Organic chemistry Flashcards
(124 cards)
1
Q
give 3 reasons why carbon can form so many compounds
A
- can form 4 bonds
- single / double / triple bonds
- can bond with other carbons
2
Q
what is the definition for homologous series?
A
a series of organic compounds having the same functional group but with each successive member differing by CH2
3
Q
what is an aromatic compound?
A
compound containing a benzene ring
4
Q
what is an aliphatic compound ?
A
compound containing straight chains, branched chains or non-aromatic rings (carbon and hydrogen)
5
Q
what is alicyclic compound?
A
aliphatic compound with non aromatic rings
6
Q
saturated is ..
A
no C=C
7
Q
what is the functional group ?
A
group of atoms responsible for the characteristic reactions of a compound
8
Q
order of organic prefixes
A
meth, eth, pro, but, pent, hex, hept, oct, non, dec
9
Q
general formula for alkanes
A
Cn H2n+2
10
Q
cyclo prefix means…
A
compound is alicyclic / aromatic
11
Q
general formula for cycloalkanes
A
Cn H2n
12
Q
general formula for alkynes
A
Cn H2n-2
13
Q
name the iodine prefix
A
iodo
14
Q
define structural isomer
A
molecules with the same molecular formula but different structural formula
15
Q
define saturated
A
only contains single bonds
16
Q
what is the bond angle for tetrahedral ?
A
109.5
17
Q
explain the shape of alkanes (VSEPR)
A
- electrons repel each other
- arrange as far as possible to minimize repulsion and hold definite shape
18
Q
what is the bond angle for linear ?
A
180
19
Q
what is the bond angle for triagonal planar ?
A
120
20
Q
what is the bond angle for non - linear ?
A
104.5
21
Q
what is the bond angle for pyrimidal ?
A
107
22
Q
what is the bond angle for octahedron ?
A
90
23
Q
define electronegativity
A
ability to attract pair of electrons in a covalent bond
24
Q
what must the molecule be for it to be polar (even with polar bonds)
A
not totally symmetrical in all directions
25
what four shapes are symmetrical in all ways (if all bonds are the same)
- linear
- triagonal planar
- tetrahedral
- octahedral
26
define radical
a species with an unpaired electron
27
what are the 3 stages in radical substitution
- initiation
- propagation
- termination
28
what type of bond breaking is in radical substitution ?
homolytic fission
29
state the conditions needed for radical substitution
UV light
30
why is UV light required for radical substitution?
to provide the activation energy needed to break halogen bond
31
In terms of radicals, what is the key feature of the initiation step ?
generates radicals
32
In terms of radicals, what is the key feature of the propagation step ?
for every radical used --- a radical is used
33
In terms of radicals, what is the key feature of the termination step ?
2 radicals combine to form non radicals
34
what are the limitations of radical substitution ?
- substitution with different carbons
- multi - substitution
- may produce large molecules
35
define stereoisomer
compounds with the same structural formula but with different arrangement in space
36
how is sigma bond formed ?
end - on overlap of orbitals
37
how is pi bond formed ?
side - on overlap of orbitals
38
where are the bonding electrons in sigma bond ?
between nuclei
39
where are the bonding electrons in pi bond ?
above and below the line joining the nuclei
40
E ...
opposite - priority
41
z ...
same side - priority
42
cis ...
same side - same
43
trans ...
opposite - same
44
what does electrophilic addition show ?
addition of an alkene and halide (from hydrogen halide)
45
Define heterolytic fission
The breaking of a covalent bond with both of the bonded electrons going to one of the atoms, forming a cation and an anion
46
what type of fission is in electrophilic addition ?
heterolytic fission
47
what is the name for the charged carbon in electrophilic addition ?
carbocation
48
Define electrophile
An atom/group that is attracted to an electron-rich center or atom, where it accepts a pair of electrons
49
what is the electrophile in electrophilic addition ?
| Why ?
Hydrogen (halide)
| accepts pair of electrons
50
How is there still a difference in electronegativity in (e.g.) Br2 ? (electrophilic addition)
Due to an induced dipole in Br - Br , caused by C = C repelling electrons in Br2 away from it
51
What is Markovnikov's Rule ?
- the more carbons attached to the carbocation, the more stable it is
- more stability means more likelihood of being formed
52
what is a primary / secondary carbocation
primary - carbocation attached to one carbon
| secondary - carbocation attached to two carbons
53
what is major product ?
more likely to be formed product (most stable)
54
what is minor product ?
less likely to be formed product
55
% yield =
actual yield / theoretical yield x 100
56
why are organic reactions rarely 100 % yield ?
- most are reversible
- side reactions
- slow reactions
57
atom economy =
Mr of useful products / Mr of all products x 100
58
name two ways to improve atom economy
- change the reaction
| - find a use for the other products
59
what are the two types of polymerization ?
condensation and addition
60
how do you name a polymer ?
poly ( alkene )
61
explain how E/Z isomerism can arise
- restricted rotation around double bond
| - each of atoms in double bond has 2 different groups attached
62
Give conditions for addition reaction of alkene and hydrogen gas
150 'C
| Nickel catalyst
63
Give conditions for addition reaction of alkene and halogen
RTP
64
Give conditions for addition reaction of alkene and hydrogen halide
RTP
65
define electronegativity
measure of attraction of a bonded atom for the pair of electrons in a covalent bond
66
why do haloalkanes have high boiling points?
polar bonds are present ( C - Halogen )
67
define hydrolysis
chemical reaction involving water / aqueous solution of a hydroxide that causes breaking of a bond
68
define nucleophile
molecule that donates a pair of electrons to form a new bond
69
what structural feature is need to act as a nucleophile
contain OH- ions
70
what type of fission is involved in nucleophilic substitution
heterolytic fission
71
what is nucleophilic substitution ?
hydrolysis of haloalkane to produce an alcohol - heated under reflux
72
state the order of the rate of hydrolysis of haloalkanes
(fastest) iodo - bromo - chloro (slowest)
73
what is ethanol used for in nucleophillic substitution
co - solvent (allows it to mix to speed reactions)
74
what is the aldehyde suffix ?
al
75
what is the ketone suffix ?
one
76
what happens the the boiling point of an alkane as it gets more branched ? why ?
lowers boiling point, as they can't pack closely together and have smaller molecular surface areas, so reduced London forces
77
what is produced in complete combustion ?
water and carbon dioxide
78
what is produced in incomplete combustion ?
water and carbon / carbon monoxide
79
what is a photochemical reaction ?
reaction started by light
80
why are alkenes more reactive than alkanes ?
- contains pi bond, which requires less energy to break than sigma bond
- not polar
81
how does stereo isomerism occur ?
- double bond can't rotate
| - two different atoms / groups attached to each carbon
82
how do you test for carbon = carbon bonds ?
- add bromine water
- shake
changes from orange to colourless if C=C present
83
how is an alcohol made ?
hydrate alkene by steam at 300'C, pressure 60-70 atm, with solid phosphoric (V) acid catalyst
84
is the yield good with making an alcohol ?
reaction is reversible and yield is low - however unreacted alkene gas can be recycled so yield overall is high
85
name the advantages of polymers
- unreactive
| - strong and durable
86
name the disadvantages of polymers
- disposing (not biodegradable)
| - damage to environment
87
when are waste plastics buried ?
- difficult to separate
- not in sufficient quantities to make separating worthwhile
- too difficult to recycle
88
how can waste plastics be reused ?
- melt / remold
| - crack into monomers, which can be used as an organic feedstock to make more plastics
89
why are waste plastics burned ?
to generate electricity
90
why / how must burning plastics be controlled ?
toxic gases produced, which pass through scrubbers which can neutralise these gases with a base
91
what is homologous series of alcohols ?
Cn H2n+1 OH
92
are alcohols polar ?
most are, due to hydrogen bonds between C - OH bond
93
describe the solubility of small alcohols
soluble, due to hydrogen bonds forming between OH and H20
94
describe the solubility of large alcohols
reduced solubility, as most of the molecule is a non-polar carbon chain
95
what are the conditions needed for reaction between alcohol and halide ?
acid catalyst (sulfuric)
96
how can you make an alkene from an alcohol ?
dehydrate (eliminate water)
97
what are conditions needed for elimination reaction of alcohol ?
```
acid catalyst (conc sulfuric)
heat
```
98
what to remember with elimination of alcohols ?
two possible products ( + watch out for E/Z)
99
what flame does ethanol produce ?
pale blue
100
what is formed when you burn ethanol in oxygen ?
CO2 and water produced
101
what oxidising agent is needed to oxidise an alcohol ?
acidified dichromate (VI)
102
primary alcohols oxidise to ...
aldehyde then carboxylic acid
103
secondary alcohols oxidise to ...
ketones only
104
tertiary alcohols oxidise to ...
they can't oxidise
105
in aldehyde, how many alkyl groups attached to carbonyl carbon atom ?
one
106
in ketone, how many alkyl groups attached to carbonyl carbon atom ?
two
107
in oxidation of alcohol, for aldehyde ...
distil
108
in oxidation of alcohol, for ketone ...
reflux
109
what is the only way to oxidise a tertiary alcohol ?
burn them
110
what does CFC stand for ?
Chlorofluorocarbon
111
what is a CFC ?
molecule containing only chlorine, fluorine and carbon
112
state the chemical properties of CFCs
stable / volatile / non-flammable / non - toxic
113
what is ozone ?
O3
114
what does the ozone layer do ?
absorbs a lot of UV radiation (good)
115
what are the three main greenhouse gases ?
water vapor, carbon dioxide and methane
116
what causes the greenhouse effect ?
bonds of gases in atmosphere absorb infrared radiation, and re-emit it in all directions (including down at earth)
117
overall greenhouse effect =
concentration x "greenhouse potential"
118
how does IR spectroscopy work ?
- IR radiation absorbed by covalent bond (causing them to vibrate more)
- bonds absorb diff. frequencies
119
name some uses for IR spectroscopy
- breathalysers
| - measuring air pollution
120
what causes the M+1 peak ?
Carbon - 13
121
what is mass spectroscopy used for ?
differentiating similar molecules
122
outline the process of removing water soluble impurities from an organic sample
1. pour into separating funnel w/ water added
2. open stopper until all aqueous layer (bottom) gone
3. remove traces of water w/ drying agent (MgSO4)
4. filter off drying agent
123
heterolytic fission forms ...
cation and anion
124
homolytic fission forms ...
2 radicals
