THIRD TERM OF CHEMISTRY STPM

Third Term

14 Introductions to Organic Chemistry

14.1 Bonding of the carbon atoms: the shapes of ethane, ethene, ethyne and benzene molecules

Candidates should be able to:

(a) use the concept of sp3, sp2 and sp hybridisations in carbon atoms to describe the bonding and shapes of molecules as exemplified by CH4, C2H4, C2H2 and C6H6;

(b) explain the concept of delocalisation of electrons in benzene ring.

14.2 General, empirical, molecular and structural formulae of organic compounds

Candidates should be able to:

(a) state general, empirical, molecular and structural formulae of organic compounds;

(b) determine empirical and molecular formulae of organic compounds.

14.3 Functional groups: classification and nomenclature

Candidates should be able to:

(a) describe the classification of organic compounds by functional groups and the nomenclature of classes of organic compounds according to the IUPAC rules of the following classes of compounds:

(i) alkanes, alkenes, alkynes and arenes,

(ii) haloalkanes,

(iii) alcohols (including primary, secondary and tertiary) and phenols,

(iv) aldehydes and ketones,

(v) carboxylic acids and their derivatives (acyl chlorides, amides and esters),

(vi) primary amines, amino acids and protein.

14.4 Isomerism: structural and stereoisomerism

Candidates should be able to:

(a) define structural and stereoisomerism (geometrical and optical);

(b) explain the meaning of a chiral centre in optical isomerism;

(c) classify isomers as structural, cis-trans and optical isomers;

(d) identify chiral centres and/or cis-trans isomerism in a molecule of given structural formula;

(e) deduce the possible isomers for an organic compound of known molecular formula.

14.5 Free radicals, nucleophiles and electrophiles

Candidates should be able to:

(a) describe homolytic and heterolytic fissions;

(b) define the terms free radical, nucleophile and electrophile;

(c) explain that nucleophiles such as OH, NH3, H2O, Br, I and carbanion are Lewis bases;

(d) explain that electrophiles such as H+, NO2+, Br2, A1C13, ZnC12, FeBr3, BF3 and carbonium ion are Lewis acids.

14.6 Molecular structure and its effect on physical properties

Candidates should be able to:

(a) describe the relationship between the size of molecules in the homologous series and the melting and boiling points;

(b) explain the forces of attraction between molecules (van der Waals forces and hydrogen bonding).

14.7 Inductive and resonance effect

Candidates should be able to:

(a) explain inductive effect which can determine the properties and reactions of functional groups;

(b) use inductive effect to explain why functional groups such as NO2, CN, COOH, COOR, >C=O, SO3H, X (halogen), OH, OR, NH2, C6H5 are electron acceptors whereas R(alkyl) is an electron donor;

(c) explain how the concept of induction can account for the differences in acidity between CH3COOH, C1CH2COOH, C12CHCOOH and Cl3CCOOH; between C1CH2CH2CH2COOH and CH3CH2CHClCOOH;

(d) use the concept of resonance to explain the differences in acidity between CH3CH2OH and C6H5OH, as well as the differences in basicity between CH3NH2 and C6H5NH2.

15 Hydrocarbons

15.1 Can understand and describe the alkanes

Candidates should be able to:

(a) write the general formula for alkanes;

(b) explain the construction of the alkane series (straight and branched), and IUPAC nomenclature of alkanes for C1 to C10;

(c) describe the structural isomerism in aliphatic alkanes and cis-trans isomerism in cycloalkanes;

(d) state the physical properties of alkanes;

(e) define alkanes as saturated aliphatic hydrocarbons;

(f) name alkyl groups derived from alkanes and identify primary, secondary, tertiary and quartenary carbons;

(g) explain the inertness of alkanes towards polar reagents;

(h) describe the mechanism of free radical substitution as exemplified by the chlorination of methane (with particular reference to the initiation, propagation and termination reactions);

(i) describe the oxidation of alkane with limited and excess oxygen, and the use of alkanes as fuels;

(j) explain the use of crude oil as a source of aliphatic hydrocarbons;

(k) explain how cracking reactions can be used to obtain alkanes and alkenes of lower Mr from larger hydrocarbon molecules;

(l) discuss the role of catalytic converters in minimising air pollution by oxidising CO to CO2 and reducing NOx to N2;

(m) explain how chemical pollutants from the combustion of hydrocarbon affect air quality and rainwater as exemplified by acid rain, photochemical smog and greenhouse effect.

15.2 Can understand and describe the alkenes

Candidates should be able to:

(a) write the general formula for alkenes;

(b) name alkenes according to the IUPAC nomenclature and their common names for C1 to C5;

(c) describe structural and cis-trans isomerism in alkenes;

(d) state the physical properties of alkenes;

(e) define alkenes as unsaturated aliphatic hydrocarbons with one or more double bonds;

(f) describe the chemical reactions of alkenes as exemplified by the following reactions of ethene:

(i) addition of hydrogen, steam, hydrogen halides, halogens, bromine water and concentrated sulphuric acid,

(ii) oxidation using KMnO4, O2/Ag,

(iii) ozonolysis,

(iv) polymerisation;

(g) describe the mechanism of electrophilic addition in alkenes with reference to Markovnikov‟s rule;

(h) explain the use of bromination reaction and decolourisation of MnO4 ions as simple tests for alkenes and unsaturated compounds;

(i) explain briefly the importance of ethene as a source for the preparation of chloroethane, epoxyethane, ethane-1,2-diol and poly(ethane).

15.3 Can understand and describe the arenes

Candidates should be able to:

(a) name aromatic compounds derived from benzene according to the IUPAC nomenclature, including the use of ortho, meta and para or the numbering of substituted groups to the benzene ring;

(b) describe structural isomerism in arenes;

(c) describe the chemical reactions of arenes as exemplified by substitution reactions of haloalkanes and acyl chloride (Friedel-Crafts reaction), halogen, conc. HNO3/conc. H2SO4 and SO3 with benzene and methylbenzene (toluene);

(d) describe the mechanism of electrophilic substitution in arenes as exemplified by the nitration of benzene;

(e) explain why benzene is more stable than aliphatic alkenes towards oxidation;

(f) describe the reaction between alkylbenzene and hot acidified KMnO4;

(g) determine the products of halogenation of methylbenzene (toluene) in the presence of

(i) Lewis acid catalysts,

(ii) light;

(h) explain the inductive effect and resonance effect of substituted groups (OH, C1, CH3, NO2, COCH3, NH2) attached to the benzene ring towards further substitutions;

(i) predict the products in an electrophilic substitution reaction when the substituted group in benzene is electron accepting or electron donating;

(j) explain the uses of arenes as solvents;

(k) recognise arenes as carcinogen.

16 Haloalkanes

16.1 Can understand and describe the haloalkanes

Candidates should be able to:

(a) write the general formula for haloalkanes;

(b) name haloalkanes according to the IUPAC nomenclature;

(c) describe the structural and optical isomerism in haloalkanes;

(d) state the physical properties of haloalkanes;

(e) describe the substitution reactions of haloalkanes as exemplified by the following reactions of bromoethane: hydrolysis, the formation of nitriles and the formation of primary amines;

(f) describe the elimination reactions of haloalkanes;

(g) describe the mechanism of nucleophilic substitution in haloalkanes (SN1 and SN2);

(h) explain the relative reactivity of primary, secondary and tertiary haloalkanes;

(i) compare the reactivity of chlorobenzene and chloroalkanes in hydrolysis reactions;

(j) explain the use of haloalkanes in the synthesis of organomagnesium compounds (Grignard reagents), and their use in reactions with carbonyl compounds;

(k) describe the uses of fluoroalkanes and chlorofluoroalkanes as inert substances for aerosol propellants, coolants and fire-extinguishers;

(l) state the use of chloroalkanes as insecticide such as DDT;

(m) describe the effect of chlorofluoroalkanes in the depletion of the ozone layer, and explain its mechanism.

17 Hydroxy Compounds

17.1 Introduction to hydroxy compounds

Candidates should be able to:

(a) write the general formula for hydroxy compounds;

(b) name hydroxy compounds according to the IUPAC nomenclature;

(c) describe structural and optical isomerism in hydroxy compounds;

(d) state the physical properties of hydroxy compounds.

17.2 Alcohols

Candidates should be able to:

(a) classify alcohols into primary, secondary and tertiary alcohol;

(b) classify the reactions of alcohols whereby the ROH bond is broken: the formation of an alkoxide with sodium, esterification, acylation, oxidation to carbonyl compounds and carboxylic acids;

(c) classify the reactions of alcohols whereby the ROH is broken and OH is replaced by other groups: the formation of haloalkanes and the dehydration to alkenes and ethers;

(d) explain the relative reactivity of primary, secondary and tertiary alcohols as exemplified by the reaction rate of such alcohols to give haloalkanes, and the reaction products of KMnO4/K2Cr2O7 oxidation in the presence of sulphuric acid;

(e) explain the reaction of alcohol with the structure CH3CH(OH) with alkaline aqueous solution of iodine to form triiodomethane;

(f) describe the laboratory and industrial preparation of alcohol as exemplified by ethanol from the hydration of ethane;

(g) describe the synthesis of ethanol by fermentation process;

(h) state the uses of alcohols as antiseptic, solvent and fuel.

17.3 Phenols

Candidates should be able to:

(a) explain the relative acidity of water, phenol and ethanol with particular reference to the inductive and resonance effects;

(b) describe the reactions of phenol with sodium hydroxide, sodium, acyl chlorides and electrophilic substitution in the benzene ring;

(c) describe the use of bromine water and aqueous iron(III) chloride as tests for phenol;

(d) describe the cumene process in the manufacture of phenol;

(e) explain the use of phenol in the manufacture of cyclohexanol, and hence, nylon-6,6.

18 Carbonyl Compounds

Candidates should be able to:

(a) write the general formula for carbonyl compounds: aliphatic and aromatic aldehydes and ketones;

(b) name aliphatic and aromatic aldehydes and ketones according to the IUPAC nomenclature;

(c) describe structural and optical isomerism in carbonyl compounds;

(d) state the physical properties of aliphatic and aromatic aldehydes and ketones;

(e) write the equations for the preparation of aldehydes and ketones;

(f) explain the reduction reactions of aldehydes and ketones to primary and secondary alcohols respectively through catalytic hydrogenation reaction and with LiA1H4;

(g) explain the use of 2,4-dinitrophenylhydrazine reagent as a simple test to detect the presence of >C=O groups;

(h) explain the mechanism of the nucleophilic addition reactions of hydrogen cyanide with aldehydes and ketones;

(i) explain the oxidation of aldehydes;

(j) differentiate between aldehyde and ketone based on the results of simple tests as exemplified by Fehling‟s solution and Tollens‟ reagent;

(k) explain the reactions of carbonyl compounds with the structure CH3C=O with alkaline aqueous solution of iodine to give triiodomethane (iodoform test);

(l) explain that natural compounds such as glucose, sucrose and other carbohydrates which have the >C=O group;

(m) explain the characteristics of glucose as a reducing sugar.

19 Carboxylic Acids and their Derivatives

19.1 Carboxylic acid

Candidates should be able to:

(a) write the general formula for aliphatic and aromatic carboxylic acids;

(b) name carboxylic acids according to the IUPAC nomenclature and their common names for C1 to C6;

(c) describe structural and optical isomerism in carboxylic acids;

(d) state the physical properties of carboxylic acids;

(e) write the equations for the formation of carboxylic acids from alcohols, aldehydes and nitriles;

(f) describe the acidic properties of carboxylic acids as exemplified by their reactions with metals and bases to form salts;

(g) explain the substitution of the OH in carboxylic acids by the nucleophiles OR and C1 to form esters and acyl chlorides respectively;

(h) describe the reduction of carboxylic acids to primary alcohols;

(i) describe the oxidation and dehydration of methanoic and ethanedioic acids (oxalic acid);

(j) state the uses of carboxylic acids in food, perfume, health (aspirin) and polymer industries.

19.2 Acyl chlorides

Candidates should be able to:

(a) write the general formula for acyl chlorides;

(b) name acyl chlorides according to the IUPAC nomenclature;

(c) describe structural and optical isomerism in acyl chlorides;

(d) state the physical properties of acyl chlorides;

(e) explain the ease of hydrolysis of acyl chlorides compared to chloroalkanes;

(f) describe the reactions of acyl chlorides with alcohols, phenols and primary amines.

19.3 Esters

Candidates should be able to:

(a) write the general formula for esters;

(b) name esters according to the IUPAC nomenclature;

(c) describe structural and optical isomerism in esters;

(d) state the physical properties of esters;

(e) describe the preparation of esters by the reactions of acyl chlorides with alcohols and phenols;

(f) describe the acid and base hydrolysis of esters;

(g) describe the reduction of esters to primary alcohols;

(h) state the uses of esters as flavourings, preservatives and solvents.

19.4 Amides

Candidates should be able to:

(a) write the general formula for amides;

(b) name amides according to the IUPAC nomenclature;

(c) describe structural and optical isomerism in amides;

(d) state the physical properties of amides;

(e) describe the preparation of amides by the reaction of acyl chlorides with primary amines;

(f) describe the acid and base hydrolysis of amides.

20 Amines, Amino Acids and Proteins

20.1 Amines

Candidates should be able to:

(a) write the general formula for amines;

(b) name amines according to the IUPAC nomenclature and their common names;

(c) describe structural and optical isomerism in amines;

(d) state the physical properties of amines;

(e) classify amines into primary, secondary and tertiary amines;

(f) explain the relative basicity of ammonia, ethanamine and phenylamine (aniline) in terms of their structures;

(g) describe the preparation of ethanamine by the reduction of nitriles, and phenylamine by the reduction of nitrobenzene;

(h) explain the formation of salts when amines react with mineral acids;

(i) differentiate primary aliphatic amines from primary aryl (aromatic) amines by their respective reactions with nitric(III) acid (nitrous acid) and bromine water;

(j) explain the formation of dyes by the coupling reaction of the diazonium salt as exemplified by the reaction of benzenediazonium chloride with phenol.

20.2 Amino acids

Candidates should be able to:

(a) write the structure and general formula for -amino acids;

(b) name -amino acids according to the IUPAC nomenclature and their common names;

(c) describe structural and optical isomerism in amino acids;

(d) state the physical properties of -amino acids;

(e) describe the acid and base properties of -amino acids;

(f) describe the formation of zwitterions;

(g) explain the peptide linkage as amide linkage formed by the condensation between two or more -amino acids as exemplified by glycylalanine and alanilglycine.

20.3 Protein

Candidates should be able to:

(a) identify the peptide linkage in the primary structure of protein;

(b) describe the hydrolysis of proteins;

(c) state the biological importance of proteins.

21 Polymers

Candidates should be able to:

(a) state examples of natural and synthetic polymers;

(b) define monomer, polymer, repeating unit, homopolymer and copolymer;

(c) identify the monomers in a polymer;

(d) describe condensation polymerisation as exemplified by terylene and nylon-6,6;

(e) describe addition polymerisation as exemplified by poly(ethene)/ polyethylene/ polythene, poly(phenylethene)/ polystyrene and poly(chloroethene)/ polyvinylchloride;

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