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Introduction of Organic Chemistry

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  1. Introduction of Organic Chemistry

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

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

  4. Branches • Organic Chemistry • Inorganic Chemistry • Physical Chemistry

  5. Discipline Branches of Chemistry • Analytical Chemistry • Industrial Chemistry • Instrumental Chemistry • Agriculture Chemistry • Medicinal Chemistry

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

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

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

  9. Ionic Bonding Sodium Atom Fluorine Atom

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

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

  12. A SIMPLE COVALENT BOND Bonded pair H H

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

  14. 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

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

  16. Normal bonding patterns

  17. Common Bonding Patterns -- Cations

  18. Common Bonding Patterns -- Anions

  19. 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

  20. 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

  21. 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

  22. 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.

  23. 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.

  24. Alkanes 1 meth methane CH4 2 eth ethane C2H6 3 prop propane C3H8 4 but butane C4H10 5 pent pentane C5H12 6 hex hexane C6H14 7 hept heptane C7H16 8 oct octane C8H18 9 non nonane C9H20 10 dec decane C10H22

  25. Naming Alkanes C1 - C10 : the number of C atoms present in the chain. - - - - Each member C3 - C10differs 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.

  26. Nomenclature of Alkyl Substituents


  28. Constitutional Isomers • Substances which have the same molecularformula but a different structural formula. • Isomers differ in connectivity.

  29. 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:

  30. 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.

  31. 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.

  32. 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.

  33. 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.

  34. 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+).

  35. 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.

  36. 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.

  37. 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.

  38. Functional Groups

  39. Functional Groups

  40. Classes of Organic Compounds


  42. Classification • Monohydric Alcohols • Polyhydric Alcohols - Dihydric Alcohols (Ethylene Glycol) - Trihydric Alcohols (Glycerol)

  43. Monohydric Alcohols • Devided in Primary, Secondary and tertiary alcohols. • CH3OH, CH3CH2OH • Methanol Ethanol • CH3CH(OH)CH3 • Isopropyl Alcohol • CH3C(OH)(CH3) • t-Butyl Alcohol

  44. 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

  45. 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

  46. 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