IB SL CHEMISTRY:
ORGANIC CHEMISTRY
Compiled by Minna Pöntinen 21/11/02

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NAMING, FUNCTIONAL GROUPS & HOMOLOGOUS SERIES

Naming the compounds:
- Identify the longest carbon chain (meth, eth, prop, but, pent, hex, hept,
  oct)
- Identify the type of bonding (-an-, -en-, -yn-)
- Identify the functional group
- Do the numbering:
  - Identify the longest C chain
  - Give the numbers for the side group(s) (start the numbering from the end
    to which the group(s) is/are closer to)

Some common functional groups
Name		Formula			Prefix/suffix
Alkane		R-H			-an-
Alcohol		R-OH			-ol
Amine		R-NH2			amino-
Halogenoalkane	R-X			chloro-, bromo-, etc
		(where X=halogene)	
Aldehyde	R-(C=O)-H		-al
Ketone		R-(C=O)-R'		-one
		(R can be R')		
Carboxylic acid	R-(C=O)-OH		-oic acid
Ester		[R-(C=O)-OR']		-oate
Amide		[R-(C=O)-NH2]		-amide

Homologous series
- Alkanes: series with a general formula C6H2n+2
- Members of a chemical series have similar chemical properties, and they
  show a slight change in physical properties

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PROPERTIES OF FUNCTIONAL GROUPS

Boiling points
- Longer C chain -> mass of molecules increases -> van der Waals' forces
  increase -> boiling point increases
- Branching lowers the boiling point (lowered surface area)
- Boiling point increases in the following order: Alkane, alkene, alkyne,
  ester, aldehyde, ketone, amine, alcohol, carboxylic acid

Solubility in water
- Depends on the polarity of the functional group & the chain length
- Alcohols, amines, aldehydes, ketones & carboxylic acids are usually water
  soluble
- Alkanes and alkenes are often not soluble in water

Acidity and basicity
- Carboxylic acids are weak acids
- Amines are weak bases

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ISOMERISM

- Structural isomerism:
  - the same molecular formula but different structural formula
  - similar physical properties
- Functional isomerism:
  - the same molecular formula but a different functional group
  - very different physical properties
- Optical isomerism:
  - common with all 2-amino acids (except glycine)
  - assymetric or chiral carbon atom: one C that contains 4 different groups
    attached to it
  - plane polarized light can rotate the molecule
  - chemical properties are the same except when they interact with other
    optically active substances

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ALKANES, ALKENES & ADDITION REACTIONS

Alkanes
- Strong C-C and C-H bonds; alkanes are quite unreactive
- Main reaction: (exothermic) combustion -> CO2 + H2O
- Hydrocarbons are used as fuels -> environmental problems: global warming;
  CO is poisonous

Alkenes
- Main reaction: addition -> C=C bonds are broken and are substituted by
  other groups
- Addition reactions include the addition of H, Br, H halides and H2O
- Uses of the addition reaction:
  - Bromination: decolourization of Br means the presence of an alkene group
  - Hydration: H2O + ethene -> ethanol
  - Hydrogenation: H + vegetable oils -> margarine
- Addition polymerization: ethene can undergo addition reaction with itself
  to produce a long chain polymer
  - Example: H2-C=C-H2 -> -(CH2-CH2)-n

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ALCOHOLS & CONDENSATION REACTIONS

- Alcohols + carboxylic acids -> condensation reaction -> esters
- Most esters have a pleasant, fruity smell
- Ethanol -> oxidation -> (aldehyde) -> ethanal

Condensation polymerization
- The reaction between two molecules to eliminate a smaller molecule
- Amines can condense with carboxylic acids to form an amide link (peptide
  bond) (example of a polyamide: nylon)

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AMINO ACIDS AND POLYPEPTIDES

- Contain an amine functional group and carboxylic acid functional group
- Attached to the same carbon = 2-amino acids = alpha-amino acids
- About 20 amino acids occur naturally; basic building blocks of the proteins
  of the body (long chains formed by condensation reactions)
- Two amino acids condense -> dipeptide & water (tripeptide is made up of
  three amino acids)
- If the three amino acids are different, six possible combinations can occur
- Amino acids feature optical isomerism

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