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Organic Chemistry > C26. Compounds Containing the Carbonyl Group (A2) > Flashcards

C26. Compounds Containing the Carbonyl Group (A2) Flashcards

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1
Q

What are carbonyls?

A

C=O functional group compounds, Carbon to oxygen double bond

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2
Q

How are aldehydes and ketones prepared?

A

Oxidise primary alcohol to form aldehydes; Oxidise secondary alcohols to form ketones

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3
Q

What’s the oxidising agent used for oxidation of aldehydes and ketones?

A

Acidified potassium dichromate K2Cr2O7 with sulfuric acid H2SO4

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4
Q

What colour change is evident when K2Cr2O7 is reduced?

A

Alcohol oxidised; Orange to green

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5
Q

What colour change is evident when KMnO4 is reduced?

A

Alcohol oxidised; Purple to colourless

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6
Q

How do you form carboxylic acids from primary alcohols?

A

Oxidation; Heat reaction mixture under reflux; Aldehyde produced but evaporates and condenses into mixture; Oxidised further into carboxylic acid

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7
Q

Why are ketones resistant to being oxidised?

A

No readily available hydrogen atoms; Extremely strong oxidising agent needed; Oxidation will likely oxidise ketones destructively, breaking C-C bond

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8
Q

How do you distinguish between aldehydes and ketones?

A

Weak oxidising agents; Tollens reagent and fehling’s solution; Or acidified potassium dichromate

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9
Q

Describe the silver mirror test.

A

Tollens’ reagent, ammoniacal silver nitrate [Ag(NH3)2]+; Colourless; Warmed gently with aldehyde, oxidises aldehyde; Causes [Ag(NH3)2]+ ion to reduce to solid Ag; Silver mirror formed

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10
Q

How is Tollens’ reagent formed?

A

Aqueous ammonia is added to a solution of silver nitrate

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11
Q

Describe the Fehling’s test.

A

Fehling’s solution (blue), Copper(II) complex ions solution is an oxidising agent; Aldehyde warmed with Fehling’s solution, aldehyde oxidised to carboxylic acid; Brick red precipitate formed, copper(I) oxide

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12
Q

Describe a common reducing agent for reduction of carbonyls.

A

Sodium tetraborohydride NaBH4(-); In aqueous solution (acidic solvent used to provide the H+ ion), generates hydride ion nucleophile :H-; Hydride ion reduces carbonyl group but not strong enough to reduce C=C; Due to high electron density of C=C and attraction to C=O; Nucleophilic addition

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13
Q

Describe the mechanism of nucleophilic addition of HCN to carbonyl groups.

A

Electrons from double bonds, C=O, move to O; CN- attacks C from C=O; Lone pair from O- attracts H+ ion;

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14
Q

Why does the nucleophilic addition of HCN to ketones and aldehydes result in optical isomers?

A

Planar shape of carbonyl group, CN- can attack from either side of the carbonyl group; Forming enantiomers

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15
Q

Describe the physical properties of carbonyls.

A

Carbonyl group is strongly planar; Permanent dipoles-dipole forces between molecules; High boiling point relative to molecular mass, less than OH though; Highly reactive due to electronegativity difference; Nucleophiles attack C; Unsaturated so addition reactions are applicable;

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16
Q

Describe the mechanism for nucleophilic addition reaction between carbonyls.

A

Nu: attacks C, double bond moves to O; O: attracts H; H+ from solvent; (R)(R)C(Nu)(OH)

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17
Q

How are aldehydes converted into primary alcohols?

A

Reduction; H+ from solvent acts as a nucleophile; :H-

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18
Q

How are ketones converted into secondary alcohols?

A

Reduction; H+ from solvent acts as a nucleophile; :H-

19
Q

What functional groups does carboxylic acids contain?

A

Carbonyl group C=O; Hydroxyl group O-H

20
Q

Describe the physical properties of carboxylic acids.

A

Able to form hydrogen bonds w H2O molecules; Acids up to butanoic acids are H2O soluble; Acids form hydrogen bonds w each other in solid state; High melting point relative to molecular mass; Characteristic smells, ethanoic acid - vinegar

21
Q

How do you name esters?

A

Chain with carbonyl group is main chain, -oate side; Named by parent alcohol (ethyl), parent acid (ethanoate)

22
Q

How do you name esters?

A

Chain with carbonyl group is main chain, -oate side; Named by parent alcohol (ethyl), parent acid (ethanoate)

23
Q

Describe the different methods carboxylic acids could react?

A

C+ is open to attack from nucleophiles; O- from C=O is open to attack from positively charged species; H+ lost as H+, behaving as acid

24
Q

Describe the formation of esters.

A

Carboxylic acids react with alcohol in presence of strong hot acid catalyst; Reversible reaction; Producing ester and water; Condensation reaction

25
Q

Describe the hydrolysis of esters.

A

Carbonyl carbon atom has delta+ charge, attacked by H2O, acting as weak nucleophile; In presence of strong acid catalyst; Forming alcohol and carboxylic acid

26
Q

Describe the hydrolysis of esters in presence of a base catalyst?

A

Salt of the acid is produced, rather than acid itself; Equilibrium is not established, resultantly more product; Ester + H2O =Hot H2SO4=> Carboxylic acid + Alcohol =NaOH=> Salt + H2O

27
Q

Describe the mechanism for base hydrolysis of an ester.

A

:OH- attacks carbonyl carbon, double bond moves into oxygen; :O- moves back into single bond, forming double bond, single bond moves into O; Hydroxyl H bond moves into O, :O- moves to H

28
Q

What’s the difference between a fats and an oil?

A

Oils are liquid in room temperature; Fats are solid

29
Q

What’s the IUPAC name of glycerol?

A

Propane-1,2,3-triol

30
Q

How are fats and oils hydrolysed?

A

Acidic conditions forming a mixture of glycerol and fatty acids; Or boil with sodium hydroxide forming glycerol and sodium salts of the three acids

31
Q

What can salts formed from base hydrolysis of fats and oils be used as?

A

Soaps

32
Q

Describe the properties of glycerol and its uses.

A

3 O-H bonds, readily forms hydrogen bonds; Very soluble in water: Used in pharmaceutical and cosmetics, attracts water and prevents drying out; Medicine, toothpaste; Solvent in food industry, food colouring

33
Q

Describe the alternative fuel source to crude oil.

A

Biodiesel; renewable; Oils deprived from crops, rape seed, triglyceride ester; Oil reacted w/ methanol w/ strong alkali catalyst to produce methyl esters (biodiesl)

34
Q

Describe the alternative fuel source to crude oil.

A

Biodiesel; renewable; Oils deprived from crops, rape seed, triglyceride ester; Oil reacted w/ methanol w/ strong alkali catalyst to produce methyl esters (biodiesel)

35
Q

What is acylation?

A

Process by which acyl group is introduced into another molecule;

36
Q

What are acid derivatives?

A

Compounds w/ acyl group as part of their structure; Acid chlorides; Acid anhydrides; Derived from carboxylic acids; General formula, RC(=O)Z

37
Q

What’s the functional group of acid chlorides and what’s their nomenclature?

A

C(=O)Cl; -Oyl chloride

38
Q

What’s the functional group of acid anhydrides and what’s their nomenclature?

A

RC(=O)OC(=O)R’; -Oic anhydride

39
Q

What are the factors affecting how readily nucleophiles attack the acyl group?

A

RC(=O)Z
Magnitude of delta+ charge on carbonyl carbon; Electron releasing or attracting power of Z; How easily Z is lost; How strong the nucleophile is

40
Q

List the order of reactivity of nucleophiles that acyl chlorides and acid anhydrides.

A

Primary amines; Ammonia; Alcohol; Water

41
Q

How do acyl chlorides and acid anhydrides react with strong nucleophiles?

A

Addition elimination reactions, nucleophiles are neutral so lose hydrogen ion when reacting

42
Q

Describe the hydrolysis reaction, addition elimination reaction, between ethanoyl chloride and water?

A

:O- attacks C, = moves into O-; :O- moves back into single bond forming double bond, single bond moves into Cl, cutting it; H2O, H moves into O, cutting it; CH3COOH and HCl formed

43
Q

Why do industries use ethanoic anhydride over ethanoyl chloride?

A

Cheaper; Less corrosive; Does not react with water as readily; Safer as byproduct is is ethanoic acid rather than hydrogen chloride

44
Q

oWhat’s the IUPAC name of aspirin?

A

2-ethanoyloxybenzenecarboxylic acid

Organic Chemistry (9 decks)

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