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CHEMISTRY
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1 ALCOHOLS
HIGH MELTING AND BOILING POINTS OF ALCOHOLS
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Because of the presence of hydrogen bonds between alcohol molecules

LOW VOLATILITY OF ALCOHOLS
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Because of high boiling points
Harder to turn from a liquid into a gas

SOLUBILITY
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Alcohols dissolve in water
Hydrogen bonds form between alcohol and water molecules
Solubility decreases as the chain length increases
 A larger non-polar hydrocarbon chain doesn’t form hydrogen bonds with water
molecules

INDUSTRIAL PRODUCTION OF ETHANOL
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Hydration of ethene
Fermentation

HYDRATION OF ETHENE
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Reaction of ethene with steam
H2C=CH2 (g) + H2O (g)  CH3CH2OH (l)

CONDITIONS FOR HYDRATION OF ETHENE
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Carried out at high temperature and moderate pressure (300⁰C 60 atm)
In the presence of an acid catalyst (H3PO4)

PROCESS OF HYDRATION OF ETHENE
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Reversible reaction
Only 5% of ethene is converted each time the reagents pass through the reactor
Unreacted gases pass through the reactor again
95% conversion, overall
100% atom economy

FERMANTATION FROM SUGARS
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Carbohydrates (sugar or starch) are converted into ethanol and CO2 (g)
C6H12O6 (aq)  2CH3CH2OH (aq) + 2CO2 (g)

CONDITIONS FOR FERMENTATION
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Low temperatures (below 37⁰C so enzyme doesn’t denature)
Catalysed by yeast (enzyme in yeast)
Absence of air – anaerobic (prevent oxidation of ethanol)

© SMARTBERG 2015
This work is shared under a Creative Commons Attribution-NonCommercial-NoDerivatives license
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OXIDATION OF TERTIARY ALCOHOLS
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Tertiary alcohols are resistant to oxidation
The oxidising agent remains orange in colour

ALDEHYDES
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C=O double bond
C-H bond

CARBOXYLIC ACIDS
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C=O double bond
C-O-H bond

KETONE


C=O double bond

OXIDATION EQUATIONS
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[O] for primary alcohol to aldehyde and secondary alcohol to ketone
2[O] for primary alcohol to carboxylic acid
Products include either an aldehyde, carboxylic acid or ketone and H2O

ESTERIFICATION
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An alcohol is warmed with a carboxylic acid
In the presence of an acid catalyst (concentrated H2SO4)
Produces an ester and water

ESTERIFICATION REACTION
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E
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propanoic acid + methanol  methyl propanoate + H2O
 CH3CH2COOH + CH3OH  CH3CH2COOCH3 + H2O
–OH taken from carboxylic acid and –H taken from alcohol to form H2O

DEHYDRATION OF AN ALCOHOL
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Elimination reaction
1 molecule  2 molecules
Saturated  unsaturated
Forms alkenes

CONDITIONS FOR DEHYDRATION OF AN ALCOHOL
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Catalysts are concentrated phosphoric acid, H3PO4 or concentrated sulfuric acid, H2SO4
Heated under reflux

DEHYDRATION EQUATION
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OH group from one carbon atom lost
H atom from adjacent carbon lost
Double bond forms between these two carbons
E
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ethanol  ethene + H2O

2
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2
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GENERAL FORMULA OF HALOGENOALKANES
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CnH2n+1X

HALOGEN PREFIXES
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F is fluoroCl is chloroBr is bromoI is iodo-

REACTIVITY OF THE HALOGENOALKANES
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Halogenoalkanes are polar (different electronegativities)
Electronegativity decreases down the group
Decrease in polarity down the group
Electron-deficient carbon atom attracts nucleophiles

HYDROLYSIS OF HALOGENOALKANES
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Nucleophilic substitution reaction
Halogenoalkanes react with an aqueous solution of hot hydroxide ions
 Usually aqueous sodium hydroxide
Product is an alcohol
Carried out under reflux

HYDROLYSIS EQUATION
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E
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CH3CH2CH2Cl (aq) + OH- (aq)  CH3CH2CH2OH (aq) + Cl- (aq)

HYDROLYSIS MECHANISM
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During hydrolysis, the halogen atom is replaced by the hydroxide ion
Lone pair of electrons of hydroxide ion are donated to the electron-deficient carbon atom
Covalent bond formed between oxygen (of the hydroxide ion) and carbon atom
Carbon-halogen bond breaks by heterolytic fission
Halide ion is formed

DRAWING HYDROLYSIS MECHANISM
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Show relevant dipoles
Show lone pair and negative charge
Curly arrow from lone pair to carbon atom
Curly arrow from bond to electronegative iodine atom

RATES OF HYDROLYSIS EXPERIMENT
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Aqueous silver nitrate in ethanol
Heated with halogenoalkane
H2O in mixture is the nucleophile

HYDROLYSIS EQUATION
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Halogenoalkane (aq) + H2O (l)  alcohol (aq) + H+ (aq) + halide ion (aq)
AgNO3 (aq) reacts with halide ions

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This work is shared under a Creative Commons Attribution-NonCommercial-NoDerivatives license
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CALCULATING ATOM ECONOMY
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Addition reactions have 100% atom economy
Substitution reactions are less efficient

BENEFITS OF HIGH ATOM ECONOMY
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Reduction of waste

ABSORPTION OF INFRARED RADIATION
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Covalent bonds vibrate with bending or stretching motion

FUNCTIONAL GROUPS IDENTIFIED WITH INFRARED SPECTROSCOPY
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Hydroxyl (O-H) group in alcohols
Carbonyl (C=O) group in aldehydes and ketones
Carboxyl (COOH) group in carboxylic acids

INFRARED SPECTRUM OF ALCOHOLS
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Peak in the first region only
O-H bond

INFRARED SPECTRUM OF ALDEHYDES AND KETONES
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Peak in the second region only
C=O bond

INFRARED SPECTRUM OF CARBOXYLIC ACIDS
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Peaks in both region
O-H bond
C=O bond

APPLICATIONS OF INFRARED SPECTROSCOPY
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Breathalysers – measures ethanol in the breath
Drug analysis
Quality control in perfume manufacture

USES MASS SPECTROMETRY
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Determination of relative isotopic masses
Method for identifying elements
Monitoring levels of pollution

CALCULATING RELATIVE ATOMIC MASS
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Add relative abundances of isotopes
E
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79% Mg-24, 10% Mg-25, 11% Mg-26 – (24x79)+… divided by 100

MASS SPECTRUM
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Shows mass to charge ratio (m/z)
Shows relative abundances of isotopes
Fingerprint for molecules
© SMARTBERG 2015
This work is shared under a Creative Commons Attribution-NonCommercial-NoDerivatives license
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