Chapter 14 Alcohols and Chpt 15Haloalkanes Flashcards
What is the functional group of alcohols?
OH
How would you describe the water solubility of alcohols?
Why?
High
Because the OH functional group forms strong hydrogen bonds with H20
Does solubility of alcohols increase as chain length increases or as it decreases?
Solubility increases as chain length decreases because the CH2 part of the molecule doesnt form H bonds with the water molecules so as there are less of them more of the compounds will form
Is the volatility of alcohols high or low?
Why?
Relatively low
Because the force of attraction is stronger than the London forces present between other molecules such as alkanes, therefore alcohols are less volatile than other organic molecules which have a similar molecular mass
Define primary alcohol
The OH group of the alcohol is attached to 1 C atom which is attached to a maximum of 1 other C atom
Define secondary alcohol
The OH group is attached to a C atom which is attached to 2 other C atoms
Define tertiary alcohol
The OH group is attached to a C atom that is attached to 3 other C atoms
When alcohols burn in sufficient oxygen what do they form?
CO2 H20
What is the oxidising agent for the oxidation of alcohols?
Acidified dichromate
When primary alcohols are distilled what do they form?
Aldehydes
When primary alcohols are refluxes what do they form?
Carboxylic acids
Define reflux
Continual heating and condensing of a reaction mixture
What is formed when a secondary alcohol is distilled?
A ketone
Can a secondary alcohol be refluxed?
No
Can a tertiary alcohol be oxidised?
No
What are the colour changes when you oxidise alcohols?
Orange —-> green
Define elimination
When 2 atoms or groups are removed resulting in the formation of a double bond
When an alcohol undergoes elimination what is removed from the alcohol and what is formed?
H20 is removed
An alkene is formed
What conditions are required for dehydration of ethanol?
Heat
Reflux
Concentrated H2SO4
Define substitution
When an atom or group is replaced by another atom or group
What is formed when a substitution reaction with a halide ion occurs?
A haloalkane
What conditions are required for substitution?
Reagents - sodium halide and H2SO4
Temperature
Reflux
Define haloalkane
An alkane in which one or more H atoms has been replaced with a halogen atom
Define nucleophile
An electron pair donor
What conditions are required for nucleophilic substitution?
NaOH - aqueous
Hot
Reflux
A haloalkane + aqueous sodium hydroxide —->
Alcohol and sodium halide
Define hydrolysis
A reaction with water or aqeuous hydroxide ions that breaks a chemical compound into 2 compounds
The rate of hydrolysis reactions of haloalkanes depends on the ——- ——- —-
Halogen atom attached
Describe the bond enthalpies between C and a halogen as you go down the group
They decrease
Which haloalkane is the most reactive our of CH3F CH3Cl CH3Br CH3I Why?
CH3I
Because the bond enthalpies are weakest which means the least amount of energy is needed to overcome the forces
How would you carry out an experiment to find the relative rates of reactions for haloalkanes?
Set up 3 test tubes with 1cm3 of ethanol and 2 drops of the haloalkane
Place them in a water bath at 50
What is the precipitate colour of chloroalkane?
White precipitate
What is the precipitate colour of bromoalkane?
cream precipitate
What is the precipitate colour of iodoalkane?
Yellow precipitate
Why is an iodoalkane expected to react more quickly than a bromoalkane?
Because C-I is the weakest bond so it needs the least amount of energy to be overcome
