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XII_Chem_New_Chap_08_Aldehydes,_Ketones_and_Carboxylic_Acids_137
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Spread the Happiness. Assertion and Reason Statements Feedback: 9008271516XII_CHEMISTRY_NEW_CHAPTER-08: ALDEHYDES, KETONES AND CARBOXYLIC ACIDS_ A&R TEST ITEMS
# Correct Assertion Correct Reason
8.1 Nomenclature and Structure of Carbonyl Group
The carbonyl group defines aldehydes, ketones, The presence of a carbonyl group (>C=O) is the fundamental
1
and carboxylic acids. characteristic of these classes of compounds.
The carbonyl group influences the physical The carbonyl group's polarity and ability to form hydrogen bonds
2
properties of carbonyl compounds. directly affects properties like boiling point.
The carbonyl group leads to polarity in aldehydes, The electronegativity difference between carbon and oxygen creates a
3
ketones, and carboxylic acids. dipole moment within the carbonyl group.
The carbonyl group influences the reactivity of The electrophilic carbonyl carbon attracts nucleophiles, facilitating
4
aldehydes, ketones, and carboxylic acids. various addition reactions.
Aldehydes have a carbonyl group bonded to a This specific structural arrangement distinguishes aldehydes from other
5
carbon and hydrogen. carbonyl compounds.
Ketones have a carbonyl group bonded to two This specific structural arrangement distinguishes ketones from other
6
carbon atoms. carbonyl compounds.
Carboxylic acids derive their acidity from the The carbonyl group increases electron withdrawal from the O-H bond,
7
carbonyl group and the hydroxyl group. making proton release easier.
Aldehydes and ketones are used in fragrances and Certain aldehydes and ketones have pleasant scents and tastes, making
8
flavors. them valuable additives.
The carbonyl group enables diverse reactions in The carbonyl group's reactivity allows for the formation of other
9
organic chemistry. functional groups like amides, esters, and anhydrides.
8.2 Preparation of Aldehydes and Ketones
Oxidation of primary alcohols yields aldehydes. Oxidizing agents remove hydrogen atoms from the alcohol's hydroxyl
10 group and its adjacent carbon, increasing the oxidation state and
forming an aldehyde.
Oxidation of secondary alcohols yields ketones. Oxidizing agents remove hydrogen from the alcohol's hydroxyl group
11 and its adjacent carbon, creating a carbonyl group characteristic of
ketones.
Dehydrogenation of alcohols yields aldehydes or Catalysts like copper facilitate hydrogen removal, enabling the
12 ketones using suitable catalysts. formation of a carbonyl group, producing aldehydes from primary
alcohols and ketones from secondary alcohols.
Ozonolysis of alkenes forms aldehydes, ketones, Ozonolysis cleaves the alkene double bond, introducing oxygen and
13 or a mixture based on substitution patterns. creating unstable ozonides, which upon reduction yield carbonyl-
containing products.
Hydration of alkynes yields aldehydes or ketones Acid-catalyzed addition of water to alkynes leads to an unstable enol
14 using specific catalysts. intermediate, which rearranges (tautomerizes) to form a more stable
aldehyde or ketone.
Reduction of acyl chlorides with tailored catalysts The Rosenmund reduction selectively converts the acyl chloride's
15 produces aldehydes. carbonyl group to an aldehyde using hydrogen and a palladium catalyst,
preventing over-reduction.
Selective reduction of nitriles affords aldehydes. Reagents like DIBAL-H partially reduce the nitrile's carbon-nitrogen
16 triple bond to an imine intermediate, which yields an aldehyde upon
hydrolysis.
Controlled oxidation of aromatic methyl groups Reagents like chromyl chloride selectively oxidize toluene, creating an
17 forms aldehydes. intermediate that resists further oxidation to a carboxylic acid and
allows aldehyde isolation.
Aromatic aldehydes are produced via the Carbon monoxide and hydrogen chloride react with aromatic
18 Gatterman-Koch reaction. compounds in the presence of a Lewis acid catalyst, introducing a
formyl group that yields an aldehyde.
Friedel-Crafts acylation synthesizes ketones from Acyl chlorides react with aromatic compounds in the presence of a
19 aromatic compounds. Lewis acid catalyst, facilitating electrophilic aromatic substitution and
introducing an acyl group, forming a ketone.
Grignard reagents transform nitriles or acyl The nucleophilic Grignard reagent adds to the carbonyl carbon in
20
chlorides into ketones. nitriles or acyl chlorides, and subsequent hydrolysis yields a ketone.
8.3 Physical Properties
Lower aldehydes and ketones are miscible with The presence of a carbonyl group (C=O) allows for hydrogen bonding
21 water in all proportions. with water molecules, overcoming the opposing effect of the non-polar
hydrocarbon chain.
Solubility of aldehydes and ketones in water As the alkyl chain lengthens, the non-polar character of the molecule
22 decreases with increasing alkyl chain length. becomes more dominant, weakening the hydrogen bonding with water
and increasing the molecule's affinity for non-polar solvents.
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, Spread the Happiness. Assertion and Reason Statements Feedback: 9008271516
XII_CHEMISTRY_NEW_CHAPTER-08: ALDEHYDES, KETONES AND CARBOXYLIC ACIDS_ A&R TEST ITEMS
# Correct Assertion Correct Reason
The boiling point of a substance is the The strength of intermolecular forces determines the energy required
23 temperature at which its vapor pressure equals to overcome them and transition from liquid to gas, influencing the
the atmospheric pressure. boiling point.
Aldehydes and ketones have higher boiling points The presence of a polar carbonyl group (C=O) facilitates dipole-dipole
than hydrocarbons and ethers of similar molecular interactions (which are stronger than the weak van der Waals forces in
24
masses. hydrocarbons and ethers), thus,it requires more energy to overcome
and transition to the vapor phase.
Alcohols have higher boiling points than aldehydes While both aldehydes/ketones and alcohols can form hydrogen bonds,
and ketones of similar molecular masses. the extensive hydrogen bonding network in alcohols requires more
25
energy to break, resulting in a higher boiling point compared to
aldehydes/ketones with a single hydrogen bonding site.
Among aldehydes, ketones, ethers, and n-Pentane molecules only exhibit weak van der Waals forces, the
26 hydrocarbons with similar molecular masses, n- weakest intermolecular force among the compared molecules,
pentane has the lowest boiling point. requiring less energy to overcome and transition to the gas phase.
8.4 Chemical Reactions
Aldehydes are generally more reactive than Steric hindrance from two alkyl groups in ketones inhibits nucleophilic
27 ketones in nucleophilic addition reactions. attack, and their electron-withdrawing nature decreases the
electrophilicity of the carbonyl carbon relative to aldehydes.
Aldehydes are readily oxidized to carboxylic acids Aldehydes are more susceptible to oxidation than ketones (due to the
28 by by mild oxidizing agents like Tollens' reagent, lack of steric hindrance & presence of a more reactive C-H bond) and
forming a silver mirror. the silver ions in the reagent are reduced to metallic silver.
The α-hydrogens in aldehydes and ketones are The electron-withdrawing carbonyl group weakens the α C-H bond,
29 weakly acidic. increasing acidity, while resonance stabilization of the resulting enolate
anion further enhances acidity.
Aldehydes and ketones with at least one α- The base deprotonates the α-carbon and creates an enolate ion, which
hydrogen undergo aldol condensation in the acts as a nucleophile attacking another carbonyl molecule; subsequent
30
presence of a base catalyst. dehydration yields an α,β-unsaturated carbonyl compound.
Methyl ketones undergo the haloform reaction The enolate ion from the methyl ketone attacks the halogen, followed
31 with sodium hypohalite. by rearrangements and a carbon-carbon bond cleavage, ultimately
producing a carboxylic acid and haloform.
8.5 Uses of Aldehydes and Ketones
The carbonyl group (C=O) is a defining This functional group largely determines the chemical properties and
32
characteristic of aldehydes and ketones. reactivity of aldehydes and ketones.
Aldehydes and ketones have higher boiling points Dipole-dipole interactions in aldehydes and ketones are stronger than
33 than similar hydrocarbons and ethers. van der Waals forces, requiring more energy to overcome during
boiling.
Aldehydes and ketones are versatile in industrial Their reactivity, polarity, and solubility make them valuable as solvents,
34
applications. starting materials, and reagents in various processes.
Formaldehyde is a useful preservative and Its reactive aldehyde group readily forms cross-links with proteins and
35 polymer building block. other molecules, promoting preservation and polymerization reactions.
Certain aldehydes and ketones have distinct odors The interaction of specific functional groups with olfactory receptors
36
and flavors. leads to characteristic sensory experiences.
Carboxylic acids are characterized by a carboxyl This group, combining a carbonyl (C=O) and hydroxyl group (-OH),
37
group (COOH). imparts unique acidity and reactivity to carboxylic acids.
Carboxylic acids are precursors to diverse organic Their reactive carboxyl group undergoes transformations, yielding
38
compounds. derivatives like esters, amides, and acid chlorides.
8.6 Nomenclature and Structure of Carboxyl Group
The carboxyl group (COOH) defines the properties This functional group's unique combination of a carbonyl (C=O) and
39 and reactivity of carboxylic acids. hydroxyl (-OH) imparts acidity, hydrogen bonding capability, and the
potential to form diverse derivatives.
Carboxylic acids participate in a wide range of Their acidity, reactivity, and ability to form derivatives such as esters
40 industrial processes due to their distinctive and amides make them valuable in the synthesis of polymers,
functional group. preservatives, pharmaceuticals, and more.
IUPAC nomenclature systematically names This standardized approach unambiguously identifies carboxylic acids
41 carboxylic acids, replacing the "-e" of the and their carbon chain length, promoting clarity in chemical
corresponding alkane with "-oic acid." communication.
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