organics II 5.4 Flashcards
what are alcohols?
organic molecules containing an -OH functional group
what is the formula of methanol?
CH3OH
what is the formula of ethanol?
C2H5OH
what is the formula of propanol?
C3H7OH
what is the formula of butanol?
C4H9OH
why is a number sometimes involved in the name of the alcohol?
as -Oh can be attached in the middle of the carbon chain instead of the end
industrial ethanol manufacture
hydration of ethene:
ethene (C2H4) gas is mixed with steam (H2O)
industrial ethanol manufacture
hydration of ethene - advantages:
makes pure ethanol
can run continuously
industrial ethanol manufacture
hydration of ethene - conditions needed:
300 degrees
65 atm pressure
phosphoric acid (H3PO4) catalsyt
industrial ethanol manufacture
hydration of ethene disadvantages:
conditions require lots of energy
non-renewable raw material used (crude oil)
industrial ethanol manufacture
fermentation of glucose:
glucose (C6H12O6) is fermented microbiologically
industrial ethanol manufacture
fermentation of glucose - conditions needed:
yeast (provides enzymes)
30 degrees (optimum temperature for enzymes)
anaerobic (no oxygen) prevents oxidation
industrial ethanol manufacture
fermentation of glucose advantages:
renewable raw material used (sugar cane)
conditions not energy-intensive
industrial ethanol manufacture
fermentation of glucose - disadvantage:
makes impure ethanol
must be done in individual batches
oxidation
ethanol combustion:
ethanol tends to completely combust because of the oxygen atom in the -OH group
resulting in a non-luminous blue flame
C2H5OH + 3O2 > 2CO2 + 2H2O
oxidation
ethanol microbial oxidation:
many micro organisms such as bacteria and fungi use oxygen in the air to oxidise ethanol into ethanoic acid
can happen aerobically
C2H5OH + 2O > CH3COOH + H2O
oxidation
ethanol chemical oxidation:
heat ethanol with potassium dichromate (VI) and dilute sulphuric acid
this forms ethnic acids
C2H5OH + 2O > CH3COOH + H2O
the orange dichromate ions are turned into a green chromium ions
meaning reaction always has colour change
what are carboxylic acids?
organic molecules containing an -COOH functional group
what is the formula for methanoic acid?
HCOOH
what is the formula for ethanoic acid?
CH3COOH
what is the formula for propanoic acid?
C2H5COOH
what is the formula for butanoic acid?
C3H7COOH
what is vinegar?
an aqueous solution of ethanoic acid
how do you form vinegar?
when ethanol undergoes microbial oxidation
C2H5OH + 2O > CH3COOH +H2O
vinegar has a very sour and acrid taste because of the acidity of ethanoic acid
how can carboxylic acids act as acids?
carboxylic acids can donate H+ to from a salt
as it looses its H and becomes negatively charged
its name changes from ethanoic acid to ethanoate
what would you observe in carboxylic acid + metal > salt + hydrogen reaction?
effervescence
- due to hydrogen gas being produced
solid disappearing
- due to metal being used up in reaction
methanoic acid + sodium > sodium methanoate + hydrogen
what would you observe in carboxylic acid + metal carbonate > salt + water + carbon dioxide reaction?
effervescence
- due to carbon dioxide being produced
solid disappears
- due to metal carbonate being used up in reaction
methanoic acid + sodium carbonate > sodium methanoate + water + carbon dioxide
what are esters?
a family of organic molecules which form when a carboxylic acid and an alcohol join together by losing an H2O molecule
what is the ester functional group?
-COO-
what is the ester reaction?
carboxylic acid + alcohol > ester + water
what is the ester that is formed called?
for example
ethyl ethanoate
what type of reaction is carboxylic acid + alcohol > ester + water?
condensation as it produces water vapour
esterification as it makes an ester
how do you produce/ make an ester?
- mix the carboxylic acid and alcohol together
- add a few drop of concentrated sulphuric acid - this acts as a catalyst for the reaction
- warm it for a while
- tip the mixture into sodium carbonate solution, this neutralises the sulphuric acid catalyst, which is otherwise corrosive
the reaction produces CO2 so wait until the fizzing has stopped
what is the use of esters?
volatile compounds with distinctive smells
making them suitable for use in food flavourings and perfumes
what are polyesters?
a polymer made up off lots of molecules joined together in a chain by ester groups
what two types of monomers do you need to make a polyester?
dicarboxylic acid (that has -COOH- at both ends)
diol (has -OH at both ends)
what type of polymerisation is this?
condensation polymerisation
why is making polyesters condensation polymerisation?
as each time a monomer joins the end of the chain a H2O molecule is lost
what are biopolyesters?
some polyesters are biodegradable, which means microbes such as bacteria and fungi can use enzymes to break down the polymer into its monomers and use them as an energy supply
this is a good thing as it reduces landfill and incineration need to dispose of polyesters
