OCR AS Chemistry (F322.2) - Alcohols, Halogenoalkanes and Analysis Revision Notes

These revision notes are for Alcohols, Halogenoalkanes and Analysis - the second module of F322 (Organic Chemistry) from OCR AS Chemistry A.

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OCR AS Chemistry Notes
ALCOHOLS
MAKING ALCOHOLS
1) HYDRATION OF AN ALKENE
2) FERMENTATION OF SUGAR
HYDRATION OF + Continuous process - The reactant (alkene) is non-renewable ­
ALKENE + Fast and efficient process supplies are running out
+ Produces a relatively pure product - Expensive (Requires a lot of energy to make
+ Few workers needed to perform process high temperature and pressure)
- The energy needed is often produced via the
burning of hydrocarbons, contributing to global
warming
- The conversion of the alkene is always
incomplete as the reaction is reversible (only 95%
overall)
FERMENTATIO + The reactant (sugar) is renewable - Is a slow process
N OF SUGAR + The reaction is quite cheap to do as it requires - Is a batch process
little energy - Poor quality product is made (e.g. low aqueous
concentration of ethanol)
- Many waste products and yeast residue must be
removed from the resulting mixture
- The alcohol produced must be distilled
- Carbon dioxide is produced (this contributes to
global warming)
- Many workers needed to harvest sugar etc.

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CLASSIFYING ALCOHOLS
Primary Alcohol (1o)
The -OH is attached to a C atom which is attached to one other carbon atom
OR
Secondary Alcohol (2o)
The -OH is attached to a C atom which is attached to two other carbon atoms
Tertiary Alcohol (3o)
The -OH is attached to a C atom which is attached to 3 other carbon atoms…read more

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PHYSICAL PROPERTIES OF ALCOHOLS
Hydrogen bonds form between polar ­OH groups:
o Strongest intermolecular force
Permanent dipoles
Lone pair makes attraction stronger
This gives relatively high boiling and melting point
And results in a lower volatility compared to alkanes
of similar molecular mass
And makes them soluble in water
o Hydrogen bonds form between polar -OH groups of alcohol and water
Alkenes are immiscible ­ they disrupt hydrogen bonds between water molecules
Although alcohols disrupt the
hydrogen bonds, it will make
new ones with the…read more

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OXIDATION OF ALCOHOLS
= reacting with an oxidising agent [o]
Agent = acidified potassium dichromate:
o = H+/K2Cr2O7
o Is orange
o Turns from orange to green during oxidation
We get different products using 1o, 2o or 3o alcohols
1o:
1)
2)
1) If we want the aldehyde:
Distillation
o Aldehydes are volatile ­ more volatile than the alcohol
2) If we want to make the carboxylic acid
Reflux:…read more

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Continual boiling and condensing of reaction mixture
o Ensures that the reaction takes place without the contents of the flask boiling dry
2o:
3o:
WRITING BALANCED EQUATIONS…read more

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MAKING ESTERS (ESTERIFICATION)
Esters smell nice
Used in:
o Perfumes
o Food flavourings
o Solvents
Be careful of 2o or 3o alcohols (but don't have to name them)…read more

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ACID CATALYSED DEHYDRATION
Mechanism:…read more

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OCR AS Chemistry Notes
MASS SPECTROSCOPY (SPECTROMETRY)
Determines Mr of a compound
Tells us some indications of the structure
1. Vaporisation
2. Ionisation
a. Give molecule positive charge by
firing aaaaaaaaaaaaaaa aaaa a beam of electrons at it
3. Acceleration
a. Using magnetic field
4. Deflection
5.…read more

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Peak furthest to right tells us Mr (ignoring tiny shoulder peaks)
o m+ +1 due to presence of 13C
EQUATIONS FOR FRAGMENTATION
Fragmentation occurs after ionisation.…read more

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