Topic 10: Organic Chemistry Flashcards
affixes for number of carbons
1 = meth- 2 = eth- 3 = prop- 4 = but- 5 = pent- 6 = hex- 7 = hept- 8 = oct-
affixes for bonding
single bond: -an-
double bond: -en-
triple bond: -yn-
affix of alkane
-ane
affix of alkene
-ene
affix of alkyne
-yne
affix of alcohol
-ol
affix of carboxylic acid
-oic acid
affix of ether
R1 = -oxy
R2 = -ane
R2 must be the longest chain (so it’ll be used as the parent name)
affix of halide
chloro-/bromo-/iodo-
affix of aldehyde
-al
affix of ketone
-one
affix of ester
R1: alkyl group name (e.g. methyl, ethyl)
R2: -oate
alkene + water -> ?
alcohol
trends in the alkene homologous series
- increase in b.pt down the homologous series
- increase in strength of Van der Waals/London/dispersion forces
- increase in size of molecule/number of electrons
features of a homologous series
- same general formula
- successive members differ by a CH2 chain
- same functional group
- similar chemical properties
- gradual change in physical properties (e.g. m.pt/b.pt)
catenation
carbon’s ability to link itself to form chains and rings
saturated compounds
contain only single bonds
unsaturated compounds
compounds containing double or triple bonds
aliphatics
- compounds that don’t contain a benzene ring
- can be saturated or unsaturated
arenes
- compounds that contain a benzene ring
- all are unsaturated
electrophile
- electron-deficient species
- attracted to electron-rich parts of molecules
- positive ions or at least have partial positive charge
- act as lewis acids
nucleophile
- electron-rich species
- attracted to parts of molecules that are electron-deficient
- nucleophiles have a lone pair of e-s and may also have negative charge
- act as lewis bases
effect of branching on b.pt
- molecules become more spherical due to branching
- ↓ contact SA = ↓ no. of London dispersion forces = ↓ boiling point
organic compounds with London dispersion forces as their strongest intermolecular force
- alkane
- alkene
- alkyne
organic compounds with dipole-dipole forces as their strongest intermolecular force
- ester
- aldehyde
- ketone
organic compounds with hydrogen bonding as their strongest intermolecular force
- amine
- alcohol
- carboxylic acid
factors affecting solubility in water of organic compounds
- polarity of functional group:
- chain length:
factors affecting solubility in water of organic compounds: chain length
- hydrocarbon chain is non-polar
- and non-polar substance prefer to dissolve in non-polar solvents
- lower members of alcohols, amines, aldehydes, ketones, and carboxylic acids are water soluble
- but as the hydrocarbon chain increases in length, solubility in water decreases
ideal solvent for organic compounds
propan-1-ol
- as it contains both polar and non-polar compounds
- so it can dissolve both types (to some extent)
reactivity of alkanes
- saturated hydrocarbons with strong C-C and C-H bonds
- as C-H and C-C bonds are non-polar, they aren’t susceptible to attack by common reactants
- so alkanes are generally stable under most conditions and can be stored/transported/compressed safely
- only readily undergo combustion reactions with oxygen
- only undergoes substitution rxns with halogens in UV light
combustion of alkanes
- alkanes release a significant amount of energy when broken
- so they are widely used as fuels
- alkane combustion reactions are highly exothermic because of the large amounts of energy released when forming CO2 and H2O
- the products are fully oxidized, so alkane undergoes complete combustion
combustion of hydrocarbons in limited oxygen conditions
- incomplete combustion
- CO and H2O produced instead
- in extreme oxygen limitation, just C and H2O will be produced
combustion of hydrocarbons
- under complete or incomplete combustion depending on oxygen availability
- large amounts of energy are released generally
- as C:H ratio increases with unsaturation, so does the smokiness of the flame due to unburned hydrocarbon
why is the combustion of hydrocarbons a problem?
- CO2 and H2O are greenhouse gases
- thus they contribute to global warming and climate change
- CO is a toxin as it combines irreversibly with blood hemoglobin, preventing it from carrying oxygen
- unburned carbon is released into the air as particulates
- they have a direct effect on human health
- they also catalyze the formation of smog in polluted air
- they are also the source of global dimming
substitution reaction
- main reaction undergone by alkanes
- occurs when another reactant (halogen) takes the place of a hydrogen atom in the alkane
- UV rays needed to provide energy to break the covalent bonds in the halogen molecule
- energy splits the halogen molecule into free radicals
- the radicals start a chain reaction in which a mixture of products (including the halogenoalkane) is formed
homolytic fission
- when a covalent bond breaks by splitting the shared pair of e-s between the 2 products
- produces 2 free radicals, each with 1 unpaired e-
heterolytic fission
- when a covalent bond breaks and the shared pair of e-s go to one product
- produces 2 oppositely-charged ions
free radical substitution
- Initiation:
Cl2 → 2Cl•
- in UV light - Propagation: (formation of new radicals)
CH4 + Cl• → CH3• + HCl
CH3• + Cl2 → CH3Cl + Cl• - Termination (when 2 radicals react together)
CH3• + Cl• → CH3Cl
addition reaction
- occurs when 2 reactants combine to form a single product
- characteristic of unsaturated compounds
substitution reaction
- occurs when 1 atom or group of atoms in a compound is replaced by a different atom or group
- characteristic of saturated and aromatic compounds
addition-elimination reaction
- AKA condensation reaction
- occurs when 2 molecules join together (addition) and in the process small molecules are lost (elimination)
- reaction occurs between a functional group in each reactant
addition reaction (alkene + H2)
alkane