Introduction to Organic

Organic chemistry summary

The chemistry of carbon containing compounds except diamond, graphite, carbonates CO and CO2

Each carbon forms 4 covalent bonds

Molecular formula definition (must know Mr)

The actual number of atoms of each element present in a molecule e.g. C4H8

Empirical formula definition

The simplest whole number ratio of atoms of each element present in a molecule e.g. CH2

What is a structural formula?

Shows how the atoms in a molecule are arranged e.g. pentane is CH3CH2CH2CH2CH3

What is a displayed formula?

Shows all the atoms and bonds in a molecule

What is skeletal formula?

Shows the shape of the carbon skeleton

Homologous series definition

A family of compounds containing the same functional group and having the same general formula but having a different carbon chain length- each successive member has an extra CH2

e.g. alcohols all have -OH (functional group)

Functional group definition

An atom or group of atoms which gives an organic compound its particular chemical properties

How to find the general formula of a compound?

• Count up the number of carbon and hydrogen atoms

• CnH2n- either subtract or add numbers to fit this formula

Suffixes of functional groups in the homologous series

• Alkene -ene

• Alkane -ane

• Amine -amine

• Alcohol -ol

• Ketone -one

• Aldehyde -al

• Nitrile -nitrile

• Acyl chloride -oyl chloride

• Ester -oate

• Carboxylic acid -oic acid

Hydrocarbons definition

Compounds containing carbon and hydrogen atoms only

Saturated (hydrocarbons) definition

Contain single carbon-carbon bonds only e.g. alkanes

Unsaturated (hydrocarbons) definition

Contain one or more carbon-carbon double bonds e.g. alkenes

What are different types of hydrocarbons?

• Aliphatic: contain carbons in chains

• Alicyclic: contain carbons in rings

• Aromatic: contain a benzene ring

How to name branched alkanes?

1. First find the longest unbranched (continuous) chain and name the stem

2. Identify the alkyl groups as side chains- these are added to the stem as a prefix

3. Give the position of the side chain by numbering the main chain starting from the end which gives the lowest number

How to name branched alkanes if there are more than one side chains?

• Name in alphabetical order

• Number the main chain from the end which gives the lowest combination of numbers

• If alkyl groups are the same- prefix with di- tri- tetra-

• Each alkyl group is given its own number

• Numbers are separated from names by hyphens, and numbers

How to name compounds?

• Stem- how many carbons there are in the longest chain

• Prefix- before the stem- position of side chains and/or functional groups

• Suffix- after the stem- tells us functional group present

• 3-methylpentane

How to find the stem and alkyl group from the number of carbons in longest chain?

• Stem: meth, eth, prop: increases as a carbon atom is added

• Alkyl group (prefix) if the length of the side chain is 1, it would be methyl, if it is 2 it would be ethyl, propyl, butyl

How to name cyclic alkanes?

• General formula C_nH₂ (functional group isomers of alkenes)

• The stem is cyclo- followed by the name of the longest continuous carbon ring

• The positions of alkyl groups are shown by numbers (if there is just one side chain, a number is not needed)

Structural isomers definition

Compounds with the same molecular formula but a different structural formula

What are the 3 types of structural isomerism?

Chain, position and functional group

What are chain isomers?

They have the same molecular formula but their structures have the hydrocarbon chain arranged differently e.g. C₄H₁₀ can be butane or methylpropane

What are position isomers?

They have the functional group in a different position (the numbers in the name will be different) e.g. C₃H₈O can be propan-1-ol or propan-2-ol

What are functional group isomers?

They have the same molecular formula but a different functional group (the suffix in the name will be different) e.g. pent-1-ene and cyclopentane

Stereoisomerism definition

Compounds with the same structural formula but a different arrangement of atoms in space