C6.2 Organic Chemistry

Compounds that only contain hydrogen atoms and carbon atoms Release carbon dioxide when burnt Example: coal

Hydrocarbons Saturated - each carbon is bonded to another carbon by a single covalent bond General formula CₙH₂ₙ₊₂ Names ending in “ane”

. H . | Methane CH4 : H - C - H . | . H . H H . | | Ethane C2H6 : H - C - C - H . | | . H H Propane C3H8 Butane C4H10 Pentane C5H12

Up to 4

Only 1

Combustion when alkanes react with oxygen in the air and burn If plentiful supply of oxygen or air complete combustion happens: carbon atoms oxidised to carbon dioxide, hydrogen atoms are oxidised to water Example: propane + oxygen -> carbon dioxide + water If poor supply of oxygen or air incomplete combustion happens instead alkane + oxygen → carbon monoxide (CO) + water problem because carbon monoxide is toxic gas and can cause suffocation Some carbon atoms may not be oxidised at all and released as carbon particles. CLEAN FLAME PRODUCED

Hydrocarbons Unsaturated: Contain a carbon - carbon double covalent bond, C=C that can open up in reactions and bond General formula CₙH₂ₙ

METHENE DOES NOT EXIST!!! . H H . | | Ethene: C2H4: C=C . | | . H H Propene: C3H6 . H H H . | | | Butene: C4H8 : H-C-C-C=C . | | | | . H H H H Pentene: C5H10 EACH CARBON ATOM MUST HAVE NO MORE THAN 4 ARMS

alkenes can burn in oxygen or air, and the products of combustion are the same as alkanes SMOKY DIRTY FLAME PRODUCED alkenes have a functional group allowing them to take part in wider range of reactions C=C is the functional group - lets alkenes undergo addition reactions where double carbon bond opens up

atom or group of atoms combines with a molecule to form larger molecule, with no other product. alkenes react with bromine in addition reactions forming colourless ‘dibromo’ compounds as they are unsaturated and C=C bond can open up but alkanes cannot as they are saturated with no C=C double bond alkene + bromine → saturated, colourless dibromo-alkane compound Example: Ethene + bromine -> dibromoethane The alkene decolourises bromine water that can be used . to test for saturation . C2H4 + Br2 -> C2H4Br2 . H H H H . | | | | H-C=C-H + Br-Br -> H-C-C-H . | | . Br Br

Hydrogenation - Undergo addition reactions with hydrogen in presence of nickel catalyst Example: Ethene + hydrogen -> ethane . C2H4 + H2 -> C2H6 C=C carbon double bond opens up to react

Functional group: -OH (hydroxyl group) General formula: CₙH₂ₙ₊₁OH

. H . | Methanol: CH3OH: H-C-O-H . | . H . HH . | | Ethanol: C2H5OH: H-C-C-O-H . | | . HH Propanol: C3H7OH Butanol: C4H9OH Pentanol: C5H11OH

alcohol + oxidising agent → carboxylic acid

general formula CₙH₂ₙ₊₁COOH functional group: -COOH (carboxyl) Made by adding acidified (with H₂SO₄) potassium manganate solution to alcohol and warming with water bath Colour change from purple to very pale pink as manganate ions are reduced to manganese atoms

same as any weak acid: Carboxylic acid + metal -> salt + hydrogen Carboxylic acid + base -> salt + water Carboxylic acid + carbonates -> salt + water + carbon dioxide

Remains of marine organisms / organic material buried under sea bed over millions of years under high temperatures and pressures Finite resource Separated by fractional distillation as larger molecules have higher boiling points, due to stronger intermolecular forces

LPG, petrol, paraffin, diesel, heating oil, fuel oil, bitumen

long alkane → smaller alkane + alkene 600-700⁰C Alumina or silica catalyst

High pressure Catalyst

Monomers are nucleotides (strands joined by hydrogen bonding)

Amino acids, each with functional group at each end (amine / amino group NH₂ and carboxyl COOH) Amino acid structure: . HH O . | | || H-N-C-C-O-H . | . R

starch, polymer of simple sugars like glucose

carboxylic acid + alcohol → ester + water