Transcript Hydrocarbons

Organics – NonHydrocarbons
Haloalkanes – uses and sources
Alcohols – uses, sources and
reactions
Carboxylic acids – uses, sources
and reactions
Esters – uses, sources and
reactions
Types of reactions - A summary
Author: J R Reid
Haloalkanes – Uses, sources
and reactions
Haloalkanes are saturated organic molecules with
halogen atoms attached.
Sources
They can be made by adding halogens or hydrogen
halides to unsaturated organic molecules
Uses
Haloalkanes can be used as solvents and they were
once used as refrigerant gases (CFCs)
Reactions
We don’t have to worry about reactions of
haloalkanes in this section of work
Alcohols – Uses and sources
Alcohols (also known as alkanols) are similar to
alkanes except they have an –OH group attached
somewhere in their structure. They are miscible
(when two liquids ‘dissolve’) in both water and nonpolar substances
Sources
Ethanol can be made by fermentation or the
hydration of ethene
Methanol can be made from natural gas (methane)
Uses
Alcohols can be used as fuels, solvents and in
beverages (ethanol only)
Alcohols – Structure
The structure of alcohols is very important to recognise
because only certain types of alcohols react in a certain way.
Alcohols react differently based on the sort of carbon that the
–OH group is bonded to. See the three chemicals below? What
makes these three molecules different?
Primary alcohols – the carbon is bonded to one other carbon
Secondary alcohols – the carbon is bonded to two other carbons
Tertiary alcohols – the carbon is bonded to three other carbons
H3C
H2C
CH2
OH
Primary
CH3
H3C
CH
CH3
OH
Secondary
H3C
C
HO
Tertiary
CH3
Alcohols - Reactions
Combustion – Alcohols burn without
producing soot or smoke (carbon)
Oxidation – Primary alcohols can be
oxidised to create carboxylic acids. We can
use acidified dichromate or acidified
permanganate as oxidising agents
Elimination – As you might have guessed
elimination reactions remove parts of the
alcohol. In this case we remove the –OH
group and one other hydrogen using
concentrated sulfuric acid. An alkene is the
product of an elimination reaction
Carboxylic Acids – Uses and
sources
Carboxylic acids are weak acids. The short chained
ones are miscible in water, but longer chained ones
do not dissolve.
Sources
They can be made by oxidising primary alcohols
Carboxylic acids are also produced by natural
processes such as the oxidation of wine. Some ants,
wasps and nettles also produce methanoic acid as a
way of making people miserable
Uses
These acids can be used in food stuffs (e.g. Acidity
regulator 260)
They are also used in the production of fruit
flavours (see the Ester section)
Carboxylic Acids – Reactions
Neutralisation – Because they are acids they
will neutralise with bases to produce a salt
and water. The salts names always end in –
oate e.g. sodium ethanoate
Esterification – When we mix an alcohol
with a carboxylic acid (and some
concentrated sulfuric acid) we get an ester
formed:
H3C
CH2
OH
+
HO
C
O
CH2 CH3
H3C
CH2 O
C
O
CH2 CH3
+ H2O
Esters – Uses and sources
Esters are non-soluble in water. As seen earlier they
are a product of reacting an alcohol with a
carboxylic acid
Uses
Esters have a number of uses. The main one is in
the production of fruit flavours – some smell nice
and fruity
Esters can also make good solvents (i.e. nail polish
remover)
Esterification is also used to produce fats and oils
Sources
Esters are made by fruits (for flavour) and by all
living things (fats and oils)
Also as discussed earlier we can make them in the
lab
Esters - Reactions
Hydrolysis – This type of reaction involves water
(hydro) breaking (lysis). In other words we get
water, break it up and shove it inside the ester
somehow. The result is that the water is absorbed
and the ester breaks into the acid and the alcohol
again:
H3C
CH2 O
C
O
CH2 CH3
+ H2O
H3C
CH2
OH
+
HO
C
CH2 CH3
O
Saponifaction – This is the production of soap from
a fat (a molecule containing three esters) reacting
with NaOH.
Types of Reactions – a
summary
Match the terms with the summaries below:
Type
Description
Combustion
Replacing a hydrogen
Elimination
Joining an alcohol and a
carboxylic acid
Oxidation
Reacting and acid and a base
Esterification
Making soaps from fat
Neutralisation
Breaking of esters (and water)
Hydrolysis
Adding oxygen
Saponification
Removing water
Dehydration*
Burning in oxygen
* What reaction(s) could be describes as dehydration reactions?
Reaction Summary Ex.
H3C
CH2
OH
H3C
CH2
Cl
Cl
O
CH2
CH3
C
CH2
O
H2C
H3C
CH2
O
CH2
Cl
H3C
C
OH
H3C
CH3
HC
CH