Introduction of Organic Chemistry 1 Syllabus v Introduction

Introduction of Organic Chemistry 1

Syllabus v Introduction of Organic chemistry v Classification v Sources v Types v Functional Groups (Aldehydes, Ketone, Acids, Alccohols) v Application 2

Chemistry v Chemistry is the study of the substances, specially their structure, properties, transformations and the energy changes accompanying these transformation. 3

Branches v Organic Chemistry v Inorganic Chemistry v Physical Chemistry 4

Discipline Branches of Chemistry v Analytical Chemistry v Industrial Chemistry v Instrumental Chemistry v Agriculture Chemistry v Medicinal Chemistry 5

Organic Chemistry v The study of Carbon Compounds or better to say the chemistry of hydrocarbons and their derivatives. 6

ATOMIC STRUCTURE v Atom: Smallest indivisible particle of an element v Molecule: Smallest particle of matter 7

Types of Bonding l Ionic bonding – electron is fully transferred from metal to non- metal – binding is by electrostatic attraction. 8

Ionic Bonding Sodium Atom Fluorine Atom 9

Ionic Bonding (2) Sodium ion Fluoride ion Attraction between the two ions is electrostatic -Ionic Bond 10

A SIMPLE COVALENT BOND A pair of electrons is shared between the two bonded atoms. . H 11

A SIMPLE COVALENT BOND Bonded pair H H 12

A LEWIS DIAGRAM H . . O. . CONSTRUCTED FROM LEWIS DOT SYMBOLS H. (note use of lines for bonds) H COVALENT BONDS . . . O. . H 13

DRAWING CONVENTIONS 1. A shared pair (bond) is drawn as a line. C O 2. An unshared pair is shown as a pair of dots. N: 3. The diagram includes formal charges (later). H . . + O H H 14

Bonding patterns v Carbon v Nitrogen (phosphorus) v Oxygen (sulfur) v Halogen (F, Cl, Br, I) v Hydrogen 4 bonds 3 bonds 2 bonds 1 bond 15

Normal bonding patterns 16

Common Bonding Patterns -- Cations 17

Common Bonding Patterns -Anions 18

Types of Carbons Primary (1°) – attached to only one other carbon Secondary (2°) – attached to two other carbons Tertiary (3°) – attached to three other carbons Quaternary (4°) – attached to four other carbons 19

Hydrocarbons Aliphatic alkanes – contain only single bonds (saturated) alkenes – contain at least one double bond (unsaturated) alkynes – contain at least one triple bond Aromatic contain a benzene ring 20

Hydrocarbons Ø Alkanes contain only single ( ) bonds and have the generic molecular formula: [Cn. H 2 n+2] Ø Alkenes also contain double ( + ) bonds and have the generic molecular formula: [Cn. H 2 n] Ø Alkynes contain triple ( + 2 ) bonds and have the generic molecular formula: [Cn. H 2 n-2] Ø Aromatics are planar, ring structures with alternating single and double bonds: eg. C 6 H 6 21

Types of Hydrocarbons Each C atom is tetrahedral with sp 3 hybridized orbitals. They only have single bonds. Each C atom is trigonal planar with sp 2 hybridized orbitals. There is no rotation about the C=C bond in alkenes. 22

Types of Hydrocarbons Each C atom is linear with sp hybridized orbitals. Each C--C bond is the same length; shorter than a C-C bond: longer than a C=C bond. The concept of resonance is used to explain this phenomena. 23

Alkanes 1 meth 2 eth 3 prop 4 but 5 pent 6 hex 7 hept 8 oct 9 non 10 dec methane propane butane pentane hexane heptane octane nonane decane CH 4 C 2 H 6 C 3 H 8 C 4 H 10 C 5 H 12 C 6 H 14 C 7 H 16 C 8 H 18 C 9 H 20 C 10 H 22 24

Naming Alkanes C 1 - C 10 : the number of C atoms present in the chain. - Each member C 3 - C 10 differs by one CH 2 unit. This is called a homologous series. Methane to butane are gases at normal pressures. Pentane to decane are liquids at normal pressures. 25

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Nomenclature of Alkyl Substituents 27

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Constitutional Isomers l Substances which have the same molecular formula but a different structural formula. l Isomers differ in connectivity. 29

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• A compound can have more than one name, but a name must unambiguously specify only one compound A C 7 H 16 compound can be any one of the following: navedmalek@yahoo. co. in 31

Functional Groups Ø Ø An atom or group of atoms which makes an organic compound reactive and decides its functions (properties) is called a Functional group. In an organic compound, the alkyl group determines the physical properties whereas the functional group determines the chemical properties of the compound. A Functional group can be introduced by displacing hydrogen of the hydrocarbon. The functional groups are directly attached to the carbon of the organic compound. 32

The basic structure of testosterone (male hormone) and estradiol (female hormone) is identical. o Both are steroids with four fused carbon rings, but they differ in the functional groups attached to the rings. o These then interact with different targets in the body. 33

v 6 functional groups, all hydrophilic v In a hydroxyl group (-OH), a hydrogen atom forms a polar covalent bond with an oxygen which forms a polar covalent bond to the carbon skeleton. v Because of these polar covalent bonds hydroxyl groups improve the water solubility of organic molecules. v Organic compounds with hydroxyl groups are alcohols and their names typically end in -ol. navedmalek@yahoo. co. in 34

A carbonyl group (-CO) consists of an oxygen atom joined to the carbon skeleton by a double bond. v If the carbonyl group is on the end of the skeleton, the compound is an aldelhyde. v If not, then the compound is a ketone. v Isomers with aldehydes versus ketones have different properties. 35

A carboxyl group (-COOH) consists of a carbon atom with a double bond with an oxygen atom and a single bond to a hydroxyl group. v. Compounds with carboxyl groups are carboxylic acids. v. A carboxyl group acts as an acid because the combined electro -negativities of the two adjacent oxygen atoms increase the dissociation of hydrogen as an ion (H+). 36

An amino group (-NH 2) consists of a nitrogen atom attached to two hydrogen atoms and the carbon skeleton. v. Organic compounds with amino groups are amines. v. The amino group acts as a base because amino groups can pick up a hydrogen ion (H+) from the solution. v. Amino acids, the building blocks of proteins, have amino and carboxyl groups. 37

A sulfhydryl group (-SH) consists of a sulfur atom bonded to a hydrogen atom and to the backbone. v. This group resembles a hydroxyl group in shape. v. Organic molecules with sulfhydryl groups are thiols. v. Sulfhydryl groups help stabilize the structure of proteins. 38

A phosphate group (-OPO 32 -) consists of phosphorus bound to four oxygen atoms (three with single bonds and one with a double bond). v. A phosphate group connects to the carbon backbone via one of its oxygen atoms. v. Phosphate groups are anions with two negative charges as two hydrogens have dissociated from the oxygen atoms. v. One function of phosphate groups is to transfer energy between organic molecules. 39

Functional Groups navedmalek@yahoo. co. in 40

Functional Groups navedmalek@yahoo. co. in 41

Classes of Organic Compounds navedmalek@yahoo. co. in 42

ALCOHOL FUNCTIONAL GROUP R –O H 43

Classification o Monohydric Alcohols o Polyhydric Alcohols - Dihydric Alcohols (Ethylene Glycol) - Trihydric Alcohols (Glycerol) 44

Monohydric Alcohols v Devided in Primary, Secondary and tertiary alcohols. v CH 3 OH, CH 3 CH 2 OH v Methanol Ethanol v CH 3 CH(OH)CH 3 v Isopropyl Alcohol v CH 3 C(OH)(CH 3) v t-Butyl Alcohol 45

Physical Properties v Lower are colorless, neutral substances with characteristic sweet alcoholic smell and burning taste. Higher are waxy solids. v Lower are readily soluble in water & organic solvents but it decreases as M. W. increases. v B. P. are higher than corresponding alkanes. e. g. Methanol-338 K and Methane-112 K 46

Preparation of Alcohol v By Hydrolysis R-X + Na. OH→ R-OH + Na. X v By Hydration CH 2=CH 2 → CH 3 CH 2 OH v Hydrolysis of Esters CH 3 COOC 2 H 5 → CH 3 COOH + C 2 H 5 OH v Reduction of Aldehyde/Ketone CHO/C=O → 1 -Alcohol/2 -alcohol v Grignard Reagent R-Mg-X →R-O-Mg. X →R-OH 47

Chemical properties v Displacement of –OH gr. By Halogen(X) R-OH + HX → RX + H 2 O v Action of Alkali Metals 2 ROH + 2 Na → 2 RONa + H 2 v Dehydration C 2 H 5 OH → CH 2=CH 2 + H 2 O v Oxidation of Alcohol(K 2 Cr 2 O 7/H 2 SO 4) 1 -alcohol → Aldehyde → Acid v Reduction of Alcohols(Red P ) C 2 H 5 OH + 2 HI → CH 3+H 2 O + I 2 48

METHANOL 49

ETHANOL 50

ISOPROPYL ALCOHOL 51

Ethylene glycol 52

GLYCEROL 53

Carbonyl Compounds If an oxygen atom is attached to carbon by a double bond the functional group –C=O is called carbonyl group. 54

ALDEHYDE 55

Physical Properties v Formaldehyde is a gas at room temp. All other members are colorless liquids at ordinary temp. The higher members are solids. v Lower aldehydes have unpleasant smell but as one goes up in the series the smell becomes more fruity. Ketones are generally pleasant smelling liquids. v Solubilities v Lower members are highly soluble in water. Solubilities decreases with increasing molecular mass. v B. P. are higher than those of non polar alkanes. v B. P. of aldehydes/Ketones are lower than the B. P. of alcohols. 56

Chemical Properties Ø Addition Across C=O bond CH 3 CHO + HCN Acetaldehyde - Ø HCH(OMg. Br)CH 3 CH=NNH 2 + H 2 O Oxidation CH 3 CHO Ø CH 3 CH=N-OH + H 2 O With Hydrazine (Phenyl Hydrazine) CH 3 CHO + H 2 NNH 2 Ø CH 3 CH 2 OH + Mg(OH)Br With Hydroxyl Amine CH 3 CHO + H 2 NOH Ø CH 3 CH(OH)COOH 2 -hydroxy propanoic. Acid Addition of Grignard Reagent HCHO + CH 3 Mg. Br Ø CH 3 CH(CN)OH Cyanohydrins CH 3 COOH Reduction (Pt / Ni) CH 3 CHO + H 2 CH 3 CH 2 OH 57

FORMALDEHYDE 58

BENZALDEHYDE 59

Ketones 60

ACETONE 61

CARBOXYLIC ACID 62

Physical Properties v v v The first nine mono carboxylic acids are colorless liquids, while the higher ones are colorless wax like solids. Solubility: The first four (formic, acetic, propeonic, butiric) are soluble while fifth (valeric) is slightly soluble and acids above six carbon are insoluble in water. B. P. & M. P. : They have abnormally high b. p. , even higher than those of alcohols of similar molecular weights. 63

Chemical Properties Reaction with alkalies R-COOH + Na. OH R-COONa + H 2 O Decarboxylation CH 3 COOH + Na. OH soda lime CH 3 COONa + H 2 O CH 3 COONa + Na. OH sodalime CH 4 + Na 2 CO 3 Reduction R-COOH Li. Al. H / 2 H R-CH 2 OH Reaction with Carbonates R-COOH + Na 2 CO 3 R-COONa + H 2 O + CO 2 Dehydration 2 R-COOH R-COOCOCH 3 + H 2 O 4 2 Acid Anhydride 64

FORMIC ACID 65

ACETIC ACID 66

BENZOIC ACID 67

ESTERS 68

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ETHER 73

DIETHYL ETHER 74

TERT-BUTYL ETHER 75

ETHYLENE OXIDE 76

AMINES 77

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