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Chemistry > 3.3.8 Aldeyhydes and ketones > Flashcards

3.3.8 Aldeyhydes and ketones Flashcards

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1
Q

What are aldehydes oxidised to?

A

Carboxylic acids

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2
Q

What are aldehydes reduced to?

A

Primary alcohols

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3
Q

What are ketones reduced to?

A

Secondary alcohols

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4
Q

What conditions are used to reduce aldehydes and ketones?

A

NaBH4 in and aqueous solution

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5
Q

What mechanism is used to reduce aldehydes and ketones?

A

Nucleophilic addition

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6
Q

What are the properties of the products from the reduction of a ketone?

A

They may form stereoisomers with a chiral carbon

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7
Q

What are the conditions and products for the nucleophilic substitution between carbonyl compounds and KCN?

A

Conditions: dilute acid
Products: hydroxynitriles

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8
Q

What are the properties of the products formed when aldehydes and unsymmetrical ketones react with KCN?

A

They form mixtures of enantiomers

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9
Q

Why are racemic mixtures formed in nucleophilic substitution with KCN and carbonyl groups occur?

A

The carbonyl group is planar. So, the nucleophile can attack from above or below the plane. If the product has a chiral centre, then, a racemic mixture is formed.

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10
Q

Why does NaBH4 reduce aldehydes but not alkenes?

A

The H- ion from NaBH4 is attracted to the delta + carbon of the aldehyde. But, the double carbon bond in the alkene repels the ions, it can only be attracted by electrophiles.

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11
Q

Why is KCN preferred over HCN for nucleophilic addition of an aldehyde?

A

It is a stronger acid
HCN is an extremely poisonous gas

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12
Q

What are the hazards of using KCN for nucleophilic substitution?

A

KCN is an irritant and is also extremely dangerous if it’s ingested or inhaled. It can react with moisture to produce HCN, a highly toxic gas.

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13
Q

How can you reduce the risks of using KCN for nucleophilic substitution?

A

Gloves
Safety goggles
Lab coat
Fume cupboard

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14
Q

Which base do carboxylic acids always react with?

A

Although they’re weak acids, they liberate CO2 from carbonates.

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15
Q

What are the reactants, products and conditions for esterification?

A

Reactants: alcohols, carboxylic acids
Conditions: concentrated acid catalyst (H2SO4)
Products: ester

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16
Q

Why are the common uses of esters?

A

Plasticisers
Solvents
Perfumes
Food flavourings

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17
Q

Why are esters suitable for food flavourings and perfumes?

A

They have a sweet smells.
Long-chain esters have fruity scents.

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18
Q

Why are esters suitable solvents? How are they used as solvents?

A

They’re polar so, polar organic compounds dissolve in it.
They have a low bpt so, they can easily be removed.
Used a solvents in glue and printing inks

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19
Q

Which esters are formed from glycerol and fatty acids?

A

Vegetable oils
Animal fats

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20
Q

What type of carboxylic acids are animal fats made up of?

A

They’re made up of saturated chains which fit together neatly. So, they have strong van der waals forces so, they have a high boiling point and are solid at room temperature.

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21
Q

What type of carboxylic acids are vegetable oils made up of?

A

Unsaturated chains which causes the chains to bend, decreasing Van der waals forces and reducing bpt. So, they’re liquid at room temperature.

22
Q

What reaction is used to turn an ester into a carboxylic acid and alcohol?

A

Hydrolysis in acid or alkaline conditions.

23
Q

What are the reactants, conditions and products for the acid hydrolysis of esters?

A

Reactants: ester, water
Conditions: reflux, dilute acid like HCl or H2SO4
Products: carboxylic acid, alcohol

24
Q

What are the reactants, conditions and products for the base hydrolysis of esters?

A

Reactants: ester, dilute alkali like NaOH
Conditions: reflux
Products: carboxylate ion, alcohol

25
Q

What substances can be produced by reactions of vegetable oils and animal fats?

A

Glycerol + soap
Glycerol + biodiesel

26
Q

What is biodiesel?

A

A mixture of methyl esters of long chain carboxylic acids.

27
Q

What are the reactants, conditions and products of the base hydrolysis of vegetable oils and animal fats, saponification?

A

Reactants: vegetable oil or animal fats, NaOH
Products: sodium salt (soap), glycerol
Conditions: alkaline conditions

28
Q

What are the reactants, conditions and products of the reaction of vegetable oils or animal fats and methanol?

A

Reactants: vegetable oil or animal fats, methanol
Products: methyl esters (biodeisel), glycerol
Conditions: catalyst (acid or alkaline)

29
Q

What nucleophiles are used in nucleophilic addition elimination?

A

Water
Alcohols
Amines
Ammonia

30
Q

How are acyl chlorides named?

A

-oyl
Ethanoyl chloride

31
Q

How are acid anhydrides named?

A

Ethanoic andhydride

32
Q

What are the advantages and disadvantages of the reaction between acyl chlorides and alcohol?

A

+ Very reactive, good rate of reaction
+ Good atom economy
- Hazardous HCl gas waste product
- Hard to store as it reacts with water in air to form HCl gas which can be explosive.

33
Q

What are the advantages and disadvantages of the reaction between acid anhydrides and alcohol?

A

+ Waste product, carboxylic acid, is not harmful
+ Decent rate of reaction
- Bad atom economy

34
Q

What are the products for the reaction between an acyl chloride and an alcohol?

A

Ester
HCl

35
Q

What are the products for the reaction between an acyl chloride and water?

A

Carboxylic acid
HCl

36
Q

What are the products for the reaction between an acid anhydride and an alcohol?

A

Ester
Carboxylic acid

37
Q

What are the products for the reaction between an acid anhydride and water?

A

2 carboxylic acids

38
Q

What are the products for the reaction between an acyl chloride and an amine?

A

An N-substituted amide
Alkyl ammonium chloride

39
Q

What are the products for the reaction between an acid anhydride and an amine?

A

An N-substituted amide
Alkyl ammonium carboxylate salt

40
Q

What are the products and observations for the reaction between ethanoyl chloride and ammonia?

A

Products: ethanamide, ammonium chloride
Observations: white smoke and solid due to both of the products

41
Q

What was aspirin used for?

A

To treat pain, fever and inflammation

42
Q

What reacts with 2-hydroxybenzoic acid to make aspirin?

A

Ethanoic acid
Ethanoyl chloride
Ethanoic anhydride

43
Q

What are the advantages and disadvantages of using ethanoic acid to make aspirin?

A

+ low hazards
+ good atom economy
+ harmless by-product
- Slow reaction as it is a reversible reaction.
- Bad yield

44
Q

What are the advantages and disadvantages of using ethanoyl chloride to make aspirin?

A

+ Fast reaction
+ Good yield
+ Good atom economy
- Hazardous by-product
- Hard to store reagent

45
Q

What are the advantages and disadvantages of using ethanoic anhydride to make aspirin?

A

+ Relatively quick rate with a catalyst
+ Harmless by-product
+ Good yield
+ Relatively harmless reagents
- Low atom economy

46
Q

What are the steps to aspirin synthesis?

A
  • Heat the reactants together, then add cold water to crystallise the aspirin.
  • Vacuum filter out the solid aspirin from the mixture.
  • Recrystallise the aspirin (purification)
  • Vacuum filter the aspirin again.
  • Dry the product in an oven and record the final mass. Dry to a constant mass.
47
Q

Describe the process of the purification step in aspirin synthesis.

A
  • Warm in the minimum amount of hot solvent, just enough to dissolve the desired product.
  • Filter hot to remove the soluble impurities
  • Cool in a salt water bath to recrystallise the product
  • Filter to remove the solvent (and any dissolved impurities.)
  • Dry by rinsing with a volatile solvent and pat dry with filter paper
48
Q

What are optical isomers?

A

A type of geometric isomer that occurs in molecules with chiral centres.

49
Q

What is an asymmetric carbon atom?

A

A chiral, with 4 different groups attached tetrahedrally around it.

50
Q

What are enantiomers?

A

Optical isomers that are non super-imposable mirror images and differ in their effect on plane-polarised light.

51
Q

What is a racemic mixture?

A

A mixture of equal amounts of enantiomers. So, rotational effects on light cancel out.

Chemistry (14 decks)

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