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Spread the Happiness. Assertion and Reason Statements Feedback: 9008271516XII_CHEMISTRY_NEW_CHAPTER-07: ALCOHOLS, PHENOLS AND ETHERS _ A&R TEST ITEMS
# Correct Assertion Correct Reason
7.1 Classification
Alcohols have OH attached to aliphatic carbon. Distinguishes alcohols from phenols based on the carbon chain type
1
(aliphatic vs. aromatic).
Phenols have OH attached to an aromatic carbon Characterizes phenols by their attachment to a specific ring structure
2
with electron delocalization. exhibiting characteristic electron delocalization.
Ethers have R-O/Ar-O groups. Defines the functional group in ethers based on the attachment of alkyl
3
(R) or aryl (Ar) groups to oxygen.
Alcohols are classified as monohydric, dihydric, Categorizes alcohols based on the number of hydroxyl groups (1-many)
4
trihydric, or polyhydric. for systematic organization.
Monohydric alcohols are further classified as Classification within monohydric alcohols depends on the number of
5 primary, secondary, or tertiary. hydrogen atoms attached to the carbon bearing the hydroxyl group
(primary, secondary, tertiary).
Allylic and benzylic alcohols are subtypes of Subclassification of monohydric alcohols is based on the position of the
6 monohydric alcohols. OH group relative to specific functional groups (adjacent to a double
bond or aromatic ring).
Ethers are classified as simple/symmetrical or Classification of ethers is based on the identity of the groups attached
7
mixed/unsymmetrical. to the oxygen atom (same/different).
The type of carbon orbital hybridization (sp³ or Carbon's orbital hybridization (sp³ or sp²) dictates the possible bonding
8 sp²) influences OH attachment in alcohols. arrangements, affecting how the OH group can be attached.
7.2 Nomenclature
Alcohols contain OH on an aliphatic carbon chain. The OH group is a defining characteristic of alcohols, allowing them to
9
form hydrogen bonds with other molecules.
Phenols have OH on an aromatic carbon ring. Phenols have unique properties due to the OH group's location on the
10
aromatic ring, influencing their reactivity.
Ethers possess R-O/Ar-O functional groups. Ethers differ from alcohols due to the presence of an oxygen atom
11 bonded to two carbon atoms (R or Ar), not directly to a hydrogen atom.
The longest carbon chain with OH is the parent The longest carbon chain containing the OH group is prioritized as the
12 chain in alcohols. base structure in IUPAC alcohol nomenclature for clarity and
consistency.
IUPAC alcohol names include a number for the OH The number in an IUPAC alcohol name indicates the exact carbon atom
13
group's position. bonded to the OH group, ensuring unambiguous identification.
The larger alkyl group is the parent chain in ethers. IUPAC ether nomenclature prioritizes the larger alkyl group as the
14
parent chain for clear designation of the core structure.
The prefix "di" precedes the alkyl group for The "di" prefix before the alkyl group in symmetrical ethers signifies the
15 symmetrical ethers. presence of two identical alkyl groups attached to the oxygen atom.
IUPAC nomenclature offers a systematic approach IUPAC nomenclature establishes a consistent and globally recognized
16 to naming organic compounds. language for naming organic compounds, facilitating scientific
communication.
Clear nomenclature is crucial for chemistry Clear and unambiguous nomenclature minimizes confusion and ensures
17 communication and understanding. accurate interpretation of chemical structures within the scientific
community.
Functional groups (OH) and their positions The presence and location of the OH group in alcohols and phenols
18 influence IUPAC naming of alcohols and phenols. determine the core chain and substituent prefixes assigned using IUPAC
nomenclature.
7.3 Structures of Functional Groups
Alcohols have OH on sp3-hybridized carbon. The sp3 hybridization of the carbon in alcohols allows for tetrahedral
19 orbital geometry, facilitating σ-bond formation with the OH group.
Phenols have OH on sp2-hybridized aromatic The sp2 hybridization of the carbon in phenols influences orbital
20 carbon. overlap with the aromatic ring, impacting the electronic structure and
aromatic character.
Ethers possess R-O/Ar-O functional groups. Ethers are differentiated from alcohols by the presence of an oxygen
21 atom bonded to two carbon atoms (alkyl or aryl) instead of a hydrogen
atom.
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, Spread the Happiness. Assertion and Reason Statements Feedback: 9008271516
XII_CHEMISTRY_NEW_CHAPTER-07: ALCOHOLS, PHENOLS AND ETHERS _ A&R TEST ITEMS
# Correct Assertion Correct Reason
Repulsive forces affect O-H bond angle in alcohols. Lone electron pairs on the oxygen atom in alcohols experience
22 electrostatic repulsion, causing a slight decrease in the C-O-H bond
angle compared to the ideal tetrahedral angle.
Electronic structure influences C-O bond length in The shorter C-O bond length in phenols compared to methanol arises
phenols. from two factors: (i) partial double bond character due to conjugation
23
with the aromatic ring, and (ii) sp2 hybridization of the attached carbon
atom (increased orbital overlap).
Steric effects influence C-O-C bond angle in ethers. Repulsive interactions between the two bulky alkyl or aryl groups in
24 ethers cause the C-O-C bond angle to deviate slightly from the ideal
tetrahedral angle, pushing it slightly wider.
7.4 Alcohols and Phenols; 7.4.1 Preparation of Alcohols
Alkenes form alcohols with water in acidic media. H+ initiates the reaction by creating a carbocation, which water then
25
attacks as a nucleophile, yielding an alcohol.
Unsymmetrical alkenes favor alcohols with the OH Revised: The more substituted carbocation intermediate (with more
26 on the more hydrogen-rich carbon. hydrogen atoms) experiences greater hyperconjugation, stabilizing it
and directing the nucleophilic attack towards that carbon.
Diborane addition to alkenes followed by Boron preferentially binds to the less-substituted carbon, leading to an
27
oxidation yields alcohols. anti-Markovnikov product upon oxidation.
Hydrogenation transforms aldehydes and ketones Hydrogen addition saturates the carbonyl double bond, creating a
28 into primary and secondary alcohols, respectively. primary alcohol from an aldehyde and a secondary alcohol from a
ketone.
Strong reducing agents like LiAlH4 convert The reducing agent breaks the carbon-oxygen bond in the carboxylic
29
carboxylic acids to primary alcohols. acid, ultimately forming a primary alcohol.
Grignard reagents yield primary, secondary, or The Grignard reagent acts as a nucleophile, adding to the carbonyl
30 tertiary alcohols depending on the starting carbon. Hydrolysis determines the final alcohol, with the carbon chain
carbonyl compound. length dictated by the Grignard reagent.
7.4.2 Preparation of Phenols
Cumene oxidation dominates phenol production. High yield (phenol & acetone), readily available cumene, and single-
31
step conversion promote economic viability and process efficiency.
Diazonium salts readily convert to phenols. Unstable diazonium ion (N₂⁺) readily loses N₂ gas, facilita ng water
32 attack and hydroxyl group formation for a more stable aromatic ring.
Sulfonation activates benzene for phenol Strongly acidic sulfonic acid group (-SO₃H) acts as an electron-
33 conversion. withdrawing group, enhancing the electrophilic character of the
benzene ring for nucleophilic attack by hydroxide.
Grignard reagents yield variable alcohols. Steric hindrance around the carbonyl carbon dictated by the size and
orientation of alkyl groups in the Grignard reagent influences the
34
nucleophilic attack and final alcohol structure (primary, secondary,
tertiary).
Haloarenes react with NaOH to form phenols. Strong nucleophilicity of hydroxide compared to the halide leaving
group drives the nucleophilic substitution reaction, displacing the
35
halide and forming a phenoxide ion that gets protonated to yield
phenol.
High temperature and pressure promote Elevated temperature increases collision frequency, while high pressure
36 chlorobenzene conversion. reduces the activation energy barrier, accelerating the nucleophilic
aromatic substitution reaction.
Sulfonation yields benzenesulfonic acid. Treatment of benzene with oleum introduces a sulfonic acid group (-
37
SO₃H).
Cumene hydroperoxide decomposes to phenol Weak O-O bond susceptibility to acidic attack favors a more stable C-O
38
and acetone. bond formation in phenol, releasing acetone as a by-product.
7.4.3 Physical Properties (Alcohols & Phenols)
Boiling points of alcohols and phenols increase Longer carbon chains experience stronger Van der Waals forces due to
39
with carbon chain length. increased surface area for interaction.
Branching in alcohols lowers boiling point Compact shape and smaller surface area in branched structures lead to
40
compared to straight-chain isomers. weaker Van der Waals forces.
Alcohols and phenols exhibit higher boiling points Intermolecular hydrogen bonding in alcohols and phenols creates
41 than similar-mass hydrocarbons, ethers, stronger attractions between molecules compared to weaker Van der
haloalkanes, and haloarenes. Waals forces in other classes.
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