Chapter Nine : Properties and reactions of organic compounds Flashcards
Intermolecular forces
Dispersion
Dipole-Dipole
Hydrogen
Dispersion forces
Non-polar molecules Electrons are momentarily distributed unevenly inducing a temporary dipole Weak forces Increase as chain length increases Decreases with branching
Dipole-Dipole
Polar molecules
The partial positive charge on one attracts the partially negative charge on the other
Stronger than dispersion
Hydrogen bonding
Hydrogen bonds to FON
Stronger than dispersion and dipole-dipole
Structural isomers
Chain isomers - different branching in carbon chain
Positional isomers - different position of functional group
Functional isomers - Same atoms different functional groups
Stereoisomers
Cis isomers - when the groups are on the same side
Trans isomers - when groups are on opposite sides
Enantiomers - non-super imposable mirror images with a chiral centre
Alkane properties
Non-polar
As size increases dispersion forces increase, so MP and BP increases
As branching increases dispersion forces decrease and BP
Insoluble in water
Viscosity increases in size decreases as temp increases
Smaller ones have lower flashpoint
Flashpoint
Is the lowest temperature at which a liquid gives off enough vapour to start burning at its surface with the application of ignition source
Alkene/alkyne properties
Alkenes are more reactive than alkanes
Alkynes have low polarity
Highly flammable
Alcohol properties
Higher BP due to hydrogen bonding BP increases as chain length increases Smaller alcohols are soluble in water Volatility decreases with length Viscosity increases with length
Carboxylic acid properties
Smaller acids are soluble in water
Higher BP than alkanes/alcohols due to H bonds
Solubility decreases with chain length
Aldehydes and ketones properties
Volatile compounds
Solubility decreases with chain length
Higher BP than alkanes but lower than alcohols or acids
Ester properties
Lower BP than acids
Small esters are soluble in water
Amine properties
Weak base that accepts protons
Lower BP than alcohols
Solubility decreases with chain length
Amide properties
Have a higher BP/MP
Soluble but less soluble than amines/COOH
Reactions of alkanes
Combustion - reacts w O2 to for CO2,CO and H2O
Substitution - reacts with halogens in presence of UV light
Cracking - Using heat to break larger molecules to smaller molecules
Reactions with alkenes
Combustion - reacts w O2 to for CO2, CO and H2O
Addition - double bond breaks when electronegative atom is reacted. H2 requires Pt, Pd or Ni catalyst
Forming alcohols - steam in presence of H3PO4 catalyst
Addition polymerisation - Adding monomers to make polymers
Alcohol reactions
Combustion - reacts w O2 to form CO, CO2 and H2O
Substitution - Removing OH group and subbing it with a different functional group
Oxidation (1) - Oxidises to aldehyde then COOH in presence of H+/MnO4 or H+/Cr2O7-
Oxidation (2) - oxidises to ketones in presence of H+/MnO4 or H+/Cr2O7-
Haloalkanes reactions
Forming alcohols - reaction NaOH or KOH with haloalkane will give an alcohol
Ester reactions
Condensation - Reaction between COOH and OH to form esters in presence of heat/sulfuric acid
Hydrolosis - When water is added to an ester to split it back into OH and COOH using heat and dilute acid
Carboxylic acid reactions
Hydrolyse - seperate in water to become COO-
Acid-base - react with bases, Mg and metal carbonates
COOH and amine reactions
Small amines act as base, COOH donates protons
COOH + NH2 > ammonium salt >(heat/dehydration) > amide + water