Basic concepts organic chemistry

Chapter 11

Application of IUPAC rules of nomenclature

1. Find the longest carbon chain → parent name.

2. Number the chain for the lowest locants.

3. Highest priority functional group = suffix (-ol, -oic acid, etc.).

4. Side groups/substituents = prefixes (methyl-, chloro-, etc.).

5. Write substituents alphabetically with their positions.

6. Use commas between numbers and hyphens between numbers/words.

7. Combine into the full IUPAC name.

General, structural and displayed formula

General: the simplest algebraic formula of a member of a homologous series (e.g. alkane - CnH2n+2)

Structural: the minimal detail that shows the arrangement of atoms in a molecule (e.g. butane - CH3CH2CH2CH3 or CH3(CH2)2CH3)

Displayed formula: the relative positioning of atoms and the bonds between them (e.g. alkene functional group C=C)

Skeletal formula

Simplified organic formula shown by removing the hydrogen atoms from alkyl chains, leaving carbon skeleton and functional groups

Homologous series

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

R may be used to represent alkyl groups, but also other fragments of organic compounds not involved in reactions.

Functional group

A group of atoms responsible for the characteristic reactions of a compound

Saturated compound contains just C-C bonds and unsaturated contains C=C, C triple bond C and aromatic rings

Degree of saturation

The degree of saturation describes how many rings or multiple bonds are present in a compound.

• More multiple bonds/rings → higher degree of saturation

• Includes:

  • double bonds (C=C)

  • triple bonds (C≡C)

  • cyclic/ring structures

Alkyl group

Alkyls are the main hydrocarbon chain or molecule (-1 hydrogen) as a substituent with the formula of CnH2n+1

For example, methyl (CH3) is alkyl of methane (CH4)

Aliphatic, alicyclic and aromatic

Aliphatic (a compound containing carbon and hydrogen joined together in straight chains, branched chains or non-aromatic rings)

Alicyclic (an aliphatic compound arranged in non-aromatic rings with or without side chains)

Aromatic (a compound containing a benzene ring)

Structural isomer

Compounds with the same molecular formula but different structural formulae


Chain isomers → different carbon chain arrangement

Position isomers → same groups, different positions

Functional group isomers → different functional groups

Covalent bond fission

Homolytic fission (in terms of each bonding atom receiving one electron from the bonded pair, forming two radicals)

Heterolytic fission (in terms of one bonding atom receiving both electrons from the bonded pair)

Radical

A species with an unpaired electron, highly reactive, represented with a dot (Chlorine radical - Cl•)

Curly arrows

Curly arrows show the movement of an electron pair, which is used in reaction mechanisms and heterolytic fission

Half curly allows are used in homolytic fission to show the movement of one electron (forming radicals)