Prep-work You are an analytical chemist working at GSK. You have been given two substances “A” and “B”. They both have the molecular formula: C4H10O. You have been told that one is primary alcohol and the other is a tertiary alcohol. Design an experiment to find distinguish the primary alcohol from the tertiary alcohol.

Combustion of alcohols A. Draw out and state what kind of alcohol the following are: Butan-1-ol Butan-2-ol 2-methylbutan-2-ol 2,4-dimethylpentan-3-ol 4,4-dibromo-3-ethyl-2-5-dimethyl-hexan-1,3-diol 1,1,4-trichloro-2,3-diiodo-5-6-diethyloctan-1,4,6,8-tetraol B. Write out the equation for the complete combustion of the first four alcohols

Combustion and oxidation of alcohols L.O.: Describe the combustion of alcohols. Describe the oxidation of primary and secondary alcohols. Outline the resistance to oxidation of tertiary alcohols

Aldehydes and ketones: Recap What’s the difference between an aldehyde and a ketone? Draw a 3 carbon and a 5 carbon aldehyde and name it. Draw a a 3 carbon and a 5 carbon ketone and name it.

Oxidation recap ALWAYS 0!!! None Element Usual oxidation state Exceptions Elements joined to themselves, e.g. Cl2 ALWAYS 0!!! None Group 1 metals always +1   Group 2 metals always +2 Fluorine always -1 Oxygen usually -2 except in peroxides and F2O Hydrogen usually +1 except in metal hydrides where it is -1 Chlorine usually -1 except in compounds with O or F

Oxidation of propan-1-ol to the aldehyde propanal

Oxidising carbon More hydrogen bound to the carbon LOWERS (makes it more negative, or reduced) its oxidation number More oxygen bound to the carbon RAISES (makes it more positive, or oxidised) its oxidation number

Oxidising alcohols Reaction conditions: 1. The oxidising agent is always acidified potassium dichromate written above the arrow like this: K2Cr2O7/H2SO4 2. The reactants are the alcohol and “[O]” symbolising the oxidation agent 3. Heat is always needed

Potassium dichromate In its oxidised state it is a bright orange liquid What kind of bonds hold this compound together?

Oxidising primary alcohols Write out the equation using displayed formula of the oxidation of ethanol to ethanal (water is also made) (The reaction conditions require GENTLE HEAT with immediate distillation)

Aldehydes vs acid problem

Further oxidation of a primary alcohol Using a process known as REFLUX, the reaction contents are continually heated at their boiling point temperature, so HOTTER and LONGER heating then alcohol conversion to an aldehyde Still uses acidified potassium dichromate Primary + Oxidising  Carboxylic + water alcohol agent acid

Reflux apperatus Clamp stand Cooling tube (tap water goes in at the top and out at the bottom continuously) Reaction container Heat source

Draw out the conversation of ethanol to ethanoic acid using the displayed formula

Oxidation of secondary alcohols Like primary alcohols, also require acidified potassium dichromate and heat (but not reflux) Converts the alcohol into a ketone Write out, using displayed formula, the oxidation of hexan-2-ol to hexa-2-one

Oxidation of tertiary alcohols The carbon attaching to the OH doesn’t have any hydrogens attached to it, so these can’t be oxidised.

Starter Using [O] to represent the oxidising agent write the equations for the full oxidation of: butan-1-ol butan-2-ol butan-1,2-diol Extension: what do oxidation, respiration and combustion have in common? What are the differences?

Esterification and dehydration of alcohols L.O.: Describe the esterification of alcohols with carboxylic acids. Describe elimination of H2O from alcohols to form alkenes.

The esterification reaction between propanoic acid and methanol

Naming esters The alcohol becomes the alkyl group, the carboxylic acid becomes the alkanOATE part e.g. ethanol and methanoic acid form ethyl methanoate

Diagram to show the bonds broken during esterification

Simple laboratory preparation of an ester

Sweet-smelling esters

Write out your own esterification reaction between methanol and methanoic acid using displayed formula Now draw out the reaction between: Ethanol and ethanoic acid 3,3-dichloro-2-methylhexanoic acid and butan-1-ol Propanoic acid and hexan-3-ol

Draw these esters and name the alcohols and the carboxylic acids that made them: The smell of oranges is from the ester: 1. Octyl ethanoate Banana is made from: 2. Pentyl ethanoate

Dehydration of ethanol to form ethene

Dehydration of cyclohexanol to form cyclohexene