Topic 10: Organic Chemistry Flashcards
Define catenation.
Process by which many identical atoms are joined together by covalent bonds, producing straight-chain, branched or cyclic structures.
Define a homologous series.
Series of compounds that can be grouped together based on similarities in their structure and reactions. Has the same general formula which varies from one member to another by one CH2
(methylene) group
The boiling point increases with an increasing number of carbon atoms due to the increasingly strong intermolecular forces (London forces).
Have similar chemical properties due to the presence of the same functional group.
What are alkanes?
Hydrocarbons, contain carbon and hydrogen only.
C(n)H(2n + 2)
What are alkenes?
Hydrocarbon with a carbon-carbon double bond.
What are alkynes?
Hydrocarbon with a carbon-carbon triple bond.
What are functional groups?
The functional groups are the reactive parts of the molecules and commonly contain elements such as oxygen and nitrogen
CH4
methane
C2H6
ethane
C3H8
protane
C4H10
butane
C5H12
pentane
C6H14
hexane
General formula for alcohols
C(n)H(2n+1)OH
General formula for aldehydes
C(n)H(2n)O
General formula for ketones
C(n)H(2n)O
What is crude oil?
Mixture of hydrocarbons that vary in the length of their carbon chain.
Combination of alkanes, cycloalkanes and aromatic hydrocarbons.
What is fractional distillation?
Physical separation process that uses differences in boiling points to separate the mixture into fractions of similar boiling point.
-CH3
methyl
-CH2CH3
ethyl
-CH2CH2CH3
propyl
-CH2CH2CH2CH3
butyl
What is a saturated hydrocarbon?
Compound with all carbon-carbon single bonds.
What is a unsaturated hydrocarbon?
Compound containing double and/or triple carbon-carbon bonds.
What is an aliphatic compound?
Straight-chain compound.
What are cycloalkanes?
Ring structures that contain single carbon-carbon bonds.
What are aromatic hydrocarbons?
Ring structures consisting of alternating single and double carbon-carbon bonds.
General formula: ROH
alcohol
-ol
General formula: RCHO
aldehyde
-al
General formula: RC(O)R’
ketone
-one
General formula: RCOOH
carboxylic acid
-oic acid
General formula: RCOOR’
ester
-oate
General formula: ROR’
ether
alkoxy group
General formula: RNH2
RNHR’
RN(R’)R”
amines
-amine
General formula: RCONH2
amide
-amide
General formula: RCN
nitriles
-nitrile
How are biofuels derived?
Are derived from carbon fixation in plants.
How is an amine classified?
An amine is classified depending on the number of alkyl groups bonded to the nitrogen atom of the functional group.
“N” signifies that the substituent, namely the methyl group in is bonded to the nitrogen atom rather than the carbon atom.
What is the octane number?
a standard method of describing the performance of fuels used in cars and aircraft. The octane number is not indicative of the energy content of the fuel but is rather a way of describing its ability to combust in a controlled manner without causing excessive engine knocking.
What is engine knocking?
the result of uncontrolled detonation of the air–fuel mixture in a combustion engine.
This is more common in fuels that have a low octane number. Automobile
Describe the carbon-carbon bonds in aromatic hydrocarbons.
Aromatic hydrocarbons have a benzene ring.
The analysis of X-ray diffraction patterns generated from the crystalline showed that all six carbon-carbon bonds have identical bond length of 140 pm as opposed to alternating double and single bonds as initially thought.
Benzene contains six sp2 hybridized carbon atoms bonded to one another and each carbon is bonded to a single hydrogen atom by sigma bonds.
The p orbitals of the six sp2 hybridized carbon
atoms overlap one another, forming a continuous π bond that lies above and below the plane of the six carbon atoms.
Define hydrogenation.
The addition of hydrogen to unsaturated hydrocarbons in the presence of a catalyst.
What is volatility?
The tendency to change state from liquid to gas.
Volatility decreases as the length of the carbon chain increases.
What are the products of complete combustion of alkanes?
in the presence of excess oxygen, the products are CO2 and H2O.
What is a free radical?
Species that is formed when a molecule undergoes homolytic fission.
What is a homolytic fission?
when two electrons of a covalent bond are split evenly between two atoms resulting in two free-radicals that each have a single electron.
What is a heterolytic fission of a bond?
Creates a cation and an anion, as the electrons involved in the bond are unevenly split between the two atoms.
What are the three stages in free radical substitution using the reaction between methane and chlorine?
1) Initiation, where the homolytic fission of chlorine molecule in the presence of UV light produces two chlorine radicals.
2) Propagation, which involves the reaction between methane and chlorine free radical resulting in methyl radical, which then reacts with chlorine molecule to produce chloromethane and chlorine free radical.
3) Termination, which reduces the concentration of radicals in the reaction mixture due to decreasing concentration of hydrocarbons.
Chlorine radicals forms chlorine molecules, chlorine radical and methyl radical form chloromethane and two methyl radicals form ethane.
What is the test for saturation?
Testing for the presence of double or triple bond in a hydrocarbon can be shown using the addition of bromine water, Br2(aq), in an addition reaction.
The mixture undergoes a colour change from brown to colourless.
Which catalyst is used in hydrogenation of ethene?
nickel catalyst at a temperature of 150°C
What is hydrogenation of ethene used for and what are the consequences?
It’s used in food industry to produce saturated ethane that increases the melting point, creating margarine.
Saturated fats and oils increase the blood concentration of low-density lipoproteins (LDL), which transport cholesterol in blood. Raised levels of LDL are associated with increased health risks.
Which catalyst is used in the production of ethanol?
phosphoriv (V) acid at 300 °C, where ehene reacts with steam.
What is addition polymerisation?
Reaction of many small monomers that contain a carbon-carbon double bond.
Oxidation of primary alcohol.
two step process, using acidified potassium dichromate (VI) or potassiu manganate (VII):
alcohol → aldehyde →carboxylic acid
Distillation
prevents further oxidation of aldehyde.
Refluxing
technique that involves the cyclic evaporation and condensation of a volatile reaction mixture, preserving the solvent (here carboxylic acid)
Oxidation of secondary alcohol.
results in the formation of a ketone
What is esterification?
reversible reaction between a carboxylic acid and an alcohol in the presence of a catalyst, usually concentrated sulfuric acid.
How to name esters?
consists of two words, 1st is derived from the alkyl chain in the alcohol and 2nd is the root name of the carboxylic acid followed by the suffix “anoate”
What are nucleophiles?
Electron-rich species that contain a lone par of electrons and sometimes carry a full negative charge.
They act as Lewis bases.
What is an electrophile?
An electrophile is an electron-poor species capable of accepting an electron pair.
It acts as a Lewis acid.