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A Level Chem - OCR > Core Organic > Flashcards

Core Organic Flashcards

1
Q

functional group of alkenes

A

CnH2n

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2
Q

what does aliphatic mean

A

carbon atoms joined together in unbranched or branched chains, or non aromatic rings

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3
Q

what does aromatic mean

A

some/all carbon atoms are found in a benzene ring

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4
Q

what does alicyclic mean

A

carbon atoms are found in ring structures, with or without branches

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5
Q

definition of structural isomers

A

same molecular structure but different structural formula

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6
Q

definition of stereoisomers

A

same molecular and structural formula but a different arrangement of atoms in space

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7
Q

what do curly arrows stand for

A

movement of an electron pair

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8
Q

what is homolytic fission

A

when the covalent bond breaks, each bonded atoms takes one of the shared pair of electrons

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9
Q

what is heterolytic fission

A

when a covalent bond breaks, one of the bonded atoms takes both of the electrons from the bond

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10
Q

addition reaction

A

a molecule is added to the unsaturated alkene, breaking double bond

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11
Q

substitution reaction

A

an atom/group of atoms is replaced by a different atom or group of atoms

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12
Q

elimination reaction

A

the removal of a small molecule from a larger one - usually water

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13
Q

properties of alkanes

A

saturated hydrocarbons
has sigma bonds
tetrahedral shape

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14
Q

what happens to bp when chain length of alkanes increases

A

it increases as there is a larger surface area of contact between molecules so the London forces are stronger - more energy is required to overcome

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15
Q

what is the effect of branching on boiling point of alkanes

A

it decreases bp as there are fewer surface points of contact between molecules, London forces are weaker - less energy required to overcome them

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16
Q

why are alkenes relatively not highly reactive

A

the C-C and C-H bonds sigma bonds are strong
the C-C bonds are non polar
the electronegativity of Carbon and hydrogen is so similar that the C-H bond can be considered non-polar

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17
Q

what are the details of an alkene reaction with halogen

A
  • Needs UV light
    CH4 + Br2 -> Ch3Br + HBr
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18
Q

What is the mechanism for the bromination of alkenes

A

radical substitution

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19
Q

what are the steps to radical substitution withh examples

A
  1. Initiation - the bromine bond is broken by homolytic fission
    Br-Br -> Br* + Br*
  2. Propagation
    a) CH4 + Br* -> *CH3 + HBr
    b) CH3 + Br2 -> CH3Br + Br
  3. Termination - when 2 radicals collide o form a molecule
    *CH3 + *CH3 -> C2H6
    *Br + *Br -> Br2
    *CH3 + *Br -> CH3Br
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20
Q

what are the limitations of radical substitution

A

further substitution can occur until all hydrogen atoms have been substituted

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21
Q

what are the properties of a double bond
C=C

A
  • a sigma bond
  • sigma locked in place by the pi bond
  • pi bond is the overlap of 2 p orbitals above and below the plane of the carbon atoms
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22
Q

what is the shape around the double bond

A

trigonal planar as
- 3 bonding pairs of electrons around each carbon atom
- 3 pairs repel each other as far apart as possible so the bond angle around each carbon atom is the same
- all atoms are on the same plane

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23
Q

why and when does E/Z isomerism arise

A

because rotation around the double C=C bond is restricted and the group attached to each carbon atom are therefore fixed

it occurs when there is a C=C bond and there are different groups attached to each carbon atom of the double bond

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24
Q

what is cis-trans isomerism

A

Zis is on ze zame zide!!

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25
what are the Cahn-Ingold-Prelog rules
if the groups of higher priority are in the same side of the double bond, it is a Z isomer if the groups of higher priority are on diagonal sides, it is an E isomer
26
which is more reactive alkenes or alkanes and why?
Alkenes because of the presence of the pi bond pi bond is more electron dense and the electrons are more exposed than in the sigma bond
27
when do alkenes undergo addition reactions
- hydrogen in presence if a nickel catalyst - halogens - hydrogen halids - steam in the presence of an acid catalyst
28
what is formed when alkenes react with steam and with what catalyst
alcohols when there is a phosphoric acid catalyst steam adds across the double bond
29
what is the mechanism of an addition reaction in alkenes
electrophilic addition
30
what is an electeophile
an electron pair acceptor an atom/group of atoms that is attracted to an electron-rich centre and accepts and electron pair is usually a positive ion or a molecule containing a partial positive charge
31
Mechanism for electrophilic addition reaction of But-2-ene with hydrogen bromide
1. bromide is more electronegative than hydrogen, so HBr is polar and has a dipole 2. the electron pair in the pi bind is attracted to partially +ve H atom - double bind breaks 3. bond forms between H atoms of the H-Be molecule and a C atom that was part of the double bond 4. the H-Br bond breaks by heterolytic fission, with the e- pair going to the Br atom 5. a bromide ion (Br-) is made and a carbocation formed 6. the Br- reacts with carbocation to form addition product
32
what examples of disposing of waste polymers
recycling PVC recycling using them as fuel feedstock recycling
33
what are the details of PVC Recycling
hazardous due to high chlorine content and range of additive when PVC. is burnt, it releases HCl and toxic dioxins Now, solvents dissolve the polymer and the PVC is recovered by precipitation if the solvent
34
what is feedstock recycling
the chemical and thermal processes that can reclaim monomers, gases or oil from waste polymers
35
how do biodegradable polymers break down
by microorganisms into water, carbon dioxide and biological compounds polymers are usually made from starch or cellulose leave no toxic residue
36
what is a primary alcohol
when. the -OH group is attached to a carbon atom that is attached to two hydrogen atoms and one alkyl group methanol is the exception
37
what is a secondary alcohol
when the -OH group is attached to a carbon atom that is attached to one H atom and 2 all groups
38
what is a tertiary alcohol
when the -OH group is attached to a carbon atom that is attached to no H atoms and 3 alkyl groups
39
what are secondary alcohol oxidised to
ketones
40
is it possible to oxidise ketones using acidified dichromate
no
41
what is is produced when a primary alcohol is heated strongly under reflux with acidified dichromate a primary alcohol is gently heated and distilled over as formed
carboxylic acid aldehyde
42
how can you test if you have made an aldehyde
using acidified dichromate will then from orange to green
43
how do you produce an alkene from an alcohol
heat the alcohol under reflux in the presence ing an acid catalyst - concentrate sulfuric acid/concentrated phosphoric acid
44
what are examples of nucleophiles
OH- H2O NH3
45
what are the steps to hydrolysis of a haloalkane where the halogen is replaced by an -OH group
1. OH- approaches carbon atom attached to halogen, on the other side of the C atom to where the bond is 2. direction of attack minimises repulsion between nucleophile and the halogen atom 3. lone pair of electrons in the OH- ion is attracted and donated to the partially +ve carbon atom 4. new bond is formed between the O atom of OH- and the C atom 5. carbon-halogen bond breaks by heterolytic fission 6. alcohol and halide ion formed
46
how can haloalkanes be converted to alcohols
using aqueous sodium hydroxide and heated under reflux - to obtain a good yield
47
what is the order of strength of the carbon-halogen bonds
strongest C-F C-Cl C-Br C-I Weakest
48
what can we predict from the carbon-halogen bind enthalpy
iodoalkanes react faster than bromoalkanes bromoalkanes react fast than chloroalkanes fluoroalkanes are unreactive as a large quantity of energy is required to break the C-F bond
49
what is the general equation for hydrolysis of primary haloalkanes
CH3CH2CH2CH2X + H2O -> CH3CH2CH2CH2OH + H+ + X-
50
how can you measure the rate of hydrolysis of primary haloalkane
Using aqueous silver nitrate Ag+ (aq) + C- (aq) -> AgX(s) precipitate of silver halide
51
what can you observe with the precipitate in hydrolysis of primary haloalkanes 1. 1-chlorobutane 2. 1-bromobutane 3. 1-iodobutane
1. a white precipitate that forms very slowly 2. a cream precipitate that forms slower than 1-iodo but faster than 1-chloro 3. a yellow precipitate that forms rapidly
52
What are CFCs
chlorofluorocarbons
53
are CFCs legal?
no they were banned due to the toxicity of haloalkanes - specifically the C-Cl bond
54
what are CFCs most detrimental to
the ozone layer
55
why is the ozone layer helpful
filters out much of the UV light that causes skin cancer
56
what is the ozone layer continuously broken down by
UV radiation is also continuously reformed
57
what is the equation for ozone depletion
O3 + UV —> O2 + O
58
what can catalyse the breakdown of the ozone
CFCs and NOx
59
What do Chlorine free radicals do to the ozone
catalyse the decomposition of the ozone layer even worse than others at is regenerated at the end of
60
what is the full equation for Chlorine radicals and breakdown of the ozone
prop 1: Cl* + O3 —> ClO* + O2 prop 2: ClO* + O —> O2 + Cl* overall equ: O3 + O* —> 2O2
61
what is the full equation for the free radical substitution with NO
prop 1: NO + O3 —> NO2 + O2 prop 2: NO2 + O• —> NO +O2 overall equ: O3 + O• —> 2O2
62
what does the regenerated Cl• mean for the ozone molecules
that thousands can be broken down due to one Cl•
63
what are the reagents for the reaction of a primary alcohol into an aldehyde
acidified dichromate and dilute H2SO4
64
what are the conditions for the reaction of a primary alcohol into an aldehyde
limited amount of dichromate warm gently and distil over as forms
65
what should you never seal in a reflux reaction
the end of the condenser as the build up of gas pressure could make the apparatus wxplode
66
what should you never deal when performing a reflux to turn a primary alcohol into a carboxylic acid
the end of the condenser as the build up of gas pressure could make the apparatus explode
67
what are the conditions for a reflux reaction of a primary alcohol into a carboxylic acid
use an excess of dichromate and heat under reflux
68
why are anti-bumping granules used in both distillation and reflux
to prevent vigorous and uneven boiling by making small bubbles form instead of large ones
69
draw a distillation setup diagram
use google
70
draw reflux setup diagram
use googke
71
how do you go from an alcohol into a ketone
using a secondary alcohol with acidified dichromate and heated under reflux
72
how do you go from an alcohol to an aldehyde
primary alcohol. acidified dichromate and heat gently and distil over as forms
73
how do you go from an aldehyde to a carboxylic acid
if primary then acidified dichromate and heat under reflux and an excess of the oxidising agent
74
how do you go from an alcohol to a haloalkane
concentrated H2SO4 and a sodium halide heat under reflux substitution reaction
75
how do you from an alkene to haloalkane
HBr, HCl room temperature electrophilic addition
76
how do you go from an alkane to a haloalkane
Br2 Cl2 UV light free radical substitution
77
how do you go from an alkene to an alkane
H2, Nickel catalyst addition/ reduction
78
how do you make a haloalkane from an alcohol
alcohol + sodium halide and H2SO4 heat under reflux substitution
79
how do you make an alcohol from a haloalkane
NaOH and heat under reflux substitution reaction
80
how do you make an alkene from an alcohol
concentrated H2SO4
81
how do you make an alcohol from an alkene
alkene + H2O (g) and H3PO4 catalyst
82
how do you make a haloalkane from an alkene
alkene + hydrogen halide room temperature electrophilic addition
83
how do you make an alkane from an alkene
alkene + H2 (g) and Nickel catalyst addition/reduction
84
how do you make a haloalkane from an alkane
alkane + a halogen with UV lgiht free radical substitution
85
how do you make an aldehyde from an alcohol
primary alcohol K2Cr2O7 distillation partial oxidation
86
how do you make a carboxylic acid from an alcohol
primary alcohol K2Cr2O7 heat under reflux with excess oxidising agent Full oxidation
87
how do you make a ketone from an alcohol
secondary alcohol K2Cr2O7 / H2SO4 heat under reflux oxidation
88
what is a target molecule
the compound a chemist is attempting to synthesise
89
what should you do to convert. starting molecule into the target molecule
identify the functional groups in starting and target identify the intermediate that links them state reagents and constitutions for each step
90
if your starting molecule js a haloalkane and your target molecule is an aldehyde what is your intermediate
primary alcohol BECAUSE an aldehyde can be made from oxidation of primary alcohol an primary alcohol can be made from hydrolysis of haloalkane reagents conditions: 1) NaOH(aq) and reflux 2) K2Cr2O7 and sulfuric acid and distil
91
if your starting molecule is an alkene and your target molecule is a ketone what is the intermediate
secondary alcohol BECAUSE a ketone is made from oxidation of secondary alcohol secondary alcohol can be made by hydration of an alkene reagents and conditions: 1) H2O(g) and an acid catalyst 2) K2Cr2O7

A Level Chem - OCR (6 decks)

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