alcohol Flashcards
How can alkenes be made sustainably
Through fermentation of glucose from
plants
What is the process that alkenes are made from alcohol
dehydration
what is a non renewable way of making alkenes from alcohols
from crude oils
what are alkenes used to be make
polymers- made into plastic
What does a dehydration of alcohol reaction require
acid catalyst- H2SO4 ( sulfuric acid) or phosphoric acid H3PO4
normal equation: C2H5OH -> C2H4 + H2O
ethanol-> ethene + water
what is the mechanism for dehydration of alcohols
Elimination mechanism
making cyclohexene step 1
add conc sulfuric acid, phosphoric acid and cyclohexane’s into round bottomed flask, add several anti bumping granules to allow a smooth boiling process
use heating mantle to warm reactants to 83°c ( boiling point of cyclohexanol) - we don’t use bunsen burner because cyclohexanol is flammable
chemicals w boiling points lower than 83°c will evaporate and enter the condenser , cool down and condense back into a liquid, the condenser has cold running water running through the wall
product is collected in vessel e.g clinical flask, however product will have small amounts of impurities such as unreavyer cyclohexanol and water
Making cyclohexene step 2
Separation and purification
add products from step 1 into a separating funnel, add water to dissolve soluble impurities to create a aqueous solution
After allowing the solution to settl, 2 layers will form
Top layer- impure cyclohexene
Bottom layer- aqueous layer containing water soluble impurities
Drain aqueous layer off ( remove stopper)
making cyclohexene step 3
Take impure cyclohexene from step 2 and add to round bottomed flask
Add anhydrous CaCl2, this is a dehydrating agent and will remove aq substances still remaining, invert flask and leave it for 20-30 mins
Hydration of alkenes:
What’s produced and what’s needed
alcohols are produces
steam and acid catalyst (H+) is needed
we can make ethanol by reacting steam and ethene with a phosphoric acid catalyst, a temp of 300° and 60atm
What is fermentation an alternative to?
Ethene and steam when making ethanol
using ethene to make ethanol requires crude oil which isn’t sustainable
using fermentation is renewable as it uses glucose from plants
What does fermentation use and in what conditions
yeast in aerobic conditions
- reaction is exothermic
What’s the fermentation reaction
C6H12O6 (aq) -> 2C2H5OH (aq) + 2CO (g)
glucose -> ethanol + Carbon dioxide
What is yeast and what does it do
it’s an enzyme and it converts glucose into CO2 and ethanol
30-40 optimum temp
fermentation advantages
Requires little equipment and uses renewable energy sources so it’s cheap
Biggest cost however is fractional distillation which requires energy and time ( to purify ethanol after fermentation )
