ORGANIC ANALYSIS/ALCOHOLS Flashcards
TEST for
Primary alcohol
Secondary alcohol
Aldehyde
Acidified pottasium dicromate
Orange to green
TESTS for aldehyde
Tollens reagent
Silver mirror formed
Fehiling reagent
Brick red precipitate
Test for alkene
Bromine water
Colourless solution
Test for carboxylic acid
Na2CO3
EFFESRRVENCE
Vibration and frequency of bonds
Strong bonds vibrate with very high frequency
Weak bonds vibrate with very low frequency
Identification if a molecule by comparison of spectra
Use fingerprinting reagent and compare with known spectrum from database
Whats the standard recfrence in mass soectrum
12C is standard refrence
Why can’t we differentiate some molecules(2 mark points)
Molecules with same Mr to 1dp so can’t be differentiated
Some molecules have same Molecular formula
Classification of alcohol
Primary
Secondary
Tertiary
2 step process convert alcohol to carboxylic acid (pathway)
Step 1
Oxidation to aldehyde from alcohol
Step 2
Oxodation to carboxylic adid from aldehyde
Why reflux id used to oxidise an alcohol into a carboxylic acid?
Reflux doesnt allow any reactant vapour to escape
What happens during reflux? (3marks)
Reaction mixture is heated to boiling point
Vapour is formed ehich escapes from the liquid , this is condensed back into liquid and returned to the liquid mixture
Any compound that initially evaporates can be oxidised
What are anti-bamping granelles added?
Prevent large bubbles forming
Explain the process of distillation
Turn the water suupky on to the condenser
Heat the flask
(Aldehyde) will vaporise
Use thermometer to maintain the temperature at the Boiliing point of (ethanal)
The (ethanal) vapours condense back into a liquid in the condenser
(Ethanal) is coklected in a cooled container to avoid is vaporsing
Explain the term biofuel (1mark)
Fuel produced from renewable plant material (biomass)
Production if alcohol from crude oil
Reaction hydration
Catalyst concentrated H3PO4
Conditions steam, 450C , 100 pressure
Reagent H+ & H2O
Production of ethanol via fermentation (condition + equation)
Yeast , no oxygen , 35C temp
C6H12O6 ——> CO2 + 2CH3CH2OH
Advantages vs disadvantages of biofuel
Advantages
Comes from renewable raw material
Considered to be carbon neutra
Conserves crude oil supplies
Disadvantages
Biofuels cant be made on a scale to meet global demand for fuels
Supply of biofuels dependent on crop harvest so less relaible
Food prices rise as crops used for biofuels therefore increase market price
Advantages and disadvantages of hydration of ethene
Advantages
Large scale production method
High purity product made
High rate of reaction
Continous production metod
Disadvantages
High temp & pressure so increases costs
Crude oil is non-renewable
Expensive & high equipment needed
Advantages & disadvantages of fermentation
Advantages
Uses renewable resourses
Low cost
Low tech method
Readily available and renewable raw materials from plants
Disadvantages
Slow rate of reaction
Impure ethanol made needs distilling
Causes food prices to rise if crops are used to pridicr alcohol instead of food
4 equation that show oxidation of alcohol
1.
CH3CH2OH +[O] ——> CH3CHO + H2O
2.
CH3CHO + [O] ———> CH3COOH
3.
CH3CH2OH + 2[O] ———-> CH3COOH + H2O
4.
CH3CH(OH)CH3 + [O] ———-> CH3COCH3 + H2O
