What’s in a medicine? Flashcards
name the three types of alcohols
primary, secondary and tertiary
where is the -OH group attached in a primary alcohol
the carbon which carriers the OH group is attached to 1 alkyl group
what are primary alcohols oxidised to
aldehydes then to carboxylic acids
what are secondary alcohols oxidised to
ketones
why does ethanol dissolve in water?
hydrogen bonding between the ethanol and the water means the IMF’s are similar so the 2 molecules dissolve
where is the -OH group attached in a secondary alcohol?
it is attached to 2 alkyl groups directly
where is the -OH group attached in a tertiary alcohol?
it is attached to 3 alkyl groups directly
how are tertiary alcohols oxidised?
they cannot be
what is produced if an alcohol is dehydrated?
an alkene
how can alcohols be dehydrated?
- pass ethanol vapour over hot catalyst of Al2CO3
or - reflux ethanol with excess concentrated sulphuric acid @ 170°c
alcohol + carboxylic acid —>
ester and water
alcohol + acid anhydride —>
ester (and carboxylic acid)
how can alcohol make a haloalkane?
-OH on the alcohol can be swapped with a halogen
what else is produced when a haloalkane is?
water
what is an ether?
a structural isomer of an alcohol
name this ether - CH3 - CH2 - O - CH3
methoxyethane
give the 4 properties of acid anhydrides
•colourless
• strong acidic odour
•react with H2O
•dissolve in organic solvents
why do acid anhydrides have lower boiling points than carboxylic acids?
larger polar molecule
with dipole-dipole and ID-ID forces
but no H bonding
so bpt not high
what is a phenol?
a benzene ring with -OH groups attached
how do you test for phenols?
add iron (lll) chloride solution and shake. turns purple if phenol present
what happens when a phenol is in water?
it dissolves slightly to form a phenoxide ion and H+ ion
phenol + alkali —>
salt and H2O
why don’t phenols react with carbonate solutions?
they’re not strong enough bases to remove H+ ion from phenol
phenol + acid anhydride —>
ester and carboxylic acid
how can you distinguish between an alcohol and phenol
phenols don’t react with carboxylic acids to make esters but other alcohols do
what can thin layer chromatography be used for?
•separate mixtures
•purify substances
•identify substances
how do you calculate Rf value?
distance travelled by spot / distance travelled by solvent
how can colourless compounds be revealed when doing chromatography?
UV light or iodine vapour
what are the two phases of chromatography?
mobile and stationary
what is the mobile phase of chromatography?
the liquid or gas
what is the stationary phase of chromatography?
the material that doesn’t move
what happens when IR radiation is absorbed by covalent bonds in the molecules?
their vibrational energy increases
what do you mean by vibrational energy increases?
they vibrate more
how can IR radiation help us identify bonds?
different bonds absorb different frequencies of IR radiation that we can check in a table
what device produces an infrared spectrum?
an infrared spectrometer
what is used to produce a mass spectrum?
a mass spectrometer
what happens when a compound is in a mass spectrometer? and what does this do to the molecule?
molecules in sample are bombarded with e- which remove an e- from the molecule to form M+ ion
which peak on a graph is the m peak?
the peak with the second highest mass/charge ratio
what causes the M+1 peak?
the presence of carbon-13
where would you find an M+1 peak on the graph?
smaller peak to the right of the M peak
what is the expected colour change when an alcohol is oxidised?
orange —> green
how do you oxidise an alcohol?
(3 points)
1.alcohol + sulphuric acid + potassium dichromate
2.heat and distill out to get aldehyde
3.reflux to get carboxylic acid
what is meant by the term reflux?
to hear or boil without losing reactants, products or solvent
how do you make ethanal from ethanol?
potassium dichromate + ethanol + sulphuric acid and heat
distill out ethanal as it forms
explain how to make ethanoic acid from ethanol
reflux potassium dichromate, sulphuric acid and ethanol
for 30 - 60mins
then distill out ethanoic acid
explain how to purify a solid by recrystallisation
- dissolve solid in minimum volume of hot solvent
- filter when hot to remove impurities
- then cool and collect pure sample by filtration
what does the carbon next to the OH in an alcohol need to have on to undergo dehydration?
a H
to eliminate water
Butan-2-ol is an isomer of butan-1-ol. What type of alcohol is butan-2-ol? Explain your answer
2 marks
secondary
only one H attached to the C atom with the OH on
explain the term pharmacore
1 mark
a part of a molecular structure that is responsible for a particular pharmacological activity
