Transcript Unit 2 revision ppt - Calderglen High School

Hydrocarbons
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Systematic naming
Alcohols. P,S,T.
Diol, triol Alcohol properties (H-bonds)
Oxidation – oxidising agents – routes
Aldehydes / Ketones - isomers
Carboxylic acids
A
Any acceptable structural
formulae for propanal
Silver mirror
Water bath (flammable reactants)
Primary alcohol
Proteins
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Amino acids (essential)
Peptide link, polypeptide
enzymes
Denaturing
Lock and key
Optimum settings
C
B
One which the human body cannot
synthesise itself. We need to get it through
our diet.
H Bonds?
Redraw the amino acids with alanine shown on the left hand
side and phenylalanine on the right hand side. Now condense
them together (losing water) to show your answer
Esters, Fats and oils
• Esters – making (catalyst),naming, structures,
uses, condensation, hydrolysis
Ethanoic acid
Concentrated
sulphuric acid
Add a wet paper towel to act as
a condenser
Esters, Fats and oils
• Fats / oils - Animal, vegetable, marine
• Fats/oils are esters (fats/oil also known as
triglycerides)
• Glycerol structure / Fatty acids (ratio)
• Properties of fat (saturated) vs oil
(unsaturated)
• London dispersion forces to explain melt
points
D
The process breaks some C=C double bonds
decreasing the level of unsaturation. This
“hardening” process results in an increase
in melting and boiling point.
Soaps, detergents,
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Soaps (salt of fatty acid)
Structure
How they work
Hydrophobic, hydrophilic
Mechanism of stain/dirt removal
Roll-up mechanism
The hydrophobic tails ‘burrow’ into
the droplet of oil or grease.
The hydrophilic heads are left to
face the surrounding water.
 This results in the formation of a
ball-like structure (a micelle).
The non-polar substances, such as
oil or grease, are held inside the ball
and suspended in water, to be
washed away.
Soaps, detergents,
• Soap scum
• Detergents
• Emulsion – small droplets of one liquid
dispersed in another
• Emulsifiers
– Allow oil and water to mix
OC
SOAP:
Carboxyl head
O
O
S
O
O-
DETERGENT:
SULPHONATE (SO3-)
head
• The calcium salt of a sulphonate is soluble in
water unlike the calcium salts of the
carboxylate.
• Hence no scum is formed
Antioxidant
• Oxygen reacts with edible oils giving them a
rancid flavour
• Antioxidants prevent this – they get oxidised
in place of the oil (or other food)
• Ion electron equation (the antioxidant LOSES
electrons)
Oxidation of food - video
• Fats and oils can go rancid in two ways:
Oxidative rancidity
• The double bonds are cleaved (broken) by free
radical mechanism
Hydrolytic rancidity
• The ester link is hydrolysed releasing the fatty
acids (some are foul smelling)
Antioxidant molecules are REDUCING AGENTS, they donate an
electron to the oxidising agent
The food is “protected” because the antioxidant is oxidised in place of
the food.
Ion-electron equations can be used to show how antioxidant
molecules are oxidised.
C6H8O6
C6H6O6 + 2H+ +
Vitamin C
DHA
(ascorbic acid)
(dehydroascorbic acid)
2e-
Fragrances
• Isoprene unit
• ID the number of units used to make terpene
• Terpenoid (oxidised terpenes)
Essential Oils
• Essential oils are the
concentrated extracts of
volatile, non-water-soluble
aroma compounds from
plants.
• Terpenes are the key
components in most
essential oils.
Absinthe – a cyclic terpenoid
CH3
H3C
This terpene has been
oxidised to a terpenoid
CH
C
H2C
CH2
HC
C
CH
CH3
Thujone
(Absinthe)
O
Terpenes
• Terpenes are unsaturated compounds
formed by joining together isoprene units.
One isoprene unit
contains
five carbon atoms
Head
Tail
CH3
C
CH2
CH
=
CH2
Isoprene
(2-methylbuta-1,3-diene)
Steam Distillation
• Steam passes over
the plant and
extracts the
essential oil.
• The mixture
evaporates and
passes into the
condenser.
• The essential oil
vapour is chilled
and collected
Skin care
• UV – high energy form of light
• Provides energy to break bonds (forms free
radicals - causes sunburn)
• Sun block prevents UV reaching the skin
• Free radicals
– Initiation
– Propagation
– Termination
• Free radical scavengers
• Initiation
Cl2(g)
Cl.(g) + .Cl(g)
• Propagation
H2 (g) + .Cl (g)
H. (g) + Cl2 (g)
H. (g) + HCl (g)
HCl (g) + Cl. (g)
• Termination
H.(g) + .Cl(g)
HCl(g)
H.(g) + .H(g)
H2(g)
Cl.(g) + .Cl(g)
Cl2(g)
Free Radical Scavengers
• Many cosmetic products contain
free radical scavengers.
• These are molecules which can react
with free radicals to form stable
molecules and prevent chain
reactions.
addition
Redraw the butanal to look as similar as
possible to the propanone in the original
example. Use this as a guide to work out the
product
CH3-CH2
H
CH3-CH2
H