Unit 3 Organic Chemistry. Chemistry 2202

Transcription

1 Unit 3 Organic hemistry hemistry 2202

2 Introduction Organic hemistry is the study of the molecular compounds of carbon. eg. 4 3 O 3 N 2 Organic compounds exclude oxides of carbon and ions containing carbon. ie. O O 2 KN ao 3 are NOT organic compounds!!

3 istory of Organic hemistry Started when medicine men extracted chemicals from plants and animals as treatments and cures First defined as a branch of modern science in the early 1800's by Jon Jacob Berzelius

4 Berzelius believed in Vitalism - organic compounds could only originate from living organisms through the action of some vital force organic compounds originate in living or once-living matter inorganic compounds come from "mineral" or non-living matter

5 In 1828, Friedrich Wöhler discovered that urea - an organic compound - could be made by heating ammonium cyanate (an inorganic compound). N 4 ON (aq) (N 2 ) 2 O (s) inorganic organic

6 What s this? (N2) 2O - (N2) 2 O di-urea

7 organic chemistry branched into disciplines such as polymer chemistry, pharmacology, bioengineering and petrochemistry 98% of all known compounds are organic

8 The huge number of organic compounds is due mainly to the ability of carbon atoms to form stable chains, branched chains, rings, branched rings, multiple rings, and multiple bonds (double and triple bonds) to itself and to many other non-metal atoms.

9 Sources of Organic ompounds 1. arbonized Organic Matter - fossil fuels such as coal, oil, and natural gas - basis for the petrochemical industry 2. Living Organisms eg: - penicillin from mold - acetylsalicylic acid (Aspirin) from the bark of a willow tree

10 3. Invention - antibiotics, aspirin, insulin, vanilla flavoring, and heart drugs are manufactured from organic starting materials - plastics

11 Structural Isomers Structures that have the same molecular formula, but different structural formulas are called structural isomers eg Practice: Draw all structural isomers of 5 12 and 6 14

12 2 butane methylpropane

13 They have the same molecular formula ( 4 10 ), but different structural formulas. They are isomers and are different compounds and have different properties such as boiling point.

14 Structural Isomers structural isomers have the same chemical formula but have different chemical and physical properties.

15 lassifying Organic ompounds ydrocarbons Organic ompounds ydrocarbon Derivatives Aliphatic AlkAnes AlkEnes AlkYnes Aromatic (benzene based) Alcohols Ethers Aldehydes Ketones arboxylic Acids Alkyl alides Esters Amines Amides

16 hydrocarbons consist of carbon and hydrogen atoms only eg. Methane - 4 hydrocarbon derivatives have one or more hydrogen atoms replaced by another nonmetallic atom eg. bromomethane - Br 3 methanol - O 3

17 aliphatic hydrocarbons have carbon atoms bonded in chains or rings with only single, double, or triple bonds aromatic hydrocarbons contain at least one 6 carbon benzene ring

18 Organic Worksheet #1

19 Aliphatic ydrocarbons 1. Alkanes Alkanes are hydrocarbons that have only single bonds between carbon atoms general formula n 2n+2 eg

20 IUPA prefixes Prefix # of carbon atoms meth 1 eth 2 prop 3 but 4 pent 5 hex 6 hept 7 oct 8 non 9 dec 10

21 omplete this table for the first 10 alkanes methane 4 ethane propane

22 methane 4 ethane 2 6 propane 3 8 butane 4 10 pentane 5 12 hexane 6 14 heptane 7 16 octane 8 18 nonane 9 20 decane 10 22

23 A series of compounds which differ by the same structural unit is called a homologous series eg. each alkane increases by 2 What is the next member of this homologous series? SiO Si O Si O

24 Representing Alkanes (4 ways) 1. Structural formulas eg. propane

25 ydrogen atoms may be omitted from structural formulas eg. propane

26 2. ondensed Structural Formula eg. propane

27 3. Line Structural Diagrams eg: propane (the endpoint of each segment is a carbon atom)

28 4. Expanded Molecular Formulas eg. propane 3 2 3

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30 Alkyl Groups An alkyl group has one less hydrogen than an alkane. General Formula: n 2n + 1 To name an alkyl group, use the prefix to indicate the # of carbon atoms followed by the suffix yl eg. - heptyl 7 15

31 Alkyl Groups methyl - 3 ethyl or propyl or

32 Alkyl Groups Branched alkanes are alkanes that contain one or more alkyl groups eg. 2,4 - dimethylpentane

33 Naming Branched Alkanes 1. Find the longest continuous chain (L) of carbons(parent chain) and give it the alkane name. 2. Number the carbons in the parent chain starting from the end closest to branching. These numbers will indicate the location of alkyl groups.

34 Naming Branched Alkanes 3. List the alkyl groups in alphabetical order. Use Latin prefixes if an alkyl group occurs more than once. (di = 2, tri = 3, tetra = 4, etc. don't count for alphabetical order) 4. Use a number to show the location of each alkyl group on the parent.

35 Naming Branched Alkanes 5. Use commas to separate numbers, and hyphens to separate numbers and letters.

36 Naming Branched Alkanes eg. 4-ethyl-3-methylheptane

37 Naming Branched Alkanes eg. ethyl ethyl-3-methylheptane methyl

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39 ,3,6,6-tetramethyloctane

40 Naming Branched Alkanes Practice: p # s 5 11 (Answers on p. 375)

41 Parent chain: Octane 2-methyl 4,6-diethyl 2 3 4,6-diethyl-2-methyloctane

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43 7-ethyl-3,4,5-trimethyldecane 3-ethyl-2,3-dimethyl-4-propylheptane 2-methyl-4,5-dipropyloctane

44 3-ethyl-2,2-dimethylhexane 3 ethyl 5 methyl 4,4 - dipropylnonane

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46 Organic Worksheet #2

47 Alkenes and Alkynes saturated hydrocarbons contain only single bonds between carbon atoms eg. alkanes saturated hydrocarbons have the maximum number of hydrogen atoms bonded to carbon atoms

48 Alkenes and Alkynes unsaturated hydrocarbons contain double or triple bonds between carbon atoms eg. alkenes and alkynes

49 Alkenes and Alkynes General Formulas: Alkenes n 2n At least one double bond Alkynes n 2n - 2 At least one triple bond

50 Naming Alkenes and Alkynes 1. Name the longest continuous chain that contains the double/triple bond. 2. Use the smallest possible number to indicate the position of the double or triple bond.

51 Naming Alkenes and Alkynes 3. Branches are named using the same rules for alkanes. 4. Number the branches starting at the same end used to number the multiple bond.

52 For you to do!! Pg. 347 #'s: 17, 18, 19 Worksheet #3: Alkenes and alkynes

53 yclic ydrocarbons ycloalkanes and cycloalkenes

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59 3-ethyl-1-methylcyclopentane 1-ethyl-3-methylcyclopentane cyclopentane ethyl methy l

60 methyl 1,2,3,4-tetramethylcyclohexane

61 Practice Pg Pg. 358 #'s: Worksheet #4

62 Aromatic ompounds Aromatic hydrocarbons contain at least one benzene ring. The formula for benzene, 6 6, was determined by Michael Faraday in The structural formula was determined by August Kekulé in 1865.

63 Aromatic ompounds Proposed formula:

64 onflicting Evidence = double bonds are shorter than - single bonds. X-ray crystallography shows that all - bonds in benzene are the same length. Benzene reacts like an alkane, not like an alkene.

65 Modified structure Kekulé proposed a resonance structure for benzene. The resonance structure is an average of the electron distributions.

66 Aromatic ompounds or 6 electrons shared 6 carbon atoms

67 Aromatic ompounds bonding electrons, once believed to be in double bonds, are delocalized and shared equally over the 6 carbon atoms the bonds in benzene are like 1½ bonds somewhere between single and double.

68 Naming Aromatic ompounds an alkyl benzene has one or more atoms replaced by an alkyl group. name the alkyl groups, using numbers where necessary, followed by the word benzene.

69 Aromatic ompounds methylbenzene ethylbenzene propylbenzene

70 Aromatic ompounds 1,3-dimethylbenzene 1,4-dimethylbenzene 1,2-dimethylbenzene

71 Aromatic ompounds ortho- means positions 1 and 2 and is represented by "o" meta- means positions 1 and 3 and is represented by "m" para- means positions 1 and 4 and is represented by "p"

72 Aromatic ompounds m-dimethylbenzene p-dimethylbenzene o-dimethylbenzene

73 Aromatic ompounds Benzene is treated as a branch if it is not attached to the terminal carbon of an alkyl group Benzene as a branch is called phenyl

74 Aromatic ompounds propylbenzene 2-phenylpropane

75 Aromatic ompounds ethyl 2 phenylhexane

76 Aromatic ompounds Pg. 361 # s 32 35

77 Geometric Isomers ompounds with the same molecular formula, but different geometry of bonds Two types of shapes is and Trans isomers is groups on the same side of the double bond Trans groups on different sides of the double bond is/trans written as part of the name Ex: cis-2-butene or trans-2-butene

78 cis and trans isomers (p. 348)

79 cis and trans isomers (p. 348)

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81 Properties of aliphatic hydrocarbons Because they are nonpolar, all hydrocarbons are insoluble in polar water. The boiling/melting point of alkanes is somewhat higher than alkenes but lower than alkynes. As the number of atoms in the hydrocarbon molecule increases, the boiling/melting point increases.

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84 ydrocarbon Production rude oil is a mixture of hydrocarbons. ydrocarbons are extracted from the ground at well sites, then processed at refineries. Fractional Distillation is a process used to separate petroleum into its hydrocarbon components. This process relies on the different boiling points of each hydrocarbon.

85 substances with the highest boiling points condense closer to the bottom

86 ydrocarbon Derivatives ydrocarbon Derivatives contain other nonmetal atoms such as O, N, or halogen atoms. 9 types of derivatives: (See p ethers and organic halides) the reactive group of atoms that gives a family of derivatives its distinct properties is a functional group

87 ydrocarbon Derivatives The general formula for a derivative is R - functional group where R stands for any alkyl group.

88 ydrocarbon Derivatives eg. ALOOLS R-O ethanol 2 5 O propanol 3 7 O ARBOXYLI AIDS R-OO ethanoic acid 3 OO propanoic acid 2 5 OO

89 1. Alcohols ave the hydroxyl functional group General Formula: R - O

90 Naming Alcohols (p. 387) The parent alkane is the longest chain that has an -O group Replace the last -e in the alkane name with the suffix -ol. Add a number (smallest one) to indicate the location of the -O group.

91 O methanol O ethanol

92 eg. O propanol O 2-propanol

93 2-methyl-2-butanol

94 Properties of Alcohols (p. 389) Alcohols have -bonding which makes their mp and bp higher than the corresponding alkane. Polarity decreases as the # of carbon atoms increases Long chain alcohols are less soluble in water than short chain alcohols.

95 Reactions of alcohols ombustion R-O + O 2 O O eg. Write the equation for the burning of butanol.

96 Reactions of alcohols Substitution R-O + -X R-X + 2 O eg. Use structural formulas to show the reaction between 2-pentanol and Br.

97 Reactions of alcohols Elimination (Dehydration) eg. 2 SO 4 O + 2 O

98 General Formula: R1 -O-R 2 2. Ethers omposed of two alkyl groups bonded to an oxygen atom. Naming ethers: p. 395 IUPA name ommon name

99 O 1-methoxyethane or ethyl methyl ether O 1-propoxybutane or butyl propyl ether

100 O 1-ethoxyethane or diethy ether P. 395, 396 # s Worksheet: Ethers

101 3. Aldehydes (p. 402) ontain a carbonyl functional group at the end of a carbon chain. General Formula: = O R-

102 Naming: Use the alkane name for the longest continuous chain. Remove the e and add the suffix al eg. O butane butanal

103 2,3 - dimethylpentanal 3 ethyl 3 - methylhexanal

104 4. Ketones (p. 402) ontain a carbonyl functional group in the middle of a carbon chain. ie. NOT on carbon #1 General Formula: =O R R 2

105 Naming: Use the alkane name for the longest continuous chain. Replace the e with the suffix one Use the smallest possible number for the position of the =O group.

106 O 2 butanone & 2 - pentanone O

107 3 fluoro 4 methyl 2 - hexanone

108 5. arboxylic Acids (p. 405) ontain a carboxyl functional group ie. -OO General Formula: =O R O

109 The of OO is always #1 Find longest chain with OO Drop the e of alkane name and replace with oic acid Don't need to use 1 in naming for OO place Branching is same as always 3 ethyl 3 methylpentanoic acid

110 O O Propanoic acid O O Butanoic acid

111 6. Alkyl alides (p. 390, 391) ontain at least one halogen atom General Formula: R X (X is F, l, Br, or I)

112 Naming alkyl halides is the same as naming all other pure hydrocarbons except now there are halogen atoms involved. The ine of the halogens are dropped for o Bromine --> Bromo; chlorine --> chloro 2,4 dichloro 1 - methylcyclohexane 4 fluoro 2 - pentene

113 Br Br Br 2,2,3 tribromobutane & 1,2,3,4 tetrabromo 4 - chloropentane l Br Br Br Br

114 Br Br Br l Br Br Br Br