EJC 2023 Intro to Organic Chem Lecture notes

2023 JC1 H2 CHEMISTRY (9729) ORGANIC CHEMISTRY Topic 9: INTRODUCTION TO ORGANIC CHEMISTRY Name: ___________________________________________ Civics Group: _________ Introduction Students should be able to: (a) interpret, and use the nomenclature, general formulae and displayed formulae of the following classes of compound: (i) hydrocarbons (alkanes, alkenes and arenes) (ii) halogen derivatives (halogenoalkanes and halogenoarenes) (iii) hydroxyl compounds (alcohols and phenols) (iv) carbonyl compounds (aldehydes and ketones) (v) carboxylic acids and derivatives (acyl chlorides and esters) (vi) nitrogen compounds (amines, amides, amino acids and nitriles) (b) interpret, and use the following terminology associated with organic reactions: (i) functional group (ii) degree of substitution: primary, secondary, tertiary, quaternary (iii) homolytic and heterolytic fission (iv) carbocation (v) free radical, initiation, propagation, termination (vi) electrophile (Lewis acid), nucleophile (Lewis base) (vii) addition, substitution, elimination, condensation, hydrolysis (viii) oxidation and reduction [in equations for organic redox reactions, the symbols [O] and [H] are acceptable] (c) interpret, and use the following terminology associated with organic reactivities: (i) delocalisation (ii) electronic effect (electron-donating and electron-withdrawing effect) (iii) steric effect (steric hindrance) (d) describe sp 3 hybridisation, as in ethane molecule, sp 2 hybridisation, as in ethene and benzene molecules, and sp hybridisation, as in ethyne molecule (e) explain the shapes of, and bond angles in, the ethane, ethene, benzene, and ethyne molecules in relation to  and  carbon-carbon bonds (f) predict the shapes of, and bond angles in, molecules analogous to those specified in (e) (g) apply (b) and (c) to the understanding of mechanisms in terms of organic structure and bonding (h) recognise that the mechanisms of polar reactions involve the flow of e lectrons from electron-rich to electron-poor sites

I N T R O D U C T I O N T O O R G A N I C C H E M I S T R Y E u n o i a J u n i o r C o l l e g e 2 Isomerism Students should be able to: (a) describe constitutional (structural) isomerism (b) describe cis-trans isomerism in alkenes, and explain its origin in terms of restricted rotation due to the presence of  bonds [use of E, Z nomenclature is not required] (c) explain what is meant by a chiral centre (d) deduce whether a given molecule is chiral based on the presence or absence of chiral centres and/or a plane of symmetry (e) recognise that an optically active sample rotates plane -polarised light and contains chiral molecules (f) recognise that enantiomers have identical physical properties except in the direction in which they rotate plane-polarised light [usage of the term diastereomers is not required] (g) recognise that enantiomers have identical chemical properties except in their interactions with another chiral molecule (h) recognise that different stereoisomers exhibit different biological properties, for example in drug action (i) deduce the possible isomers for an organic molecule of known molecular formula (j) identify chiral centres and/or cis-trans isomerism in a molecule of given structural formula

I N T R O D U C T I O N T O O R G A N I C C H E M I S T R Y E u n o i a J u n i o r C o l l e g e 3 LECTURE CONTENT 1 Introduction ................................ ................................ ................................ .............................. 4 2 Representations in Organic Chemistry ................................ ................................ .................. 5 2.1 Formulae of Organic Compounds ................................ ................................ ....................... 5 3 Classification of Organic Compounds ................................ ................................ ................... 7 3.1 Nature of structure ................................ ................................ ................................ .............. 7 3.2 Functional groups ................................ ................................ ................................ ............... 7 3.3 Alkyl and Aryl Groups ................................ ................................ ................................ ....... 10 3.4 Degree of Substitution ................................ ................................ ................................ ...... 10 4.1 Special cases ................................ ................................ ................................ ................... 17 5 Bonding in Carbon Compounds ................................ ................................ ........................... 19 5.1 Hybridisation ................................ ................................ ................................ ..................... 19 6 Organic Reactions ................................ ................................ ................................ ................. 27 6.1 Types of Reactions ................................ ................................ ................................ ........... 27 6.2 Reaction Mechanisms ................................ ................................ ................................ ...... 29 6.2.1 The Breaking and Forming of Bonds ................................ ................................ ........ 29 6.2.2 Types of Reagents ................................ ................................ ................................ ... 31 7 Isomerism ................................ ................................ ................................ ............................... 34 7.1 Constitutional (Structural) Isomerism ................................ ................................ ................ 34 7.2 Stereoisomerism ................................ ................................ ................................ ............... 37 7.2.1 cis-trans Isomerism ................................ ................................ ................................ .. 37 7.2.3 Biological Importance of Stereochemistry ................................ ................................ 48 7.2.4 Number of Stereoisomers ................................ ................................ ........................ 50 REFERENCES 1. Chemistry (for CIE AS Texts) by David G. Morris & A Level) by Peter Cann & Peter Hughes 2. Cambridge International AS and A Level Chemistry Revision Guide by Judith Potter and Peter Cann 3. Organic Chemistry (Eleventh Edition) by Graham Solomons, Craig Fryhle & Scott Snyder 4. Organic Chemistry by John McMurry 5. Keynotes in Organic Chemistry (Second Edition) by Andrew F. Parsons 6. Guidebook to Mechanism in Organic Chemistry (Sixth Edition) by Peter Skyes 7. Stereochemistry (RSC Tutorial Chemistry)

I N T R O D U C T I O N T O O R G A N I C C H E M I S T R Y E u n o i a J u n i o r C o l l e g e 4 1 Introduction Organic chemistry, one of the major branches of chemistry, is concerned with “the study of the structure, properties, composition, reactions, and preparation of carbon- containing compounds, which include not only hydrocarbons but also compounds with any number of other elements, such as hydrogen (most compounds contain at least one carbon – hydrogen bond), nitrogen, oxygen, halogens, phosphorus, silicon, and sulfur”. Carbon is special in that • it has a strong tendency to form long chains and/or rings of carbon atoms due to the strength of the carbon–carbon bond • it can form four bonds with its neighbouring atoms which allows for significant branching on carbon chains • it forms strong -bonds, making double and triple bonds possible within the structures Hence, it can form a vast array of compounds, from the simple methane with o