alcohols

how can alcohols be produced?

hydration
fermentation

conditions for hydration?

aqueous

300 degrees

high pressure

hydration process?

alkene + water → alcohol

what is hydration catalysed by?

acid catalyst

why does hydration produce a high % yield?

alcohol is the only product

features of hydration?

non-renewable

expensive

properties of alcohols?

high MP + BP due to hydrogen bonding [O-H]

short chained

soluble in water

contain all forces

how does chain length affect solubility?

longer chain = less soluble

equation for fermentation?

C₆H₁₂O₆ → 2CH₂CH₅OH + 2CO₂

conditions for fermentation?

35 degrees

enzyme controlled

happens in barrels to keep air out for anaerobic respiration to take place

why is the %yield for fermentation low?

doesn’t produce pure ethanol;

• mix of water, sugar + dead yeast

• separated by distillation

done in batches

features of fermentation?

renewable - plants doing process can be regrown

cheaper - uses less energy

• lower temps + pressures

• but distillation may be costly

slower

why is fermentation useful?

ethanol burnt as a bio fuel

fuel is carbon neutral

bio fuel?

fuel produced from biomass like plants

carbon neutral meaning?

CO₂ released when burnt = to amt. when being grown

why may fermentation + burning biofuel process not be carbon neutral?

CO₂ taken in and released during process being equal doesn’t take into account:

• energy for transport + prepping crops

issues w/ fermentation?

land for crops used for fuel rather than food

→ food shortages

oxidising agent used of oxidisation?

acidified potassium dichromate

what’s produced when a primary alcohol is gently oxidised?

aldehyde formed

gently oxidised meaning?

use small amount of agent; alcohol is in excess

how is a primary alcohol oxidised?

distilled setup

alcohol heated then condensed

ethanal + water drip into flask

what is produced when a primary alcohol is vigorously oxidised?

forms a carboxylic acid

how can a carboxylic acid be produced?

vigorously oxidising a primary alcohol

gently oxidising a primary alcohol twice; once as an alcohol, and again once it becomes an aldehyde

how is a primary alcohol vigorously oxidised

reflux set up

water leaves but everything else falls back into vessel ensuring everything is fully oxidised

top of set up is open to prevent pressure build up

then distilled to separate excess agent + water from acid

what happens when secondary alcohol is oxidised?

ketone formed

use reflux then distillation

dif between aldehyde + ketone?

in a ketone → O is in middle of chain

aldehyde → at the end

can you oxidise a tertiary alcohol?

no

test for tertiary alcohol?

acidified potassium dichromate

no colour change

dif between a + k via acidified potassium dichromate?

aldehyde: orange → green

ketone: no change

a vs k tollens reagent?

aldehyde: oxidised to carboxylic acid

ketone: no reaction

a vs k fehlings reagent?

aldehyde: blue → red in warm bath

ketone: no reaction