alcohols part 1 Flashcards
general formula
CnH2n+1OH
functional group
-OH
what can alcohols be classified as
primary, tertiary or secondary
what do primary alcohols have
1 variable group attached to the same carbon as the OH(besides the OH)
what do secondary alcohols have
2 variable groups attached to the same carbon as the OH (besides the OH)
what do tertiary alcohols have
3 variable groups attached to the same carbon as the OH (besides the OH)
what must be indicated if there are 3 or more carbon atoms in the molecule
the position of the OH group
structural isomers
compounds with the same molecular formula but different structural formula
why do alcohols have relatively high melting and boiling points
they form hydrogen bonds
which alcohols are soluble in water
those with a low Mr
why are alcohols with a low Mr soluble in water
hydrogen bonding
how are alcohols generally prepared industrially
by hydration of alkenes
what is the reagent in the production of alcohols by the hydration of alkenes
the alkene and steam
what conditions are needed for the production of alcohols by the hydration of alkenes
- phosphoric acid catalyst
- high temp and pressure
how can the mechanism of hydration be shown
using curly arrows
curly arrows
shows the movement of a pair of electrons
what is the role of the H+ ion in the hydration of alkenes
catalyst (its regenerated)
uses of ethanol
- alcoholic beverage industry
- sterilising medical equipment
- solvents/fuel
what are the two different methods for the industrial preparation of ethanol
- fermentation
- hydration of ethene
examples of carbohydrate crops used in fermentation
sugar cane/sugar beet
what are carbohydrate crops broken down into during fermentation
sugars such as glucose
how are the sugars converted into ethanol during fermentation
by anaerobic respiration
how is ethanol removed from the reaction mixture in fermentation
by fractional distillation
what is the reagent in fermentation
sugar
conditions needed for fermentation
water, 30-35 degrees Celsius, yeast, lack of O2
equation for fermentation
C6H12O6> 2C2H5OH + 2CO2
why is air kept out of the fermentation reaction
prevents oxidation of alcohol into vinegar
why must a compromise temperature of 35 degrees celcius be used
optimum temp for yeast
why does the fermentation stop when the reaction mixture contains about 15% ethanol
at this level of alcohol the yeast is poisoned
what is fractional distillation
separating two or more liquids with differing boiling points eg ethanol and water
why should you heat the flask during fractional distillation
it causes the water and ethanol to vapourise
what happens as a result of the vapour passing up the fractionating column in fractional distillation
the water and ethanol will separate
why will water condense back into the flask in fractional distillation
it has a higher boiling point than ethanol
observe the temperature and keep the temperature at or just below… (FD)
the boiling point of ethanol
where does ethanol vapour pass into during fractional distillation
the condenser
what does the condenser do in fractional distillation
cools the ethanol vapour back into a liquid which is collected in a conical flask
reagents in hydration of ethene
ethene and steam
conditions in hydration of ethene
phosphoric acid catalyst
300 degrees celcius and 60atm
equation for hydration of ethene
CH2=CH2(g) + H2O > CH3CH2OH(g)
comparison of the two processes that produce ethanol: raw material
H: crude oil (finite)
F: sugar (renewable)
comparison of the two processes that produce ethanol: quality of product
H: pure
F: very impure
comparison of the two processes that produce ethanol: rate of reaction
H: very fast
F: slow
comparison of the two processes that produce ethanol: energy requirements
H: high energy use
F: low energy use
comparison of the two processes that produce ethanol: type of process
H: continuous
F: batches
