answers

What is the effect of the alkoxy group (-OR) on an aromatic ring during electrophilic substitution?

It is ortho, para directing and activates the ring. Signup and view all the answers

What hybridization is associated with the carbon in the phenyl group?

sp Signup and view all the answers

Study Notes

Alcohols, Phenols, and Ethers: Overview

Ordinary spirit for polishing is primarily ethanol, a compound with a hydroxyl group (-OH).
Common substances containing –OH groups include sugars, cotton, and paper products, vital in daily life.
Alcohols feature one or more hydroxyl groups connected to carbon atoms in aliphatic systems (e.g., CH3OH).
Phenols have hydroxyl groups directly attached to carbon atoms in aromatic systems (e.g., C6H5OH).
Ethers are formed by substituting hydrogen in hydroxyl groups with alkyl or aryl groups (e.g., CH3OCH3).

Acidity Characteristics

Alcohols are weaker acids than water, as evidenced by reactions with alkoxides, showcasing that water is a better proton donor.
Alkoxide ions act as stronger bases compared to hydroxide ions, demonstrating that alcohols can also function as Brønsted bases.
Phenols demonstrate acidic characteristics through reactions with metals and bases, being stronger acids than alcohols and water due to resonance stabilization.

Acid Strength Comparison

pKa values indicate phenols are significantly more acidic than ethanol; for instance, phenol has a pKa of 10.0 while ethanol's is 15.9.
A ranking of acidity shows: propan-1-ol < 4-methylphenol < phenol < 3-nitrophenol < 3,5-dinitrophenol < 2,4,6-trinitrophenol.

Esterification Process

Alcohols and phenols react with carboxylic acids, acid chlorides, and anhydrides to form esters.
The bond strength between O–CH3 is weaker than O–C6H5 due to the sp hybridization in phenyl groups which exhibits partial double bond character.

Electrophilic Substitution Reactions

Alkoxy groups (-OR) are ortho and para directing, activating the aromatic ring for electrophilic substitution, similar to phenolic behavior.

Synthesis of Alcohols and Phenols

Alcohols can be synthesized via:
- Hydration of alkenes (with acid).
- Hydroboration-oxidation reactions.
- From carbonyl compounds through catalytic reduction or Grignard reagents.
Phenols can be synthesized by:
- Substitution of halogen in haloarenes or sulfonic acids by –OH.
- Hydrolysis of diazonium salts.
- Industrial processes from cumene.

Physical Properties

Alcohols exhibit higher boiling points than aliphatic hydrocarbons, ethers, and haloalkanes of similar molecular masses due to intermolecular hydrogen bonding.
Alcohols, phenols, and ethers are soluble in water owing to their ability to form hydrogen bonds.

Chemical Reactions of Alcohols and Phenols

Alcohols are nucleophilic and can undergo substitution with hydrogen halides to produce alkyl halides.
Dehydration of alcohols results in alkenes.
Oxidation of primary alcohols yields aldehydes or carboxylic acids, while secondary alcohols yield ketones; tertiary alcohols resist oxidation reactions.

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Description

This quiz examines the correlation between the structures and physical properties of alcohols, phenols, and ethers. It also discusses the chemical reactions of these three classes of compounds, highlighting their presence in everyday materials such as sugar and paper.