Module 4: Section 2- Alcohols, Haloalkanes And Synthesis Flashcards
Alcohols
What is the functional group
-OH
Alcohols
What’s the suffix for one alcohol
-ol
Alcohols
What is the suffix for two alcohol
-diol
Alcohols
What’s the prefix
Hydroxy-
Alcohols
What are the three types of alcohol
Primary secondary and tertiary
Alcohols
What’s a primary alcohol
1 carbon around the carbon of the OH group
(End of chain )
Alcohols
Notation for a primary alcohol
1°
Alcohols
What’s a secondary alcohol
2 carbon around carbon with OH group
(In chain)
Alcohols
Notation for secondary alcohol
2°
Alcohols
What is a tertiary alcohol
3 carbon around carbon with OH group
Branched
Alcohols
Notation for tertiary alcohol
3°
Alcohols
Are alcohols polar
Yes due to the electronegative hydroxyl group which pulls the electrons in the C-OH bond away from the carbon atom
Alcohols
What type of IMF can alcohols form
Hydrogen bonds
Alcohols
Compared to alkanes what is alcohols solubility like
High water solubility
Alcohols
Why do alcohols have high water solubility
Hydrogen bonds form between the -OH and H2O so lets it mix freely
Alcohols
What happens to water solubility as alchohl gets larger and why
Solubility decreases because most of the molecule is non polar so there’s less attraction for the polar H2O
Alcohols
Do alcolhs have low or high melting and boiling points compared to alkanes and why
Hydrogen bonds formed between alcohols which are the strongest type of IMF and requires the most energy to overcome
Alcohols
Are alcohol volatile
Relative low volatility compared to alkanes
Reactions of alcohols
What is combustion
Burnt in oxygen
Reactions of alcohols
What is produced in the combustion of alcohol
CO2 and H2O
Reactions of alcohols
Why are alcohols more likely to undergo complete combustion in comparison to incomplete combustion that alkanes
Already have oxygen in structure
Reactions of alcohols
Important to remember whilst balancing equation fo combustion
Oxygen atom in the alcohol
Reactions of alcohols
What is dehydration
Removal of H2O
Reactions of alcohols
In dehydration where is the H2O removed form
Loses the -OH and -H groups
Reactions of alcohols
What does dehydration produce
A new Alkene and water
Reactions of alcohols
What type or reaction is dehydration
Elimination
Reactions of alcohols
What is the conditions for dehydration
An acid catalyst and reflux (heat)
Reactions of alcohols
What acid catalysts can be used for dehydration
Concentrated sulfuric acid or concentrated phosphoric acid
Reactions of alcohols
How many products can be formed by dehydration
Often multiple as hydrogen can be removed from either side of -COH and EZ isomerism can be present
Reactions of alcohols
What happens in a substitution reaction
-OH group substituted by a halide when reacted with compounds containing halide ions
Reactions of alcohols
What formed in a substitution reaction with halide ion
Haloalkane
Reactions of alcohols
How does an alcohol have to be heated for substitution and with what
Heated under reflux with sulfuric acid and a sodium halide
Reactions of alcohols
For substitution when is hydrogen halide formed
In situ in the reaction
Reactions of alcohols
For substitution what is the equation for when the hydrogen halide is formed egwith Br
NaBr + H2SO4 —> NaHSO4 + HBr
Reactions of alcohols
For substitution what is the general reaction for just alcohol with hydrogen halide after being formed in situ
Alcohol + hydrogen halide —> haloalkane + water
Reactions of alcohols
Overall general equation for substitution of alcohol
Alcohol + H2SO4 + NaBr —> haloalkane + H2O + NaHSO4
Reactions of alcohols
What are the two methods to heat an alcohol for oxidation
Distillation
Reflux
Reactions of alcohols
What does distillation do
Heat gently and remove products as its formed
Reactions of alcohols
What does distillation prevent
Further reaction of product
Reactions of alcohols
What needs to be considered for distillation
How to heat organic substance as may be flammable
Reactions of alcohols
How does reflux work
Substance evaporated then recondensed and returns back to substance in flask by continuous heating
Reactions of alcohols
Why in reflux is the top open
So pressure doesn’t build up
Reactions of alcohols
What does oxidation of a alcohol require
An oxidising agent
Reactions of alcohols
What is an oxidising agent
Oxidise other species by gaining electrons and are reduced themselves
Reactions of alcohols
How is oxidising agent shown in reactions
[o]
Reactions of alcohols
What oxidising agent is used in oxidation
Acidified potassium dichromate
Reactions of alcohols
What colour is acidified potassium dichromate
Orange then goes green when reduced
Reactions of alcohols
How do you know when alcohol has been oxidised
When the oxidising agent is reduced and changes colour
Reactions of alcohols
What happens if you partially oxidise a primary alcohol
Forms aldehyde on primary carbon
Reactions of alcohols
To partially oxidise a primary alcohol what method should be used
Distillation
Reactions of alcohols
What is formed if you fully oxidise a primary alcohol
Carboxylic acid
Reactions of alcohols
To fully oxidise a primary alcohol what method should be used
Reflux
Reactions of alcohols
Equation for partially oxidising a primary alcohol (but an-1-ol)
Butan-1-ol + [o] —> butanal + water
Reactions of alcohols
Equation for fully oxidising porimary alcohol butan-1-ol
Butan-1-ol + 2[o] —> butanoic acid + water
Reactions of alcohols
What is formed when secondary alcohol is oxidised
Forms ketone on secondary C
Reactions of alcohols
What method is best to use to oxidise a secondary alcohol and why
Reflux so all compound reacted
Reactions of alcohols
Equation of oxidising secondary alcohol but an-2-ol
Butan-2-ol + [o] —> butanone + water
Reactions of alcohols
What happens when tertiary alcohol oxidised
No reaction and acidified potassium dichromate remains orange
Reactions of alcohols
Why can’t tertiary alcohols be oxidised
Because C atom whcih has -OH group has 3 other C atoms bonded to it and no H atom, in oxidation the carbon atom with the -OH group b=must be able to release an attached atom to form double C=O bond,
C-H bond easily broken but not C-C bond
Haloalkanes
What are they
Compound containing carbon, hydrogen and at least one halogen
Haloalkanes
Suffix for chlorine
Chloro-
Haloalkanessuffix for bromine
Bromo-
Haloalkanes
Suffix for iodine
Iodo-
Haloalkanes
Suffix for fluorine
Fluoro-
Haloalkanes
What can they be classified as
Primary
Secondary
Tertiary
Haloalkanes
What is a primary haloalkane
Halogen at end of chain
C only attached to one other C
Haloalkanes
What is a secondary haloalkane
Halogen in chain
C attached to two other C
Haloalkanes
What is a tertiary haloalkane
Halogen at a branch
C attached to three C
Haloalkanes
What bond is polar in haloalkanes
Carbon-halogen bond
Haloalkanes
Why is the carbon-halogen bond polar
Halogens is more electronegative than carbon so electron pair in covalent bond is closer to halogen
Haloalkanes
What is definition for nucleophile
Electron pair don’or
Haloalkanes
What actually is a nucleopjhile
Atom or group which is attracted to a positive centre where is donates a pair of electrons to form a new covalent bond
Haloalkanes
Where is a nucleophile attracted to on a haloalkane
Electron deficient slightly positive carbon atom
Haloalkanes
Example of three nucleophile
:OH-
H2O:
:NH3
Haloalkanes
What is nucleophilic substitution for a haloalkane
When haloalkane reacts with a nucleophile replaces the halogen in a substitution reaction
Haloalkanes]
What does the rate of the nucleophilic substitution reaction depend on
Strength/length of the C-halogen bond
Haloalkanes
Ranking for rate of substitution reaction for each halogen-carbon bond
C-I>C-Br>C-Cl>C-F
Haloalkanes
In general, what is a hydrolysis reaction
Reaction involving water or aqueous solution of a hydroxide that causes breaking of a bond and molecule split into two products
Haloalkanes
What happens in the hydrolysis of a haloalkane
Halogen atom replaced by an -OH group
Haloalkanes
General equation for hydrolysis
Haloalkane + OH- —> alcohol + halide
Haloalkanes
What is the process for hydrolysis (6)
- Nucleophile (OH-) attracted to slightly + carbon atom on opposite side from halogen
- Direction of attack minimises repulsion between nucleophile , -OH and delta- halogen
- Lone pair of electrons on OH- is donated to the + on the delta + carbon atom
- New bond formed between oxygen on OH- and carbon atom
- Carbon-halogen bond breaks through heterolytic fission
- Alcohol and halide ion formed
Haloalkanes
Hydrolysis
LEARN MECHANISN
Haloalkanes
Reagent needed for hydrolysis
NaOH
Haloalkanes
Conditions needed for hydrolysis
Warm, aqueous
Haloalkanes
Equation for hydrolysis of chloroethane
C2H5Cl + NaOH —> C2H5OH + NaCl
Haloalkanes
What side of the haloalkane is a nucleophile added onto
Opposite halogen
Haloalkanes
Practical for hydrolysis of haloalkanes method
Hydrolysis of haloalkanes
Set up three test tubes as follows:
Tube 1: Add 1 cm3 of ethanol and two drops of
I-chlorobutane
Tube 2: Add I cm3 of ethanol and two drops of
I-bromobutane
Tube 3: Add I cm3 of ethanol and two drops of
I-iodobutane
2 Stand the test tubes in a water bath at 60 oc.
3 Place a test tube containing 0.1 mol drn-3 silver
nitrate in the water bath and allow all tubes to reach a
constant temperature.
4 Add lcm3 of the silver nitrate quickly to each of the
test tubes. Immediately start a stop-clock.
5 Observe the test tubes for five minutes and record
the time taken for the precipitate to form.
.
Haloalkanes
Practical for hydrolysis results
Chloro- form a white precipitate very slowly
Bromo- forms cream precipitate moderately time
Iodo- yellow precipitate very quickly
Haloalkanes
For practical of hydrolysis How are the products identifies
Using silver nitrate
Haloalkanes
Why does C-I bond hydrolyse the quickest
Weakens bond due to its bond enthalpy
Haloalkanes
Why does the C-Cl bond hydrolyse the slowest
Strongest bond due to its bond enthalpy
Haloalkanes
What maintains the ozone level for life on earth
The equilibrium
Haloalkanes
Why are oxygen radicals present in the ozone layer
Uv light causes homoltic fission
Haloalkanes
Equation for homolytic fission of oxygen
O2 -> 2 O
Haloalkanes
What is the quilibrium equation to maintain ozone levels
O2 + O <=> O3
Haloalkanes
What was originally used in fridges and why was it bad
NH3(l) was unhealthy
Haloalkanes
What was found that could be used in fridges
CFCs
Haloalkanes
What are CFCs
Chlorofluorocarbons
Haloalkanes
Example of CFC
Freeon CCl2F2
Haloalkanes
What are the three properties of CFCs
Volatile, non flammable and low toxicity
Haloalkanes
What happened to the ozone layer in the 1990s
Depletion started
Haloalkanes
Initiation equation for depletion of ozone using CF2CL2
CF2Cl2 –uv—> Cl. + CF2Cl.
Haloalkanes
Propagation for depletion of ozone using CF2Cl2
- Cl. +O3 —> ClO. + O2
- ClO. + O —> O2 + Cl.
Haloalkanes
Where does O cone from in the depletion if ozone
Already in the mixture from equilibrium
Haloalkanes
What is the overall equation for depletion of ozone
O3 + O —> 2 O2
Haloalkanes
Is CFCs rhe only way for depletion of ozone
Other radicals present can also break down ozone
Haloalkanes
What radical often breaks down ozone
NO.
Haloalkanes
What are NO. Radica,s formed from
Lightning storms and aircraft travel
Haloalkanes
Propagation of depletion of ozone by NO. Radicals
NO. + O3 —> O2 + NO2.
NO2. + O —> NO . + O2
Haloalkanes
Overall equation for depletion of ozone for NO. Radicals
O3 + O —> 2 O2