p.4
Preparation of Aldehydes and Ketones from Alcohols
How can aldehydes be prepared from primary alcohols?
By oxidation using distillation.
p.9
Laboratory Preparation and Identification of Aldehydes and Ketones
What does CCEA stand for?
Council for the Curriculum, Examinations & Assessment.
p.8
Condensation Reactions with 2,4-Dinitrophenylhydrazine
What is the reaction between cis hex-3-enal and 2,4-dinitrophenylhydrazine used for?
To form a hydrazone derivative.
p.3
Distinguishing Aldehydes and Ketones Using Reagents
What observation indicates the presence of an aldehyde when using Fehling's solution?
A red precipitate occurs.
p.4
Nucleophilic Addition Reactions with Hydrogen Cyanide
What is the role of the cyanide ion in the reaction with aldehydes?
It acts as the nucleophile.
p.3
Preparation of Aldehydes and Ketones from Alcohols
What is the process to prepare ketones?
Oxidation of secondary alcohols.
p.2
Reduction of Aldehydes and Ketones
What happens to aldehydes during oxidation?
Aldehydes can be oxidized into carboxylic acids.
p.4
Preparation of Aldehydes and Ketones from Alcohols
What happens when ethanol is oxidized with acidified dichromate?
It is converted into ethanal (aldehyde).
p.6
Laboratory Preparation and Identification of Aldehydes and Ketones
What is the first step in preparing 2,4-dinitrophenylhydrazones?
Place 5 cm³ of 2,4-dinitrophenylhydrazine solution in a suitable container.
p.2
Condensation Reactions with 2,4-Dinitrophenylhydrazine
What is the purpose of 2,4-dinitrophenylhydrazones in chemistry?
For identification purposes with reference to melting point determination.
p.6
Laboratory Preparation and Identification of Aldehydes and Ketones
What is the first step in the recrystallisation method?
Dissolve the impure crystals in the minimum volume of hot solvent.
p.1
Mechanisms of Reactions Involving Aldehydes and Ketones
What is the mechanism for the nucleophilic addition reaction of hydrogen cyanide and propanone?
It involves the attack of the cyanide ion on the carbonyl carbon.
p.1
Reduction of Aldehydes and Ketones
What is the reducing agent used for the reduction of aldehydes and ketones?
Lithium tetrahydridoaluminate(III) (lithal).
p.3
Distinguishing Aldehydes and Ketones Using Reagents
What happens to the solution when a ketone is tested with Fehling's solution?
The solution remains blue.
p.2
Boiling Points and Solubility of Aldehydes and Ketones
How do boiling points of aldehydes and ketones compare to similarly sized hydrocarbons?
They have higher boiling points due to additional dipole-dipole attractions.
p.2
Reduction of Aldehydes and Ketones
What is the condition for oxidizing an aldehyde?
Warm with acidified potassium dichromate(VI) solution.
p.1
Molecular and Structural Formulae of Aldehydes and Ketones
What is the functional group present in both aldehydes and ketones?
The carbonyl group (C=O).
p.9
Laboratory Preparation and Identification of Aldehydes and Ketones
What is the significance of the number 7 in the document?
It is unclear without additional context.
p.8
Distinguishing Aldehydes and Ketones Using Reagents
What is the fragrance attributed to some Scotch whiskies?
The fragrance of cut grass.
p.6
Laboratory Preparation and Identification of Aldehydes and Ketones
What should be added to the test liquid if crystals do not form?
Some dilute sulfuric acid.
p.2
Molecular and Structural Formulae of Aldehydes and Ketones
What is the naming convention for ketones?
The names are based on the carbon skeleton, with the ending changed to –anone.
p.1
Molecular and Structural Formulae of Aldehydes and Ketones
How are aldehydes named based on their carbon skeleton?
The ending is changed to –anal.
p.7
Distinguishing Aldehydes and Ketones Using Reagents
What is the organic compound X that gives an orange crystalline product with 2,4-dinitrophenylhydrazine but does not precipitate with Fehling's solution?
B C6H5CH2CHO (benzaldehyde).
p.7
Nucleophilic Addition Reactions with Hydrogen Cyanide
Outline the mechanism for the reaction of CH3CH2CHO with HCN.
The mechanism involves nucleophilic addition where HCN attacks the carbonyl carbon, forming a cyanohydrin.
p.4
Nucleophilic Addition Reactions with Hydrogen Cyanide
What is a nucleophile?
An atom or group that donates a lone pair to form a new covalent bond.
p.3
Distinguishing Aldehydes and Ketones Using Reagents
What is the outcome when a ketone is tested with Tollens' reagent?
The solution remains colorless.
p.6
Laboratory Preparation and Identification of Aldehydes and Ketones
What indicates that a solid is pure when determining its melting point?
A melting range of 1-2 °C.
p.5
Racemic Mixtures in Reactions with Hydrogen Cyanide
Why is the product of the reaction between ethanal and potassium cyanide optically inactive?
Because a racemic mixture is formed, which is a 50/50 mixture of two optical isomers.
p.5
Condensation Reactions with 2,4-Dinitrophenylhydrazine
What is produced in a condensation reaction with 2,4-dinitrophenylhydrazine?
A 2,4-dinitrophenylhydrazone.
p.8
Distinguishing Aldehydes and Ketones Using Reagents
What would be observed if cis hex-3-enal is warmed with Fehling's solution?
A color change indicating the presence of an aldehyde.
p.4
Nucleophilic Addition Reactions with Hydrogen Cyanide
What type of reaction do aldehydes and ketones undergo due to their carbonyl group?
Nucleophilic addition reactions.
p.3
Distinguishing Aldehydes and Ketones Using Reagents
What is the result of using Tollens' reagent on an aldehyde?
A silver mirror forms on the inside surface of the test tube.
p.2
Boiling Points and Solubility of Aldehydes and Ketones
What types of intermolecular forces do aldehydes and ketones exhibit?
Van der Waals’ forces and dipole-dipole attractions.
p.5
Condensation Reactions with 2,4-Dinitrophenylhydrazine
What is the observation when aldehydes and ketones react with 2,4-dinitrophenylhydrazine?
Orange/yellow precipitates are produced.
p.5
Condensation Reactions with 2,4-Dinitrophenylhydrazine
Why are aldehydes and ketones reacted with 2,4-dinitrophenylhydrazine?
To form solid crystals of the 2,4-dinitrophenylhydrazone for easier identification.
p.8
Molecular and Structural Formulae of Aldehydes and Ketones
What is the general structure of cis hex-3-enal represented as?
C6H10O (with a carbonyl group).
p.7
Racemic Mixtures in Reactions with Hydrogen Cyanide
How is a racemic mixture formed in the reaction of CH3CH2CHO with HCN?
A racemic mixture is formed because the nucleophilic attack on the carbonyl carbon can occur from either side, leading to two enantiomers.
p.6
Laboratory Preparation and Identification of Aldehydes and Ketones
What is the purpose of cooling the mixture in iced water during the preparation?
To promote crystallisation of the product.
p.3
Reduction of Aldehydes and Ketones
What is the reducing agent used to reduce aldehydes and ketones?
Lithium tetrahydridoaluminate(III) (LiAlH₄).
p.6
Laboratory Preparation and Identification of Aldehydes and Ketones
What is the significance of determining the melting point of the crystals?
To compare it with data book values for identification of the original compound.
p.1
Molecular and Structural Formulae of Aldehydes and Ketones
What are the molecular and structural formulae of aldehydes and ketones based on?
The carbon skeleton, including branched structures with up to six carbon atoms in the main chain.
p.1
Nucleophilic Addition Reactions with Hydrogen Cyanide
What is the reaction of aldehydes and ketones with hydrogen cyanide?
They undergo nucleophilic addition reactions.
p.1
Distinguishing Aldehydes and Ketones Using Reagents
What reagent can be used to distinguish aldehydes and ketones?
Acidified potassium dichromate(VI), Fehling's solution, and Tollens’ reagent.
p.5
Condensation Reactions with 2,4-Dinitrophenylhydrazine
What is a condensation reaction?
A reaction in which the elements of water are removed.
p.7
Molecular and Structural Formulae of Aldehydes and Ketones
What is the name of the compound CH3CHO and its functional group?
Acetaldehyde; functional group is aldehyde.
p.2
Boiling Points and Solubility of Aldehydes and Ketones
Why are smaller aldehydes and ketones soluble in water?
Due to hydrogen bonding between polar hydrogen of water and the lone pair on the oxygen.
p.6
Laboratory Preparation and Identification of Aldehydes and Ketones
What is the purpose of using a Buchner funnel in suction filtration?
To quickly filter and dry the solid.
p.5
Racemic Mixtures in Reactions with Hydrogen Cyanide
What type of mixture do aldehydes and unsymmetrical ketones form when reacting with hydrogen cyanide?
A racemic mixture of enantiomers.
p.5
Racemic Mixtures in Reactions with Hydrogen Cyanide
What do symmetrical ketones produce when reacting with hydrogen cyanide?
A product that does not have an asymmetric carbon and is optically inactive.
p.6
Laboratory Preparation and Identification of Aldehydes and Ketones
What is the purpose of recrystallisation in the laboratory preparation of aldehydes and ketones?
To purify the compound and determine its melting point for identification.
p.3
Oxidation of Aldehydes and Ketones
What is the result of oxidizing an aldehyde using acidified potassium dichromate(VI)?
The orange dichromate(VI) ion is reduced to the green chromium(III) ion, Cr³⁺.
p.4
Nucleophilic Addition Reactions with Hydrogen Cyanide
How is the first carbon counted in hydroxynitriles?
The carbon with nitrogen attached is counted as the first carbon.
p.5
Racemic Mixtures in Reactions with Hydrogen Cyanide
What is the condition required to generate hydrogen cyanide in the reaction mixture?
Add dilute acid to an aqueous solution of potassium cyanide.
p.2
Boiling Points and Solubility of Aldehydes and Ketones
How does solubility change with increasing chain length in aldehydes and ketones?
Solubility decreases as chain lengths increase due to longer hydrocarbon parts interfering with water molecules.
p.2
Reduction of Aldehydes and Ketones
Can ketones be oxidized?
No, ketones cannot be oxidized.
p.1
Preparation of Aldehydes and Ketones from Alcohols
How can aldehydes and ketones be prepared?
From the corresponding primary or secondary alcohol using a suitable oxidising agent.
p.1
Racemic Mixtures in Reactions with Hydrogen Cyanide
Why can racemic mixtures be produced when hydrogen cyanide reacts with aldehydes and ketones?
Due to the formation of a chiral center during the reaction.
