Alcohols Flashcards
What is the functional group of haloalkanes?
Haloalkane
What is the alcohol functional group
OH
Describe and explain the polarity in alcohol molecules
Polar molecules because oxygen is more En than C causing dipole
As chain length of alcohols increases what occurs to their properties?
Become more similar to that of the same alkane
Describe and explain the volatility of alcohols
Not very volatile
High BP due to hydrogen bonds
Compare the volatility of alcohols and alkanes of the same chain length
Alcohols have higher volatility
Describe and explain the solubility of alcohols
Soluble in water
Can form H bonds with water molecules due to OH group (H and lone pair on O)
What occurs to the solubility of alcohols as the chain length increases?
Decreases so becomes similar to alkanes
Describe the classification of alcohols
Depending on how many C bonded to C bonded to OH
1° 2 ° 3 °
Describe the combustion of alcohols
Complete combustion in excess O2
Very exothermic so good fuel
Describe how the energy released via combustion of alcohols changes as chain length increases
More exothermic
What functional group do all the product of alcohol oxidation have?
Carbonyl (=0)
Name the reagents used in the oxidation of alcohols
Acidfied Potassium dichromate
Sate the observation when oxidation of alcohols occurs
Orange to green
Name the conditions and classification of the alcohol used to form an aldehyde
1°
Distillation
Name the conditions and classification of the alcohol used to form a carboxylic acid
1°
Reflux
Name the conditions and classification of the alcohol used to form a ketone
2°
Reflux
Why is potassium dichromate hazardous
Carcinogenic
What do aldehydes end in
Al
What do carboxylic end in
Oic acid
What do ketones end in
One
What do esters end in
Ethyl
Why is potassium dichromate added in excess to form carboxylic acid
To ensure all the aldehyde is oxidised
What is formed when an alcohol is oxidised
A carbonyl and water
What occurs when a 3° alcohol is oxidised
No reaction
Stays orange
What equipment is used in reflux
Pear shaped flask
Liebig condenser flask
Reciever adaptor
What equipment is used in distillation
Pear shaped flask Liebig condenser flask Reciever Anti bumping granules Cold water flask Test tube
Why are anti bumping granules used
To allow a calm boil
Prevent spitting due to water produced evaporates
To prevent dry boiling
Describe dehydration of alcohols
Elimination reaction of water to produce alkene
What are the reagents and conditions used to convert alcohol to alkenes
Acid catalyst
Reflux
How are alcohols formed
Fermentation
Alkene + steam + acid catalyst
How do you form a haloalkane from an alcohol
Add sodium halides and acid to alcohol
Describe what occurs when sodium bromide and acid are added to an alcohol
Bromide combines with hydrogen to form hydrogen bromide
Bromide displaces OH
What is signified when potassium dichromate goes from orange to green
Oxidation
What colour is universal indicator when a carboxylic acid is produced?
Red
Whats the difference in the observation when sodium carbonate is added to aldehyde and carboxylic acid
Carboxylic acid= effervescence
Aldehyde= nothing
Acid and carbonate produce salt water and co2
What are the classifications of haloalkanes and what do they mean
1°/2°/3°
How many C bonded to C bonded to Halogen
Describe and explain the reactivity of haloalkanes compared to alkanes
More reactive
Halogen is more electronegetive so causes dipole
Compare and explain the reactivity of F and Br
Br more reactive
Larger atomic radius and more shielding meaning less nuclear attraction
So larger bond length, less electronegetive
So weaker bonds so react more easily
Why are halobutanes used in investigation of rate of hydrolysis not methanes
Butane have longer carbon chain so more electrons and stronger LF so not liquid at rt
What is a nucleophile
A species able to donate a pair of electrons
Name the mechanism for turning haloalkanes into alcohols
Nucleophillic substitution
Describe nucleophillic substition with sodium hydroxide
Hydrodie ions act as nucleophile
OH approaches carbon bonded to Halogen (partial positive charge) on the opposite side of the molecule to the Halogen
OH attacts positive charge and donates electron pair forming a bond with the carbon and substituting the Halogen atom which is left as a halide ion
Carbon Halogen bond breaks via heterolytic fission
Why must haloalkanes be heated when hydrolysed
Slow reaction otherwise
What are the two ways to convert haloalkanes to alcohols?
Add sodium hydroxide under reflux
Add aqueous silver nitrate and ethanol
Name the mechanism by which haloalkanes are converted to alcohols
Hydrolysis
Why is ethanol added to haloalkanes and aqueous silver nitrate to convert them to alcohols?
Haloalkanes are not soluble in water so are dissolved in ethanol
How can you measure the rate of hydrolysis of haloalkanes?
Used aqueous silver nitrate
The displaced Halogen ions will combine with the silver ions to form a precipitate
How can you compare the bond strength of carbon Halogen bonds
Add aqueous silver nitrate and ethanol
Water displaces Halogen which combines with silver ion to produce precipitate
Measure how long precipitate takes to form
Short time= weaker bond
With what type of nucleophile is an intermediate formed and not formed in hydrolysis of haloalkanes
Intermediate = compounds with lone pairs
No intermediate = ions
What is the reverse of haloalkane hydrolysis
Nucleophillic substitution
What is an órganohalogen compound
Carbon chain bonded to one or more Halogen atoms
What are the uses of órgano halogens?
Refrigerants Solvents Aerosol propellants Flame retardents Making polymers
Why are organohalogens stable
Strong carbon Halogen bond
Hard to break down
What is ozone and where can it be found
Makes up small proportion of ozone in stratosphere
What are the benefits of ozone
Absorb UV light which would otherwise cause skin cancer, eye crop an immune system damage
Why is UV bad for you
UVA Causes crop damage Eye damage Damage immune system Skin cancer
Why is UV good for you
Vitamin D
What constantly occurs in the ozone layer
Ozone breaks down and reforms
Why is ozone only broken down in the ozone layer
Enough high energy UV radiation
What does CFC stand for
Chlorofluorocarbons
What are the uses for CFCs
Refrigerants
Aerosol propellants
Air con
Why are chlorine radicals produced and not fluorine radicals when CFC decompose
C–Cl weaker than c–F
What is the process of free radical production of CFCs
Photodissociation
What is photodissociation
Splitting of bond with radiation
What evidence is there that free radicals act as catalysts
Regenerated in depletion of ozone
Doesn’t matter what radical it is, the overall equation is always the same
How do nitrogen oxide radicals form
Lightning
Air travel
Name uses for CFCs and link to property
Fire extinguisher - non flammable
Degreasing agent - good solvent for organic material
Propellants - unreactive and volatile
Why might sodium carbonate be added after the production of an alcohol from an alkene for example?
To remove acid impurities
