Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Chemistry > Organic Chemistry > Flashcards

Organic Chemistry Flashcards

1
Q

When does optical isomerism occur

A
  • substances that have the same molecular + structural formula but cannot be superimposed on each other
  • occurs in molecules which contain a chiral centre
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is an enantiomer

A
  • non-super impossible mirror image molecules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the properties of optical isomers?

A
  • same physical properties
  • same chemical properties
  • different biological activity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is biological activity

A
  • the way they interact with other optically active molecules, receptors or active sites
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why are non-superimposable mirror image molecules called optical isomers?

A
  • they differ in the way they rotate the plane of plane polarised light
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is plane polarised light?

A
  • light that has been passed through a Polaroid
  • only oscillates in one plane
  • when passed through solutions of different optical isomers, the plane will be rotated by an equal angle but in opposite directions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Is rotation of plane polarised light clockwise + or -

A

+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens if the sample contains equal amounts of both enantiomer

A
  • it will be optically inactive
  • no effect on plane polarised light
  • RACEMIC MIXTURE
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is plane polarised light

A

Waves having vibration in the same direction for all waves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does optically active mean

A
  • capable of rotating the plane of vibration of polarised light left or right
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a racemic mixture

A
  • mixture of equal quantities of enantiomer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What sort of compounds undergo nucleophilic addition reactions?

A
  • aldehydes
  • ketones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a nucleophile?

A
  • electron pair donor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is addition?

A
  • the addition of a molecule across a double bond (breaks it, gives one product)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the two types of reaction which occur via nucleophilic addition?

A
  • reduction of aldehydes/ketones
  • addition of HCN to an aldehyde/ketone (to form hydroxynitriles)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

State the conditions for a reduction reaction through nucleophilic addition

A

Reagent: NaBH4
Nucleophile: :H- (hydride ion)
Conditions: Aqueous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

State the conditions for an addition reaction via nucleophilic addition

A

Reagent: KCN
Nucleophile: :CN- (cyanide ion)
Conditions: dilute acid (HCl)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Outline the mechanism for nucleophilic addition

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Where does the H+ in the mechanism come from?

A

I) when NaBH4 is used - H+ comes from the aqueous solvent (H2O)
II) when KCN in dilute acid is used - H+ comes from the dilute acid solvent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is reduction?

A
  • loss of bonds to oxygen (or the gain of hydrogen)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How do u form primary alcohols

A

Reduction of aldehydes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How do u form secondary alcohols

A

Reduction of ketones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Can tertiary alcohols be formed from the reduction of an aldehyde or ketone?

A

NO

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why do we use HCN instead of KCN?

A
  • because KCN only supplies :CN-
  • H+ comes from acid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Why is addition of HCN a useful reaction?
- useful in synthesis - increases length of carbon chain
26
Why is 2-hydroxypropane nitrile formed as a racemic mixture?
- the carbonyl group is planar so attack by the :CN- ion is equally likely from either side - enantiomer are formed in equal amount
27
What is the general formula for carboxylic acids?
CnH2n+1COOH
28
Why are carboxylic acids soluble in water?
- form hydrogen bonds with water
29
Why does solubility decrease as chain length increases?
- increased non-polar proportion of the molecule - larger proportion of the molecule cant form hydrogen bonds
30
What is an acid
H+ donor
31
What does it means when an acid is weak?
- Low concentration of H+ ions (does not fully disassociate)
32
What do carboxylic acids disassociate to?
- carboxylate anion - hydrogen ion
33
Why are carboxylic acids weak acids?
- they are partially dissociated
34
What does it mean when a carboxylic acid is partially disassociated?
- position of equilibrium is over to the left hand side, so there is a low concentration of H+ present
35
Describe electrons in the carboxylate ion
- delocalised in the Pi system (formed by overlap of p orbitals)
36
Carboxylic acids react in very similar ways to…
Inorganic acids
37
What is an acid dissociation constant?
- Ka - Quantitative measure of the strength of an acid in solution
38
Why is dimethylpropanoic acid weaker than trifluoroethanoic acid
Dimethlypropanoic acid - Negative charge is more available to act as a base due to the inductive effect of the neighbouring carbon groups - disassociation less likely to happen, p.o.e to left Trifluoroethanoic acid - negative charge less available to act as a base due to the electron withdrawing effect of the fluorine’s - disassociation more likely to happen, p.o.e to right
39
Give the formula for sodium propanoate
CH3CH2COO-Na+
40
What is the functional group for esters?
- COO
41
How are esters produced
Alcohols + carboxylic acids -> ester + water
42
What are the conditions needed for esterification?
- warming - concentrated acid catalyst - H2SO4
43
Describe an esterification reaction
- the H from the -OH group in alcohol and the -OH from the carboxylic acid join together to make water - covalent bond formed between O in the alcohol and C in carboxylic acid group
44
Is esterification reversible?
Yes
45
What is acid catalysed hydrolysis?
Ester -> alcohol and carboxylic
46
What is acid catalysed hydrolysis?
Ester -> alcohol and carboxylic
47
What is base catalysed hydrolysis?
- alcohol and sodium salt of the carboxylic acid are formed - reaction goes to completion (not reversible) - sodium or potassium hydroxide are most commonly used
48
What are the uses of ester?
- perfume - flavouring
49
Describe properties of esters?
- polar (polar molecules dissolve in them) - low bp (so can evaporate easily from mixtures) - used as plasticisers
50
Describe esters of glycerol
- oils and fats from animals and vegetables
51
Describe the structure of fats and oils
Triglycerides - three long chain hydrocarbons, unbranched carboxylic acids (fatty acids,) molecule of glycerol
52
What does having unsaturated fatty acids in a triglyceride mean on its melting point?
- less of a region of overlap between the molecule, meaning less vdw forces - lower mp - unsaturated fats are often liquid at room temperature
53
What happens when a triglyceride is hydrolysed in acidic conditions
- forms glycerol + 3 molecules or original fatty acids
54
What is saponificaiton?
- when triglycerides are hydrolysed under basic conditions - forms molecule of glycerol and 3 sodium salts of the original fatty acids - salts are used as soaps
55
What do the sodium salts of fatty acids dissociate to
Ionic - Na+ - RCOO-
56
Describe the structure of RCOO-
- non-polar tail - polar head
57
Why is RCOO- good as a cleaning agent v
- non polar hydrocarbon chain mixes with grease (hydrophobic) - polar COO_ mixes with water (hydrophilic) - allows grease and water to mix
58
Is glycerol soluble in water?
Yes
59
What are uses of glycerol
- pharmaceutical and cosmetic industries - prevents creams drying out - solvent in medicines and is present in toothpaste - Solvent in food industry (food colouring) - used to plasticise some materials
60
Why was glycerol used as antifreeze
- it can form strong hydrogen bonds with water, lowering freezing point
61
What is the chemical name of glycerol
Propane-1,2,3-triol
62
What is biodiesel?
Mixture of methyl esters and long chain carboxylic acids
63
How are methyl esters produced?
Trans-esterification - reacting vegetable oils (triglyceride) with 3 equivalents of methanol in presence of a catalyst
64
What are two ways of forming biodiesel?
- esterification of free fatty acids and methanol - transesterification of triglyceride and three methanol
65
What is a disadvantedge of using biodiesel over fuel from crude oil
Crops for fuel > food
66
Describe the homologous series of acyl chlorides
67
What is the general formula for acyl chlorides
CnH2n+1COCL
68
What is the functional group of acyl chlorides
-COCl
69
What is the nomenclature for acyl chlorides?
-oyl chloride
70
What is the general structure of acid anhydride
71
What is the general formula for acid anhydrides
RCOOCOR’
72
What is the functional group of acid anhydride
-COOCO-
73
How do you name acid anhydride
- oic anhydride
74
What mechanism do acylation reactions proceed via?
Nucleophilic addition-elimination
75
What are the four nucleophile that can be involved in an acylation reaction
- water - H2O - alcohol - ROH - ammonia - NH3 - primary amine - RNH2
76
Describe an acylation reaction
- hydrogen atom in one of the 4 nucleophiles is replaced by acyl group - hydrogen atom that left combines with the leaving group in the acyl chloride or acid anhydride
77
What is more reactive acyl chlorides or acid anhydrides?
Acyl chlorides - even though O2 is more electronegative than chloride the oxygen pull on the carbon is diminishes as it is bonded to two C atoms. - Cl is only taking density from 1 carbon
78
List nucleophiles in the order from most to least reactive
- A 1* amine - ammonia - alcohol - water
79
Display a nucleophilic addition elimination reaction
80
What are the advantedges of using acyl chlorides in synthesis
- faster - not reversible - pure product
81
What are the advantedges of using acid anhydrides in synthesis
- reaction less violent - no corrosive HCl fumes formed - less toxic byproduct - cheaper

Chemistry (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions