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Overview of organic chemistry

The general formulae of the four important classes of organic compounds are listed below.

  • Alkanes: $$\text{C}_\text{n}\text{H}_\text{2n+2}$$
  • Alkenes: $$\text{C}_\text{n}\text{H}_{2\text{n}}$$
  • Alcohols: $$\text{C}_\text{n}\text{H}_{2\text{n}+1}\text{OH}$$
  • Carboxylic acids: $$\text{C}_\text{n}\text{H}_{2\text{n}+1}\text{COOH}$$

The table shows a summary of the properties of each homologous series.

Class Alkanes Alkenes Alcohols Carboxylic acids
Functional group $$\ce{C-C}$$ $$\ce{C=C}$$ $$\ce{-OH}$$ $$\ce{-COOH}$$
Solubility (water) Insoluble Insoluble Soluble Soluble
State at r.t.p. (for $$\text{n}\leq 4$$) Gas Gas Liquid Liquid
Flame Clean, blue Sooty flame - -

Important reactions:

  • Alkanes: combustion, substitution
  • Alkenes: combustion, addition (with hydrogen/bromine/steam)
  • Alcohols: combustion, oxidation to form carboxylic acids
  • Carboxylic acids: react with reactive metals/bases/carbonates, react with alcohols to produce esters

Methods of preparation:

  • Alcohols: fermentation, addition of steam to ethene
  • Carboxylic acids: oxidation of alcohol by exposure to atmospheric oxygen, oxidation of alcohol by addition of potassium dichromate (VI)