What's In A Medicine Flashcards
Why do alcohols have a higher boiling point than their corresponding alkanes?
The -OH group on the alcohol is able to form hydrogen bonds which require more energy to break
What is the difference between a primary, secondary, and tertiary alcohol?
Primary: -OH group bonded to a carbon bonded to one other carbon
Secondary: -OH group bonded to a carbon bonded to two other carbons
Tertiary: -OH group bonded to a carbon bonded to three other carbons
Oxidation of primary alcohols
Products: Aldehyde made first, if there is excess oxidsing agent then a carboxylic acid is formed
Oxidsing agent: Acidified potassium dichromate (VI)
Final Colour of reaction mixture: Green
Oxidation of secondary alcohols
Products: Ketone
Oxidsing agent: Acidified potassium dichromate (VI)
Final colour of reaction mixture: Green
Oxidation of tertiary alcohols
Products: Does not oxidise
Final colour of reaction mixture: Orange
How does reflux work
Liquid is boiled in a vertically mounted condenser so the vapour condenses and returns back into the reaction mixture
Used for heating volatile and flammable liquids
Dehydration of alcohols
Alcohols can loose a molecule of water to form an alkene
Conditions: Alumina (Al2O3) catalyst at 300°C OR reflux with concentrated sulphuric acid
Dehydration is an example of a elimination reaction
Substitution reactions will alcohols
Nucleophilic substitution with halide ions in the presence of a strong acid
Esterification with carboxylic acids and acid anhydrides
Carboxylic acid:
Alcohol + Acid –> Ester + Water
Small amount of concentrated acid as catalyst
Named by alcohol then acid
Acid anhydride:
Alcohol + Acid anhydride –> Ester + Acid
Higher yelid of ester
Named by alcohol then anhydride
Ethers
General formula of R-O-R
Structural isomers of alcohols
Which molecules contain a hydroxyl group
Alcohols, phenols, and carboxylic acid
The order of acidic strength; water, carboxylic acids, phenol, alcohol
Alcohol < Water < Phenol < Carboxylic Acids
Reactions with carbonates
Only carboxylic acids have a high enough concentrations of H+ ions to produce carbon dioxide on reactions with carbonates
Alcohols and phenols will not react
How to test for phenols
Reaction with iron (III) chloride
If phenol present, the mixture turns purple
Ester formation with phenols
Phenol + Acid anhydride –> Ester + Acids
Under alkaline conditions
Phenols do not reaction with carboxylic acids to produce esters
Equation linking speed of light, wavelength, and frequency
Speed of light = Wavelength x Frequency
What does quantise mean
Molecules must take a small number of definite energy values rather than any energy values
Different types of bond deformation
- Symmetric stretch
- Asymmetric stretch
- Symmetric bend
Two most important regions on IR spectra
-OH group, around 3000
C double bond O, around 1600
Fingerprint region
The region below 1500 which is characteristic of the particular molecule
What can be told from mass spectrometry
- The molecular ion, M+
- The fragment pattern
- The relative abundance of fragment ions
Recrystallisation
1) Seleft a solvent in which the desired substance is very soluble at high temperatures and and insoluble at low temperatures
2) Dissolve the mixture in the minimum quantity of hot solvent to better the yield
3) Filter to remove any insoluble impurities
4) Leave to cool until crystals form
5) Collect crystals by vacuum filtration
6) Leave the crystals to dry
Thin Layer Chromatography
Used to test the purity of a substance
Melting point determination
Used to test the purity of substances. A pure compound should melt within 0.5°C of it’s true melting point
