chemistry Unit 4.5

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Unit 4.5 Organic chemistry II Unit 4.5 Organic chemistry II

Recognise structural isomers, stereoisomerism as geometrical (cis-trans) or o Recognise structural isomers, stereoisomerism as geometrical (cis-trans) or opticalptical

Explain the existence of geometrical (cis-trans) isomerism resulting from restricted rotation about a carbon-carbon double bond Explain the existence of geometrical (cis-trans) isomerism resulting from restricted rotation about a carbon-carbon double bond Understand the existence of optical isomerism resulting from a chiral centre in molecules with a single asymmetric carbon atom, Understand the existence of optical isomerism resulting from a chiral centre in molecules with a single asymmetric carbon atom, Understand optical isomers as object and

non-Understand optical isomers as object and non-superimposable mirror imagessuperimposable mirror images

Recall optical activity as the ability of a single optical isomer to rotate the plane of polarisation of plane polarised monochromatic Recall optical activity as the ability of a single optical isomer to rotate the plane of polarisation of plane polarised monochromatic light and understand the nature of a racemic mixture

light and understand the nature of a racemic mixture Isomer

Isomer Same molecular formula, different structural formulaeSame molecular formula, different structural formulae

Structural isomerism

Structural isomerism Occurs when 2 or more different structural formulae can be written for the same molecular formulaOccurs when 2 or more different structural formulae can be written for the same molecular formula Chain isomers

Chain isomers Different arrangements of carbon skeletonDifferent arrangements of carbon skeleton Similar chemical properties, differ in

Similar chemical properties, differ in physical properties(Mt)because of changephysical properties(Mt)because of change in shape of molecule

in shape of molecule

Positional isomers

Positional isomers Same skeleton and functional group, sidSame skeleton and functional group, sid e chains/functionale chains/functional groups are in different positions on the carbon chain

groups are in different positions on the carbon chain Differ in physical properties

Differ in physical properties

Functional group isomers

Functional group isomers Same atoms arranged into different fuSame atoms arranged into different fu nctional groupsnctional groups Differ in

Differ in physical & physical & chemical propertieschemical properties

2 bonds in the C=C double bond are not the same, bond energy of C=C (612kJmol

2 bonds in the C=C double bond are not the same, bond energy of C=C (612kJmol – – 11) is greater than C-C (348kJmol) is greater than C-C (348kJmol – – 11) but not as twice as) but not as twice as hence pi bond is weaker than the sigma bond

hence pi bond is weaker than the sigma bond Stereoisomerism

Stereoisomerism Molecules have same molecular formula, same structuralMolecules have same molecular formula, same structural formula, but atoms have a

formula, but atoms have a different 3d arrangement(orientation in space).different 3d arrangement(orientation in space). Differ in physical properties

Differ in physical properties

Stereoisomerism found in any molecule of

Stereoisomerism found in any molecule of the type:the type:

Geometric Isomerism

Geometric Isomerism Occurs when there’Occurs when there’s restricted rotation about a bond(C=C double bond where each of the two C atos restricted rotation about a bond(C=C double bond where each of the two C ato ms carries 2ms carries 2 different atoms/groups)differ in physical properties(different

different atoms/groups)differ in physical properties(different positions of groups, chains affects positions of groups, chains affects shape, dipoles, intermolecular forces)shape, dipoles, intermolecular forces) Single sigma bond

Single sigma bond Free rotation about this bond without any reduction in degree of overlapFree rotation about this bond without any reduction in degree of overlap Double bond

Double bond Restricted rotation about C=C double bond because rotation would lead Restricted rotation about C=C double bond because rotation would lead to a decrease in overlap of to a decrease in overlap of p orbitals that give the p orbitals that give the pipi

Optical Isomerism

Optical Isomerism Where molecules(chiral molecules) have mirror-image isomers that are Where molecules(chiral molecules) have mirror-image isomers that are not superimposable on the originalnot superimposable on the original compound.

compound. Sole criterion for chSole criterion for chirality is existence irality is existence of non-superimposable mirror imagesof non-superimposable mirror images

•• Commonest origin of chirality is a carbon atom having 4 diff groups attached to it(the chiral Commonest origin of chirality is a carbon atom having 4 diff groups attached to it(the chiral centre)centre)

•• Molecules will not be chiral if one chiral centre is the mirror image of the other in Molecules will not be chiral if one chiral centre is the mirror image of the other in a 2 chiral centred moleculea 2 chiral centred molecule •

• Possible to have chirality in molecules that don’t have chPossible to have chirality in molecules that don’t have chiral centres(molecule is helical)iral centres(molecule is helical)

Chiral molecules rotate plane of polarisation if

Chiral molecules rotate plane of polarisation if plane-polarised monochromatic light isplane-polarised monochromatic light is shone through them(sodium light) must be

shone through them(sodium light) must be monochromatic because angle of rotationmonochromatic because angle of rotation depends on wav

depends on wavelength of light used. elength of light used. In some wavelengths In some wavelengths it’s 0it’s 0 Dextrorotatory

Dextrorotatory (+) in front of the name, molecules that rotate the plane to the(+) in front of the name, molecules that rotate the plane to the right(clockwise looking into the sample)

right(clockwise looking into the sample) Laevorotatory

Laevorotatory (-) in front of the name, molecules rotating the plane to the left(-) in front of the name, molecules rotating the plane to the left Racemic Mixture

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forms of chiral molecule.

forms of chiral molecule. Clockwise rotation of one isClockwise rotation of one isomer cancelled by anticlockwiseomer cancelled by anticlockwise rotation from the other

rotation from the other Chiral

Chiral Has 2 isomers that are Has 2 isomers that are non superimposable mirror imagesnon superimposable mirror images Chiral molecule

Chiral moleculeA molecule that is non-superimposable on its A molecule that is non-superimposable on its mirror imagemirror image Questions

Questions

How is optical activity detected ex

How is optical activity detected experimentally? perimentally? Rotation of plane polarised lighRotation of plane polarised lightt bond polarity

bond polarity Electronegativity

Electronegativity(EN) Strength(of an atom)to attract(the pair of)electrons(EN) Strength(of an atom)to attract(the pair of)electrons in a covalent bondin a covalent bond -- _{EN affects bond length with larger differences giving shorter bonds}_{EN affects bond length with larger differences giving shorter bonds}

-

- More electronegative atoms attract sMore electronegative atoms attract shared electrons more towardshared electrons more towards, itself and acquire a partial negative , itself and acquire a partial negative chargecharge •

• Electronegativity decreases going Electronegativity decreases going down a group(most electronegdown a group(most electronegative element is fluorine)ative element is fluorine) •

• Electronegativity Electronegativity increaseincreases across period 3, elements on the LHS lose electrons and elements on the RHS gain electrons to achieve as across period 3, elements on the LHS lose electrons and elements on the RHS gain electrons to achieve a stable structure

stable structure *

* Ionic bonds Ionic bonds are partially are partially covalent whencovalent when_EN_{EN is}_{is small}_{small *}_{* Covalent}_{Covalent bonds}_{bonds are}_{are partially}_{partially ionic(creation}_{ionic(creation of}_{of dipoles)when}_dipoles)when _{EN is large}_{EN is large}

Polarisability

Polarisability The ease with which the electron cloud of an anion is distorted by a cation The ease with which the electron cloud of an anion is distorted by a cation so there’s electron sharingso there’s electron sharing • Smaller and higher the charge(higher the charge density)on the cation, the more polarising it is

• Smaller and higher the charge(higher the charge density)on the cation, the more polarising it is • Larger and higher the charge on

• Larger and higher the charge on the anion, the more easily it is polarizedthe anion, the more easily it is polarized

Features favouring ionic bonding: Features favouring ionic bonding:

• Large cation metal, of low charge, having a low IE • Large cation metal, of low charge, having a low IE • Large anion non metal, of low charge, having a high EA • Large anion non metal, of low charge, having a high EA -

- Large anions mLarge anions most stable with largost stable with large cationse cations Small cations most stable with small a Small cations most stable with small a nionsnions

- A covalent bond is polar if electrons in the bond are unequally shared - A covalent bond is polar if electrons in the bond are unequally shared

formation of polyesters and pol

formation of polyesters and polyamidesyamides

Condensation polymers Condensation polymers

esters with acids and alkalis in

esters with acids and alkalis in aqueous solutionaqueous solution carbonyl compounds with hydrogen cyanide, carbonyl compounds with hydrogen cyanide, 2,4-dinitrophenylhydrazine,

2,4-dinitrophenylhydrazine,

alkaline ammoniacal silver nitrate solution, alkaline ammoniacal silver nitrate solution, Fehling’s solution,

Fehling’s solution,

ethanoyl chloride with water, alcohols, ammonia and pr

ethanoyl chloride with water, alcohols, ammonia and primary aminesimary amines primary amines with aqueous hydrogen ions, acid

primary amines with aqueous hydrogen ions, acid chlorideschlorides nitriles undergoing hydrolysis and undergoing reduction nitriles undergoing hydrolysis and undergoing reduction amides with phosphorus(V) oxide and bromine in

amides with phosphorus(V) oxide and bromine in aqueous alkaliaqueous alkali amino acids with acids and bases, their z

amino acids with acids and bases, their zwitterion structures.witterion structures.

iodine in the presence of alkali (or potassium iodide and sodium chlorate(I)), iodine in the presence of alkali (or potassium iodide and sodium chlorate(I)), (sodium borohydride) sodium tetrahydridoborate(III)

(sodium borohydride) sodium tetrahydridoborate(III) (lithium alum

(lithium aluminium hydride) inium hydride) lithium telithium tetrahydridoaluminate(III)trahydridoaluminate(III) Halogeno-compounds with magnesium to form Grignard reagents. Halogeno-compounds with magnesium to form Grignard reagents. Grignard reagents reactions with water, carbon dioxide

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Recall that Grignard reagents act as nucleophiles Recall that Grignard reagents act as nucleophiles

Carboxylic acids with alcohols, (lithium aluminium hydride),

Carboxylic acids with alcohols, (lithium aluminium hydride), phosphorus pentachloride, sodium carbonate and sodiumphosphorus pentachloride, sodium carbonate and sodium hydrogencarbonate

hydrogencarbonate rules for nomenclature rules for nomenclature Functional group

Functional group An atom/group of atoms in An atom/group of atoms in an organic compound that determines all an organic compound that determines all the possible chemical reactions for thatthe possible chemical reactions for that compound

compound Compound type

Compound type Functional groupFunctional group Compound typeCompound type Functional groupFunctional group Halogenoalkanes Halogenoalkanes Grignard reagent Grignard reagent Aldehydes Aldehydes Ketones Ketones R-R-XX((XXis Cl, Br, I)is Cl, Br, I) R-MgX (X is a halogen ato R-MgX (X is a halogen atom)m) R

R11--CHOCHO RR11can be a H atomcan be a H atom R

R11--COCO-R-R22 R

R11& R& R22must contain at leastmust contain at least one C atom one C atom Acid chlorides Acid chlorides Amines Amines Amides Amides Nitriles Nitriles Amino acids Amino acids R-R-COClCOCl R-R-NHNH22 R-R-CONHCONH22 R-R-CNCN RCH RCH(NH(NH33 + + )COO )COO-

-Names based on longest continuous C chain Names based on longest continuous C chain Meth

Meth = = 1 1 Eth Eth = = 2 2 Prop Prop = = 33 But

But = = 4 4 Pent Pent = = 5 5 Hex Hex = = 66 Hept = 7 Oct = 8

Hept = 7 Oct = 8

Carbonyl(C=O) compounds Carbonyl(C=O) compounds aldehydes & ketones

aldehydes & ketones Alkyl groups

Alkyl groups A

Amethylmethylgroup is CHgroup is CH33

An

Anethylethylgroup is CHgroup is CH33CHCH22

2-methylpentane 2,3-dimethylbutane 2-methylpentane 2,3-dimethylbutane 2,2-dimethylbutane 1,1,1-trichloroethane 2,2-dimethylbutane 1,1,1-trichloroethane pentan-3-one pentan-3-one ethylamine ethylamine Propanamide Propanamide Dimethylamine Trimethylamine Dimethylamine Trimethylamine 2-aminopropane 2-aminopropane Ethanenitrile Ethanenitrile 2-hydroxypropanenitrile 2-hydroxypropanenitrile

ethanoyl chloride(acid chloride) ethanoyl chloride(acid chloride)

primary

primary(1°),(1°),secondarysecondary(2°) and(2°) andtertiarytertiary(3°) alcohols is (3°) alcohols is based upon based upon thethe number of carbon atoms the

number of carbon atoms theC-OHC-OH group's carbon is bonded to.group's carbon is bonded to. Ene

Ene – – means C=C bondmeans C=C bond

Alkyl group names come before name of longest C chain preceded, by a Alkyl group names come before name of longest C chain preceded, by a number to indicate C atom at which substitution occurred

number to indicate C atom at which substitution occurred Alkyl group number comes from shortest C chain

Alkyl group number comes from shortest C chain

3-ethyl-2-methylhexane 3-methylhex-2-ene 3-ethyl-2-methylhexane 3-methylhex-2-ene 2-bromo-2-methylpropane 1-iodo-3-methylpent-2-ene 2-bromo-2-methylpropane 1-iodo-3-methylpent-2-ene 2-methylpropan-1-ol ethane-1,2-diol 2-methylpropan-1-ol ethane-1,2-diol HCHO

HCHO methanol methanol CHCH33COCHCOCH33 butanonebutanone

CH

CH33CHO ethanolCHO ethanol

2-methylpentanal(aldehyde) propanone(ketone) 2-methylpentanal(aldehyde) propanone(ketone)

2-hydroxypropanoic acid(carboxylic acid) 2-hydroxypropanoic acid(carboxylic acid) The

The hydroxyhydroxypart of the name shows the presence of an -OH group. Normally,part of the name shows the presence of an -OH group. Normally, you would show that by the ending

you would show that by the ending olol, but this time you can't because you've, but this time you can't because you've already got another ending.

already got another ending.

esters esters

Alanine (2-aminopropanoic acid) Alanine (2-aminopropanoic acid)

An amino acid contains both an amino group, -NH2, and a carboxylic acid An amino acid contains both an amino group, -NH2, and a carboxylic acid group,

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Grignard reagent Grignard reagent

recognise oxidation, reduction, condensation, nucleophilic substitution or nucleophilic addition recognise oxidation, reduction, condensation, nucleophilic substitution or nucleophilic addition Redox (reduction oxidation reaction)

Redox (reduction oxidation reaction)describesdescribes / / all chemical reactions in which atoms have all chemical reactions in which atoms have their oxidation number/state changedtheir oxidation number/state changed Oxidation state

Oxidation state is theis thehypotheticalhypotheticalcharge that an atom would have if all bonds to atoms of different elements were 100% ioniccharge that an atom would have if all bonds to atoms of different elements were 100% ionic Oxidation

Oxidationdescribes the loss of describes the loss of electronselectrons by aby a molecule,molecule, atomatom oror ionion (From +2 to +4)(From +2 to +4) Reduction

Reductiondescribes the gain of describes the gain of electronselectrons by aby a molecule,molecule, atomatom oror ionion (From +4 to +2)(From +4 to +2) Elimination reaction

Elimination reaction Elements of a simple molecule(HElements of a simple molecule(H22O)are removed from the organic molecule and not replaced by any otherO)are removed from the organic molecule and not replaced by any other

atom/group of atoms atom/group of atoms Addition reaction

Addition reaction 2 molecules react together forming a single product2 molecules react together forming a single product Electrophilic addition

Electrophilic additionAddition reaction where, electrophile attacks a molecule at a region of high electron densityAddition reaction where, electrophile attacks a molecule at a region of high electron density Substitution reaction

Substitution reaction(atom/group of atoms in a molecule replaced by another atom/group of atoms)(atom/group of atoms in a molecule replaced by another atom/group of atoms) Nucleophilic substitution

Nucleophilic substitution δδ+ C atom can be attacked by a nucleophile+ C atom can be attacked by a nucleophile OH

OH – – , CN, CN – – , NH, NH33nucleophiles which react with haloalkanesnucleophiles which react with haloalkanes ::OHOH – – provides provides a a pair pair of of electrons electrons for for C C CC – – Br bond breaksBr bond breaks

heterolytically, both electrons from the bond taken by Br

heterolytically, both electrons from the bond taken by Br – – then OHthen OH – – bonds to Cbonds to C Nucleophile

Nucleophile(literally nucleus lover as in(literally nucleus lover as in nucleusnucleus andand phile)phile) is ais a reagentreagent that forms athat forms a chemical bondchemical bond to its reaction partner (theto its reaction partner (the electrophile)

electrophile) by donating both bondingby donating both bonding electronselectrons Electrophile

Electrophile(literally electron-lover) is a(literally electron-lover) is a reagentreagent attracted toattracted to electronselectrons that participates in a chemical reaction bthat participates in a chemical reaction b y accepting any accepting an electron pair

electron pair in order toin order to bondbond to ato a nucleophilenucleophile Condensation reaction

Condensation reactionis ais a chemical reactionchemical reaction in which twoin which two moleculesmolecules oror moietiesmoieties combine to form one single molecule, with thecombine to form one single molecule, with the loss of a small molecule. When this small molecule is water, it is known as a

loss of a small molecule. When this small molecule is water, it is known as a dehydration reaction;dehydration reaction;other possible small moleculesother possible small molecules lost are

lost are hydrogen chloride,hydrogen chloride, methanol,methanol, oror acetic acid.acetic acid. Compound

Compound Reagent Reagent Product Product Reaction Reaction typetype

Alkane

Alkane Halogen Halogen Haloalkane Haloalkane SubstitutionSubstitution Alkene

Alkene Acidic(purple)KMnOAcidic(purple)KMnO44 Alcohol Alcohol (colourless) (colourless) ReductionReduction Alkaline(purple)KMnO

Alkaline(purple)KMnO44 Alcohol (green)Alcohol (green) HBr

HBr haloalkane haloalkane Electrophilic Electrophilic additionaddition H

H22SOSO44 Alcohol Alcohol Electrophilic Electrophilic additionaddition

Bromine

Bromine water water Decolourised Decolourised from from orange orange toto colourless colourless Dihaloalkane Dihaloalkane Addition Addition Haloalkane

Haloalkane NaOH(aq) NaOH(aq) or or KOH(aq) KOH(aq) Alcohol Alcohol NucleophilicNucleophilic substitution substitution NaOH(ethanol)

NaOH(ethanol) or or KOH(ethanol) KOH(ethanol) Alkene Alkene EliminationElimination KCN(ethanol)

KCN(ethanol) Nitrile Nitrile NucleophilicNucleophilic

substitution substitution Dilute

Dilute nitric nitric acid, acid, then then silver silver nitrate nitrate ppt ppt of of silver silver halide,halide, white- chloride, yellow

white- chloride, yellow – – iodideiodide Alcohol

Alcohol Combustion Combustion Carbon Carbon dioxide dioxide and and waterwater PCl

PCl55 RCl + POClRCl + POCl33+ HCl+ HCl

Misty fumes of HCl which turn blue Misty fumes of HCl which turn blue litmus red

litmus red

HX Haloalkane

Primary

Primary alcohol alcohol Acidified Acidified potassium potassium dichromatedichromate (orange)

(orange)

(green) aldehyde that will react (green) aldehyde that will react withwith Tollens reagent to give a silver mirror Tollens reagent to give a silver mirror Secondary

Secondary alcohol alcohol (green) (green) ketone ketone will will not not react react withwith Tollens reagent

Tollens reagent Tertiary

Tertiary alcohol alcohol (orange) (orange) no no reactionreaction Grignard reagent

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• Metal carbon bond has

• Metal carbon bond has ionic character because electronegativitiesionic character because electronegativities (ability to attract electrons) of metals are less than that of (ability to attract electrons) of metals are less than that of carbon

carbon

Ether must be perfectly dr

Ether must be perfectly dry since water destroys resulting Grignard reagenty since water destroys resulting Grignard reagent dry ether, heat(reflux) dry ether, heat(reflux) C

C22HH55I + MgI + Mg  CC22HH55MgIMgI

Halogenalkane

Halogenalkane ethyl ethyl magnesium magnesium iodide(Grignard iodide(Grignard reagent)reagent) Compound

Compound Reagent Reagent Product Product Reaction Reaction typetype Grignard reagent

Grignard reagent RMgX

RMgX

Water

Water Alkane Alkane RH RH Nucleophilic Nucleophilic substitutionsubstitution Carbon

Carbon dioxide dioxide Carboxylic Carboxylic acid acid RCOOHRCOOH Methanal

Methanal HCHO HCHO Primary Primary alcohol alcohol RCHRCH22OHOH

Aldehydes R

Aldehydes R11CHO CHO Secondary Secondary alcoholalcohol RCH(OH)R RCH(OH)R11 Ketones R

Ketones R11CORCOR22 Tertiary alcohol RRTertiary alcohol RR11RR22COHCOH Carboxylic

Carboxylic acids acids RCOOH RCOOH Alcohol Alcohol RR11OH OH Ester Ester RCOORRCOOR11 Nucleophilic substitutionNucleophilic substitution followed by elimination followed by elimination LiAlH

LiAlH44 Alcohol RCHAlcohol RCH22OH OH ReductionReduction

PCl

PCl55 Acid Acid chloride chloride RCOCl RCOCl Nucleophilic Nucleophilic substitutionsubstitution

Na

Na22COCO33and NaHCOand NaHCO33 Sodium salt RCOOSodium salt RCOO

--Na Na++ CO

CO22gas(gives white ppt withgas(gives white ppt with

limewater) limewater)

Acid-base Acid-base

Esters RCOOR

Esters RCOOR11 Aqueous Aqueous mineral mineral acid acid eg eg HCl(aq) HCl(aq) Alcohol RAlcohol R11OH and acidOH and acid RCOOH

RCOOH

Hydrolysis (equil) Hydrolysis (equil) NaOH(aq)

NaOH(aq) Alcohol Alcohol RR11OH andOH and salt RCOO salt RCOO--NaNa++ Hydrolysis (equil) Hydrolysis (equil) Aldehydes RCHO or Aldehydes RCHO or ketones RCOR ketones RCOR11 Hydrogen Hydrogen cyanide(HCN(covalent)) and cyanide(HCN(covalent)) and potassium cyanide potassium cyanide Cyanohydrin RCH(OH)CN or Cyanohydrin RCH(OH)CN or RR RR11C(OH)CNC(OH)CN Nucleophilic substitution Nucleophilic substitution 2, 4-dinitrophenylhydrazine 2, 4-dinitrophenylhydrazine Test for carbonyl(C=O) group Test for carbonyl(C=O) group

2, 4-dinitrophenylhydrazine 2, 4-dinitrophenylhydrazine (Orange ppt) (Orange ppt) Nucleophilic substitution Nucleophilic substitution followed by elimination followed by elimination Sodium borohydride NaBH

Sodium borohydride NaBH44oror

lithium aluminium hydride lithium aluminium hydride LiAlH LiAlH44 Primary alcohol RCH Primary alcohol RCH22OH orOH or secondary alcohol secondary alcohol RCH(OH)R RCH(OH)R11 Reduction Reduction Aldehydes

Aldehydes RCHO RCHO (not(not ketones)

ketones)

Test for CHO group Test for CHO group

Ammonical silver nitrate solution Ammonical silver nitrate solution (Tollens reagent)

(Tollens reagent)

Silver

Silver mirror mirror Reduction Reduction of of the the silver silver ionion Fehling’s solution/Benedicts

Fehling’s solution/Benedicts solution(Blue)

solution(Blue)

Copper(I)

Copper(I) oxide oxide ppt ppt (Red) (Red) Reduction Reduction of of the the copper(II)copper(II) ion ion potassium potassium dichromate(VI)(orange) dichromate(VI)(orange) (green) (green) Aldehydes

Aldehydes RCHO RCHO acidic acidic conditions conditions Carboxylic Carboxylic acid acid RCOOH RCOOH OxidationOxidation alkaline

alkaline conditions conditions salt salt RCOORCOO--XX ketone, 2

ketone, 2°°alcohol alcohol NaOH NaOH + + II22 RCOONa + CHIRCOONa + CHI33 (iodoform/yellow ppt) (iodoform/yellow ppt)

Haloform Haloform Acid

Acid chlorides chlorides ROCl ROCl Water Water Acid Acid RCOOH RCOOH Nucleophilic Nucleophilic substitutionsubstitution Ammonia

Ammonia Amide Amide RCONHRCONH22

Alcohol R

Alcohol R11OH OH Ester Ester RCOORRCOOR11 Amine R

Amine R11NHNH22 N- substituted amideN- substituted amide

R

R11CONHRCONHR Amines RNH

Amines RNH22 Aqueous Aqueous acid acid eg eg HCl(aq) HCl(aq) RNHRNH33 + +

Cl

Cl-- Acid-baseAcid-base Acid chloride R

Acid chloride R11OCl OCl N-substituted N-substituted amideamide R

R11CONHRCONHR

Nucleophilic substitution Nucleophilic substitution Amides RCONH

Amides RCONH22 Phosphorus(V) oxide PPhosphorus(V) oxide P44OO1010 Nitrile Nitrile RCN RCN DehydrationDehydration

Bromine

Bromine followed followed by by NaOH(aq) NaOH(aq) Amine Amine RNHRNH22 Substitution followed bySubstitution followed by

rearrangement and rearrangement and elimination

elimination Nitriles

Nitriles RCN RCN Aqueous Aqueous acid acid eg eg HCl(aq) HCl(aq) Acid Acid RCOOH RCOOH HydrolysisHydrolysis NaOH(aq)

NaOH(aq) Salt Salt RCOORCOO--NaNa++ lithium aluminium hydride

lithium aluminium hydride LiAlH

LiAlH44

Amine RCH

Amine RCH22NHNH22 ReductionReduction

Amino acids Amino acids RCH(NH

RCH(NH33++)COO)COO

--Aqueous

Aqueous acid acid eg eg HCl(aq) HCl(aq) Salt Salt RCH(NHRCH(NH33 + +

)COOH Acid-base

NaOH(aq)

NaOH(aq) Salt Salt RCH(NHRCH(NH22)COO)COO

--Na Na++ Questions

Questions

State the reagents and conditions necessary to

State the reagents and conditions necessary to convert CHconvert CH33CHCH22CH(CONHCH(CONH22)CH)CH33to 2-aminobutaneto 2-aminobutane • heat • with bromine • and sodium hydroxide

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A

A CH_CH33CH_{CH22CH(MgBr)CH}_CH(MgBr)CH33 BB _CH33CHCH _{CH22CH(COOH)CH}_CH(COOH)CH33 CC CH_CH33CH_{CH22CH(COCl)CH}_CH(COCl)CH33 Reagents and conditions for

Reagents and conditions forCCDD •• ammoniaammonia • and room temperature• and room temperature

Butanone can be made from 2-bromobutane by a synthetic route involving two steps, the first using aqueous sodium hydroxide and the Butanone can be made from 2-bromobutane by a synthetic route involving two steps, the first using aqueous sodium hydroxide and the second potassium dichromate(VI) solution acidified with dilute sulphuric acid.

second potassium dichromate(VI) solution acidified with dilute sulphuric acid. (i)

(i) Give Give the the structural structural formula formula of of the the intermediate intermediate compound compound in in this this synthetic synthetic route.route.

(ii)

(ii) Butanone Butanone reacts reacts with with 2,4-2,4-dinitrophenylhydrazine solution but not with Fehling’s solution. Why is this?dinitrophenylhydrazine solution but not with Fehling’s solution. Why is this? •• contains C=O so reacts with 2,4 dnpcontains C=O so reacts with 2,4 dnp • but cannot be oxidised so no reaction with Fehlings’ solution• but cannot be oxidised so no reaction with Fehlings’ solution

(iii)

(iii) Butanone Butanone also also reacts reacts with with iodine iodine in in sodium sodium hydroxide hydroxide solution. solution. What What structural structural feature feature of buof butanone tanone is is shown shown by by this this reaction?reaction?

(iv)

(iv) Give Give the the structural structural formulae formulae of of bothboththe organic products from the reaction in (iii).the organic products from the reaction in (iii). CHI

CHI33 and and CHCH33CHCH22COONaCOONa (a)

(a) Write Write the the structural structural formulae formulae of of the the organic organic products products obtained obtained when when ethanoyl ethanoyl chloride chloride reacts reacts with with the the following following compounds. compounds. GiveGive the names of these products.

the names of these products. (i)

(i) Ammonia, Ammonia, NHNH₃₃ (ii) (ii) Methanol, Methanol, CHCH₃₃OH.OH. CH

CH33CONHCONH22 CHCH33COOCHCOOCH33 (b)

(b) Bromoethane Bromoethane reacts reacts with with magnesium magnesium to to form form the the Grignard Grignard reagent reagent CHCH33CHCH22MgBr.MgBr. This G

This Grignard rignard reagent reagent reacts reacts with: with: COCO22, followed by hydrochloric acid, to form compound, followed by hydrochloric acid, to form compoundAA;; water to form compound

water to form compoundBB;;

methanal, followed by hydrochloric acid, to

methanal, followed by hydrochloric acid, to form compoundform compoundCC.. Compounds

CompoundsAAandandCCreact together, in the presence of a suitable catalyst, to form compoundreact together, in the presence of a suitable catalyst, to form compound DD.. (i)

(i) Write Write the the structural structural formulae formulae of of compoundscompoundsAA,,BB, and, andCC.. A = CH

A = CH33CHCH22COOH or CCOOH or C22HH55COOHCOOH B = CH

B = CH33CHCH33 C = CH

C = CH33CHCH22CHCH22OH or COH or C22HH55CHCH22OHOH (ii)

(ii) Draw Draw the the full full structural structural formula formula of of compoundcompoundDD

(iii)

(iii) Give Give the the names names of of compoundscompounds CCandandDD C = propan-1-ol

C = propan-1-ol D = propyl propanoateD = propyl propanoate (iv)

(iv) Identify Identify a a catalyst catalyst for for the the reaction reaction between between compoundscompounds AAandandCC sulphuric acid / phosphoric acid / hydrochloric acid

sulphuric acid / phosphoric acid / hydrochloric acid (a)

(a) Write Write equations equations to to show show the the reactions reactions of of the the amino amino acid acid alanine, alanine, CHCH₃₃CH(NHCH(NH₂₂)COOH, with:)COOH, with:

CH CH CH CH CHBrCH CHBrCH GrignardGrignard AA BB PCL PCL CH CH CH CH C C CHCH CC CONH CONH H H 2 2 2 2 3 3 3 3 22 33 2 2 5 5 3 3 D D Mg Mg i) CO i) CO ii) HCl(aq) ii) HCl(aq)

C

CH

H

C

CH

H C

CH

H

CH

OH

3 3 22 33 (1) (1) C C CHCH C CHH CCHH CCHH O O OHOH 3 3 33

iiff iinncclluuddeed d tthheenn zero zero

H

O

H

C

O

C

H

(7)

(i)

(i) HCl HCl CHCH33CH(NHCH(NH22)COOH + HCl)COOH + HCl CHCH33CH(NHCH(NH33++ClCl)COOH)COOH (ii)

(ii) NaOH NaOH CHCH33CH(NHCH(NH22)COOH + NaOH)COOH + NaOHCHCH33CH(NHCH(NH22)COO)COONaNa+++ H+ H22OO (b)

(b) Explain Explain why why alanine alanine has has a a relatively relatively high high melting melting temperature temperature (290 (290 °C)°C) 

 _{Exists as zwitterion}_{Exists as zwitterion}  _{Strong attraction between oppositely charged ions}_{Strong attraction between oppositely charged ions} (c)

(c) Explain Explain why why alanine alanine exists exists as as two two optical optical isomersisomers

Draw diagrams to show the structures of the two optical isomers. Draw diagrams to show the structures of the two optical isomers.

(ii)

(ii) Explain Explain how how separate separate pure pure samples samples of of each each optical optical isomer isomer can can be be distinguished distinguished from from each each other.other. 

 _Rotates_Rotates_{the plane of (plane) polarised}_{the plane of (plane) polarised (monochromatic) light}_{(monochromatic) light in opposite directions}_{in opposite directions} 

 _{measure rotation (of plane of polarised light) in opposite directions}_{measure rotation (of plane of polarised light) in opposite directions} (d)

(d) A A mixture mixture of of isomeric isomeric alkenes alkenes is is obtained obtained when when butan-2-ol butan-2-ol is is dehydrated.dehydrated. (i)

(i) Draw Draw diagrams diagrams to to show show the the twotwo structuralstructuralisomers obtained when butan-2-ol is dehydrated.isomers obtained when butan-2-ol is dehydrated.

but-1-ene but-2-ene

(ii)

(ii) One One of of the the above above structural structural isomers isomers can can itself itself exist exist as as two two different different stereoisomers. stereoisomers. Draw Draw diagrams diagrams to to clearly clearly illustrate illustrate these twthese twoo stereoisomers, and name this type of stereoisomerism.

stereoisomers, and name this type of stereoisomerism.



 _geometric_geometric _cis-_{cis- but-2-ene}_but-2-ene _{trans-but-2-ene}_{trans-but-2-ene}

(a)

(a) Give Give the the structural structural formula formula of:of:HH J K MJ K M

H

His CHlis CHl33 JJis CHis CH33COONa/CHCOONa/CH33COOCOO – – KKisis MMisis

(b)

(b) Identify: Identify: Reagent1/2/3Reagent1/2/3 Reagent 1

Reagent 1Named dilute acid e.g. HCl(aq) or NaOH (aq) then add HClNamed dilute acid e.g. HCl(aq) or NaOH (aq) then add HCl Reagent 2

Reagent 2PClPCl55/ SOCl/ SOCl22/ PCl/ PCl33

Reagent 3

Reagent 3(Conc) ammonia (solution) / NH(Conc) ammonia (solution) / NH₃₃

C

N

NH

H

N

NH

H

C

CH

H

33

C

CH

H

33 2 2 22

C

CO

OO

OH

H

C

CO

OO

OH

H

H H H H H H H H C C C C C C C C H H HH H H HH H H H H H H H H C C C C C C C C H H HH H H HH

CH

H

CH

H

H C

C

H

H C

C

3 3

H

3 3 33 3 3 H H+ + JJ C C OO KK CH CH CH CH 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 3 3 3 3 3 3 propanone

propanone Reagent 1Reagent 1

Reagent 3 Reagent 3 Reagent 2 Reagent 2 CH CH OHOH CH COOH CH COOH CH Cl CH Cl CH CH C C OO CH Cl CH Cl CH CH C C OO C C C C C C Cl Cl NH NH Br Br NaOH NaOH HCN HCN NaCN NaCN II NaOH NaOH M M

CH

C

OH

CH

CN

3 3 3 3

C

CH

H

C

CH

H

C

N

NH

H

C

O

OH

H

C

CH

H

or

C

CH

H

C

Cll

N

NH

H

3 3 33 3 3 22 33 2 2 (1) (1)

(8)

(c)

(c) Compounds Compounds produced produced when when glucose glucose CC₆₆HH₁₂₁₂OO₆₆, is metabolised include:, is metabolised include: CH

CH22(OH)CH(OH)CHO (OH)CH(OH)CHO CHCH33COCOOH COCOOH CHCH33CH(OH)COOHCH(OH)COOH 2,3-dihydroxypropanal

2,3-dihydroxypropanal 2-oxopropanoic 2-oxopropanoic acid acid 2-hydroxypropanoic acid2-hydroxypropanoic acid (i)

(i) Draw Draw the the full full structural structural formula formula for for 2,3-dihydroxypropanal.2,3-dihydroxypropanal.

(ii) Suggest

(ii) Suggesttwotwo of of these these compounds compounds which which would would give give a a positive positive test test with with 2,4-dinitrophenylhydrazine 2,4-dinitrophenylhydrazine solution. State solution. State what what youyou would see for a positive te

would see for a positive test result.st result. 2,3-dihydroxypropanal

2,3-dihydroxypropanal and 2-oxopropanoic acidand 2-oxopropanoic acid _{yellow / orange / orange}_{yellow / orange / orange –}_{– red ppt / solid / crystals}_{red ppt / solid / crystals} (iii)

(iii) Describe Describe a a test test which which would would enable enable you you to to distinguish distinguish between between thethetwotwo compounds identified in part (ii).compounds identified in part (ii). Add Fehlings’ solution/ Benedicts’ solution

Add Fehlings’ solution/ Benedicts’ solution red/orange ppt for2,3-dihydroxypropanal

red/orange ppt for2,3-dihydroxypropanalandandno result for 2-oxopropanoic acidno result for 2-oxopropanoic acid Add ammoniacal silver nitrate

Add ammoniacal silver nitrate

silver mirror for2,3dihydroxypropanal

silver mirror for2,3dihydroxypropanalandandno result for 2-oxopropanoic acidno result for 2-oxopropanoic acid Add named carbonate

Add named carbonate

effervescence/ bubbling for 2-oxopropanoic acid and no result for2,3-dihydroxypropanal effervescence/ bubbling for 2-oxopropanoic acid and no result for2,3-dihydroxypropanal Add iodine + sodium hydroxide solution / Kl + NaClO

Add iodine + sodium hydroxide solution / Kl + NaClO yellow ppt for 2-oxopropanoic acid

yellow ppt for 2-oxopropanoic acid andandno result for 2,3no result for 2,3 -dihydroxypropanal-dihydroxypropanal Add dilute sulphuric acid + po

Add dilute sulphuric acid + potassium dichromatetassium dichromate dichromate goes green for 2,3-dihydroxypropanal

dichromate goes green for 2,3-dihydroxypropanal andandno result for 2-oxopropanoic acidno result for 2-oxopropanoic acid Draw two diagrams to clearly represent the optical isomers that result from the chirality of this alcohol

Draw two diagrams to clearly represent the optical isomers that result from the chirality of this alcohol CC44HH99OHOH

(b)

(b) Alcohols Alcohols react react with with carboxylic carboxylic acids acids to to form form esters. esters. Write Write an an equation equation for for a a typical typical esterification esterification reaction.reaction. CH

CH33COOH + CCOOH + C22HH55OH OH CHCH33COOCCOOC22HH55 + + HH22OO (ii)

(ii) Suggest Suggest how how this this type type of of reaction reaction could could be be used used to to form form polyesterspolyesters 

_{Alcohol group at one end and acid group at the other}_{Alcohol group at one end and acid group at the other} _{React at each end}_{React at each end} (iii)

(iii) Give Give anotheranothertypetypeof reagent that could be used to make an ester from an alcoholof reagent that could be used to make an ester from an alcohol Acyl chlorides / acid chlorides / acid halides / RCOCl / acid anhydride

Acyl chlorides / acid chlorides / acid halides / RCOCl / acid anhydride (a)

(a) (i) (i) Give Give the the structural structural formula formula of of a a nitrile, nitrile, CC44HH77N, that has an unbranched chain.N, that has an unbranched chain.

(ii)

(ii) Primary Primary amines amines can can be be made made by by reducing reducing nitriles. nitriles. Suggest Suggest a a reagent reagent that that could could be be used used for for this this purpose.purpose. LiAlH

LiAlH44 (iii)

(iii) Draw Draw the the structural structural formula formula of of the the amine amine produced produced by by reducing reducing the the nitrile nitrile given given in in (a)(i).(a)(i).

(b)

(b) Draw Draw the the structure structure of of an an isomer isomer of of CC44HH1111N which has a chiral centre in the molecule and identify the chiral centreN which has a chiral centre in the molecule and identify the chiral centre

H H H H HH C C CC CC CC OO O OHH OOHH (1)(1) C C CC H H HH O OHH HHOO C CHH CCHH C C HH55 CC HH55 3 3 33 2 2 22

H

C

H

N

H

(1) (1) H H H H H H H H H H H H C C C C C C C C H H NN H H H H H H H H (1) (1) H H H H H H H H H H C C C C C C H H C C H H H H N N H H HH HH * *

(9)

(c) (i)

(c) (i) What fWhat feature of eature of an amine an amine molecule molecule makes makes it both it both a base a base and a and a nucleophile?nucleophile? lone pair of electrons on the N atom

lone pair of electrons on the N atom (ii)

(ii) Give, Give, by by writing writing an an equation, equation, an an example example of of an an amine amine acting acting as as a a base.base. C

C44HH99NHNH22+ H+ H++  CC44HH99NHNH33++ (d)

(d) Ethanoyl Ethanoyl chloride, chloride, CHCH₃₃COCl, reacts with both amines and alcohols.COCl, reacts with both amines and alcohols. (i)

(i) Give Give the the name name of of the the type type of of compound compound produced produced when when ethanoyl ethanoyl chloride chloride reacts reacts with with ethylamine, ethylamine, CC22HH55NHNH22 Amide

Amide (ii) State

(ii) Stateoneone of the advantages of reacting ethanoyl chloride with ethanol to make an ester rather than reacting ethanoic of the advantages of reacting ethanoyl chloride with ethanol to make an ester rather than reacting ethanoic acid withacid with ethanol.

ethanol.

faster / more control / better yield / not

faster / more control / better yield / not equilibrium / no need to heatequilibrium / no need to heat (e)

(e) Ethanoyl Ethanoyl chloride chloride can can be be made made from from ethanoic ethanoic acid.Suggest acid.Suggest a a reagent reagent suitable suitable for for this this conversion.conversion. PCl

PCl55/ PCl/ PCl33SOClSOCl22 (ii)

(ii) Suggest Suggest how how chloromethane chloromethane can can be be converted converted into into ethanoic ethanoic acid acid via via a a Grignard Grignard reagent.reagent.

(a)

(a) Three Three isomersisomersAA,,BBandandBBhave the molecular formula Chave the molecular formula C₄₄HH₈₈O.O. All three compounds give an

All three compounds give an orange precipitate with 2,4-dinitrophenylhydrazine reagent.orange precipitate with 2,4-dinitrophenylhydrazine reagent. BBandandCCalso give a silver mirror also give a silver mirror when warmedwhen warmed with

with ammoniacal ammoniacal silver silver nitrate nitrate solution. solution. Write Write the the structural structural formulae formulae of of AA,,BBandandCC.. A is CH

A is CH₃₃CHCH₂₂COCHCOCH₃₃ B and C are CHB and C are CH₃₃CHCH₂₂CHCH₂₂CHO CHO and and CHCH₃₃CH(CHCH(CH₃₃)CHO)CHO (b) Substance

(b) SubstanceAAreacts with the Grignard reagent, Creacts with the Grignard reagent, C22HH55MgBr. Give the equation for the preparation of this Grignard reagent.MgBr. Give the equation for the preparation of this Grignard reagent. C

C22HH55Br + MgBr + MgCC22HH55MgBrMgBr (ii)

(ii) State State the the conditions conditions for for this this preparation preparation dry dry etherether (iii)

(iii) Write Write the the structural structural formula formula of of the the product product obtained obtained when when this this Grignard Grignard reagent reagent reacts reacts with with substancesubstanceAA.. CH

CH33CHCH22C(OH)(CHC(OH)(CH33) C) C22HH55

(c) C

(c) C22HH55MgBr reacts with carbon dioxide to form tMgBr reacts with carbon dioxide to form t he acid Che acid C22HH55COOH, converted to propanamide in a tCOOH, converted to propanamide in a t wo step process.wo step process. C

C22HH55COOH COOH CC22HH55COCl COCl CC22HH55CONHCONH22 State theState thereagentreagentrequired for each steprequired for each step step

step 1 1 PClPCl₅₅/PCl/PCl₃₃SOClSOCl₂₂ step step 2 2 NHNH₃₃

(d) C

(d) C22HH55MgBr also reacts with ethanal to forMgBr also reacts with ethanal to for m substancem substanceDD, which exists as a pair of optical isomers, which exists as a pair of optical isomers (i)

(i) Draw Draw the the structural structural formulae formulae of of these these two two isomers isomers and and use use them them to to explain explain why why these these isomers isomers existexist

Has asymmetric carbon atom (4 diff groups on a carbon) mirror image non-superimposable Has asymmetric carbon atom (4 diff groups on a carbon) mirror image non-superimposable (ii)

(ii) What What is is the the difference difference in in property property between between these these isomers? isomers? rotate the rotate the plane plane of of planeplanepolarisedpolarised light inlight inoppositeopposite directionsdirections (e)(i)

(e)(i) Write dowWrite down n the nthe name ame and and the sthe structural tructural formula formula of the of the organic comorganic compound formed pound formed when when substancesubstanceDDis heated under reflux with ais heated under reflux with a solution of potassium dichromate(VI) in dilute

solution of potassium dichromate(VI) in dilute sulphuric acid.sulphuric acid. Name

Name and and Structural Structural formula. formula. State State the the colour colour of of the the solution solution remaining remaining after after this this reactionreaction

Butanone CH

Butanone CH33CHCH22COCHCOCH33 greengreen

3 3 3 3 22 2 2 2 2 3 3 22 4 4 2 2 77 2 2 3 3 33 C CH H CCll CCH H MMggCCll CCH H CCOOOOHH M Mgg //ddrryy ether ether (1) (1) (1) (1) CO CO acid acid (1) (1) (1) (1) HCHO HCHO acid acid (1)(1) K Cr O K Cr O H H SOSO CH CH OH CH CH OH CH CO H CH CO H (1)

(1) for all of for all of the steps the steps and reagents and reagents apart from apart from acid which is acid which is stand alone stand alone

sstteep

p

1

1 sstteep

p

2

2 C

C

H

C

H

C

H

C

CH

H

O

OH

H

HO

O

C

CH

H

2 2 55 22 55 3 3 33

(10)

(b)

(b) (i) (i) Draw Draw the the structural structural formula formula of of the the secondary secondary alcohol, alcohol, CC55HH1212O, which doesO, which doesNOTNOTexist as optical isomers.exist as optical isomers.

(ii)

(ii) XXis obtained by oxidising this secondary alcohol is obtained by oxidising this secondary alcohol with potassium dichromate(VI) acidified with dilwith potassium dichromate(VI) acidified with dil ute sulphuric acid.ute sulphuric acid. Draw the structural formula of

Draw the structural formula of XX..

(v)

(v) XXdoes not give a yellow precipitadoes not give a yellow precipitate when treated with iodine in the te when treated with iodine in the presence of sodium hydroxide solutionpresence of sodium hydroxide solution. . Explain why notExplain why not no CH

no CH33CO / CHCO / CH33CH(OH) / methyl ketone / CH(OH) / methyl ketone / methyl secondary alcohol presentmethyl secondary alcohol present •None of the compounds in the scheme shows cis

•None of the compounds in the scheme shows cis -trans isomerism-trans isomerism ••D reacts with KCN to form 2-methylpropanonitrileD reacts with KCN to form 2-methylpropanonitrile

•An isomer of

•An isomer of A will form C by the same route but will not pA will form C by the same route but will not p roduce B by reaction withroduce B by reaction with potassium dichromate(VI) acidified with (dil) H

potassium dichromate(VI) acidified with (dil) H22SOSO44 Instead it makes E, CInstead it makes E, C33HH66OO22

Identify using a name or

Identify using a name or structural formulae:A,B,C,D,Estructural formulae:A,B,C,D,E A

A Propan-2-olPropan-2-ol B B PropanonePropanone C C PropenePropene D D 2-bromopropane2-bromopropane E E PropanoicPropanoic acid

acid

Ethanol can be converted into ethylamine by two different routes. Ethanol can be converted into ethylamine by two different routes.

(a) Identify organic compounds

(a) Identify organic compoundsVVandandWWby writing their full structural formulae showing all bonds.by writing their full structural formulae showing all bonds.

(b) Identify the reagents used in Steps A to E (b) Identify the reagents used in Steps A to E

Step A

: NH: NH33

Step B

: K: K22CrCr22OO77and Hand H22SOSO44

Step C

: PCl: PCl55OR SOClOR SOCl22OR PClOR PCl33

Step D

: P: P22OO55OR POR P44OO1010

Step E

: LiAlH: LiAlH44 (c) (i) What

(c) (i) Whattypetypeof organic compound would be forof organic compound would be for med when ethylamine, CHmed when ethylamine, CH33CHCH22NHNH22reacts with ethanoyl chloride, CHreacts with ethanoyl chloride, CH33COCl?COCl? (N-substituted) amide

(N-substituted) amide

(ii) A polymer is formed when the two monomers shown below react together under suitable conditions. (ii) A polymer is formed when the two monomers shown below react together under suitable conditions.

H

H22N(CHN(CH22))66NHNH22 ClOC(CHClOC(CH22))44COCl COCl Draw Draw sufficient sufficient of of the the polymer polymer chain chain to to make make its its structure structure clear.clear.

H H H H HH HH H H OH OH HH H H HH HH C C C C C C C C C C H H HH H H H H HH OO HH HH H H HH HH H H CC CC CC CC CC HH

C

C H

H O

O

C

C H

H O

O

A

B

K K Cr Cr O O inin dilute sulphuric dilute sulphuric acid acid

C

D

3 3 2 2 22 77 3 3 8 8 66

conc sulphuric acid conc sulphuric acid

HBr HBr

(11)

An organic compound,

An organic compound,AA, with molecular formula C, with molecular formula C55HH1010O contains a carbonyl group.O contains a carbonyl group. (a) Compound

(a) CompoundAAis reacted with iodine in the presence of alkali. A pale yellow precipitate forms.is reacted with iodine in the presence of alkali. A pale yellow precipitate forms. (i) What is the

(i) What is theformulaformulaof of this this precipitate? precipitate? CHICHI33 (ii) What does this reaction indicate about the structure of

(ii) What does this reaction indicate about the structure of AA? ? methyl methyl ketoneketone (iii) Compound

(iii) CompoundAAhas has a a branched branched carbon carbon chain. chain. Draw the Draw the structural structural formula formula and and give give the the name name of of AA

methylbutanone methylbutanone (b) Pentanal is a structural isomer of

(b) Pentanal is a structural isomer of AA. When heated with Fehling’s solution, it reacts to pr . When heated with Fehling’s solution, it reacts to pr oduce sodium pentanoate and a red oduce sodium pentanoate and a red precipitate.precipitate. (i)

(i) Identify Identify the the homologous homologous series series to to which which pentanal pentanal belongs. belongs. aldehydealdehyde (ii)

(ii) Suggest Suggest the the identity identity of of the the red red precipitate precipitate formed formed in in this this reaction. reaction. copper(I) copper(I) oxideoxide

(c) State a reagent which could be used to convert the sodium pentanoate made in the reaction above into pentanoic acid. (c) State a reagent which could be used to convert the sodium pentanoate made in the reaction above into pentanoic acid.

Conc HCl/conc H Conc HCl/conc H22SOSO44

(d) Solid sodium hydrogencarbonate, NaHCO

(d) Solid sodium hydrogencarbonate, NaHCO33, is reacted with excess concentrated pentanoic acid , is reacted with excess concentrated pentanoic acid solution.solution. (i)

(i) State State what what you you would would see see as as this this reaction reaction proceeds. proceeds. effervescence/fizzing/bubbleseffervescence/fizzing/bubbles (ii) Write a balanced chemical equation for this reaction

(ii) Write a balanced chemical equation for this reaction CHCH

3

3(CH(CH22))33COOH + NaHCOCOOH + NaHCO33→→CHCH33(CH(CH22))33COONa + HCOONa + H22O + COO + CO22

3.

3.Two compounds,Two compounds,AAandandBB, are isomers with molecular formula C, are isomers with molecular formula C44HH88O.O.

•

•A and B give an A and B give an orange-yellow precipitate with 2,4-dinitrophenylhydrazine.orange-yellow precipitate with 2,4-dinitrophenylhydrazine. •

•Both compounds react with sodium borohydride (sodium tBoth compounds react with sodium borohydride (sodium t etrahydridoborate(III)).etrahydridoborate(III)). •

•When the compounds are warmed separately with Fehling’s solution,When the compounds are warmed separately with Fehling’s solution, AAforms a red-brown precipitate butforms a red-brown precipitate butBBdoes not.does not. •

•CompoundCompoundBBforms yellow crystals when warmed with aqueous iodine forms yellow crystals when warmed with aqueous iodine and sodium hydroxide, and sodium hydroxide, whereaswhereasAAdoes not.does not.

(a) Draw

(a) Drawfullfullstructural formulae forstructural formulae forAAandandBB, showing all bonds., showing all bonds.

A

A BB

Give name and formula for the organic product of the reaction between compound

Give name and formula for the organic product of the reaction between compound BBand sodium borohydride in waterand sodium borohydride in water butan(-)2(-)ol

butan(-)2(-)ol CH CH 33CH CH ((OH OH ))C C 22 H H 55

(e) Compound

(e) CompoundCChas the molecular formula Chas the molecular formula C44HH88O.O.

•

•When phosphorus pentachloride, PClWhen phosphorus pentachloride, PCl55, was added to a dry sample of , was added to a dry sample of CC, steamy fumes were observed., steamy fumes were observed. •

•When bromine water was shaken with a sample When bromine water was shaken with a sample of of CC, the bromine water turned colourless., the bromine water turned colourless. •

•CompoundCompoundCCcan be oxidised to a carboxylic acid which has a geometric isomer.can be oxidised to a carboxylic acid which has a geometric isomer.

Use the information above to draw the formulae of the two i

Use the information above to draw the formulae of the two i somers which could be compoundsomers which could be compoundCC

Cinnamaldehyde Cinnamaldehyde

(a) To show the presence of the carbonyl group, a few drops of a solution of

(a) To show the presence of the carbonyl group, a few drops of a solution of 2,4-dinitrophenylhydrazine are added to a sample of 2,4-dinitrophenylhydrazine are added to a sample of cinnamaldehyde.

cinnamaldehyde. (i)

(i) What What observation observation is is made made in in the the reaction reaction above? above? yellow yellow / / orange/red orange/red and and precipitate precipitate / / crystals crystals / / solidsolid (iii) Suggest a further

(iii) Suggest a further reaction, including the result, to show reaction, including the result, to show that cinnamaldehydecontains an aldehyde group.that cinnamaldehydecontains an aldehyde group. (warm with) Fehling’s/Benedict’s sol

(warm with) Fehling’s/Benedict’s solution, red pptution, red ppt (iv) Why does the reaction you have given in (iii)

(iv) Why does the reaction you have given in (iii) notnotgive give a a positive positive result result with with a a ketone? ketone? ketone ketone cannot cannot be be oxidisedoxidised (b) Cinnamaldehyde can be converted into co

(12)

(i)

(i) Give Give the the reagents reagents and and conditions conditions which which bring bring about about this this conversion. conversion. HCN+base HCN+base or or KCN+acidKCN+acid (ii) State, with a

(ii) State, with a reason, how many stereoisomers exist for compoundreason, how many stereoisomers exist for compound AA. . FourFour (c) Compound

(c) CompoundAAreacts with lithium tetrahydridoaluminate(III), LiAlHreacts with lithium tetrahydridoaluminate(III), LiAlH44. The mixture is then treated with dilute acid to give the . The mixture is then treated with dilute acid to give the finalfinal organic product.

organic product. (i) Name the type of reaction occ(i) Name the type of reaction occurring between compoundurring between compoundAAand LiAlHand LiAlH44. . reductionreduction (ii)

(ii) Draw Draw the the structural structural formula formula of of the the final final organic organic product. product. CC

6

6HH55CH=CHCH(OH)CHCH=CHCH(OH)CH22NHNH22

(d) Cinnamaldehyde reacts with the Grignard reagent ethyl magnesium bromide, C

(d) Cinnamaldehyde reacts with the Grignard reagent ethyl magnesium bromide, C22HH55MgBr.MgBr. (iii) Draw the structural formula of product formed when

(iii) Draw the structural formula of product formed when cinnamaldehyde reacts with Ccinnamaldehyde reacts with C22HH55MgBr, and the intermediate is hydrolysed.MgBr, and the intermediate is hydrolysed. C

C

6

6HH55CH=CHCH(OH)CHCH=CHCH(OH)CH22CHCH33

(iv)

chemistry Unit 4.5

Full text

C

CH

H

C

CH

H C

CH

H

CH

CH

OH

OH

H

H

H

H

O

O

H

H

H

H

H

H

C

C

C

C

C

C

O

O

C

C

C

C

C

C

H

H

H

H

H

H

H

H

H

H

H

H

H

H

C

C

C

C

N

NH

H

N

NH

H

H

H

H

H

C

CH

H

C

CH

H

C

CO

OO

OH

H

C