OCR F334 What's in a Medicine

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F334 Chemistry of Materials: What's in a Medicine?
(a) describe acids in terms of the BrønstedLowry theory as proton donors, and bases as proton acceptors, and
identify the proton donor and proton acceptor in an acidbase reaction
An acid is a proton donor.
A base is a proton acceptor .
An acid reacts with water to form an oxonium ion (H
) e.g.H A + H
2O H
3O + A
Conjugate Pairs:
In many cases, the donation of a proton by an acid is reversible . When an acid loses a proton it forms a base.
When the base accepts a proton back again it reforms the acid this a conjugate base. Members of a conjugate
pair differ from each other by the presence or absence of the transferable hydrogen ion.
Every acid has a conjugate base .
Every base has a conjugate acid .
NH 3 + H
2O NH 4
+ OH
Base Acid Conjugate Conjugate
Acid Base
H 2O donates protons and acts as an acid. OH
acts as a base in the reverse reaction.
NH 3 accepts protons and acts as a base. NH 4 acts as an acid in the reverse reaction.
They are called a conjugate acidbase pairs .
Depending on the circumstance, many substances can act as both an acid and a base they are amphoteric.
Water can act as either an acid or a base:
With a strong acid it acts as a base. H+ + H H
With a strong base it acts as an acid. H H
2O + OH
Strength of Acids and Bases:
A strong acid is a powerful
H+ donor; it is fully dissociated. It has a weak conjugate base.
HA H+ + A
A weak acid is a moderate/weak H donor; it is weakly dissociated. It has a strong conjugate base.
H+ + A
Acidbase indicators, such as litmus and methyl orange, are coloured organic substances which are themselves
weak acids. In order for them to behave as an indicator, the conjugate acid and base forms of the molecule must
have different colours.

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F334 Chemistry of Materials: What's in a Medicine?
Bonding and Structure
(b) draw and interpret simple electron 'dot and cross' diagrams to sow how atoms bond through ionic, covalent
and dative covalent bonds and be able to describe a simple model of metallic bonding
What happens to electrons
Ionic Gains or loses electrons::
Bondin Lose electron (metal) = positive ion.
g Gain electron (nonmetal) = negative ion.
Covalen Electrons are shared.
Dative Lone pairs are shared between atoms.…read more

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F334 Chemistry of Materials: What's in a Medicine?
BondAngle 180o 120o Approx 109o
Approx 109o Approx 109o
90o and 120o
recall the typical physical properties (melting point, solubility in water, ability to conduct electricity)
characteristic of giant lattice (metallic, ionic covalent network) and simple molecular structure types
Giant Ionic Covalent Simple Giant Covalent Giant Metallic
Lattice Molecular Network Lattice
Examples Sodium Chloride Carbon Dioxide Diamond Iron
Melting Point High Low High High
Solubility in Water Soluble Insoluble Insoluble Insoluble
Conduct Only when liquid or…read more

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F334 Chemistry of Materials: What's in a Medicine?
(d) use systematic nomenclature to name and interpret:
Diols e.g. butane1,4diol
Carboxylic oic acid
e.g. methanoic acid
Dicarboxyli dioic acid
c Acids
e.g. propanedioic acid
Esters e.g. propyl butanoate
Aldehydes al
e.g. ethanal, butanal
Ketones one
e.g.…read more

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F334 Chemistry of Materials: What's in a Medicine?
Only carboxylic acids have a pH low enough to react with carbonates.
(g) describe the reaction of alcohols with carboxylic acids in the presence of concentrated sulfuric acid or
concentrated hydrochloric acid to form esters
Carboxylic Acid + Alcohol Ester + Water
This reaction only occurs in the presence of concentrated sulphuric acid or concentrated hydrochloric acid .…read more

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F334 Chemistry of Materials: What's in a Medicine?
Oxidation of Primary Alcohols:
Primary Alcohol Aldehyde Carboxylic
Acidified potassium dichromate (VI)
Carboxylic Acid Aldehyde
Acidified potassium dichromate (VI)
Oxidation of Secondary Alcohols:
Secondary Alcohol Ketone
Acidified potassium dichromate (VI)
Making Cyanohydrin:
Aldehyde/Ketone + Hydrogen Cyanide
(j) describe the techniques for heating and purifying volatile liquids: heating under reflux and distillation
Heating Under Reflux:
1.…read more

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F334 Chemistry of Materials: What's in a Medicine?
(k) describe the mechanism of the nucleophilic addition reaction between a carbonyl compound and hydrogen
cyanide, using 'curly arrows' and bond polarities
Applications of Organic Chemistry
(l) understand that more effective medicines can be obtained by modifying the structure of existing medicines
When chemists find out that a particular molecule has medicinal properties, they try to improve the properties by
tweaking the molecular structure . An example would be the development of aspirin.…read more

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F334 Chemistry of Materials: What's in a Medicine?
However, on closer inspection, a condensation reaction is actually an addition reaction followed by an elimination
(i) recall and understand that rearrangement and addition reactions have a higher atom economy than
substitution and condensation reactions, which have a higher atom economy than elimination reactions
Type of Example Atom
Reaction Economy
Rearrangemen 86.0 x 100 = 100%
t 86.0
Addition 241.8 x 100 = 100%
Substitution 92.5 x 100 = 100%
Elimination 42.…read more

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F334 Chemistry of Materials: What's in a Medicine?
Modern Analytical Techniques
(p) describe the technique of thinlayer chromatography (TLC), including location of spots using iodine or
ultraviolet radiation, and interpret results in terms of number of spots and matching heights or Rf values with
known compounds; understand that chromatography can be used for the purification of an organic substance
ThinLayer Chromatography:
This technique is used to purify organic compounds and to separate small quantities of organic compounds.
1.…read more

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F334 Chemistry of Materials: What's in a Medicine?
Type of stationary phase
(q) interpret and predict mass spectra: identify the M+ peak and explain that it indicates the M r; explain how the
molecular formula can be worked out from the highresolution value of the M peak; recall that other peaks are
due to positive ions from fragments and the mass differences between peaks; indicate the loss of groups of
atoms, suggest the origins of peaks, e.g.…read more


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