B6 Organic Chemistry II Flashcards
(165 cards)
1
Q
Which model of benzene is this
A
Kekulé’s model
2
Q
Which model of benzene is this
A
Delocalised model
3
Q
Describe the structure and bonding in Kekulé’s model of benzene
A
- P-orbitals overlap to form pi-bonds
- Pi-electrons are localised between carbon atoms
- Alternating pi-bonds
4
Q
What is the similarity between Kekulé’s benzene model and the delocalised benzene model
A
Both have overlap of p-orbitals
5
Q
Describe the delocalised model of benzene
A
P-orbitals overlap to form pi-bonds, with pi-electrons delocalised into delocalised ring pi-system
6
Q
What is the evidence to suggest that Kekulé’s model of benzene isn’t correct
A
- Carbon-carbon bond lengths are all the same size in benzene, but not in Kekule’s model
- Enthalpy of hydrogenation of benzene is less exothermic than Kekule’s model
- Benzene is less reactive than alkenes - bromination requires a catalyst for benzene but not for alkenes
7
Q
Name this molecule
A
Phenylamine
8
Q
Name this molecule
A
Benzonic acid
9
Q
Catalyst for benzene electrophillic substitution - nitration
A
Concentrated Sulfuric Acid
10
Q
Conditions for benzene electrophillic substitution - nitration, and why
A
Less than 50c to prevent further substitutions occuring
11
Q
Inorganic product for benzene electrophillic substitution - nitration
A
Water
12
Q
Electrohphile generator step for benzene electrophillic substitution - nitration
A
13
Q
Mechanism step for benzene electrophillic substitution - nitration
A
14
Q
Catalyst regeneration step for benzene electrophillic substitution - nitration
A
15
Q
Catalyst for benzene electrophillic substitution - halogenation
A
Halogen carrier - AlCl3 or FeCl3
16
Q
Inorganic product for benzene electrophillic substitution - halogenation
A
Hydrogen halide
17
Q
Catalyst generation for benzene electrophillic substitution - halogenation
A
18
Q
Mechanism for benzene electrophillic substitution - halogenation
A
19
Q
Catalyst regeneration for benzene electrophillic substitution - halogenation
A
20
Q
Reactant for Friedel-Crafts alkylation
A
Haloalkane
21
Q
Catalyst for Friedel-Crafts alkylation
A
Halogen carrier - AlCl3 or FeCl3
22
Q
Inorganic product of Friedel-Crafts alkylation
A
Hydrogen halide
23
Q
Reactant of Friedel-Crafts acetylation
A
Acyl chloride
24
Q
Catalyst for Friedel-Crafts aceytlation
A
Halogen carrier - AlCl3 or FeCl3
25
Inorganic product of Friedel-Crafts acetylation
Hydrogen halide
26
Structure of acyl chloride
27
Describe and explain why benzene is more resistant to bromination than alkenes
* In alkenes, electrons in the pi-bond are localised between carbon atoms
* In benzene, electrons in the pi-bond delocalise into the delocalised ring pi-system
* Alkenes therefore have a higher electron density
* So can polarise electrophiles more
* So are more suseptible to electrophillic attack
28
Structure of phenol
29
How to determine whether a molecule is a phenol or an alcohol
* -OH must be directly bonded to the benzene ring to be a phenol
* Otherwise, properties will be that of an alcohol
30
Evidence to proove that phenols are weak acids
* Will react with NaOH (Strong base)
* Will not react with carbonates (weak base)
31
How to test for the presence of a phenol in a compound
* No reaction with carbonates, but reaction with strong bases (NaOH)
* Decolourises bromine water, and forms a white precipitate
32
Observations of bromination of phenol
* Bromine water is decolourised
* White precipitate forms
33
Catalyst for phenol's electrophillic substitution with bromine
None
34
Equation for bromination of phenol
35
Products of phenol's bromination
* 2,4,6-tribromophenol
* 3HBr
36
Catalyst for phenol's nitration
No catalyst required
37
What shows that phenol is more reactive than bromine with it's nitration reaction
* **Dilute nitric acid not concentrated**
* No catalyst requried
38
What must all acids be in benzene's electrophillic substitutions
Concentrated
38
Reactant of benzene's electrophillic substitution - nitration
Concentrated nitric acid
39
Products of phenol's nitration
Mix of 2-nitrophenol and 4-nitrophenol
40
Equation of phenol's nitration
41
Describe and explain why phenol is more suseptible to electrophillic substitution than benzene
* Lone pair of electrons from oxygen in phenol partially delocalises into the delocalised ring pi-system
* Therefore, electron density is higher than benzene
* Electrophile is more polarised by phenol
* Phenol is more suseptible to electrophillic attack
42
What are the 2- and 4- directing groups
-OH and -NH3
43
What are the -3 directing groups
-NO2
44
What directing group is -NO2
3-
45
What directing group is -NH2
2- and 4-
46
What directing group of -OH
2- and 4-
47
Is benzene, unsaturated or saturated depending on the model (Kekule or delocalised)
For both, benzene is unsaturated
48
Conditions and reagents for oxidation of aldehydes to carboxylic acids
* K2Cr2O7
* H2SO4
* Heat under reflux
49
Equation for oxidation of ethanal to ethanoic acid
50
Reducing agent for reduction of carbonyl to alcohol
NaBH4
51
What is the product of reduction of aldehyde
Primary alcohol
52
What is the product for the reduction of a ketone
Secondary alcohol
53
Equation for reduction of ethanal to ethanol
54
Equation for reduction of propanone to propan-2-ol
55
What is the type of reaction when carbonyls are reduced to form alcohols with BaNH4
Nucleophillic Addition
56
Reducing agent in nucleophillic addition reaction of carbonyls forming alcohols
NaBH4
57
Draw the mechanism for the nucleophillic addition of carbonyl reduction to form alcohols
58
What is the nucleophille in the nucelophillic addition reaction of carbonyl reduction to form alcohols
Hydride ion, H-
59
Hydride Ion
H-
60
Type of reaction is converting carbonyls to hydroxynitriles
Nucleophillic Addition
61
Conditions/Reagents for nucleophillic addition reaction of carbonyl to hydroxynitrile
* NaCN
* Acid Catalyst (H+)
62
Nucleophile in nucleophillic additon reaction of carbonyl to hydroxynitrile
Cyanide ion, CN-
63
Cyanide Ion
CN-
64
Mechanism for nucleophillic addition reaction for carbonyl to hydroxynitrile
65
Describe the test and the confirmation to determine of a compound is a carbonyl
* Add 2,4-DNP
* Orange precipitate forms
* Confirms the presence of C=O bond
66
Describe the test and the confirmation (and what has occured) to test if a compound is an aldehyde
* Add Tollen's reagent
* Silver mirror forms
* Aldehyde is oxidised to carboxylic acid
67
How can you distingush the identity of two carbonyl compounds from one another
* Measure the melting point of their crystals
* Compare to known values from a database
68
Where is the lone pair of electrons on the cyanide nucleophile ion
Carbon atom
69
Why are carboxylic acids soluble
* Contain -OH (hydoxyl) group
* -OH group can form hydrogen bonds with water
70
Product of carboxylic acid + metal
Salt + hydrogen
71
Product of carboxylic acid + base
Salt and water
72
Draw the displayed formula for an acid anyhydride
73
Equation for formation of ester using carboxylic acid
Carboxylic acid + alcohol --> ester + water
74
Conditions for esterfication with carboxylic acid and alcohol
Concentrated H2SO4
75
Displayed formula equation for esterfication with carboxylic acid and alcohol
76
Ways to form ester
* carboxylic acid + alcohol (+conc sulfuric acid)
* Acid anyhydride + alcohol
* Acyl Chloride + alcohol
77
Formula for formation of ester from acid anydride and alcohol
Acid anyhdride + alcohol --> ester + carboxylic acid
78
Displayed formula equation for acid anhydride + alcohol
79
Products of ester hydrolysis under acidic conditions
Carboxylic acid and alcohol
80
Reagents and conditions for ester acidic hydrolysis
HOT aqueous acid
81
Products for alkaline hydrolysis of ester
Carboxylate + alcohol
82
Reagents and conditons for alkaline ester hydrolysis
Alkali and HEAT
83
Dispalyed formula equation for acidic hydrolysis of ester
84
Displayed formula for alkaline hydrolysis of ester
85
Conversion carboxylic acid to acyl chloride
SOCl2
86
Acyl chloride conversion to carboxylic acid
H2O
87
Two way arrow to show interconversion between carboxylic acid and acyl chloride
88
Equation of esterfication using acyl chloride
acyl chloride + alcohol --> ester + **HCl**
89
Displayed formula equation for acyl chloride esterfication
90
Equation for primary amide synthesis
Acyl chloride + ammonia --> primary amide + HCl
91
Equation for secondary amide synthesis
Acyl chloride + primary amine --> secondary amide + HCl
92
Displayed formula equation for primary amide synthesis
93
Displayed formula equation for secondary amide synthesis
94
What is the compound that can esterify phenols
Acyl chlorides
95
Can carboxylic acids and acyl chlorides esterify phenols
Just acyl chlorides
95
Nomenclature for amines when -NH2 group is on carbon-1
Suffix -amine is used
96
Nomenclature for amines when -NH2 is side chain
N-amino...
97
Basic structure for primary amine
98
Basic structure for secondary amine
99
Basic structure for tertiary amine
100
Describe and explain how amines act as bases
Nitrogen's lone pair of electrons accepts H+ from acid
101
Equation of formation of a primary amine from haloalkane
Haloalkane + NH3 --> primary amine + HCl
102
Reagents and conditions for formation of primary amine from haloalkane
Excess of hot ethanolic ammonia
103
Equation for formation of secondary amine from haloalkane
Haloalkane + primary amine ---> secondary amine + HCl
104
Reagents and conditions for formation of secondary amine from haloalknae
Primary amine + hot ethanol solvent
105
Reagents and conditions for tertiary amine formation from haloalkane
Secondary amine + hot ethanol solvent
106
Reaction type of nitroarene to aromatic amine
Reduction
107
Conditions and reagents for reduction of nitroarene to aromatic amine
* Tin catalyst
* Concentrated HCl catalyst
108
How many [H] for reduction of nitroarene to aromatic amine
6
109
Products of nitroarene reduction to aromatic amine
aromatic amine + **2**H2O
110
Displayed equaiton for reduction of nitroarene to aromatic amine
111
General formula for amino acid
112
Reactions of carboxylic acid group of amino-acid
* Alkalis to form salt and water
* Alcohols to form ester and water (with concentrated sulfuric acid catalyst)
113
Reactions of amine group of amino acid
Acids to form salts
114
Describe isomerism within dipeptides
* Two isomers
* e.g gly-ser and ser-gly
115
Basic structure of primary amide
116
Basic structure of secondary amide
117
Basic structure of tertiary amide
118
Define optical isomerism
Non-superimposable mirror images about a chiral centre
119
What must be present for the possibility of a centre to be chiral
Four different groups bonded to them
120
How to immediatly tell that a carbon is not a chiral centre
Has a double bond attached
121
What are the benefits to having fewer steroisomers in medicines
* Fewer side-effects
* Increases pharmalogical activity
* Reduces cost of seperating stereoisomers
122
What type of rreaction is formation of polyesters
Condensation polymerisation
123
Why are polyesters biodegradeable
Ester bond can be hydrolysed with water
124
Displayed formula equation for polyester formation from one monomer with both carboxylic acid and alcohol group
125
Displayed formula for formation of polyester from two monomers - diol and dicarboxylic acid
126
Type of reaction forming polyamides
Condensation polymerisation
127
Displayed formula equation for polyamide formation with one monomer - with both carboxylic acid and amine group
128
Alternative reactant to polyamide formation, and therefore alternative product
Acyl chlrodies instead of carboxylic acids give HCl product not water
129
Product of acyl chlrodies to form polyamides, not carboxylic acids
HCl not water
130
Polyester hydrolysis under acidic conditions products
Polyester --> carboxylic acid and alcohol
131
Polyester hydrolysis under alkaline conditions products
Carboxylate + alcohol
132
Polyamide hydrolysis under acidic conditoins products
133
what happens to any amine groups when hydrolysis under acidic conditons occurs
All protonated - each nitrogen has maximum of 4 covalent bonds
134
Polyamide hydrolysis under alkaline conditions products
135
Equation for formation of nitriles
Haloalkane + CN- --> Nitrile + Cl-
136
Type of equation for formation of nitriles
Nucleophilic Substitution
137
What acts as nucleophilie when making nitriles
CN-
138
Displayed formula equation for formation of nitriles
139
Type of reaction is formation of amine from nitrile / hydroxynitrile
Reduction
140
Reagents and conditions to form amine from nitrile / hydroxynitrile
Hydrogen and nickel catalyst
141
How many H2 molecules to convert nitrile / hydroxynitrile to amine
2
142
Displayed formula equation for conversion of nitrile / hydroxynitrile to amine
143
Reagents and conditions for conversion of nitriles to carboxylic acids
* Dilute acid (H2O + HCl)
* Heat
144
Equation for acid hydrolysis of nitriles to carboxylic acids
Nitrile + 2H2O + HCl --> carboxylic acid + ammonium salt
145
How many water molecules in acid hydrolysis of nitrile to carboxylic acid
2
146
How many HCl molecules for acid hydrolysis of nitriles to carboxylic acid
1
147
Displayed formula equation for acid hydrolysis of nitrile to form carboxylic acid
148
Order of practical techniques for purification of organic solid
1. Filtration under reduced pressure
2. Recrystallisation
3. Measurement of melting points
149
Describe the purification step of filitration under reduced pressure
* Dissolve impure solid in minimum volume of hot solvent
* Cool solution and filter solid under reduced pressure using Buchner flask
150
Describe the purification step of recrystalisation
* Dissolve solid in minimum volume of hot solvent
* Cool solution and filter solid under reduced pressure using Buchner flask
* Scratch with glass rod
* Wash with cold solvent and dry
151
Describe the purification step measurement of melting point
* Measure melting point of crystals
* Compare to known value from data book
* Pure sample will have sharp melting point very close to data book value
152
When given the melting point to compare to data book, how do you know if it's pure
Pure sample will have sharp melting point very close to data book value
153
Stationary phase in TLC chromatography
TLC plate
154
Mobile phase in TLC chromatography
Compound being tested
155
Rf equation
156
Affect of Rf value, the more strongly a compound is absorbed onto stationary phase
Lower Rf value
157
Why is a control spot used sometimes during TLC chromatography
Show the formation of the desired product and show when the reaction has finsihed
158
Purpose of gas chromatography
Seperate compounds based on their relative solubility in the stationary phase
159
What does retention time mean in gas chromatography
How long a component stays in the column
160
What does retention time identify in gas chromatography
Identifies components in a mixture
161
What does relative peak area identifiy in gas chromatography
Proportions of componetns in a mixture
162
What can calibration curves be used for in gas chromatography
Confirm the concentrations of components in a mixture
163
What is the mobile phase in gas chromatography
Carrier gas
