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ORGANIC CHEMISTRY

ORGANIC CHEMISTRY. Organic chemistry is the study of carbon containing compounds derived from living organisms. Oil is formed over millions of years from the break down of dead creatures and plants . 80+ million compounds- natural & synthetic.

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ORGANIC CHEMISTRY

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  1. ORGANIC CHEMISTRY • Organic chemistry is the study of carbon containing compounds derived from living organisms. • Oil is formed over millions of years from the break down of dead creatures and plants. 80+ million compounds- natural & synthetic. • Crude Oil (petroleum)is a mixture of many thousands of these different compounds and is the main source of many of these chemicals. • They are called hydrocarbons because they predominantly contain the elements hydrogen and carbon.

  2. Distillation of Crude Oil

  3. Distillation of Crude Oil

  4. Homologous series This is a series of compounds which all contain the same functional group, and have similar chemical properties.  ALKANESALKENESALCOHOLS CH4 CH2 =CH2 CH3OH CH3-CH3 CH2 =CH –CH3 CH3CH2OH Each has a general formula: ALKANES: CnH2n+2 The members of the series differ by the number of CH2 units. CH3-CH3, CH3-CH2-CH3, CH3-CH2-CH2-CH3 Graduation in physical properties:  eg: boiling points. CH4(GAS), C8H18 (LIQUID), C30H62 (SOLID)

  5. ALKANES • SATURATED HYDROCARBONS – contain maximum amount of hydrogen - only single bonds (no multiple bonds) NAMING ALKANES All alkanes end with ‘ANE’. All belong to the same HOMOLOGOUS series • GENERAL FORMULA CnH(2n+2)

  6. Functional groups The functional groups are atoms or combinations of atoms which determine the properties of organic molecules. 

  7. H H C H H STRUCTURES OF ALKANES METHANE CH4 Bond Angle 109.5o Shape Tetrahedral Can be illustrated as:

  8. Structural formula: CH3 CH3 or H H H C C H H H ETHANE. Molecular formula C2H6

  9. Structural formula: CH3 CH2 CH3 or H H H H C C C H H H H PROPANE. Molecular formula: C3H8 Both ethane and propane are “straight” chain molecules BUT!! Bonds are NOT 90o molecules are NOT STRAIGHT!!! Schematic formula

  10. “Straight” chain. CH3 CH2 CH2 CH3 BUTANE & ISOMERS. Molecular formula: C4H10 - can have two different structures BUTANE Schematic formula: Branched chain CH3 CH CH3 CH3 METHYL PROPANE branch Isomers Compounds that have the same molecular formula but different structural formula.

  11. TASK: Illustrate the structures of the three different isomers of C5H12.

  12. CH3 CH3 CH CH2 CH3 CH3 CH3 C CH3 CH3 TASK: illustrate the structures of: 2-methylpentane. 2,3 – dimethylbutane. 2,2,3 -trimethylpentane Names & Structures Examples 2- methylbutane 2,2 – dimethyl propane CH3CH(CH3)CH2CH2CH3 CH3CH(CH3)CH(CH3)CH3 CH3C(CH3)2CH(CH3)CH2CH3

  13. THE RULES FOR NAMING ORGANIC COMPOUNDS • Choose the longest unbroken chain of Carbon atomsand assign a name for the carbon chain using the prefixes; meth-1, eth-2 etc. • Identify any carbon chain branches (alkyl groups). These are assigned names using the same prefixes as above along with the suffix “-yl” – methyl, ethyl etc. • Identify the functional groups present in the molecule. Assign a prefix or suffix according to their homologous series. These will be written in front of the name of the carbon chain. • There is an order of precedence, to decide the suffix for the carbon chain: • COOH / C=C > OH > Br / Cl • Number the Carbon atoms in the longest chain so that the branches/functional groups have the lowest number possible. Allocate a number for every group/branch no matter how many times it occurs. Where groups are on the same carbonwrite their names inalphabetical order. • Numbering takes precedence "wins" over alphabetical spelling. Prefixesare used for groups that occur more than once. • Di – 2 Tri – 3 Tetra – 4 Penta – 5 etc. • The final name is written as one word with commas between numbers, hyphens separating numbers from words.

  14. CH3 CH2 CH CH2 CH3 • CH3 (b) CH3 CH CH2 CH CH3 CH3 CH3 (c) CH3 C(CH3)2 CH2 CH(CH3) CH2 CH3 (d) CH3CH2CH(CH3)C(CH3)3 Give the names of the following alkanes

  15. CH3 CH2 CH CH2 CH3 • CH3 (b) CH3 CH CH2 CH CH3 CH3 CH3 (c) CH3 C(CH3)2 CH2 CH(CH3) CH2 CH3 (d) CH3CH2CH(CH3)C(CH3)3 Give the names of the following alkanes 3-methyl pentane 2,4-dimethylpentane 2,2,4-trimethyl hexane 2,2,3-trimethylpentane

  16. Example Cyclic Alkanes • When C atoms bond together to form a ‘ring’ – known as a ‘cyclic’ structure. What is the molecular formula of this alkane? How does the molecular formula compare to the general formula for alkanes? Why does it belong to the series of alkanes? Can you think of a name for this molecule Illustrate the cyclic structures of (a) C4H8 and (b) C5H10 and name the molecules. CYCLOHEXANE

  17.  bond C C 120o PLANAR  Represented as C C Structure of Alkenes • The shapearound the double bond is planar. • The bond angle around the double bond is 120o

  18. H H C C H H PROPENE CH2 CH CH3 Examples of Alkenes ………………, C2H4 OR ……………………. TASK: Use ball & stick models or sketches to construct and name 3 different structures for C4H8 each one with one double bond.

  19. H H C C H H OR CH2 CH2 H H C C H CH3 PROPENE CH2 CH CH3 CH3C CH2 CH3 CH3CH CHCH3 CH3CH2CHCH2 Examples of Alkenes ETHENE, C2H4 TASK: Use ball & stick models or sketches to construct and name 3 different structures for C4H8 each one with one double bond. BUT-1-ENE METHYL PROPENE BUT-2-ENE

  20. CH3CHCHCH2CH3 CH2 CHCH(CH3)CH2CH3 CH3CH(CH3)CH CHCH2CH3 (CH3)3CCH C(CH3)2 More Alkenes Illustrate structures of the following alkenes: Pent-1-ene Hex-3-ene 2-methylbut-1-ene Cyclohexene Name the following alkenes

  21. CH2 CHCH2CH2CH3 CH3CH2CH CHCH2CH3 CH2 C(CH3)CH2CH3 CH3CHCHCH2CH3 CH2 CHCH(CH3)CH2CH3 CH3CH(CH3)CH CHCH2CH3 (CH3)3CCH C(CH3)2 More Alkenes Illustrate structures of the following alkenes: Pent-1-ene Hex-3-ene 2-methylbut-1-ene Cyclohexene Name the following alkenes Pent-2-ene 3-methylpent-1-ene 2-methylhex-3-ene 2,4,4-trimethylpent-2-ene

  22. BUT–2-ENE CH3 CH CH CH3 CH3 CH3 C C H H CH3 H C C H CH3 GEOMETRIC ISOMERS • There is no rotation about the doublebond. GEOMETRIC ISOMERISM each C atom in the doublebond has two differentatoms/groups attached. trans but-2-ene cis but-2-ene Geometric isomerism is a form of STEREOISOMERISM – Same molecular and structural formula but atoms are arranged differently in space

  23. Alkynes H-C≡C-H Ethyne Very reactive Triple bond unstable! Attracts electrophiles. H-C≡C-CH3 propyne H-C≡C-CH2-CH3 But–1-yne But–2-yne CH3-C≡C-CH3

  24. CH3–CH–CH2 CH3 I HALOALKANES • Substituted alkane with at least onehalogen atom • General formulaCnH(2n+1)X Structures & Names CH3Cl chloromethane CH3–CH2 –CH2Br 1- bromopropane 2- iodobutane

  25. CH3–CH2–CH–CH3 Br CH3 CH3 CH2–C–CH3 Br Primary, Secondary & Tertiary Haloalkanes CH3–CH2–CH2–CH2Br 1- bromobutane PRIMARY 10 2-bromobutane SECONDARY20 2-bromo-2-methylbutane TERTIARY30

  26. CH3—CH—CH3 OH Propan-2-ol 2o ALCOHOLS Hydroxyl group • General formula CnH(2n+1)OH • CH3OH Methanol • CH3CH2OH Ethanol • C3H7OH – two isomers CH3—CH2—CH2OH Propan-1-ol 1o TASK: C4H9OH has 4 isomers. Draw the structures of each isomer giving the name and class of each one.

  27. C6H12O6 yeast2C2H5OH + 2CO2 CH2=CH2 + H2O CH3CH2OH MANUFACTURE OF ETHANOL • FERMENTATION – sugars (glucose)/yeast/25oC – 35OC • HYDRATION OF ETHENE Renewable sources Batch Low energy Slow Cheap Impure/Low yield Fast High energy Pure Non-renewable High yield /continuous Expensive

  28. BOND ANGLE 120O C O R C O H ALDEHYDES & KETONES • KNOWN AS CARBONYLS STRUCTURE ALDEHYDES GENERAL STRUCTURE EXAMPLES HCHO - methanal CH3CHO - ethanal CH3CH2CHO - NAME? • Illustrate the structures of these examples

  29. R C O R1 KETONES GENERAL FORMULA R and R1 may be the same or different NOTE: ALDEHYDES & KETONES EXHIBIT FUNCTIONAL GROUP ISOMERISM EXAMPLES • Illustrate the structures of these examples – show & name the corresponding aldehyde isomer. CH3COCH3 propanone CH3COCH2CH3 butanone CH3CH2COCH2CH3 pentan-3-one

  30. Carboxyl group -COOH R C O OH Carboxylic Acids GENERAL FORMULA Acidic reaction CH3COOH + H2O  ……………………………. + H3O+ EXAMPLES • Illustrate the structures of these examples – show & name the corresponding aldehyde isomer. HCOOH ................... acid CH3COOH .................... acid CH3CH2COOH.......................... acid

  31. Carboxyl group -COOH R C O OH Carboxylic Acids GENERAL FORMULA Acidic reaction CH3COOH + H2O  CH3COO- + H3O+ EXAMPLES • Illustrate the structures of these examples – show & name the corresponding aldehyde isomer. HCOOH methanoic acid CH3COOH ethanoic acid CH3CH2COOHpropanoic acid

  32. FORMATION OF ESTERS • GENERALLY: .........+ ........... ESTER + WATER catalysed by H+ ions normally from conc. H2SO4 O O R C + H O R/R C + H2O OH O R/ O O H C + CH3OH H C + H2O OH O CH3 methanoic methanol ............. .......................... CH3CH2OH + CH3CH2COOH CH3CH2........CH2CH3 + H2O ethanol propanoic ............ .........................

  33. FORMATION OF ESTERS • GENERALLY: ACID + ALCOHOL ESTER + WATER catalysed by H+ ions normally from conc. H2SO4 O O R C + H O R/R C + H2O OH O R/ O O H C + CH3OH H C + H2O OH O CH3 methanoic methanol methyl methanoate CH3CH2OH + CH3CH2COOH CH3CH2COOCH2CH3 + H2O ethanol propanoic ethyl propanoate

  34. NAMING OF ESTERS GENERALLY: ACID + ALCOHOLESTER + WATER ESTER NAME: .......................YL............ANOATE CH3CH2OH + CH3CH2COOHCH3CH2COOCH2CH3 +H2O ethanolpropanoic.........yl ............anoate methanoic methanol ..............hyl ..........anoate

  35. NAMING OF ESTERS GENERALLY: ACID + ALCOHOLESTER + WATER ESTER NAME: ALCOHOLYLACIDANOATE CH3CH2OH + CH3CH2COOHCH3CH2COOCH2CH3 +H2O ethanolpropanoicETHyl PROPanoate methanoic methanol METHyl METHanoate

  36. HYDROLYSIS OF ESTERS • Hydrolysis can take place in either acid or alkaline solution • Hot alkaline solution is usually preferred • Ester ishydrolysedto alcohol and sodium saltof acid. Generally RCOOR’ + NaOH ROO-Na+ + R’OH EXAMPLES CH3COOCH2CH3 + NaOH CH3COO-Na++ CH3CH2OH ethyl ethanoate sodium ethanoate ethanol CH3CH2COOCH3 + NaOH CH3CH2COO-Na+ + CH3OH methyl propanoate sodium propanoate methanol • Addition of dil.H2SO4 or dil. HCl to sodium salt regenerates the carboxylic acid.

  37. USES OF ESTERS esters have characteristic sweet smells and are used as food ................. they are also widely used as ............ and as ...................

  38. USES OF ESTERS esters have characteristic sweet smells and are used as food flavourings. they are also widely used as solvents and as plasticisers

  39. NATURALLY OCCURING ESTERS • Occur as fats and oils, known as triglycerides • Triesters of long-chain carboxylic acid and propane –1,2,3-triol (glycerol). • On hydrolysis using hot NaOH, 3 moles of long chain acid are produced together with 1 mole of glycerol. C17H35COOCH2 CH2OH C17H35COOCH+ 3NaOH CHOH + 3C17H35COONa C17H35COOCH2 CH2OH sodium glycerol stearate Sodium stearate is used in the manufacture of soap.

  40. AMINES

  41. AMIDES

  42. Physical Properties Recognize and apply to particular examples the relationship between melting points, boiling points, vapour pressure, viscosity and intermolecular forces (hydrogen bonding, Van der Waals forces including dispersion or London forces number and type of functional group, chain length, branched chains)

  43. Addition reactions • Unsaturated compounds undergo addition reactions to form saturated compounds e.g. CH2=CH2 + Cℓ2 → CH2Cℓ-CH2Cℓ - • hydrohalogentaion - addition of HX - halogenation - addition of X2 – • hydration - addition of H2O – • The X-atom or OH-group attaches to the more substituted C-atom.) • hydrogenation - addition of H2 (During additon of HX and H2O to unsaturated hydrocarbons, the H-atom attaches to the C-atom already having the greater number of H-atoms. ·    

  44. Elimination reactions • * Saturated compounds (haloalkanes, alcohols, alkanes) undergo elimination reactions to form unsaturated compounds e.g. CH2Cℓ-CH2Cℓ → CH2=CHCℓ + HCℓ • - dehydrohalogentaion - elimination of HX from a haloalkane (alkene with the more highly substituted double bond is the major product). – • dehydration - elimination of H2O from an alcohol (alkene with the more highly substituted double bond is the major product). – • dehydrogenation - elimination of H2 from an alkane. - cracking of alkanes. ·     

  45. Substitution reactions • * Reactions of HX with alcohols e.g. (CH3)3OH + HBr → (CH3)3Br + H2O • Reactions where the OH of alcohols are substituted with a halogen e.g. (CH3)3Br + KOH → (CH3)3OH + KBr • Two types of saturated structure can be inter-converted by substitution as shown in the above two reaction equations. • * Reactions of X2 with alkanes in the presence of light (prior knowledge from Grade 11).

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