Alcohols, Haloalkanes and Analysis Flashcards
What is a primary alcohol?
An alcohol where is the functional group is attached to a carbon atom with no more than one alkyl group
What is a secondary alcohol?
An alcohol where is the functional group is attached to a carbon atom with two alkyl groups
What is a tertiary alcohol?
An alcohol where is the functional group is attached to a carbon atom with three alkyl groups
What happens to the boiling point of alcohols as chain length increases? why?
BP increases as chain length increases because as the molecules get longer there are more surface area contacts and so stronger dipole-dipole inter-molecular forces therefore meaning more energy is needed to overcome these attractive forces
Why are the boiling points of alcohols higher than their corresponding alkanes?
There are hydrogen bonds between alcohol molecules thus more energy is needed to break these stronger bonds.
Are alcohols soluble in water? why?
Water molecules are polar and so is the OH group, meaning methanol, ethanol and propanol are soluble in water by creating hydrogen bonds.
What is produced when an alcohol is completely combusted?
Carbon dioxide and water
What are the reaction conditions required to turn a primary alcohol into an aldehyde and what observations would be made?
Gentle heating
colour change: orange -> green
What are the reaction conditions required to turn a primary alcohol into a carboxylic acid and what observations would be made?
Stronger heating under reflux with excess potassium dichromate (oxidising agent)
colour change: orange -> green
What are the reaction conditions required to turn a secondary alcohol into a ketone and what observations would be made?
Heat under reflux
Colour change: orange -> green
Can you oxidise a tertiary alcohol?
No
If you gently heat a primary alcohol, what is produced?
An aldehyde
If you heat a primary alcohol under reflux with excess potassium dichromate, what is produced?
A carboxylic acid
If you heat a secondary alcohol under reflux, what is produced?
A ketone
How do you make an ester?
- A few cm3 of alcohol and carboxylic acid are added to a test tube
- Add a few drops of sulphuric acid as a catalyst
- Heat test tube to 80 degrees.
- Once you can smell the fruity ester smell, the ester has been formed.
What is dehydration?
A chemical reaction in which water is lost from an organic compound.
How do you dehydrate an alcohol?
Heat the alcohol under reflux with concentrated sulphuric acid for about 40 mins.
What is elimination?
An organic reaction in which one reactant forms two products, usually releasing a small molecule like water.
What is a primary haloalkane?
A chain of carbon atoms with a halogen atom at the end of the chain
Are haloalkanes polar or non-polar?
Polar
What are nucleophiles?
Electron pair donars
How does the strength of the carbon-halogen bond increase down group 7? why?
Going down the group, atoms get larger so their bonding electrons are further away from the nuclei and feel stronger shielding. This results in lower mean bond enthalpies and the bonds are easier to break.
What is nucleophilic substitution?
A chemical reaction in which an atom or group of atoms are exchanged for a nucleophile
What is hydrolysis?
A chemical reaction in which water is a reactant
How do you investigate the rate of hydrolysis for a primary haloalkane?
- Add 1 cm3 of haloalkane into test tube
- Put test tubes into 50 degree water bath
- Half fill a separate test tube with ethanol, water and silver nitrate ions and place them into the water bath
- When the liquids have reached the same temperature, add 1 cm3 of the mixture into the haloalkane and time how long it takes for the precipitate to appear.
How does the rate of hydrolysis change as you go down the halide group?
The rate of hydrolysis increases due to a C-I bond being easier to break than a C-Br bond.
What are Chloro-fluoro-carbons (CFCs)?
A class of inert organic compounds containing chlorine and fluorine atoms
What is the ozone layer?
An area of high ozone (O3) concentration in the stratosphere
What is a radical?
A highly reactive species with one or more unpaired electrons
At what wavelength in infrared spectroscopy would the C=O bond peak at?
1640-1750
At what wavelength in infrared spectroscopy would the O-H bond peak at for carboxylic acids?
2500-3300
At what wavelength in infrared spectroscopy would the O-H bond peak at for alcohols?
3200-3550
What is the molecular ion?
The positive ion formed in mass spectrometry when a molecule loses an electron
