chap 5- whats in a medicine Flashcards
what is a primary alcohol
an alcohol where the -OH is bonded to a carbon that is bonded to one other carbon atom
what is a secondary alcohol
an alcohol where the -OH group is bonded to a carbon that is bonded to 2 other carbon atoms
what is a tertiary alcohol
an alcohol where the -OH group is bonded to a carbon that is bonded to 3 other carbon atoms
how are alcohol and water molecules similar
both are polar due to the polarised O-H bond. which causes a strong attractive force between molecules
what do the different alcohols produce when oxidised by acidified potassium dichromate
primary- aldehydes and then carboxylic acid
secondary- ketones only
tertiary- aren’t oxidised
how do secondary alcohols oxidise to ketones
reflux a secondary alcohol with acidified dichromate (VI) to produce a ketone. Ketones can’t be oxidised easily so even prolonged refluxing wont produce anything more
how do you make an alkene from an alcohol
eliminate water from the alcohol in a dehydration reaction
what are the 2 methods of dehydrating an alcohol to obtain an alkene
1) pass ethanol vapour over a hot catalyst of pumice stone or Al2O3 (catalyst provides large SA)
2) reflux the ethanol with excess conc sulfuric acid at 170c. then collect the ethene produced over water
how can you produce an ester from an alcohol
react the alcohol with carboxylic acid or acid anhydrides
alcohol + carboxylic acid=?
ester (in the presence of an acid catalyst) usually conc sulfuric or hcl
how can an alcohol be transformed into a haloalkane
alcohols react with compounds containing halide ions in a substitution reaction. The -OH is replaced by the halide
what is the formula of phenol
C6H5OH
describe the test for phenols
add phenol to neutral iron (III) chloride solution and shake, will turn purple
why are phenols described as weak acids
they dissolve a little bit in water to form a phenoxide ion and a H+ ion- weakly acidic
what is produced when a phenol reacts with an alkali
salt and water
why do phenols not react with carbonate solutions
not a strong enough base to remove the hydrogen ion form phenol
how can you tell phenols apart from carboxylic acids
carboxylic acids react with alkalis and carbonates and give off CO2 gas.
phenols don’t react with carbonates and react with strong alkalis
how can you test whether something is a phenol or a different alcohol
alcohols and phenols react with acid anhydrides to form an ester and a carboxylic acid.
but phenols will not react with carboxylic acids to form an ester
what problem does refluxing avoid
organic reactions are slow and substances are flammable and volatile (low bp) so in a beaker they would evaporate or catch fire before they have time to react
how do you carry out reflux
heat the solution in a flask fitted with a vertical liebig condenser- causes the solution to continuously boil/ evaporate and then condense back into the flask giving it time to react.
why should reflux be heated electronically
avoids naked flames that could ignite the compoundsq
outline the process of distillation
heat a mixture in distillation apparatus, substances will evaporate in order of increasing boiling points, evaporated substance enters condenser cools and condenses back into liquid
it can then be collected, themometer shows bp of substance evaporating at any given time
