4.2 Alcohols, Haloalkanes and Analysis (started) Flashcards
4.2.1 Alcohols 4.2.2 Haloalkanes 4.2.3 Organic synthesis 4.2.4 Analytical techniques
How do alcohols boiling points compare to similar sized alkanes?
Higher as alcohols have hydrogen bonds between molecules
What internolecular forces are present in alcohols?
Hydrogen bonds between formula groups
What is a primary, secondary and tertiary alcohol?
1° Primary - end of the carbon chain
2° Secondary - middle of the carbon chain
3° Tertiary - middle with another branch attached of the carbon chain
What are the products of a combustion of an alcohol?
Carbon dioxide and water
What is the general formula for an alcohol?
Cn H2n+1 OH
What is the oxidising agent used to oxidise primary and secondary alcohols?
Acidified potassium dichromate
H+/Cr2O7 2-
How are oxidising agents represented in chemical equations?
[O]
How do you produce an aldehyde?
Oxidise a primary alcohol by distillation
Produces water as well
Colour change from orange to green
How do you produce a carboxylic acid?
Further oxidise an aldehyde
Reflux a primary alcohol
Produces water as well (only from alcohol not from aldehyde)
Colour change from orange to green
How do you produce a ketone?
Oxidise a secondary alcohol by reflux
Produces water as well
Colour change from orange to green
What happens when you react tertiary alcohols with acidified potassium dichromate?
Nothing happens
Colour remains orange
What is reflux?
Continual boiling and condensing of a reaction mixture to ensure the reaction goes to completion without the mixture boiling dry
What is distillation?
The technique of heating a liquid to create vapour which is collected when cooled seperate from the original liquid
What is an elimination reaction?
Dehydration an alcohol to form an alkene and water
Conc sulphuric acid
Heat
Reflux
How do alcohols produce a haloalkane?
Substitution in the presence of an acid
Why do you use infra red for spectrometry instead of ultra violet?
Ultra violet will break the bonds
What happens if you shine the right amount of energy on a bond with infra red energy?
You can kick it into a higher state of vibration
The amount of energy needed will change and each bond will absorb a different frequency
What are applications of infra red spectroscopy?
Breathalysers
Monitoring air pollution
How do breathalysers work?
Identifying ethanol by absorbance in C-O O-H bonds
Identifying amount of ethanol by amount if IR absorption
What bonds do the common greenhouse gases contain that can be found in IR sprectroscopy?
Carbon Dioxide C=O bonds
Water vapour O-H bonds
Methan C-H bonds
What is the moleculer ion peak?
Furthest right peak which is the Mr of the molecuke
Why could there be smaller peak just to the right of the molecular ion peak?
Due to a Carbon 13 isotope which will increase the Mr
What does each peak show on a mass spectrometer?
Positive ions from fragments of molecule
e.g. CH3OCH3 can have fragments at 31for [CH3O]+ and 15 [CH3]+
How does the rate of hydrolysis of a haloalkane depend on the halogen present?
The weaker the bond the faster the rate of reaction
C-I is the weakest and therefore fastest, rate decreases up the group
