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…

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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…

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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…

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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…

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o 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

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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)

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ACID CATALYSED DEHYDRATION




Mechanism:

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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. Detection

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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.
When a molecule fragments, it always produces a positive ion and a free radical




Example:

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