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A-Level Chemistry > Organic Chemistry > Flashcards

Organic Chemistry Flashcards

1
Q

what is optical isomerism?

A
  • same structural formula, different arrangement of atoms in space
  • mirror images of each other
  • have chiral carbon atom
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2
Q

what is a chiral carbon?

A

has 4 different groups attached

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3
Q

what are enantiomers?

A

molecules that are mirror images of each other and are non-superimposable

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4
Q

how can you tell if isomers are optically active?

A

will rotate plane polarised light

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5
Q

what is a racemic mixture?

A

mixture with equal amounts of each enantiomer

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6
Q

why don’t racemates rotate plane polarised light?

A

2 enantiomers rotate light in opposite directions + they cancel out

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7
Q

what are aldehydes oxidised to?

A

carboxylic acids

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8
Q

outline how tollens reagent is made

A

add a few drops of NaOH and a few drops of dilute NH3 to silver nitrate until the pale brown ppt dissloves

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9
Q

what can tollens reagent be used for? how?

A
  • testing for aldehydes and ketones
  • aldehydes: tollens reduced to silver mirror
  • ketones: no ppt formed
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10
Q

what can Fehling’s solution be used for? how?

A
  • test for aldehydes and ketones
  • add warm to aldehyde/ketone
  • aldehyde will turn blue solution to red red ppt (Cu2)
  • ketone solution remain blue
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11
Q

name one reducing agent used to reduce aldehydes/ketones? what is formed?

A
  • NaBH4
  • primary (aldehydes) or secondary alcohols (ketones)
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12
Q

what is esterification?

A

formation of esters by reacting alcohols with carboxylic acids or acid anhydrides

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13
Q

give a word equation for the production of an ester from an alcohol and carboxylic acid. include the name of the catalyst

A

carboxylic acid + alcohol –sulfuric acid–> ester + water

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14
Q

give a word equation for the production of an ester from an alcohol and acid anhydride

A

acid anhydride + alcohol —-> ester + carboxylic acid

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15
Q

give an example of an ester. which alcohol and carboxylic acid is required to make this?

A

methyl ethanoate
methanol + ethanoic acid

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16
Q

what are the uses of esters?

A
  • perfumes + food flavourings
  • solvents -> polar so compounds will dissolve readily in esters
  • glues -> low bp + evaporate easily
  • plasticisers
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17
Q

what are the conditions required for the acid hydrolysis of esters? what is produced?

A
  • dilute acid (sulfuric/HCl)
  • reflux
  • carboxylic acid + alcohol
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18
Q

what are the conditions required for the base hydrolysis of esters? what is produced?

A
  • dilute base, e.g. NaOH
  • reflux
  • carboxylate ion + alcohol
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19
Q

what is the IUPAC name for glycerol?

A

propane-1,2,3-triol

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20
Q

give an example of a fat or oil with unsaturate hydrocarbon chains?

A

vegetable oils

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21
Q

what are the properties of oils/fats with unsaturated hydrocarbon chains? why?

A
  • liquids at room temp
  • chains not straight = can’t pack closely together = weaker vdw = lower mp
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22
Q

give an example of an oil/fat with saturated hydrocarbon chains

A

animal fats

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23
Q

what are the properties of oils/fats with saturated hydrocarbon chains?

A
  • solids at room temp
  • staight + more uniform chains = can pack closely together = stronger vdw = higher mp
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24
Q

how can soap be produced? give a word equation.

A

hydrolysing animal fats and vegetable oils by heating with NaOH
fat + sodium hydroxide –> glycerol + soap (sodium salt)

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25
Q

what is biodiesel? how can it be produced? give a word equation.

A
  • mixture of fatty acids made from methyl esters + can be made from rapeseed oil
  • reacting vegetable oils with methanol with a potassium hydroxide catalyst
    oil + methanol –> glycerol + methyl ester
26
Q

what is the functional group of acyl chlorides?

A

-COCl

27
Q

give an example of an acyl chloride

A

ethanoyl chloride
CH3-C\Cl=O

28
Q

what does the reaction of acyl chlorides with water produce? give a word equation for the reaction of ethanoyl chloride and water.

A

ethanoyl chloride + water –> ethanoic acid + HCl

29
Q

what does the reaction of acyl chlorides with ammonia produce? give a word equation for the reaction of ethanoyl chloride and ammonia.

A

amides
ethanoyl chloride + ammonia –> ethanamide + HCl

30
Q

what does the reaction of acyl chlorides with alcohol produce? give a word equation for the reaction of ethanoyl chloride and methanol.

A

esters
ethanoyl chloride + methanol –> methyl ethanoate + HCl

31
Q

what does the reaction of acyl chlorides with primary amines produce? give a word equation for the reaction of ethanoyl chloride and methylamine.

A

ethanoyl chloride + methylamine –> N-methylethanamide + HCl

32
Q

what is an acid anhydride?

A

molecule made from 2 carboxylic acids that are the same

33
Q

give an example of an acid anhydride

A

ethanoic anhydride

34
Q

which reactions are more vigorous, acyl chloride reactions or acid anhydride reactions

A

acyl chloride reactions

35
Q

what does the reaction of acid anhydrides with water produce? give a word equation for the reaction of ethanoic anhydride and water.

A

carboxylic acids
ethanoic anhydride + water –> ethanoic acid + ethanoic acid

36
Q

what does the reaction of acid anhydrides with ammonia produce? give a word equation for the reaction of ethanoic anhydride and ammonia.

A

amides
ethanoic anhydride + ammonia –> ethanamide + ethanoic acid

37
Q

what does the reaction of acid anhydrides with alcohol produce? give a word equation for the reaction of ethanoic anhydride and methanol.

A

esters
ethanoic anhydride + methanol –> methyl ethanoate + ethanoic acid

38
Q

what does the reaction of acid anhydrides with primary amines produce? give a word equation for the reaction of ethanoic anhydride and methylamine.

A

N-substituted amides
ethanoic anhydride + methylamine –> N-methylethanamide + ethanoic acid

39
Q

by what mechanism do acyl chlorides react?

A

nucleophilic addition elimination

40
Q

why are acyl chlorides susceptible to attack from nucleophiles?

A

have a strong partial negative on the carbon, as oxygen/chlorine atoms are electronegative

41
Q

outline nucleophilic addition elimination

A
  • nucleophile attacks partially pos carbon
  • e move from double bond to oxygen
  • e move from oxygen to the bond
  • e move from bond to chlorine
  • e move from detached chlorine to a hydrogen
42
Q

what is aspirin? how is it made?

A

ester made by reacting ethanoic anhydride or ethanoyl chloride + salicylic acid

43
Q

why is ethanoic anhydride is used instead of ethanoyl chloride in industry?

A
  • safer as less corrosive, doesnt produce harmful HCl gas and doesnt react vigorously with water
  • cheaper
44
Q

describe the structure of benzene

A
  • cyclic, planar molecule
  • each carbon is bonded to 2 other carbons and 1 hydrogen atom
  • e form delocalised e ring
  • all C-C bond same length
45
Q

why is benzene more stable than the theoretical alternative cyclohexa-1,3,5-triene?

A
  • measure stability by comparing enthalpy change of hydrogenation in both
  • if cyclohexene hydrogenated has enthalpy change of -120 so benzene expected to have -360 due to 3 double bonds but actually has -208
  • suggests more energy is required to break bonds = more stable due to delocalised e structure
46
Q

what are aromatic compounds/arenes?

A

molecules that contain a benzene ring

47
Q

what kind of reactions do aromatic compounds/arenes undedrgo?

A

electrophilic substitution

48
Q

why does benzene not undergo electrophilic addition reactions?

A

stable

49
Q

list 2 types of electrophilic substitution

A
  • friedel crafts acylation
  • nitration
50
Q

what is friedel crafts acylation?

A

acyl chloride and halogen carrier (AlCl3) react to create a strongly positive electrophile

51
Q

why is friedel crafts acylation necessary?

A
  • stability makes benzene harder to react
  • adding acyl group makes benzene molecule weaker
52
Q

give an equation for friedel crafts acylation

A

RCOCl + AlCl3 –> RC+=O + AlCl4-

53
Q

outline the mechanism for friedel crafts acylation (what to draw)

A
  1. arrow from circle in benzene ring to RC+=O
  2. arrow from AlCl4- to RC+=O
  3. R-C-benzene ring with =O on c + HCl + AlCl3
54
Q

what is nitration of benzene used for?

A

making dyes and explosives

55
Q

what conditions are required for the nitration of benzene?

A
  • conc nitric acid
  • conc sulfuric acid
  • 50c
56
Q

give 2 equations for the reactions that take place before the nitration of benzene

A
  1. HNO3 + H2SO4 –> H2NO3+ + HSO4-
  2. H2NO3+ –> NO2+ + H2O
57
Q

outline the mechanism for the nitration of benzene (what to draw)

A
  1. arrow from circle in benzene e ring to +NO2
  2. NO2 attached to benzene, arrow from H on benzene to half benzene e ring with + in middle
    3 NO2 attached to benzene + H+ (to react with HSO4- to regenerate catalyst)
58
Q

how does temperature affect the nitration of benzene?

A
  • temp below 55c will ensure a single NO2
  • above will result in multiple substitutions
59
Q

what kind of molecule is phenylamine?

A

aromatic primary amine

60
Q
A

A-Level Chemistry (23 decks)

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