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Chemistry 30 – Organic Chemistry – Part 1 To accompany Inquiry into Chemistry PowerPoint Presentation prepared by Robert Schultz

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Presentation on theme: "Chemistry 30 – Organic Chemistry – Part 1 To accompany Inquiry into Chemistry PowerPoint Presentation prepared by Robert Schultz"— Presentation transcript:

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 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 H C H H H

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

4 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 O — H C = O

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, CO 2

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

9 Organic Chemistry – 14.2 - Hydrocarbons Alkanes - saturated hydrocarbons Term saturated used because alkanes have the maximum number of hydrogens General formula: C n H 2n+2 butane first 4 alkanes methaneethane propane

10 Organic Chemistry – 14.2 - Hydrocarbons The unbranched alkanes are a homologous series because they differ by the number of CH 2 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: 3 3 3 2 we won’t use this type

12 Organic Chemistry – 14.2 – Hydrocarbons: Alkanes Nomenclature of alkanes: You must learn the following prefixes: # of C’sprefix 1meth 2eth 3prop 4but 5pent 6hex 7hept 8oct 9non 10dec

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 Organic Chemistry – 14.2 – Hydrocarbons: Alkanes Example 1: CH 3 – CH – CH – CH 2 – CH 2 – CH 3 CH 3 CH 2 - CH 3 CH 3 – CH – CH – CH 2 – CH 2 – CH 3 Root name: hexane CH 3 CH 2 - CH 3

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

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

18 Organic Chemistry – 14.2 – Hydrocarbons: Alkanes CH 3 – CH – CH – CH – CH 3 CH 3 CH 3 – CH – CH – CH – CH 3 CH 3 CH 3 – CH – CH – CH – CH 3 CH 3 CH 3 – CH – CH – CH – CH 3 CH 3 CH 3 – CH – CH – CH – CH 3 CH 3 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 Organic Chemistry – 14.2 – Hydrocarbons: Alkanes Example: CH 3 – CH 2 – C – CH 3 CH 2 – CH 3 CH – CH 3 CH 2 – CH 3

20 Organic Chemistry – 14.2 – Hydrocarbons: Alkanes CH 3 – CH 2 – C – CH 3 CH 2 – CH 3 CH – CH 3 CH 2 – CH 3 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 Note dienes and trienes also exist – we’ll focus on compounds with 1 double bond Alkenes with 1 double bond have the general formula, C n H 2n Since they have 2 less hydrogens than corresponding alkanes, they’re called unsaturated hydrocarbons

24 Organic Chemistry – 14.2 – Hydrocarbons: Alkenes Alkene formulas: Alkenes are trigonal planar around the doubly bonded C’s and tetrahedral around the others 3 3 3 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 Organic Chemistry – 14.2 – Hydrocarbons: Alkenes Example: CH 3 – CH 2 – CH 2 – C = CH 2 CH 2 CH 3 CH 3 – CH 2 – CH 2 – C = CH 2 CH 2 CH 3 2 – ethylpent-1-ene length of long chain containing double bond side- group position of side- group position of double bond

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

28 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 carbons Why? Smaller # of electrons, weaker LDF lower boiling point

29 Organic Chemistry – 14.2 – Hydrocarbons: Alkynes Alkynes are unsaturated hydrocarbons with 1 triple bond General formula C n H 2n-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 C n H 2n, cycloalkenes C n H 2n-2, cycloalkynes C n H 2n-4 Small cycloalkynes don’t exist because of the large bond strain that would exist around the linear triple bond

35 Organic Chemistry – 14.2 – Hydrocarbons: Cyclics Line structures are commonly used for the ring part of cyclic hydrocarbons Always draw them this way Examples: CH 2 cyclopropane: not CH 2 CH not cyclobutene:

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 Organic Chemistry – 14.2 – Hydrocarbons: Cyclics CH 2 – CH 3 ethylcyclopentane No numbers needed. Why? CH 2 – CH 3 3-ethylcyclopentene Always start at far side of double bond and number clockwise or counter- clockwise towards group CH 2 – CH 3 CH 3 4-ethyl-3-methlycyclopentene As above. This one must be numbered counter-clockwise to give lowest set of numbers, even though 1 st group gets a higher number

38 Organic Chemistry – 14.2 – Hydrocarbons: Cyclics CH 2 – CH 3 CH 3 1-ethyl-2-methylcyclopentane This time the numbering is clockwise since double bond isn’t a factor and when possible lowest number goes on first group Do Practice Problems 18 – 23 page 559 and 560 Do Aliphatics Review WS Quiz coming up!

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

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

43 Organic Chemistry – 14.2 – Hydrocarbons: Aromatics Examples: CH 3 CH 2 – CH 3 CH 2 – CH 2 – CH 3 CH 3 – CH – CH 3 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 Organic Chemistry – 14.3 – Hydrocarbon Derivatives hydrocarbon derivatives C and H along with O, N, and/or halogen atoms alkanes – all single bonds – C n H 2n+2 organic compounds hydrocarbons C and H only aliphatics without aromatics with alkynes – 1 triple bond between C’s – C n H 2n-2 alkenes – 1 double bond between C’s – C n H 2n alcohols R-OH akyl halides R-X carboxylic acids R-C-OH = O esters R 1 – C – O – R 2 = O

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

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 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alcohols CH 3 – CH 2 – CH 2 CH 3 – CH – CH 2 – CH 2 – OH CH 3 – CH 2 – CH 2 CH 3 – CH – CH 2 – CH 2 – OH 3-methylhexan-1-ol side group position of side group position of OH length of long chain containing OH* * don’t count OH in length of chain Example

51 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alcohols Example CH 2 – CH – CH 2 OH CH 2 – CH – CH 2 OH propane - 1, 2, 3 - triol length of long chain containing OH’s position of OH’s number of OH’s common name of this compound: glycerol Advantages to above name??

52 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alcohols Do Practice Problems 28 – 30 on page 567 Omit 28d, 29c, 30a

53 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alcohols Physical properties of alcohols Because of the hydrogen bonding between OH groups in adjacent molecules, alcohols have much higher boiling points than hydrocarbons (1-12 C’s are liquids at SATP) small alcohols are totally miscible with water, but ……………

54 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alkyl Halides Alkyl halides contain at least 1 halogen atom, (F, Cl, Br, I) Alkyl halides are all synthetic compounds CFC’s (chlorofluorocarbons) are alkyl halides

55 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alkyl Halides Nomenclature of alkyl halides: long chain must be attached to halogen atom(s) identical to nomenclature of hydrocarbons side groups end in o, not yl – fluoro, chloro, bromo, iodo

56 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alkyl Halides Example: CH 3 – CH 2 – CH – CH – CH – CH 3 Br Cl Br CH 3 – CH 2 – CH – CH – CH – CH 3 Br Cl Br 2, 4 – dibromo – 3 - chlorohexane

57 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alkyl Halides Do Practice Problems 31, 32, page 569 Do Alcohols/Alkyl Halides Nomenclature WS Br Cl 1,4 – dibromo – 2 - chlorocyclohexane

58 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Carboxylic Acids Carboxylic acids are weak organic acids containing the carboxyl functional group, often written –COOH When carboxylic acids, ionize, the process is: - C – OH, = O R - C – OH, = O R - C – OH(aq) = O R - C – O - (aq) = O H + (aq) + 

59 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Carboxylic Acids Common carboxylic acids, acetic acid (active ingredient of vinegar) and citric acid Nomenclature of carboxylic acids: In all carboxylic acids the carboxyl group is at one end of the molecule It is always carbon #1 in the chain

60 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Carboxylic Acids Example: CH 3 – C – CH 2 – CH 2 – C – OH = O CH 2 CH 3 CH 3 – C – CH 2 – CH 2 – C – OH = O CH 2 CH 3 4, 4 – dimethylhexanoic acid note that the carboxyl carbon does get counted in the long chain – it is carbon #1

61 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Carboxylic Acids Do Practice Problems 33 – 35, page 570

62 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Carboxylic Acids Physical properties of carboxylic acids: Like alcohols they have hydrogen bonding, but hydrogen bonding at 2 sites, -C=O and –OH This leads to higher boiling points and greater solubility than alcohols with same number of C’s Carboxylic acids with 1-4 C’s are completely miscible in water

63 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Esters Esters have the general formula: often written RCOOR′ Esters are formed from the reaction of an alcohol and a carboxylic acid; the formation or esterification reaction is the key to naming them R(or H) - C – O – R ′ = O

64 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Esters R - C – O - H = O + H - O - R′ R - C – O - R′ = O + HOH carboxylic acid alcohol ester water It’s important that when you look at ester, that you’re able to recognize part that came from alcohol and part that came from acid Acid part contains C; alcohol part is bonded directly to O O =

65 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Esters General form of name: _______yl _________oate from alcohol from acid

66 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Esters Examples: CH 3 – CH 2 – C – O – CH 3 = O alcohol part: methyl acid part: propanoate methyl propanoate CH 3 – CH 2 – CH 2 – CH 2 – O – C – H = O alcohol part: butyl acid part: methanoate butyl methanoate

67 Organic Chemistry – 14.4 – Refining and Using Organic Compounds Do questions 37 and 38 page 572

68 Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Esters Physical properties of esters: fruity odour in some cases polar but lack of OH bond means no hydrogen bonding, so lower boiling points than alcohols and carboxylic acids esters with few carbons are polar enough to be soluble in water

69 Organic Chemistry – 14.3 – Hydrocarbon Derivatives Structural isomers: compounds with same molecular formula but different structural formulas

70 Organic Chemistry – 14.4 – Refining and Using Organic Compounds Petroleum: mixture of hydrocarbons (primarily alkanes and alkenes) found in natural gas, crude oil, and bitumen (from tar sands) Petrochemicals: hydrocarbon materials from petroleum used to produce plastics and other synthetic materials

71 Organic Chemistry – 14.4 – Refining and Using Organic Compounds Fractional distillation: a means of separating petroleum components based on differing boiling points

72 Organic Chemistry – 14.4 – Refining and Using Organic Compounds Read and discuss page 578 regarding fractional distillation Fractional distillation is a physical process; mixture is separated into fragments with a small range of boiling points – there is no chemical change in the fractions

73 Organic Chemistry – 14.4 – Refining and Using Organic Compounds Next stages of petroleum refining are chemical processes: cracking – breaks carbon-carbon bonds reforming – forms carbon-carbon bonds alkylation (special case of reforming) forms 2,2,4-trimethylpentane from smaller hydrocarbons Both of these can be divided into many subgroups Read page 579-80 and page 581

74 Organic Chemistry – 14.4 – Refining and Using Organic Compounds

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