Organic Chem 7 Flashcards
elimination reactions
a reaction where a small molecule is removed from a larger molecule which leaves a double bond in one of the product molecules
example of elimination reaction
dehydration of an alcohol to from an alkene and water
dehydrating agent for ethanol
aluminium oxide
second example of elimination reaction
second stage in the preparation of PVC from ethene gas
conversion of 1,2dichloroethane to chloroethene and hydrogen chloride
oxidising agent for alcohols
sodium dichromate
colour change during oxidation of alcohol
orange Cr(+6) to green Cr(+3)
primary alcohol oxidised to
aldehyde
aldehyde oxidised to
carboxylic acid
secondary alcohol oxidised to
ketone
sodium dichromate
Na2Cr2O7
what must also be present
H+
are ketones easily oxidised?
no
apparatus to prepare aldehyde
distillation
apparatus to prepare ketone
distillation
apparatus to prepare carboxylic acid
reflux
3 social and applied aspects of oxidation of these
breathalyser test
ethanol oxidised in human body
oxygenates added to petrol
breathalyser test
bag contains sodium dichromate crystals - orange
alcohol in breath will be oxidised and crystals turn green
ethanol oxidised in human body
occurs in liver
further oxidised to carbon dioxide and water
rate is dependent on metabolic rate, sex etc.
carboxylic acid reduced to
aldehydes
aldehydes reduced to
primary alcohols
ketones reduced to
secondary alcohol
reagent for reduction
H2
catalyst for reduction
Ni
nickel catalyst
combustion of alcohol gets
carbon dioxide and water
fully halogenated alkanes
no Hs
flammability of fully halogenated alkanes
not very combustible, hence they are flame-retardant
where would you find fully halogenated alkanes and why?
added to fire extinguishers as they do not allow combustion and are denser than air
2 homologous series that can act as acids
alcohols
carboxylic acids
ethanol and sodium react to give
sodium ethoxide and hydrogen gas
sodium ethoxide
C2H5Na
why does ethanol act as an acid
polar hydroxyl group, oxygen is delta minus and hydrogen is delta plus
explain ethanol as an acid
extremely weak acid, only acts as an acid with an extremely reactive metal such as sodium
why are carboxylic acid, acids?
carboxyl group, contains a carbonyl group C=O
carbon is delta positive
this attracts electrons from -OH group
this is the inductive effect - allows H to be donated
when a carboxyl group loses a proton
a carboxylate ion is formed
stability of carboxylate
length of C=O and C-O bonds are equal so negative charge is not localised but spread over the 3 atoms - gives extra stability
Ethanoic acid and magnesium
magnesium ethanoate and hydrogen
ethanoic acid and sodium hydroxide
sodium ethanoate and water
ethanoic acid and sodium carbonate
sodium ethanoate and carbon dioxide and water
ethanoate
CH3COO
organic synthesis
involves making organic compounds from simpler substances
what does organic synthesis take
many steps and intermediate molecules before target molecule is reached
how can ethanoic acid be synthesised from ethene
hydration of ethene to get ethanol
then oxidised to get ethanoic acid
describe the organic synthesis of PCV from ethene
- ethene undergoes addition reaction with chlorine to form 1,2-dichloroethane
- this is cracked to form chloroethene with the removal of HCl (elimination reaction)
- chloroethene then undergoes polymerisation to form PVC
