3.3.5 Alcohols Flashcards
How alcohols classified
How many carbon atoms bonded to the carbon the oh bonded to
2 = secondary
3 = tirsuary
Bonding alcohols has
Hydrogen bonding as o nad h
Test to tell the difference between the types of alcohols
Primary alcohols - oxidised-aldehydes
Secondary alcohols - oxidised - ketones
Oxidising agent potassium dichromate
Tertiary alcohols do not undergo oxidation
Orange → green
Oxidation of alkenes formula
alkene + oxidising agent = alkane
o in square brackets
Oxidation of alcohols digram
1st - aldehydes - carboxylic acid
2nd - keton
Method for oxidising the alcohols
Primary alcohol is added to the oxidising agent and warmed
The aldehyde product has a lower boiling point so is distilled of before it turns into a carboxylic acid in excess oxidising agents
(ketones don’t need to b e distilled of
hydration/electrophilic addition to make an alcohol
Conditions - alkene and steam - heta with h2p04 catalyst
Nucleophilic substitution for production of alcohols
Conditions - halogenoalkane - acquiesce sodium hydroxide - heat
Reduction to make alcohols not carboxylic acids
aldehydes/ ketones - nabh4 / lialh4
Reduction to make alcohols from carboxylic acids
Reduction to make alcohols from carboxylic acids
What is the oxidising agents to make alcohols
Acidified potassium dichromate k2cr207
Or acidified [potassium manganate kmno4 (purple to colourless when oxidised )
How to test for oxidation products
Fehling’s solution
Alkaline copper 2+ions
Aldehyde to carboxylic acids cu2+ is reduced to cu
Ketone = neg result
Pos = clear blue to opaque red ppt
Tollens reagent
Alkaline solution silver nitrate in excess ammonia
Warmed with aldehyde - carboxylic acids
Ag+ to ag
Ketones result is negative as doest oxidise further
Clear → silver mirror
Elimination reaction mechanism
alchol vapour passed over hot catalyst Al2O3
or sulfuric acid or phosphoric acid
the lone pair on the alchol group electrons move to the the h+ from the catalyst - arrow
arrow breaking the bond between the now water and teh carbon
creats a carbo cation
the h on the other carbon next to c-h bond collapeses into c-c
creats a double bond
Elimination from alcohols to alkenes conditions
Thai si dehydration
Alcohol vapour is passed over a hot catalyst (al2o3) or sulfuric acid or phosphoric acid
Ways of making ethanol
Fermentation of glucose
Hydration of ethene
Fermentation of glucose points
C6h12o6 → 2ch3ch2oh +co2
Yeast
Anaerobic respiration
Low temperature
Renewable
Cheap
Made in batches
Ethanol needs distilling
Elimination of ethene points
C2h4 + h2o reversible → ch3ch2oh
High temp 300 degrees
High pressure
6oatm
Catalyst of conc h2so4
Continuous
Non renewable
Pure product that doesn’t need to be distilled
Ketone and aldehyde shape
Ketone = middle 0
Aldehyde = end 0h
Double bond for both
Ethanol as a biofuel equations and limitations
Limitations - doest take into account the transport and machinery
Photosynthesis : 6co2 +6h20 → c6h12o6
Ferment: c6h12o6 _> 2c2h5oh + 2c02
Combust: 2c2h5oh + 6o2 → 4co2 + 6h2o
Electrophilication
carbocations , form depending on what is more stable
