organic niruja Flashcards
(99 cards)
1
Q
hydrocarbons
A
compounds that
contain only carbon and hydrogen atoms.
form series of compounds with similar structures and
formulas that can be represented in many different ways.
2
Q
why iupac is important
A
This ensures each compound is universally named the same - which helps to avoid
potentially dangerous confusion.
3
Q
alkane suffix
A
ane
4
Q
alkene suffix
A
ene
5
Q
alcohol suffix
A
ol
6
Q
carboxylic suffix
A
oic acid
7
Q
ketone suffix
A
one
when group attahed to carbon in middle
8
Q
aldehyde suffic
A
al - when group is attached to carbon at end
9
Q
ester suffix
A
ate
10
Q
amine suffix
A
amine
11
Q
6 rules of naming
A
- Functional groups and side chains are given, if necessary, with the number corresponding to the carbon they are attached to.
- Numbers are separated by commas.
- Numbers and words are separated by hyphens.
- If more than one particular side chain or functional group is present then one of the following prefixes is added: di- (2), tri- (3), tetra- (4),
etc. - The carbon chain is numbered in ascending order from the end of the chain nearest a functional group.
- If multiple prefixes are present, they are included in alphabetical order.
12
Q
when is diol used
A
two hydorxyl functional groups
13
Q
empirical formula
A
- The simplest whole number ratio of atoms of each element in a compound.
14
Q
molecular formula
A
The true number of atoms of each element in a compound
15
Q
general formula
A
The simplest algebraic formula of a member of a homologous series. All members of a homologous organic series follow the general formula. Example: Alkanes have the general formula CnH2n+2.
16
Q
strucutral formula
A
The minimal detail that shows the arrangement of atoms in a molecule. - The carboxyl group will be represented as COOH and the ester group as COO. Example: The structural formula of 2-methylpropanoic acid is (CH3 )2CHCOOH.
17
Q
displayed formula
A
The relative positioning of atoms and the bonds between them. Shows every atom and every bond in an organic compound
18
Q
skeletal formula
A
The simplified organic formula of just a carbon skeleton and functional groups. - Shows only the bonds in a compound and any non-carbon atoms. - Vertices are carbon atoms. - Hydrogen is assumed to be bonded to them unless stated otherwise
19
Q
homologus series
A
A homologous series is a series of organic compounds with the same functional group but with each successive member differing by CH2 . Organic compounds are often part of a homologous series, in which all members follow a general formula and react in a very similar way. There is an increase in boiling points as the chain length increases.
20
Q
alcohol functional group
A
R-OH
21
Q
ALDEHYDE FUNCTIONAL GROUP
A
R-=O-H
22
Q
KETONES FUNCTIONAL GROUP
A
R-=O-R
23
Q
CARBOXYLIC ACID FUNCTIONAL GROUP
A
R-=O-OH
24
Q
ESTERS FUNCTIONAL GROUP
A
R-=O-O-R
25
Alkyl group
hydrocarbon chain with the general formula CnH₂₊₁. Sometimes R may be used to represent alkyl groups, as well as other fragments of organic compounds not involved in reactions.
26
aliphatic
compound containing carbon and hydrogen joined together in straight chains, branched chains or non-aromatic rings
27
alicyclic
an aliphatic compound arranged in non-aromatic rings, with or without side chain
28
aromatic
containing a fully conjugated ring. Benzene is aromatic.
29
saturated
contains single carbon-carbon bonds only.
30
unsaturated
contains multiple carbon–carbon bonds, including C=C, C≡C, and aromatic rings.
31
isomers
are molecules with the same molecular formula but a different arrangement of atoms within the molecule. This gives the isomers a different structural formula.
32
chain isomers
same molecular formula but a different arrangement of the carbon skeleton.
33
position iosmers
functional group of the molecule in a different position on the carbon chain
34
functional group iosmers
the same molecular formula, but the molecules have a different functional group.
35
homolytic fission
each bonding atom receives one electron from the bonded pair, forming two radicals. Movement of one electron is shown by a single-headed curly arrow
36
heterolytic fission
one bonding atom receives both electrons from the bonded pair. This leads to the formation of a positive and negative ion. Movement of two electrons is shown by a double-headed curly arrow. Most mechanisms involve heterolytic fission
37
what is a radical
a species with an unpaired electron. Radicals are represented by a dot, as shown above in the homolytic fission of Cl₂
38
addition
the reactants combine to form a single product
39
substition
- one functional group is replaced by a different functional group
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oxidation
a species loses at least one electron and is oxidised.
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reduction
a species gains at least one electron and is reduced.
42
polymerisation
a reaction in which many small molecules, known as monomers, join to form a long, repeating molecule called a polymer
43
eliminaiton
a small molecule is removed from a larger molecule
44
alkane properties
saturated hydrocarbons containing single C-C and C-H bonds
pi bonds
formula CnH2n+2.
Cycloalkanes are an exception to this general formula but are still saturated hydrocarbons.
have tetrahedral geometry and a bond angle of 109.5°. This shape minimises electron-electron repulsion between bonding pairs.
45
variation in boiling points in alkanes
Induced dipole-dipole interactions act between organic alkane chains and are affected by the chain length and any branching. As the chain length of the alkane increases, so does the Mr of the molecule. This results in stronger intermolecular forces between the chains and the compound has a higher boiling point as a result. Branching of alkane chains weakens van der Waals forces between the chains as they are less able to pack tightly together. Therefore, the distance over which the intermolecular forces act is increased and the attractive forces weakened. This means branched chain alkanes have lower boiling points than straight chain alkanes.
46
fractional distillation
. The mixture of hydrocarbons is vaporised and fed into the fractionating column. Vapours rise, cool and condense at their different boiling points. The column is hotter at the bottom and cooler at the top. Products with short carbon chains have lower boiling points, meaning they rise higher up the column before reaching their boiling point. Therefore, they are collected at the top of the column. Products with long carbon chains have higher boiling points, meaning they don’t rise very far up the column before reaching their boiling point. They condense and are collected at the bottom of the fractionating column
47
alkanes reactivity
a low reactivity with many reagents due to the high bond enthalpy of the C-C bonds and very low polarity of the σ-bonds present.
48
combustion of alkanes
Alkanes make good fuels as they release a lot of energy when burned. With sufficient oxygen present, they undergo complete combustion to produce carbon dioxide and water
oxygen present is insufficient, combustion is incomplete and carbon monoxide or carbon particulates are produced alongside water
49
carbon monoxide
a toxic, gaseous product that is especially dangerous to humans as it is odourless and colourless. Carbon monoxide is dangerous because it replaces oxygen in the blood, starving the brain and other organs of oxygen and causing people to suffocate.
50
Oxides of nitrogen and sulfur
produced as a byproduct of alkane combustion along with carbon particulates from unburnt fuel. In clouds, these oxides can react with water and form dilute acids, which result in acid rain
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catalytic converters
Oxides of nitrogen and carbon monoxide can be removed from systems using a catalytic converter. This uses a rhodium catalyst to convert harmful products into more stable products such as CO2 , N2 or H2O.
52
alkenes properties
unsaturated hydrocarbons with at least one carbon-carbon double bond
CnH2n.
is trigonal planar geometry around the carbon atom and a bond angle of 120°.
53
what is used to test alkenes
Bromine water is used to identify an alkene double bond and other unsaturated compounds. Alkenes cause bromine water to change colour from orange-brown to colourless. This is because bromine forms bonds to the carbon atoms, removing the C=C bond, causing the compound to become saturated.
54
why alkenes 120
°. This angle minimises electron-electron repulsion between bonding pairs. The π bond has electron density above and below the plane of the 𝜎 bonds. There is restricted rotation in alkenes due to this π bond
55
carbon double bond in alkenes
is an area of high electron density, making it susceptible to attack from electrophiles .It consists of a normal covalent σ bond and a π bond.
The π-bond is formed by sideways overlap of adjacent p-orbitals above and below the bonding C atoms. The σ-bond is formed by overlap of orbitals directly between the bonding atoms.
56
what are electrophiles
(species that are attracted to electron dense areas)
57
how ez isomers occur
type of stereoisomerism, which occurs due to the limited rotation around a double carbon bond. The limited rotation means that ‘high priority’ groups attached to the C=C can either be ‘together’ or ‘opposite
58
addition reactions of alkenes
The carbon-carbon double bond in alkenes has a relatively low bond enthalpy. This makes them relatively reactive. During their reactions, the double bond opens up to form single bonds to other atoms. These are called addition reactions. The pi bond is an area of high electron density. This attracts electrophiles
Alkenes can undergo electrophilic addition with hydrogen to produce alkanes.
hydrogenation reaction
59
producimg alkanes
Alkenes can undergo electrophilic addition with hydrogen to produce alkanes. The C=C bond opens up and forms single bonds to each of the hydrogen atoms. This reaction requires a nickel catalyst.
60
producing haloalkanes
Alkenes undergo addition reactions with halogens to form di-substituted haloalkanes, and with hydrogen halides to form mono-substituted haloalkanes. The electrophilic addition mechanism for this reaction is given on the following page of these notes. Br₂ is present in bromine water in the test for unsaturation. This is an electrophilic addition reaction, forming a dihaloalkane
61
producing alcohols
Alkenes undergo addition reactions with steam to form alcohols. This reaction requires an acid catalyst, such as phosphoric acid
62
elecrophillic addition
double bond is broken, a carbocation intermediate forms. This is a carbon atom with only three bonds, so it has a positive charge. Carbocations can have varying stability, with tertiary being the most stable and primary the least. The more stable the carbocation, the more likely it is to form. Therefore, in an addition reaction of a hydrogen halide, multiple products can form but the major product will always be the one that is formed via the most stable carbocation possible
63
additionpolymers
Addition polymers are produced from alkenes which are short chain monomers which join together to form long chain polymers. The double bond of the alkene is broken to form a repeating unit - the repetition of which would form the complete polymer chain. The repeating unit must always be shown with extended bonds through the brackets, showing that it bonds to other units on both sides
64
where are polymers obtained from
made from alkenes which are obtained from crude oil, a non-renewable resource. The extraction and cracking of crude oil are both high energy processes and additional energy is then needed to convert these alkenes into polymers.
65
use of polymers
useful for manufacturing many everyday plastic products such as poly(ethene) shopping bags.
However, the unreactive nature of the bonds in addition polymers means they are not biodegradable and cannot be broken down by species in nature.
66
fisposal of polymers
: Addition polymers are non-biodegradable which means disposal of them can be difficult. Waste polymers can be processed in different ways. Some can be recycled, some are used as organic feedstock for production of plastics and other organic chemicals, and some are combusted to produce energy for other industrial processe
67
combustion of polmers
Combustion can release toxic gases which must be removed to reduce the impact on the environment. During disposal by combustion of chlorine-containing haloalkanes, HCl may be released. This is toxic and needs to be removed.
As well as this, scientists are developing biodegradable polymers and photodegradable polymers to overcome these waste issues. This helps to reduce dependency on finite resources and alleviates problems from disposal of persistent plastic waste
68
alcohol general formula
formula CnH2n+1OH
69
two methods alcohols formed
fermentation or hydration
70
alcohol properties
polar molecules since there is a large difference in electronegativity between carbon and oxygen. The oxygen is very electronegative, so can hydrogen bond to water molecules. This ability means that alcohols are water soluble
Hydrogen bonds are a much stronger intermolecular force than van der Waals forces so more energy is required to overcome them. Alcohols have both types of intermolecular force present between molecules, so are much less volatile than alkanes which only have van der Waals forces present
71
combustion reaction with alcohols
When burned in air, alcohols react with oxygen to form carbon dioxide and water. Alcohols make good fuels by reacting in this way as lots of energy is also released.
72
alcohols and halogenating agents
via nucleophilic substitution. The -OH group is replaced by a halogen, producing a haloalkane. PCl5 is used to produce chloroalkanes. This can be used as a test for alcohols because their reaction with PCl5 produces white steamy fumes that turn damp blue litmus paper red. A reaction mixture of concentrated sulfuric acid and potassium bromide can be used to produce bromoalkanes.
73
potassium bromide and sulfuric acid
form HBr
then reacts with the alcohol to produce the bromoalkane. CH3CH2OH + HBr → CH3CH2Br + H2O
74
alcohols and eliminatiion
Alkenes can be formed from the dehydration of alcohols, where a molecule of water is removed from the molecule. In order to do this, the alcohol is heated with concentrated phosphoric acid
75
oxidation of alcohols
Primary and secondary alcohols can be oxidised to produce various products but tertiary alcohols are not easily oxidised. When primary alcohols are heated in the presence of acidified potassium dichromate(VI), they are oxidised to aldehydes
76
hpow to seperate aldehydes
Distillation
When an aldehyde is heated further with acidified potassium dichromate(VI) under reflux conditions, the aldehyde is oxidised to produce carboxylic acids. This shows primary alcohols are oxidised to aldehydes and then to carboxylic acids
77
potassium dichromate
used in the oxidation of alcohols as the oxidising agent. It is reduced as the alcohol is oxidised. A colour change from orange to green is observed when the alcohol is oxidised with potassium dichromate(VI). This colour change occurs due to a change in oxidation state of the chromium ion.
78
haloalkanes bonds
contain polar bonds since the halogens are more electronegative than the carbon atom. This means electron density is drawn towards the halogen, forming ∂+ and ∂- regions.
The electronegative carbon-halogen bond here X indicates the halogen atom. Haloalkanes can be classed as primary, secondary or tertiary haloalkanes depending on the position of the halogen within the carbon chain
79
reactivity of halogens
Electronegativity of the halogens decreases down the group,
carbon-fluorine bond is much more polar than a carbon-iodine bond
increased polarity
carbon-fluorine bond is shorter, means that the carbon-fluorine bond is much stronger
The greater the Mr of the halogen in the polar bond, the lower the bond enthalpy. A lower bond enthalpy means the bond can be broken more easily. Therefore, the rate of reaction increases for haloalkanes as you move down the group.
80
UV
cause CFCs to produce halogen radicals. These radicals catalyse the breakdown of the Earth’s protective ozone layer. CFCs are chlorofluorocarbons - haloalkanes containing carbon, chlorine and fluorine atoms only
80
Heating under reflux
Reflux apparatus is used to continually heat the contents of the flask to allow reactions like the oxidation of primary alcohols to proceed all the way to the formation of carboxylic acids. The condenser helps ensure the vapours condense and return to the flask for further heating. This ensures the product vapours can not escape
81
distillation
Distillation apparatus is used to separate liquids with different boiling points. The round-bottomed flask is heated and the liquid with the lower boiling point will evaporate first. It rises out of the flask and into the attached tubing which is surrounded by a condenser. The condenser causes the vapour to cool and condense back into a liquid, which is then collected in a separate flask
82
seperating funnel
A separating funnel is used to separate two liquids with different densities. The mixture is added to the flask, and then the flask is stoppered and inverted to mix the contents. The liquids are allowed to separate into two layers. The tap can then be opened to collect the bottom, denser liquid in one flask and the second, less dense liquid in a second flask. Usually these layers will be distinguished to be an aqueous and an organic layer.
83
redsitillation
carried out to obtain a purer product. Boiling point determination Determining the boiling point of a compound and comparing it to a databook value is a way of testing the purity of a substance. The purer a substance, the closer to the databook boiling point value it will be. If a sample has a low purity, the melting or boiling point will take place over a range of temperatures.
84
how to determine bp
substance is packed into a Thiele tube which has an inverted capillary tube in it. The substance is heated to above its boiling point and allowed to cool. When it condenses into a liquid it will be drawn into the capillary tube and the temperature at which this change occurs is taken to be the boiling point.
85
drying after distillation
A compound can be dried by the addition of an anhydrous (contains no water) salt. The anhydrous salt will absorb moisture and water present, thus drying and purifying the compound. Common anhydrous salts used for drying are magnesium sulphate and calcium chloride
86
reaction of haloalkanes to produce alcohols
Haloalkanes can react with an aqueous alkali, such as aqueous sodium or potassium hydroxide, to produce alcohols in a nucleophilic substitution reaction. The hydroxide ion acts as a nucleophile
87
reactions of haloalkanes to produce
Haloalkanes can react with ethanolic potassium hydroxide (KOH) to produce alkenes in an elimination reaction. The hydroxide ion acts as a base.
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Reactions of haloalkanes
Hydrolysis with Silver Nitrate
Haloalkanes can be broken down in their reaction with aqueous silver nitrate and ethanol. The water in the solution acts as a nucleophile which leads to formation of the alcohol and releases the halide ions into the solution. The halide ions then react with the silver ions from silver nitrate to form silver precipitates.
89
what does reactivity depend on for haloalkanes
depends on the strength of the C-X bond (where X is a halogen atom) and not the bond polarity. Bond strength decreases with increasing Mr. Therefore, iodoalkanes react faster than bromoalkanes and chloroalkanes, and bromoalkanes react faster than chloroalkanes
90
what does the rate at which precipitates form tell us
identify the relative stability of the haloalkanes, because the faster the precipitate forms, the less stable the haloalkane, and therefore the more quickly it is hydrolysed
91
what is infrared spectroscopy
causes covalent bonds to vibrate and absorb energy. Infrared spectroscopy is an analytical technique that uses infrared (IR) radiation to determine the functional groups present in organic compounds. The IR radiation is passed through a sample where the different types of bonds absorb the radiation in different amounts. These varying amounts of absorbance are measured and recorded, allowing certain bonds, and thus functional groups, to be identified. A spectrum is produced from the measurements, which has characteristic curves for the different functional groups
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infrared and environment
There is a link between the absorption of infrared radiation by atmospheric gases containing C=O, O–H and C–H bonds (e.g. CO₂, H₂O and CH₄), and global warming. As a result, there is a need for changes to be made to renewable energy resources.
92
fingerprint refgion
Each IR spectrum has a fingerprint region on the right-hand side, from 500-1500 cm-1. This is unique for each species, containing tiny differences between each species. This means it acts as a molecules’ ‘fingerprint’, allowing it to be identified.
93
uses of infrared
to monitor gases causing air pollution (e.g. CO and NO from car emissions) and in modern breathalysers to measure ethanol in people’s breat
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electrophile
electron acceptor
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Nucleophilic Substitutions n of Halogenoalkanes
with aqueous hydroxide ions
with cyanide ions.
with ammonia
96
elimination of Halogenoalkanes
ethanolic
hydroxide ions
97
electrophillic addition of of Alkenes
Bromine
hydrogen bromide
sulphuric acid
