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Introduction of Organic Chemistry 1 Syllabus Introduction of Organic chemistry Classification Sources Types Functional Groups (Aldehydes,Ketone,Acids,Alccohols) Application 2 Chemistry Chemistry is the study of the substances, specially their structure, properties, transformations and the energy changes accompanying these transformation. 3 Branches Organic Chemistry Inorganic Chemistry Physical Chemistry 4 Discipline Branches of Chemistry Analytical Chemistry Industrial Chemistry Instrumental Chemistry Agriculture Chemistry Medicinal Chemistry 5 Organic Chemistry The study of Carbon Compounds or better to say the chemistry of hydrocarbons and their derivatives. 6 ATOMIC STRUCTURE Atom: Smallest indivisible particle of an element Molecule: Smallest particle of matter 7 Types of Bonding Ionic bonding – electron is fully transferred from metal to non- metal – binding is by electrostatic attraction. 8 Ionic Bonding Na Sodium Atom F Fluorine Atom 9 Ionic Bonding (2) Na Sodium ion F 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. .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 Carbon Nitrogen (phosphorus) Oxygen (sulfur) Halogen (F, Cl, Br, I) Hydrogen 4 bonds 3 bonds 2 bonds 1 bond 1 bond 15 Normal bonding patterns Carbon (4 bonds) Nitrogen (3 bonds) C N C C C N N (Phosphorus) Oxygen (2 bonds) O O (Sulfur) Halogen (1 bond) X (F, Cl, Br, I) Hydrogen (1 bond) H 16 Common Bonding Patterns -- Cations + C + .. + O N + + O .. N + N + O: + N 17 Common Bonding Patterns -- Anions _ B .. C _ .. _ N.. .. N .. .. _ O: .. _ 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 Alkanes contain only single ( ) bonds and have the generic molecular formula: [CnH2n+2] Alkenes also contain double ( + ) bonds and have the generic molecular formula: [CnH2n] Alkynes contain triple ( + 2) bonds and have the generic molecular formula: [CnH2n-2] Aromatics are planar, ring structures with alternating single and double bonds: eg. C6H6 21 Types of Hydrocarbons Each C atom is tetrahedral with sp3 hybridized orbitals. They only have single bonds. Each C atom is trigonal planar with sp2 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 ethane propane butane pentane hexane heptane octane nonane decane CH4 C 2 H6 C 3 H8 C4H10 C5H12 C6H14 C7H16 C8H18 C9H20 C10H22 24 Naming Alkanes C1 - C10 : the number of C atoms present in the chain. - Each member C3 - C10 differs by one CH2 unit. This is called a homologous series. Methane to butane are gases at normal pressures. Pentane to decane are liquids at normal pressures. 25 26 Nomenclature of Alkyl Substituents 27 [email protected] 28 Constitutional Isomers Substances which have the same molecular formula but a different structural formula. Isomers differ in connectivity. 29 30 • A compound can have more than one name, but a name must unambiguously specify only one compound A C7H16 compound can be any one of the following: [email protected] 31 Functional Groups 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. Both are steroids with four fused carbon rings, but they differ in the functional groups attached to the rings. These then interact with different targets in the body. 33 6 functional groups, all hydrophilic 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. Because of these polar covalent bonds hydroxyl groups improve the water solubility of organic molecules. Organic compounds with hydroxyl groups are alcohols and their names typically end in -ol. [email protected] 34 A carbonyl group (-CO) consists of an oxygen atom joined to the carbon skeleton by a double bond. If the carbonyl group is on the end of the skeleton, the compound is an aldelhyde. If not, then the compound is a ketone. 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. Compounds with carboxyl groups are carboxylic acids. 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 (-NH2) consists of a nitrogen atom attached to two hydrogen atoms and the carbon skeleton. Organic compounds with amino groups are amines. The amino group acts as a base because amino groups can pick up a hydrogen ion (H+) from the solution. 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. This group resembles a hydroxyl group in shape. Organic molecules with sulfhydryl groups are thiols. Sulfhydryl groups help stabilize the structure of proteins. 38 A phosphate group (-OPO32-) consists of phosphorus bound to four oxygen atoms (three with single bonds and one with a double bond). A phosphate group connects to the carbon backbone via one of its oxygen atoms. Phosphate groups are anions with two negative charges as two hydrogens have dissociated from the oxygen atoms. One function of phosphate groups is to transfer energy between organic molecules. 39 Functional Groups [email protected] 40 Functional Groups [email protected] 41 Classes of Organic Compounds R H R Alkane R O R R' Ether R R C R H Aldehyde C R' C R OH Carboxylic Acid C Ketone O O O R O R Alkene R OH Alcohol NH2 O C R R Amine R C X Alkyl Halide C Alkyne R' C O R R' Ester [email protected] C NH2 Amide R C Nitrile N 42 ALCOHOL FUNCTIONAL GROUP R –O H 43 Classification Monohydric Alcohols Polyhydric Alcohols - Dihydric Alcohols (Ethylene Glycol) - Trihydric Alcohols (Glycerol) 44 Monohydric Alcohols Devided in Primary, Secondary and tertiary alcohols. CH3OH, CH3CH2OH Methanol Ethanol CH3CH(OH)CH3 Isopropyl Alcohol CH3C(OH)(CH3) t-Butyl Alcohol 45 Physical Properties Lower are colorless, neutral substances with characteristic sweet alcoholic smell and burning taste. Higher are waxy solids. Lower are readily soluble in water & organic solvents but it decreases as M.W. increases. B.P. are higher than corresponding alkanes. e.g. Methanol-338 K and Methane-112K 46 Preparation of Alcohol By Hydrolysis R-X + NaOH→ R-OH + NaX By Hydration CH2=CH2 → CH3CH2OH Hydrolysis of Esters CH3COOC2H5 → CH3COOH + C2H5OH Reduction of Aldehyde/Ketone CHO/C=O → 1-Alcohol/2-alcohol Grignard Reagent R-Mg-X →R-O-MgX →R-OH 47 Chemical properties Displacement of –OH gr. By Halogen(X) R-OH + HX → RX + H2O Action of Alkali Metals 2ROH + 2Na → 2RONa + H2 Dehydration C2H5OH → CH2=CH2 + H2O Oxidation of Alcohol(K2Cr2O7/H2SO4) 1-alcohol → Aldehyde → Acid Reduction of Alcohols(Red P ) C2H5OH + 2HI → CH3CH3+H2O + I2 48 METHANOL H H H C OH Methanol (methyl alcohol) or wood alcohol a. Made by the destructive distillation of wood b. Or by… CO + 2H2 CH3OH c. Used as a solvent d. Possible replacement for gasoline e. Forms formaldehyde in body causing blindness 49 ETHANOL H H C H H C H OH Ethanol (ethyl alcohol) or grain alcohol a. Made from the fermentation of grain, fruit, or sugar b. C6H12O6 + yeast 2C2H5OH + CO2 c. The alcohol that is in beverages d. Added to automotive fuels – 10% as gasohal e. 1 pint of pure alcohol will kill most people f. caused deterioration of the liver, memory loss and is harmful to unborn babies 50 ISOPROPYL ALCOHOL OH H C C H H C H H H H Isopropyl alcohol (rubbing alcohol) a. Alcohol used for cuts and cleaning b. Will not be absorbed by the skin c. Toxic if taken internally d. Sold as a 70% solution – 140 proof 51 Ethylene glycol H Ethylene glycol a. Used for antifreeze in cars b. Very sweet tasting c. Toxic – caused kidney failure and death H H C C H HO OH H H H C C H HO OH O O Liver C C HO Kidney CaC2O4 OH Oxalic acid Calcium Oxalate 52 GLYCEROL H H C HO Glycerol a. Used in lotion to keep skin soft H H b. Food additive that keeps cookies soft H C C c. Can add to nitric acid to form nitroglycerin Nitroglycerin (nitro) taken to relieve angina OH OH heart pain 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 O R C H 55 Physical Properties Formaldehyde is a gas at room temp. All other members are colorless liquids at ordinary temp. The higher members are solids. Lower aldehydes have unpleasant smell but as one goes up in the series the smell becomes more fruity. Ketones are generally pleasant smelling liquids. Solubilities Lower members are highly soluble in water. Solubilities decreases with increasing molecular mass. B.P. are higher than those of non polar alkanes. B.P. of aldehydes/Ketones are lower than the B.P. of alcohols. 56 Chemical Properties Addition Across C=O bond CH3CHO + HCN Acetaldehyde - HCH(OMgBr)CH3 CH3CH=NNH2 + H2O Oxidation CH3CHO CH3CH=N-OH + H2O With Hydrazine (Phenyl Hydrazine) CH3CHO + H2NNH2 CH3CH2OH + Mg(OH)Br With Hydroxyl Amine CH3CHO + H2NOH CH3CH(OH)COOH 2-hydroxy propanoicAcid Addition of Grignard Reagent HCHO + CH3MgBr CH3CH(CN)OH Cyanohydrins CH3COOH Reduction (Pt / Ni) CH3CHO + H2 CH3CH2OH 57 FORMALDEHYDE Formaldehyde O C H H a. b. c. d. Soluble in water 40% solution is called formaline Used in some plastic manufacturing Makes a good disinfectant 58 BENZALDEHYDE O Benzaldehyde a. called synthetic oil of almond b. used as flavoring – maraschino cherries c. used in perfumes C H 59 Ketones O R C R 60 ACETONE O Acetone a. Made from Isopropyl alcohol CH3 O OH H3 C CH H3C C CH3 -H H3 C C CH3 b. Used as a solvent for fats, rubber, plastics, and varnishes c. Used as fingernail polish remover d. Will not mix with water Washes water off of glassware after cleaning 61 CARBOXYLIC ACID O R C OH R COOH 62 Physical Properties 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 + NaOH R-COONa + H2O Decarboxylation CH3COOH + NaOH soda lime CH3COONa + H2O CH3COONa + NaOH sodalime CH4 + Na2CO3 Reduction R-COOH LiAlH4/ 2H2 R-CH2OH Reaction with Carbonates R-COOH + Na2CO3 R-COONa + H2O + CO2 Dehydration 2R-COOH R-COOCOCH3 + H2O Acid Anhydride 64 FORMIC ACID O H C OH Formic Acid a. Irritant to skin b. Part of the venom in ants, bee’s, or wasps 65 ACETIC ACID The acid in vinegar O CH3 C OH 66 BENZOIC ACID O C OH Benzoic acid Used to make benzene type compounds in organic synthesis 67 ESTERS O R C O R 68 O O Apricot (pentyl buterate) 69 O O Orange (Octyl acetate) 70 O CH3 C O Jasmine (benzyl acetate) 71 O C O CH3 Wintergreen (methyl salicylate) OH 72 ETHER R O R 73 DIETHYL ETHER O Diethyl ether a. Used as a solvent b. Used for thinning paints c. Boils at 36 C (dries quickly) d. Used as anesthetic or as a drug e. Dissolves organic compounds readily f. Reacts with oxygen to form unstable peroxides 74 TERT-BUTYL ETHER CH3 CH3 O C CH3 CH3 Tert-butyl ether (MTBE) a. Gasoline additive b. Reduces CO emissions c. Replaced lead as the antiknock compound 75 ETHYLENE OXIDE H H Ethylene Oxide a. Very toxic gas b. Used in the formation of ethylene glycol c. Ethylene glycol is used in antifreeze and in polyester fibers. C C H H O 76 AMINES R primary H N H H R H N R N H H amonia secondary R R N tertiary R 77 H CH2 CH2 N Amphetamine (stimulant drug) H 78 H N Analine (used in dyes) H 79 CH3 CH3 N H Dimethyl amine used in volcanizing rubber, tanning hydes and making of soaps 80 CH2CH3 CH3CH2 N CH2CH3 Triethyl amine attracts insects warning agent in natural gas 81