C7: Reactions​ ​of​ ​alkenes​ ​and​ ​alcohols​

• Alkenes have the general formula C n H 2n and contain at least one carbon-carbon double bond, making them unsaturated because they contain two fewer hydrogen atoms than the alkane with the same number of carbon atoms.
• The first four alkenes are ethene, propene, butene and pentene.
• Alkenes are hydrocarbons with the functional group C=C, which are usually responsible for the reactions of organic compounds.
• Alkenes react with oxygen in combustion reactions in the same way as other hydrocarbons, but they tend to burn in air with smoky flames because of incomplete combustion, meaning carbon or carbon monoxide is formed (CO).
• Alkenes also react with hydrogen, water and the halogens, by the addition of atoms across the carbon-carbon double bond so that the double bond becomes a single carbon-carbon bond.
• In each reaction with hydrogen, water and halogens, every reaction works the same for all alkenes, the table just shows examples.
• Methanoic acid, ethanoic acid, propanoic acid, and butanoic acid do not ionise completely in solutions, so they do not release many H+ ions, making carboxylic acids weak acids.
• Methanoic acid, ethanoic acid, propanoic acid, and butanoic acid react with alcohols in the presence of an acid catalyst to produce esters.
• The lack of complete ionisation in solutions of methanoic acid, ethanoic acid, propanoic acid, and butanoic acid results in a higher pH (less acidic) than solutions of strong acids of the same concentration.
• The first four members of the carboxylic acid family are methanoic acid, ethanoic acid, propanoic acid, and butanoic acid, represented by the formulas CHOOH, CH 3 COOH, C 2 H 5 COOH, and C 3 H 7 COOH respectively.
• Methanoic acid, ethanoic acid, propanoic acid, and butanoic acid dissolve in water to produce acidic solutions with a pH less than 7.
• Methanoic acid, ethanoic acid, propanoic acid, and butanoic acid react with alcohols to produce esters.
• Methanoic acid, ethanoic acid, propanoic acid, and butanoic acid react with metal carbonates to produce carbon dioxide, a salt, and water.
• Alcohols contain the functional group –OH.
• H2 splits into 2 H’s, H2O splits into a H and an OH, Br2 splits into 2 Br’s, the same applies for Cl2 or I2.
• Ethanol can be produced by fermentation of sugar with yeast, using renewable sources, conditions: about 35°C, anaerobic (without oxygen) and yeast enzyme catalyst, sugar → ethanol + carbon dioxide.
• In an alkene the C=C bond is broken to form a C-C bond.
• Reactions of methanol, ethanol, propanol and butanol include burning in air, which produces carbon dioxide and water, dissolving in water to form a neutral solution (has a pH of 7), and reacting with sodium to produce hydrogen and a salt.
• Ethanoic acid is a member of the carboxylic acids, they have the functional group –COOH.
• The compound added splits into two groups and the two groups are added to the 2 different carbons in the C=C bond, each group can be added to either carbon.
• Ethanol can be represented by CH3CH2OH.
• Uses of methanol, ethanol, propanol and butanol include methanol as a chemical feedstock, in anti-freeze, to make biodiesel, ethanol as the main alcohol in alcoholic drinks, used as a solvent and fuel, all 4 can be used as fuels.
• The first 4 members of the series are methanol, ethanol, propanol and butanol: methanol CH3OH, ethanol C2H5OH, propanol C3H7OH, butanol C4H9OH.
• Alcohols can be represented by: CH3OH, CH2OH, CH2CH2OH, CH2CH2CH2OH, CH3CH2OH, CH3CH2CH2OH, CH3CH(OH)CH2OH, CH3CH2CH(OH)CH2OH, CH3CH2CH2CH(OH)CH2OH, CH3CH2CH2CH2CH(OH)CH2OH.