alcohols
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what is the general formula for alcohols?
Cn H2n+2 O
what is the functional group of alcohols?
R-OH
what can we classify alcohols as?
primary secondary or tertiary
what are functional group isomers of alcohols?
ethers (hydrogen from R-OH replaced with another R group)
what is hydrolysis?
breaking a bond using water
what are the three mechanisms of making alcohols?
-hydrolysis of organic hydrogensulfates -nucleophilic substitution -electrophilic addition (steam hydration of ethene)
how do we get alcohols from organic hydrogensulfates?
they are easily hydrolysed so hydrolyse using warm water to form alcohols
what is regenerated at the end of hydrolysis of organic hydrogensulfates and what does this act as?
sulfuric acid (H2SO4) so it acts as a catalyst
what are the 3 uses of alcohols?
-alcoholic drinks -solvents -chemical feedstock (used to make other chemicals)
what kind of boiling points do alcohols usually have and why?
high because they form hydrogen bonds with each other
why are only some alcohols soluble?
ones with a lower Mr are soluble in water because they can form hydrogen bonds with water
what are the conditions for making an alcohol via nucleophilic substitution?
aqueous sodium hydroxide, warm
what reaction is used in industry to produce ethanol and what mechanism does it use?
steam hydration (addition of water) of ethene electrophilic addition
what are the conditions for steam hydration of ethene?
steam (300 degrees), pressure of 60atm and phosphoric acid catalyst (H3PO4)
what type of reaction is steam hydration of ethene and what does this mean for the yield?
it is reversible and the yield is very low
how is yield improved by steam hydration of ethene?
any unreacted ethene gas can be recycled and increases the overall yield
what are some advantages of using steam hydration of ethene?
-product is pure (No waste product including CO2) -we can manipulate the reversible reaction to increase yield -higher temperature, therefore, fast rate of reaction -can recycle unused reactants such as ethene gas.
what are some disadvantages of steam hydration of ethene?
-reversible reaction so not 100% yield -ethene is from crude oil contributing to environmental pollution. Thermal cracking of crude oil requires energy. -higher temps required so higher energy consumption
what is the alternative industrial method for making alcohols that doesn’t use a mechanism?
fermentation
what are the reagents of fermentation?
yeast and glucose (C6H1206)
what are the conditions for fermentation?
30-40 degrees, aqueous, anaerobic
what is the role of yeast in fermentation?
catalyst
why is it important that fermentation occurs in anaerobic conditions?
yeast won’t ferment in oxygen and oxyegn would cause the ethanol to be oxidised to ethanal
why do we use 30-40 degree temperatures for fermentation?
compromise because too high temp causes yeast to denature and not ferment