derivitives of carboxylic acids Flashcards
monoester
an ester which contains only 1 ester group
transesterification
a reaction where the alkyl group of an ester is exchanged with the alkyl group of an alcohol
biodiesel
a fuel, similar to diesel, which is made from vegetable sources, eg from the reaction of rape seed oil with methanol
what are the 2 ways to prepare an ester
-reaction with alcohol and carboxylic acid
-reaction with alcohol and acyl chloride
reaction of alcohol with carboxylic acid
eg. methanol + ethanoic acid <> methyl ethanoate + water
observations: sweet smell of ester
conditions: conc sulfuric acid catalyst, heat under reflux
general formula of esters
CnH2nO2
reaction with acyl chloride
propanoyl chloride + pentanol > pentyl propanoate
conditions: room temperature
observations: vigorous reaction, heat released and steamy fumes of HCl
why is the reaction with an acyl chloride favoured
-produces a higher yield (as reaction is not reversible ie goes to completion)
-is a faster reaction and occurs at room temp
-a purer ester is produced because the by product is gas
physical properties of ester
- neutral liquids with a pleasant fruity odour
- solubility in water
boiling points
-have permanent dipole-dipole attraction as they are polar
NO H BONDS
whys is % yeild not 100% ?
- some product lost is distillation
-some product lost in solvent extraction
-side reactions occur
acid hydrolysis
reflux with dilute hcl forming carboxylic acid and an alcohol
base hydolysis
sodium hydroxide solution
forms sodium salt
liberate by adding dilute mineral acid
acyl chloride reaction with water
propanoyl chloride + water > propanoic acid + hydrogen chloride
condition: room temperature
observations: reaction warms up,misty fumes, vigorous reactions
reaction of acyl chloride with alcohol
propanoyl chloride + propanol > propyl proanoate + hydrogen chloride
what is glycerol
propane-1,2,3-triol
examples of saturated and unsaturated fatty acids
- saturated: stearic acid (C17H35COOH)
- unsaturated: oleic acid (C17H33COOH)
how are fats formed
in a condensation reaction between glycerol and fatty acids
how are esters formed
condensation reaction between alcohol and carboxylic acid
why is oleic acid insoluble in water but sodium oleate is soluble
oleic acid has only one polar group attached to a long non-polar hydrophobic hydrocarbon chain
which hinders the formation of hydrocarbons
sodium olelate is soluble as it exhibits ionic bonding
what are fats with more than one c=c called
polyunsaturated
what do more c=c cause
the fat to have a lower melting point and so is most likely an oil
what do saturated fats provide
energy and insulation in the body
what can fats cause in the body
increased levels of LDL (low density lipoprotein) and can lead to coronary heart disease
