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Chemistry 30 – Organic Chemistry – Part 1

Chemistry 30 – Organic Chemistry – Part 1. To accompany Inquiry into Chemistry. PowerPoint Presentation prepared by Robert Schultz robert.schultz@ei.educ.ab.ca. H. • •. • •. H C H. • •. • •. H. Organic Chemistry – Preparation – VSEPR.

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Chemistry 30 – Organic Chemistry – Part 1

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  1. Chemistry 30 – Organic Chemistry – Part 1 To accompany Inquiry into Chemistry PowerPoint Presentation prepared by Robert Schultz robert.schultz@ei.educ.ab.ca

  2. H •• •• H C H •• •• H Organic Chemistry – Preparation – VSEPR • Recall VSEPR Theory (valence shell electron pair repulson theory) from Chemistry 20 • Organic chemistry will involve 3 particular groupings: • 0 lone pairs, 4 bonding pairs - tetrahedral

  3. •• •• O •• •• •• •• H C H •• •• •• •• •• •• O C O •• •• Organic Chemistry – Preparation - VSEPR • 0 lone pairs, 3 bonding pairs – trigonal planar • 0 lone pairs, 2 bonding pairs - linear

  4. C = O O — H Organic Chemistry - Preparation • Recall polarity of covalent bonds from Chemistry 20:2 particular polar bonds important in organic chemistry • C – H bonds are virtually non-polar

  5. Organic Chemistry – Preparation – Intermolecular Forces • London Dispersion Forces – all moleculars – temporary dipoles – affected by total # of e- and shape • Dipole-dipole Forces – polar moleculars • Hydrogen Bonding (H covalently bonded to F, O, or N) affect melting point, boiling point, and solubility

  6. Organic Chemistry – 14.1 - Introduction • Organic compounds – originally defined to be compounds from living or once-living organisms • Wohler, 1828, synthesized urea (an organic compound) from inorganic chemicals • Today organic compounds defined to be molecular compounds of carbon – exception: oxides of carbon – CO, CO2

  7. Organic Chemistry – 14.1 - Introduction • Most existing compounds are organic! • Special things about carbon that allow it to form so many different compounds: • 4 bonding electrons • ability to form single, double, triple bonds with itself • ability to bond with itself in many different configurations

  8. hydrocarbon derivativesC and H along with O, N, and/or halogen atoms hydrocarbons C and H only aliphatics without aromatics with alkenes – 1 double bond between C’s – CnH2n alkynes – 1 triple bond between C’s – CnH2n-2 alkanes – all single bonds – CnH2n+2 Organic Chemistry – 14.1 - Introduction • Classification: organiccompounds

  9. first 4 alkanes methane ethane propane butane Organic Chemistry – 14.2 - Hydrocarbons • Alkanes - saturated hydrocarbons • Termsaturated used because alkanes have the maximum number of hydrogens • General formula: CnH2n+2

  10. Organic Chemistry – 14.2 - Hydrocarbons • The unbranched alkanes are a homologous series because they differ by the number of CH2 units in each • Alkanes are tetrahedral around each carbon

  11. Organic Chemistry – 14.2 - Hydrocarbons • Since carbons and hydrogens can join up in so many ways, structural formulas are used • Different types of structural formulas: we won’t use this type 3 3 2 3

  12. Organic Chemistry – 14.2 – Hydrocarbons: Alkanes • Nomenclature of alkanes: • You must learn the following prefixes:

  13. Organic Chemistry – 14.2 – Hydrocarbons: Alkanes • Start naming by finding the longest continuous chain of carbon atoms. Name the long chain using its prefix with an ane ending. • Identify branches, and name using their prefix with a yl ending. • Number the longest continuous chain from the end closest to the branching and use the numbers like addresses for the branches.

  14. Organic Chemistry – 14.2 – Hydrocarbons: Alkanes • These rules will be introduced by the following examples • Several additional rules will be presented with the examples

  15. CH3 CH3 – CH – CH – CH2 – CH2 – CH3 CH2 - CH3 CH3 CH3 – CH – CH – CH2 – CH2 – CH3 Root name: hexane CH2 - CH3 Organic Chemistry – 14.2 – Hydrocarbons: Alkanes Example 1:

  16. CH3 CH3 – CH – CH – CH2 – CH2 – CH3 CH2 - CH3 1 2 3 4 5 6 number carbon chain to locate branches Organic Chemistry – 14.2 – Hydrocarbons: Alkanes Example 1: methyl CH3 CH3 – CH – CH – CH2 – CH2 – CH3 Root name: hexane CH2 - CH3 ethyl Identify side groups

  17. side group side group long chain position on long chain Organic Chemistry – 14.2 – Hydrocarbons: Alkanes • Compound name: 3-ethyl-2-methylhexane Additional rule: list side groups in alphabetical order

  18. CH3 CH3 – CH – CH – CH – CH3 CH3 CH3 CH3 CH3 CH3 CH3 – CH – CH – CH – CH3 CH3 – CH – CH – CH – CH3 CH3 – CH – CH – CH – CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 – CH – CH – CH – CH3 CH3 CH3 Organic Chemistry – 14.2 – Hydrocarbons: Alkanes Example: No matter how the long chain is selected, the name is the same: 2, 3, 4 - trimethylpentane Note the tri; use di, tri, tetra, etc, but don’t use them for alphabetical order

  19. CH2 – CH3 CH3 – CH2 – C – CH3 CH – CH3 CH2 – CH3 Organic Chemistry – 14.2 – Hydrocarbons: Alkanes • Example:

  20. Organic Chemistry – 14.2 – Hydrocarbons: Alkanes CH2 – CH3 CH3 – CH2 – C – CH3 CH – CH3 CH2 – CH3 3 – ethyl – 3, 4 – dimethylhexane or 4 – ethyl – 3, 4 - dimethylhexane Which one??? lowest set of numbers

  21. Organic Chemistry – 14.2 – Hydrocarbons: Alkanes • Doing the reverse process is actually easier – draw your long chain and attach the groups in the addressed spots • Start by drawing the long chain without any hydrogens – don’t worry about orientation • Add side groups in their addressed spots • Add hydrogens (each C gets 4 bonds) • Do alkane nomenclature worksheet

  22. Organic Chemistry – 14.2 – Hydrocarbons: Alkanes • Physical Properties of Alkanes: • All alkanes are non-polar, only intermolecular forces = London Dispersion Forces – boiling point and melting point increase with number of carbons (see chart page 551) KNOW all alkanes are insoluble in water

  23. Organic Chemistry – 14.2 – Hydrocarbons: Alkenes • Alkenes are hydrocarbons with 1 double bond • Notedienes and trienes also exist – we’ll focus on compounds with 1 double bond • Alkenes with 1 double bond have the general formula, CnH2n • Since they have 2 less hydrogens than corresponding alkanes, they’re called unsaturated hydrocarbons

  24. 3 3 3 Organic Chemistry – 14.2 – Hydrocarbons: Alkenes • Alkene formulas: • Alkenes are trigonal planar around the doubly bonded C’s and tetrahedral around the others we won’t use this type

  25. Organic Chemistry – 14.2 – Hydrocarbons: Alkenes • Nomenclature of alkenes: find longest continuous chain of carbons that contains the double bond – same prefixes as for alkanes add ene to the prefix along with a number to indicate the position of the double bond (for ethene and propene a position number is not needed) number the long chain from the end closest to the double bond (not the branching)

  26. CH3 – CH2 – CH2 – C = CH2 side-group CH2 position of double bond CH3 – CH2 – CH2 – C = CH2 CH3 CH2 CH3 position of side-group length of long chain containing double bond Organic Chemistry – 14.2 – Hydrocarbons: Alkenes • Example: 2 – ethylpent-1-ene

  27. Organic Chemistry – 14.2 – Hydrocarbons: Alkenes • Do questions 10 – 14 on pages 554-5

  28. Smaller # of electrons, weaker LDF lower boiling point Organic Chemistry – 14.2 – Hydrocarbons: Alkenes • Physical properties of alkenes: • Like alkanes, alkenes are non-polar and are insoluble in water • Boiling points are slightly lower than those for alkanes with the same number of carbonsWhy?

  29. Organic Chemistry – 14.2 – Hydrocarbons: Alkynes • Alkynes are unsaturated hydrocarbons with 1 triple bond • General formula CnH2n-2 • Alkynes are linear around the triply bonded carbons and tetrahedral around other carbons

  30. Organic Chemistry – 14.2 – Hydrocarbons: Alkynes • Alkynes are non-polar aliphatic hydrocarbons like alkanes and alkenes • They are insoluble in water

  31. Organic Chemistry – 14.2 – Hydrocarbons: Alkynes • Note that alkynes have higher boiling points than alkanes or alkenes • Obviously the explanation used for alkenes being lower than alkanes doesn’t apply here Table 14.5, page 557

  32. Organic Chemistry – 14.2 – Hydrocarbons: Alkynes • Accepted explanation is that for short chain alkynes, the linear structure around triple bond allows them to come closer together than alkanes or alkenes with same number of carbons, causing stronger London Dispersion Forces

  33. Organic Chemistry – 14.2 – Hydrocarbons: Alkynes • Nomenclature of alkynes is identical to that of alkenes, the only exception is the ending: yne, not ene • Do Practice Problems 16 and 17 on pages 556 and 557

  34. Organic Chemistry – 14.2 – Hydrocarbons: Cyclics • Cyclic analogues exist for alkanes, alkenes, and alkynes • General formulas will contain 2 less hydrogens than the open chain hydrocarbons: cycloalkanes CnH2n, cycloalkenes CnH2n-2, cycloalkynes CnH2n-4 • Small cycloalkynes don’t exist because of the large bond strain that would exist around the linear triple bond

  35. CH2 cyclobutene: cyclopropane: CH2 CH2 CH2 CH not not CH2 CH Organic Chemistry – 14.2 – Hydrocarbons: Cyclics • Line structures are commonly used for the ring part of cyclic hydrocarbons • Always draw them this way • Examples:

  36. Organic Chemistry – 14.2 – Hydrocarbons: Cyclics • Cyclics will always have names ending with cyclo_____ane or cyclo_____ene • Don’t worry about cyclo_____ynes, you will not encounter them, except my favourite one, • Consider the following examples to learn how to do the nomenclature for substituted cyclics Name? stopsyne! STOP

  37. ethylcyclopentane CH2 – CH3 No numbers needed. Why? CH2 – CH3 CH2 – CH3 CH3 Organic Chemistry – 14.2 – Hydrocarbons: Cyclics Always start at far side of double bond and number clockwise or counter-clockwise towards group 3-ethylcyclopentene As above. This one must be numbered counter-clockwise to give lowest set of numbers, even though 1st group gets a higher number 4-ethyl-3-methlycyclopentene

  38. CH2 – CH3 CH3 This time the numbering is clockwise since double bond isn’t a factor and when possible lowest number goes on first group 1-ethyl-2-methylcyclopentane Organic Chemistry – 14.2 – Hydrocarbons: Cyclics Do Practice Problems 18 – 23 page 559 and 560 Do Aliphatics Review WS Quiz coming up!

  39. Organic Chemistry – 14.1 - Introduction hydrocarbon derivativesC and H along with O, N, and/or halogen atoms hydrocarbons C and H only aliphatics without aromatics with alkenes – 1 double bond between C’s – CnH2n alkynes – 1 triple bond between C’s – CnH2n-2 alkanes – all single bonds – CnH2n+2 organiccompounds finished with aliphatics; aromatics today Classification:

  40. Organic Chemistry – 14.2 – Hydrocarbons: Aromatics • Aromatics: all contain the grouping • Originally this grouping thought to be: • Problems:• all bonds found to be equal length • this compound should be very reactive but is actually very stable or

  41. Organic Chemistry – 14.2 – Hydrocarbons: Aromatics • Today we believe it to be made up of bonds that are neither single nor double but a hybrid of both • We draw the structure • Its name is benzene • Benzene is the root common to all aromatics

  42. Where numbering starts Organic Chemistry – 14.2 – Hydrocarbons: Aromatics • Nomenclature of Aromatics:page 561

  43. CH3 CH2 – CH2 – CH3 CH2 – CH3 CH3 – CH – CH3 Organic Chemistry – 14.2 – Hydrocarbons: Aromatics • Examples: propylbenzene 1-ethyl-3-methylbenzene 2-phenylpropane

  44. Organic Chemistry – 14.2 – Hydrocarbons: Aromatics • Do Practice Problems 24 – 27, page 562 • Aromatics WS

  45. Organic Chemistry – 14.2 – Hydrocarbons: Aromatics

  46. organiccompounds hydrocarbon derivativesC and H along with O, N, and/or halogen atoms hydrocarbons C and H only alcoholsR-OH carboxylic acids R-C-OH aliphatics without esters R1 – C – O – R2 aromatics with O = akyl halidesR-X O = alkenes – 1 double bond between C’s – CnH2n alkynes – 1 triple bond between C’s – CnH2n-2 alkanes – all single bonds – CnH2n+2 Organic Chemistry – 14.3 – Hydrocarbon Derivatives

  47. Organic Chemistry – 14.3 – Hydrocarbon Derivatives • Hydrocarbon derivatives contain other elements besides C and H; most commonly O, N, or halogen atom • Functional group: group of atoms that gives the compound its characteristic properties

  48. 3 3 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alcohols • Alcohols – functional group:“-OH” hydroxyl group • Common alcohols: table 14.7, page 566

  49. Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alcohols • Nomenclature of alcohols • Key points – long chain must have “–OH” attached to it • Numbering of the long chain starts from the end closest to “-OH” • Ending of root is ol

  50. CH3 – CH2 – CH2 CH3 – CH – CH2 – CH2 – OH position of OH side group CH3 – CH2 – CH2 CH3 – CH – CH2 – CH2 – OH position of side group length of longchain containing OH* Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alcohols Example 3-methylhexan-1-ol * don’t count OH in length of chain

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