IB Chemistry SL - Classification of Organic Compounds (S3.2)

organic chemistry

the study of all chemicals containing carbon

homologous series

a series of organic compounds with the same functional group, but with each successive member differing by CH2

properties of hydrocarbons

hydrophobic, nonpolar, good source of stored energy.

melting and boiling points increase as the carbon length increases because the atomic weight of the molecule increases.

alkanes

a hydrocarbon containing only single covalent bonds. with suffix -ane. general formula CnH2n+2

alkene

hydrocarbon containing >1 double C=C bond. suffix -ene, general formula CnH2n

alkyne

hydrocarbon containing a triple bond between carbons. suffix -yne, with general formula CnH2n-2

functional group

group of atoms within a molecule that interacts in predictable ways with other molecules, typically hydrocarbons

structural formula

a formula that shows the arrangement of atoms in the molecule of a compound.

condensed structural formula

a structural formula that leaves out some bonds and/or atoms; the presence of these atoms or bonds is understood

skeletal formula

A simplified organic formula, with hydrogen atoms removed from alkyl chains, leaving just a carbon skeleton and associated functional groups. Remember that carbons are always at the ends and bends

branched alkenes

Alkenes with side chains off the main chain. Typically have lower boiling points. Named in a series of -yne- (e.g. methylheptane)

alcohol

has a suffix -ol, containing an -OH group at the end. if there is a more prestigious suffix, it contains an infix of n-hydroxy-n

primary, secondary, tertiary and quaternary structures of alcohol

determines where the -ol group is attached

aldehydes

terminal ending with double bond =O and H. Has an ending of -al

ketones

internal functional groups containing a carbonyl bonded to two alkyl chains. In nomenclature, they use the suffix -one

carboxylic acid

always has an ending of __anoic acid. Contains a double bond =O and -OH functional groups (COOH)

ether

R-O-R. contains a single oxygen which joins two structures together. First chain is called -oxy, second chain is called -ane

ester

R-C-O-O-R. contains an additional oxygen bonded to a carbon and a =O bond. First chain is called -yl, second chain is called -oate

a smelly, aromatic molecule.

esterification

The process of joining molecules together to form ester bonds

amine

contains a nitrogen group attached to 2 hydrogens.

am-, az-, amino-, -amine

benzene

Consists of a ring of six carbon atoms with alternating single and double carbon-carbon bonds.

phenol

Benzene ring with an OH group directly attached to it

halogenoalkanes

fluoro, chloro, bromo, iodo added to alkanes.

Term: Homologous series – melting point & boiling point

each successive compound differs by a –CH₂– group. As more - CH₂– units are added, mass and surface area increase, strengthening London dispersion forces.

causes the boiling point to increase steadily, while the melting point generally increases

Term: Homologous series (identification)

Alkanes: C–C single bonds only

Alkenes: C=C double bond

Alkynes: C≡C triple bond

Halogenoalkanes: –X (F, Cl, Br, I) attached to carbon

Alcohols: –OH

Aldehydes: –CHO (terminal carbonyl)

Ketones: C=O within carbon chain

Carboxylic acids: –COOH

Ethers: –O– between two carbon chains

Amines: –NH₂ (or –NHR / –NR₂)

Amides: –CONH₂

Esters: –COO–

Term: Structural isomers

Definition: Structural (constitutional) isomers are molecules that have the same molecular formula but different connectivities of atoms, resulting in different structural arrangements.

Term: Types of structural isomers

Definition:
• Straight-chain vs branched isomers: differ in the arrangement of the carbon chain
• Positional isomers: same functional group, but in different positions on the carbon chain
• Functional group isomers: same molecular formula, but different functional group