Organic Flashcards
1
Q
Why can SN1 molecules form 2 enantioners while sn2 onlt does 1
A
The structure of sn1 allows molecules to attack from both sides, creating two different molecules
2
Q
What alcohols undergo sn2
A
Primary and secondary
3
Q
What alcohols undergo sn2
A
Tertiary
4
Q
Basic formula for chlorination to create Halogenoalkane
A
R-OH + PCl5 becomes R-Cl + POCl3 + HCl
5
Q
Conditions for chlorination
A
Room temperature
6
Q
Basic formula for Bromination
A
2KBr + H2SO4 becomes K2SO4 + 2HBr
R-OH + HBr becomes R-Br + H2O
7
Q
Conditions and reagents for Bromination
A
KBr and 50% concentrated H2SO4
8
Q
Why is full strength H2SO4 not used in Bromination
A
Would oxidise Br-
50% conc reduces chance of oxidation happening
9
Q
Basic formula for iodination
A
2P + 3I2 becomes 2PI3
3R-OH + PI3 becomes 3R-I + H3PO3
10
Q
Conditions and reagents for iodination
A
Red phosphorus and I2
Reflux
11
Q
What is a nucleophile
A
all have a lone pair and full or partial negative charge
All attracted to areas of positive charge
12
Q
Regents and conditions for reaction of Aqueous alkali and Halogenoalkane
A
Aqueous alkali
50/50 ethanol/water and reflux
13
Q
Conditions and reagents Hydrolysis of halogenoalkanes
A
H2O from AgNO3
Ethanol solvent and warm
14
Q
Appearance of silver halides
A
AgCl white ppt
AgBr cream ppt
AgI yellow ppt
Darker in colour down group
15
Q
What affects bond reactively for halogenoalkanes
A
Bond strength
Most reactive R-I as weakest bond
16
Q
Conditions and reagents for reaction of ammonia and Halogenoalkane
A
NH3 solution
Heat in sealed tube
17
Q
Conditions and reagents of potassium cyanide and halogenoalkanes
A
KCN
In ethanol + heat
18
Q
Where does OH- attack carbon from in Sn2
A
Attacks from opposite side to halogen
Does so as S- hydrogen on other side will repel OH- ion
19
Q
Overall equation for Halogenoalkane and NaOH
A
R-X + NaOH becomes R-OH and NaX
20
Q
Reagents and conditions for Halogenoalkane and NaOH
A
NaOH
Aqueous warm
21
Q
Overall equation for Halogenoalkane and KCN
A
R—X + KCN becomes R-CN + KX
22
Q
Reagents and conditions for Halogenoalkane and KCN
A
KCN
Ethanolic, warm
23
Q
Overall equation for Halogenoalkane and NH3
A
R-X + 2NH3 becomes R-NH2 + NH4X
24
Q
Conditions and reagents for Halogenoalkane and NH3
A
NH3
Excess conc ammonia dissolved in ethanol under pressure
25
Reagents and conditions for Halogenoalkane and KOH
KOH
Ethanolic, hot
26
Energy profile for SN2 reaction
Rises during formation of transition state
Drops for final product
Overall exothermic
27
How does hydrogen bonding occur
When a hydrogen atom is bonded to a highly electronegative atom (N, O or F) that forms a strong attraction to another highly electronegative atom on another molecule
28
Basic equation for oxidation of primary alcohol
CH3OH + 2[O] becomes H-COOH + H20
29
How to isolate the aldehyde when oxidising a primary alcohol
Set up for distillation and the aldehyde distils before being oxidised
30
How to isolate the carboxylic acid when oxidising a primary alcohol
Reflux first so aldehyde goes into reaction mixture and is oxidised
When reaction complete set up for distillation and distill RCOOH
31
Basic formula for oxidation of secondary alcohol
CH3-CHOH-CH3 + [O] becomes CH3-CO-CH3 + H2O
32
Why don’t tertiary alcohols oxidise
No H available to make H2O
Not energetically favourable
33
Why do we crack alkanes
Shorter alkanes burn more easily, with less volatility and a clearer flame
This makes them useful fuels
Demand for short alkanes is high but supply is low, so we crack alkanes to increase supply of short alkanes
34
What is knocking and when does it occur
Knocking is when hydrocarbons ignite too early
Occurs with a low octane number
35
What is reforming
Where straight chain carbons are rearranged into cyclic alkanes or benzene rings
36
Reagents and conditions for reforming
Platinum and aluminium oxide catalyst
500 degrees C
20 atmospheres
37
When is carbon monoxide formed in hydrocarbon combustion
When there is an insufficient supply of oxygen
38
What is a free radical
A very reactive species that has an unpaired electron
39
What is homolytic fission
When the covalent bond breaks, 1 electron goes to each bonding atom
40
What is heterolytic fission
When one atom gains both bonding electrons
Forms ions
41
What are the requirements for cis/trans isomerisation to occur
Must be no rotation within the molecule (aka a double bond)
Each carbon atom either side of double bond needs two different groups
42
When is E/Z isomerism used
When cis/trans can’t be used
43
When is an isomer given E notation
When the highest atomic number groups on both carbons are on opposite sides
44
When is an isomer given Z notation
When the highest atomic number groups on both carbons are on the same side
45
When is an isomer given cis notation
The heaviest groups on the same side
46
When is an isomer given trans notation
The heaviest groups on opposite sides
47
Conditions and reagents for reaction of hydrogen and Alkene
Alkene and hydrogen
High temperature, nickel catalyst
48
Conditions and reagents for halogenation of Alkene
Alkene and halogen
Room temp
49
Conditions and reagents to change ethene to ethane
Hydrogen
Nickel catalyst
150 degrees C
50
Conditions and reagents to change ethene to ethanol
Steam
H3PO4 catalyst
300-600 degrees C
70 atm
51
Difference between creating bromethane and dibromoethane from ethene
Bromethane uses hydrogen bromine
Dibromoethane uses bromine
52
What is markovnikovs rule
When a hydrogen halide is added to an unsymmetrical Alkene, the hydrogen is attached to the carbon with the most hydrogens already attached
53
How is Markovnikovs rule used
Predicts the minor and major products of a reaction between hydrogen halides and hydrocarbons
54
Reagent and conditions for oxidation of Alkene
Alkene KMnO4 (oxidising agent)
Dilute H2SO4 catalyst
55
How to test for a carbon- carbon double bond
Potassium manganate (VII)
Bromine water
56
Positive result for C-C double bond potassium manganate
Purple/pink to colourless
57
Positive result for C-C double bond bromine water
Decolourises bromine water orange to colourless
58
Where is a sigma bond found
In a region of space between the nuclei of two atoms sharing the electrons
59
How is a sigma bond held together
By the electrostatic attraction between the electrons and the nuclei
60
Why are pi bonds formed
The overlap between two p orbitals leads to pi bonds being formed
61
Are sigma or pi bonds stronger
Sigma
62
What is necessary for free radicals to be formed
UV light
63
What affects the rate a precipitate is formed when silver nitrate is added to a Halogenoalkane
The strength of the C-X bond
Therefore Tertiary is the slowest as the C-X bond is weakest in tertiary alcohols
64
Reagents to test for alcohols
PCl5
K2Cr2O7
65
Result on positive result for alcohol with PCl5
Steamy white fumes
66
Colour change on positive result for alcohol with K2Cr2O7
Orange solution turns green
67
Why do primary alcohols not undergo SN1 reactions
Primary carbocation is less stable than a tertiary carbocation
68
Test for carbonyl group
Brady’s reagent
69
Test for aldehyde
Fehlings solution
70
Difference between acid hydrolysis and alkali hydrolysis of an ester
Acid is a catalyst
Reaction is reversible for acid
Produced carboxylic acid in acid
H+ electrophile for acid
71
What does LiAlH4 do
Converts aldehydes, carboxylic acid and esters to primary alcohols
Converts ketones to secondary alcohols
72
Positive test for Brady’s reagent
Yellow ppt
73
Positive result for Fehlings test
Red ppt
74
Why are molecules with a benzene ring sparingly soluble in water
Because of the London forces because of the rings between the molecules
75
Reagents and conditions to form ester
Heat
Conc H2SO4
76
What is stereoisomerism
Same molecular and structural formula but a different arrangement in space
77
What is structural isomerism
Same molecular formula, different structural formula
78
What is the property that gives optical isomerism
Ability to rotate the plane of polarised light
79
Which Sn reaction produced a racemic mixture and why
SN1
Creates a planar intermediate ion so that the OH- ion can attack from either side
Therefore produces two entaniomers- racemic mixture
80
Why does sn2 only create one enantiomer
OH group can only attack from one side, creates an asymmetrical molecule
81
Structure of an aldehyde
R-CH=O
82
Structure of a ketone
R-CO-R
83
Intermolecular forces in aldehydes and ketones
London forces
Permanent dipole
84
Solubility of aldehydes and ketones
Small carbonyls soluble in water
As carbon chain gets longer London forces become dominant force, not enough energy to break H bonds in water
85
Conditions and reagents for reduction of carbonyls (ketones and aldehydes)
LiAlH4
Dry ether
86
Tollens reagent test
Add a drop of NaOH to some AgNO3 to form Tollens reagent, Ag2O
Aldehyde reduces this complex to appear as black ppt or silver mirror
87
How to test for CH3CO
(Include method)
Add I2 and NaOH until colour just disappears
Add substance to be tested and heat
Yellow ppt with antiseptic smell formed
88
Reagents and conditions for carbonyl and hydrogen cyanide
Excess KCN or NaCN in water
Little H2SO4
Room Temp
89
What type of reaction is HCN and carbonyl
Nucleophilic addition
90
What is a chiral centre
A carbon atom with 4 groups attached to it
91
What does tollens reagent test for
Aldehyde
92
Why is the Kekule structure for benzene incorrect
Lack of reactivity of benzene- benzene undergoes subsitution reactions not addition
Thermodynamic stability- benzene is more thermally stable than should be expected
Bond lengths- alternating C-C and C=C bond would have varying lengths
93
What is the Kekule structure
A six carbon cyclohydrocarbon with alternating C-C single and C=C double bonds
94
Why does Benzene undergo subsitution reactions
Tends to retain delocalised system
95
What type of subsitution reactions does benzene undergo
Electrophilic
96
Reagents and conditions for halogenation of benzene
Reagents- benzene, halogen
Conditions- halogen carrier catalyst eg AlCl3 or FeBr3
Room temp and pressure
97
Steps in mechanism for halogenation of benzene
Generation of electrophile eg Br2 + AlBr3 becomes Br+ and AlBr4-
Benzene reacts with electrophile
Regeneration of catalyst
98
Reagents and conditions for nitration of benzene
Reagents- benzene and nitric acid
Conditions- 50 degrees C, conc sulfuric acid
99
What do all friedel-crafts reactions involve
Halogen-carrier catalyst
Formation of C-C bond
100
What is alkylation
Subsitution of a halogen from the benzene with an alkyl group
101
Reagents and conditions of alkylation of benzene
Reagents- benzene and haloalkane
Conditions- halogen carrier catalyst
102
What do friedel-crafts reactions do
Increase the length of a carbon chain
103
Conditions and Reagants for acylation
Reagents- acyl chloride, benzene
Conditions- halogen-carrier catalyst, reflux
104
Standard equation for alkylation of benzene
Benzene and R(alkyl group) becomes C6H5R(eg ethylbenzene) and HCl
105
Standard reaction for acylation
Benzene and R-COOH becomes Benzene attached to a COR and H+
106
What is a phenol
A phenol is a an organic compound with a benzene ring with an -OH group attached
The oxygen must be directly bonded to a carbon in the ring
107
What is the use of alkyl phenols
Detergents
108
What is the use of chlorophenols
Antiseptics
109
Properties of phenol
Phenol is solid under standard conditions
It is a slightly soluble in water due to hydrogen bonding between OH groups
The large, non-polar benzene ring decreases its solubility
110
Why is phenol a solid at RT and benzene a liquid
Phenol has H bonding while benzene only has london forces
H bonding are stronger and thus require more energy to overcome
111
Why is phenol slightly soluble in water while benzene is immiscible
The OH of phenol can form hydrogen bonds with water
Non polar benzene ring reduces solubility
112
Why is phenol highly soluble in NaOH while benzene is immiscible
Phenol reacts with NaOH
Products of neutralisation are soluble
113
Why can phenol act as an acid with string bases
Forms the phenoxide ion C6H5O-
C6H5OH becomes C6H5O- and H+
114
Reaction of phenol with NaOH
NaOH and C6H5OH becomes C6H5O-Na+ and H2O
115
Why does phenol not react with CO32-
Phenol is not a strong enough acid
116
What is a primary amine
R-N-H2
An amine with one alkyl chain attached to an N in amine
117
What is a secondary amine
R-N-HR’
An amine with 2 alkyl groups attached to the N
118
What is a tertiary amine
R-N-R’R”
Am amine with 3 alkyl chains attached to the N
119
What does N notation represent (eg N-methylpropane)
That the alkyl chain is attached directly to the N atom
120
Bonding in primary, secondary and tertiary amines
Primary and secondary amines have London forces, permanent dipole interactions and H bonding
Tertiary amines have London forces and permanent dipole
121
Solubility of amines
Small amines are soluble
Solubility decreases as the size of the alkyl chain increases
122
What is the Brønsted-Lowry definition of a base
A base is a proton (H+ hydrogen ion) acceptor
123
What is the Lewis definition of a base
A base is an electron pair donor
124
What does a Kb value tell us
Large Kb value means [products] is greater than [reactants]
The larger the Kb the further right the position of equilibrium
The larger the Kb value, the stronger the base
125
Why are longer alkyl chain amines more basic
Greater inductive effect causes more electron density to be pushed into N atom
Means N atom more readily attracts a H+
126
Why is phenylamine not as basic as would be expected
The lone pair of electrons on the N overlap with the delocalised electrons on the benzene ring
Causes reduction in electron density
Means it is difficult to attract a H+
127
Reagents and conditions to synthesise and aliphatic amine
Reagents- Halogenoalkane, ammonia
Conditions- high temp, sealed tube
128
What are aliphatic amines synthesised from
Halogenoalkanes
129
What type of reaction occurs in the production of an aliphatic amine
Nucleophilic substitution
130
How is further substitution prevented to synthesise a primary amine
Excess ammonia is used- ensures all the Halogenoalkane is used up
131
What is produced if the Halogenoalkane is not entirely used up in the synthesis of a primary aliphatic amine
A secondary aliphatic amine is produced
132
If I reacted Halogenoalkane is present after the production of a secondary amine, what will happen
The reaction will continue to occur
133
Conditions and reagents for forming an amine from a nitrile
Reagent: LiAlH4
Conditions : dry ether
134
Standard equation for forming amine from nitrile
R-CN + 4[H] becomes R-C-NH2
135
Why do aromatic amines not react with ammonia
The high electron density of the benzene ring repels ammonia
136
Equation for reaction of a primary amine acting as a base
RNH2 + H+ becomes RNH3+
137
Equation for secondary amine acting as a base
RR’NH + H+ becomes RR’NH2+
138
Equation for tertiary amine acting as a base
RR’R”N + H+ becomes RR’R”NH+
139
How does an amine act as a base in a complex ion
It accepts a proton from the water ligands
140
Functional group of an amide
O=C-NH
141
What is a quaternary ammonium salt and is it an amine
A N with 4 alkyl groups attached
It is not an amine
142
What variable affects the base strength of an amine
The electron density on the N atom
143
Why can nucleophilic substitution continue to occur with amines
Amines produced all have a lone pair on the N atom, so they can continue to react
144
In a reaction between a Halogenoalkane and ammonia, what is the main product if ammonia is in a large excess
Primary amine
145
In a reaction between a Halogenoalkane and ammonia, what is the main product if Halogenoalkane is in a large excess
Quaternary ammonium salt
146
What are the uses of properties ammonium salts
Contain an ionic “head”- dissolve in water and are hydrophilic
A long alkyl chain “tail”- dissolves grease and is hydrophobic
147
Equation to form primary aromatic amine
C6H5NO2 + 4[H] becomes C6H5NH2 + 2H2O
148
Conditions and reagents to form primary aromatic amine
Tin, conc HCl then later NaOH
149
Steps to form an amine from a nitrile
Formation of nitrile from Halogenoalkane: R-X and KCN becomes R-CN and KX
Reduction of nitrile to an amine
R-CN + 4[H] becomes R-CH2-NH2
150
What is acylation of an amine
Where an amine and an acyl chloride react to replace an H on the N with an alkyl group
Produces an amine and a molecule of HCl/ carboxylic acid
Second molecule of amine reacts with HCl/carboxylic acid to form a salt
151
Standard equation for acylation of amine
R-CO-Cl + 2 R’-NH2 becomes R-CO- NHR’ and N+-H3R’
152
What two functional groups are contained in an amino acid
Amine
Carboxylic acid
153
Why do amino acids acts as both acids and bases
Amine functional group is basic
Carboxylic acid functional group is acidic
154
What are zwitterions
Ions formed by the internal transfer of a proton
155
Properties of amino acids and explanations
High melting point- strong electrostatic forces require lots of energy to overcome
Soluble- form ion/dipole interactions with water molecules, which release enough energy to overcome IMFs between water molecules and electrostatic forces between zwitterions
156
Attraction of zwitterions and property this gives
Strong electrostatic attraction between other zwitterions
Allows them to exist in the solid state
157
Equation for amino acid acting as a base
H2N-CHR- COOH becomes H2N-CHR—COO + H2O
158
Equation for amino acid acting as an acid
H2N-CHR-COOH becomes H3N-CHR-COOH
159
Affect on amino acid if reacted with NaOH
Amino acid loses a H
160
Affect if amino acid reacts with HCl
Gains a H
161
Affect when amino acid reacts with ethanol in presence of small amount of conc H2SO4
Ester group formed
162
Affect when amino acid reacts with ethanol chloride
Amide bond formed
163
How are peptides formed
In a condensation reaction between amino acids
164
What is a peptide bond
An amide bond
-HN-CO-
165
What is polypeptide
The result of 50+ amino acids joining in a chain
166
How does the condensation reaction between amino acids occur
The amine group on one amino acid attacks the C atom of the carboxylic acid group of another amino acid
A molecule of water is lost
167
What is the result of a condensation reaction between amino acids
A secondary amide group that links the two amino acid residues together
168
How to identify amino acids
Break down the polypeptide using hydrolysis
Separate and identify amino acids produced using TLC:
Amino acids are colourless- need to be sprayed with a locating agent and heated
Locating agent forms coloured compound
Calculate the retention factor of amino acid
Compare Rf value to known value
169
What is the hydrolysis of polypeptides
The breaking down of the polypeptide into the amino acid monomers
170
Conditions and reagents for hydrolysis of polypeptides
Reflux with conc HCl
171
What is addition polymerisation
Where lots of monomers join together to form a longer molecule
Occurs with unsaturated monomers eg C=C
100% atom economy
172
Equation to produce poly(ethene) from ethene
H2C=CH2 becomes -H2C-CH2-
173
What is condensation polymerisation
The removal of a small molecule, eg H2O or HCl, to form a polymer
174
What is used to form a polyester
A dialcohol and a dicarboxylic acid
175
What is a diol
A dialcohol eg HO-CH2-CH2-OH
176
Standard equation for forming a polyester
HO-CH2-R-CH2-OH + HOOC-R-COOH becomes -O-CH2-R-CH2-O-CO-CO- +2H2O
177
What atoms are lost to form a polyester
The H atoms from the diol -OH group s and the OH from the -COOH carboxylic acid group
178
Why is a polyamide also known as
A nylon
179
How are polyamides formed
Diamine and dicarboxylic acid
Diamine and diacylchloride
Amino acid
180
Standard equation for formation of polyamide
H2N-R-NH2 + HOOC-R-COOH becomes -HN-R-NH-OC-R-CO- + 2H2O
181
What atoms are lost in the formation of a polyamide
A H from each -NH2 amine group
OH from each -COOH carboxylic acid group
182
What is an AAA polymer
Where only one monomer is used to form the polymer
183
What is an ABAB polymer
Where copolymerisation occurs- more than one monomer used
184
What can a condensation polymer be AAA
If the monomer is bifunctional- it contains a carboxylic acid/acyl chloride group and a amine/hydroxyl group
185
Properties of any nylons
Tough and Durable
High tensile strength due to H bonding between polymer chains
186
How are polyamides named
Nylon- x,y
Where x is the number of C atoms in the Diamine and y is the number of C atoms in the dicarboxylic acid
187
How can you extend the length of a Carbon chain
Halogenoalkane and CN-
Carbonyl and CN-
Friedel-crafts alkylation
Gringards reagents
188
What is a gringards reagent and give its formula
A gringards reagent is an organometallic compound used to extend a carbon chain
R-Mg-X where R is an alkyl chain and X a halogen
189
Why do gringards reagents typically not use F or Cl as it’s halogen
The C-F and C-Cl bonds are very strong, making it difficult to synthesise the reagent
190
Conditions and reagents for synthesis of gringards reagent
Reagents- Halogenoalkane and Mg turnings
Conditions- dry ether, I2 catalyst and reflux
191
Standard equation for synthesis of gringards reagent
RMgX + H2O becomes RH + Mg(OH)X
192
Why is the whole reaction mixture used as a gringards reagent
Gringards reagents are difficult to isolate
Using whole reaction mixture is easier
193
Why are gringards reagents very reactive
A S- C atom is very unstable, so the S- C in the Gringards Reagant will attach a S+ C in another reagent
194
Reaction of Gringards reagents with Carbon Dioxide and how much longer is the C chain made
CO2 + RMgBr becomes RCOOH
C chain made one C longer
195
Reaction of Gringards reagents with methanal and how much longer is the C chain made
CH2O + RMgBr becomes RCH2OH
Forms primary alcohol- C chain extended by one C atom
196
Reaction of Gringards reagents with an aldehyde (not methanal) and how much longer is the C chain made
CHRO + RMgBr becomes CRR’HOH
Forms secondary alcohol- extension of chain determined by the R group on the aldehyde
197
Reaction of Gringards reagents with ketone and how much longer is the C chain made
CRR’O + RMgBr becomes CRR’R”OH
Forms a tertiary alcohol
C chain extension dependant on alkyl groups
