describe the structural formulae and reactions of compounds containing selected functional groups 4...
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Describe the structural Describe the structural formulae and reactions formulae and reactions
of compounds of compounds containing selected containing selected functional groupsfunctional groups
4 credits4 credits
• HaloalkaneHaloalkane
• AlcoholAlcohol
• AlkeneAlkene
• AlkyneAlkyne
• EsterEster
• Carboxylic acidCarboxylic acid
Selected organic functional groups are Selected organic functional groups are limited to:limited to:
Compounds are limited to:Compounds are limited to:
Those containing no more than 8 Those containing no more than 8 carbons. Larger organic molecules may carbons. Larger organic molecules may be used in Qs linking structure & be used in Qs linking structure & reactivity.reactivity.
Acid Acid reactions of reactions of carboxylic carboxylic
acidacid
DistinguishinDistinguishing testsg tests
Structural Structural and and
geometric geometric isomersisomers
Knowledge Knowledge of primary, of primary, secondary secondary & tertiary & tertiary alcohols & alcohols &
haloalkaneshaloalkanes
Naming Naming compouncompoun
dsds
ClCl22
HH22O/HO/H++ & HCl & HCl identify identify major & major & minor minor
productsproducts
BrBr22
MnOMnO44-- Oxidation of Oxidation of
primary primary alcohols to alcohols to carboxylic carboxylic
acidacid
polymerisatipolymerisationon
HH22/Pt/Pt
HalogenatioHalogenation of alkanesn of alkanes
Elimination Elimination of water of water
from alcoholfrom alcohol
Organic ChemistryOrganic ChemistryReactions of Reactions of
alkenesalkenes
Formation & Formation & hydrolysis of hydrolysis of esters e.g. esters e.g.
triglyceridestriglycerides
Fats, oils and Fats, oils and soapssoaps•Triglyceride is a fat that contains 3 ester Triglyceride is a fat that contains 3 ester
linkslinks
•Made from 3, long-chain carboxylic acids Made from 3, long-chain carboxylic acids + glycerol (triol)+ glycerol (triol)
•In the esterfication reaction, 3HIn the esterfication reaction, 3H220 is 0 is formed (OH from acid + H from glycerol)formed (OH from acid + H from glycerol)
Beware; Beware; they can they can change change
the the orientatioorientatio
nn
Divide Divide between C between C and O, add and O, add Hs to form Hs to form
triol and OHs triol and OHs to form acidto form acid
Fats, oils and Fats, oils and soapssoapsLike all esters, triglycerides undergo Like all esters, triglycerides undergo
hydrolysis. This reaction can be catalysed hydrolysis. This reaction can be catalysed by either acid or base.by either acid or base.
1.1.With acidWith acid
An acid catalyst is used (not conc. acid) to An acid catalyst is used (not conc. acid) to form glycerol (triol) and carboxylic acid form glycerol (triol) and carboxylic acid again:again:
2.With alkali (OH2.With alkali (OH--))
If NaOH is used, it reacts with the If NaOH is used, it reacts with the carboxylic acid to form a sodium salt and carboxylic acid to form a sodium salt and glycerol. The sodium salt in this case is glycerol. The sodium salt in this case is called ‘soap’ and the reaction is called called ‘soap’ and the reaction is called ‘saponification’‘saponification’
Acid conditions: glycerol and palmitic Acid conditions: glycerol and palmitic acid formed.acid formed.
Alkali conditions: glycerol and the Alkali conditions: glycerol and the sodium salt of palmitic acid formedsodium salt of palmitic acid formed
Notice Notice there are there are
3 diff. 3 diff. acidsacids
In basic conditions: glycerol would In basic conditions: glycerol would still form but instead of the acid a still form but instead of the acid a sodium salt would form.sodium salt would form.
Na
PolymerisatiPolymerisationon•A polymer is a large molecule made of A polymer is a large molecule made of
small molecules called monomerssmall molecules called monomers
•In addition polymerisation, nothing else In addition polymerisation, nothing else is madeis made
•All monomers are alkenesAll monomers are alkenes
•Could be asked to draw monomers from Could be asked to draw monomers from polymers or vice versapolymers or vice versa
OH
CH=CH2
Isolate 2 Isolate 2 carbons to form carbons to form the basis of the the basis of the
alkene alkene monomermonomer
Break the Break the double bond, double bond, attach to next attach to next
monomermonomer
Isolate 2 Isolate 2 carbons, carbons,
straighten them straighten them and put the and put the
double bond indouble bond in
Naming Naming compoundscompoundsLearn functional groups and endings!Learn functional groups and endings!
GroupGroup StructureStructure Name endingName ending
AlkaneAlkane C-CC-C -ane-ane
AlkeneAlkene C=CC=C -ene-ene
AlkyneAlkyne C=CC=C -yne-yne
AlcoholAlcohol -OH-OH -anol -anol
HaloalkanHaloalkanee
e.g. –Cle.g. –Cl e.g Chloro-e.g Chloro-aneane
Carboxylic Carboxylic acidacid
OHOH
C=OC=O-anoic acid-anoic acid
EsterEster -C=O-C=O
OO-thyl-anoate-thyl-anoate
1-1-chloropropchloropropaneanemethylpropmethylpropanoateanoate
Crocodiles! Crocodiles! What is eaten What is eaten first is named first is named
first!first!Numbering Numbering
begins at ene begins at ene endend
-anoic grp is -anoic grp is always on always on carbon 1carbon 1
Structural Structural isomersisomersSame number of atoms in a different Same number of atoms in a different
arrangementarrangement
Geometric Geometric isomersisomers• Different arrangements of atoms in Different arrangements of atoms in
spacespace
• Cis (same side) & trans (across) Cis (same side) & trans (across)
• Due to double bond being unable to Due to double bond being unable to rotaterotate
• Can have different properties e.g. Can have different properties e.g. polarity & boiling pointpolarity & boiling point
methylpromethylpropenepene
cyclobucyclobutanetane
Don’t need to give Don’t need to give number placing for number placing for methyl and ene. methyl and ene.
They can be They can be nowhere else!nowhere else!
But-1-But-1-eneene
But-2-But-2-eneene
Cannot Cannot form cis & form cis & trans trans because the because the groups on groups on each C are each C are not not differentdifferent
Can form cis & trans Can form cis & trans because the groups because the groups on each C are on each C are different and the different and the double bond doesn’t double bond doesn’t allow rotationallow rotation
Base the drawing Base the drawing around the double around the double
bond to examine the bond to examine the groupsgroups
Remember this! It’s Remember this! It’s the stock answer for the stock answer for
explaining explaining geometric isomersgeometric isomers
Reactions of Reactions of alkenesalkenes
Reaction Reaction typetype
ReagentReagent ConditioConditionsns
ProductProduct
HydrogenatiHydrogenationon
HydrogenHydrogen Pt/HPt/H22 or or Ni/HNi/H22
AlkaneAlkane
HydrationHydration WaterWater HH++/H/H2200 AlcoholAlcohol
HalogenatioHalogenationn
HalogenHalogen BrBr22 or Cl or Cl22 HaloalkaHaloalkanene
HalogenatioHalogenationn
Hydrogen Hydrogen halidehalide
HCl or HCl or HBrHBr
HaloalkaHaloalkanene
OxidationOxidation Potassium Potassium permanganpermanganateate
HH++/MnO/MnO44-- DiolDiol
All types of All types of addition addition reactionsreactions
Watch out for Watch out for Markovnikov’s! Markovnikov’s! Asymmetrical Asymmetrical
alkene = 2 alkene = 2 productsproducts
Watch out for Watch out for Markovnikov’s! Markovnikov’s! Asymmetrical Asymmetrical
alkene = 2 alkene = 2 productsproducts
Primary, secondary & Primary, secondary & tertiarytertiary• Classifications in alcohols and Classifications in alcohols and
haloalkaneshaloalkanes
• Look at the Carbon the alcohol/halogen Look at the Carbon the alcohol/halogen is attached to. Is this attached to 1, 2 or 3 is attached to. Is this attached to 1, 2 or 3 carbons?carbons?
• Form straight line (!), T-shape or crossForm straight line (!), T-shape or cross
primaprimaryry
seconsecondarydary
primaprimaryry
tertiartertiaryy
Reactions of Reactions of alcoholsalcohols• Elimination of water (dehydration):Elimination of water (dehydration):
alcohol alcohol Alkene + water Alkene + water
• Oxidation of 1Oxidation of 1° alcohol:° alcohol:
11° alcohol ° alcohol (aldehyde) (aldehyde) Carboxylic Carboxylic acidacid
Can use HCan use H++/MnO/MnO44- - as oxidising agent instead. Purple to as oxidising agent instead. Purple to
colourlesscolourless
• Esterfication:Esterfication:
alcohol + Carboxylic acid alcohol + Carboxylic acid ester ester
Conc. HConc. H22SOSO44
HH++/Cr/Cr22OO772-2-
Dichromate turns from Dichromate turns from orange to greenorange to green
Conc. HConc. H22SOSO44
This is a This is a dehydration dehydration
reaction reaction (elimination)(elimination)
Alcohol + acid…Alcohol + acid…
Oxidation of a Oxidation of a primary primary alcohol…alcohol…
Potassium permanganate will Potassium permanganate will turn from purple to colourlessturn from purple to colourless
Reactions of carboxylic Reactions of carboxylic acidsacids• Normal acid reaction e.g. fizzing with Normal acid reaction e.g. fizzing with
metal metal H H22 & fizzing with carbonates & fizzing with carbonates COCO2 2 & litmus turning red& litmus turning red
• Form metal salts involving the organic Form metal salts involving the organic acid e.g. sodium methanoateacid e.g. sodium methanoate
• Form esters when reacted with alcoholsForm esters when reacted with alcohols
Distinguishing testsDistinguishing testsGroupGroup DamDam
p p litmulitmuss
HH++/Cr/Cr22OO772-2- Sodium Sodium
carbonacarbonate sol.te sol.
SmellSmell Warm Warm HH++/MnO/MnO44
--
BrominBromine e waterwater
AlcoholAlcohol 11° turns ° turns from from orange to orange to greengreen
Forms 1 Forms 1 layerlayer
11° turns ° turns from from purple purple to to colourlecolourlessss
Stays Stays orangorangee
HaloalkaHaloalkanene
Stays Stays orangeorange
Forms 2 Forms 2 layerlayer
Stays Stays purplepurple
Stays Stays orangorangee
Carbox. Carbox. AcidAcid
TurnTurns reds red
Stays Stays orangeorange
Forms 1 Forms 1 layer layer that that fizzesfizzes
pungepungentnt
Stays Stays purplepurple
Stays Stays orangorangee
EsterEster Stays Stays orangeorange
Forms 2 Forms 2 layerslayers
fruityfruity Stays Stays purplepurple
Stays Stays orangorangee
AlkaneAlkane Stays Stays orangeorange
Forms 2 Forms 2 layerslayers
Stays Stays purplepurple
Slowly Slowly decolodecolour w/ ur w/ uVuV
AlkeneAlkene Stays Stays orangeorange
Forms 2 Forms 2 layerslayers
strongstrong Purple Purple to to colourlecolourlessss
Quickly Quickly decolodecolourur
Acidified potassium Acidified potassium dichromate dichromate (H(H++/Cr/Cr22OO77
2-2-))Propan-1-ol will turn acidified Propan-1-ol will turn acidified potassium dichromate from orange potassium dichromate from orange to green. Propanoic acid will remain to green. Propanoic acid will remain orange.orange.
There are other There are other possible possible
answers, see answers, see how many you how many you can come up can come up
with!with!
hexhexaneane
hex-1-hex-1-eneeneDecolourises Decolourises
bromine slowly bromine slowly with UV lightwith UV light
Decolourises Decolourises bromine quicklybromine quickly
Saturated so Saturated so undergoes a undergoes a substitution substitution reactionreaction
unsaturated so unsaturated so undergoes an undergoes an addition reactionaddition reactionForms 1-Forms 1-
bromohexanebromohexaneForms 1,2-Forms 1,2-dibromohexanedibromohexaneCHCH33CHCH22CHCH22CHCH22CHCH22CHCH3 3
+ Br+ Br22
CHCH22BrCHBrCH22CHCH22CHCH22CHCH22CHCH
33 + HBr + HBr
CHCH22CHCHCHCH22CHCH22CHCH22CHCH3 3 + + BrBr22
CHCH22BrCBrCHBrCBrCH22CHCH22CHCH22CHCH
33 + HBr + HBr
Adding water Adding water to an to an
asymmetric asymmetric alkene…but alkene…but
which product which product goes where?goes where?
End product End product = ester. = ester.
Reagent = Reagent = alcohol. So C alcohol. So C
must be…must be…
Propanoic Propanoic acidacid
So B must be So B must be a primary a primary
alcohol and alcohol and reagent D reagent D
must be an must be an oxidantoxidant
Propan-1-Propan-1-olol HH++/Cr/Cr22OO77
2-2-Propan-2-Propan-2-olol
To form a To form a sodium salt sodium salt of an ester…of an ester…
NaOHNaOH