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CHAPTER 8 INTRODUCTION TO ORGANIC CHEMISTRY BASIC CHEMISTRY CHM 138.

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Presentation on theme: "CHAPTER 8 INTRODUCTION TO ORGANIC CHEMISTRY BASIC CHEMISTRY CHM 138."— Presentation transcript:

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2 CHAPTER 8 INTRODUCTION TO ORGANIC CHEMISTRY BASIC CHEMISTRY CHM 138

3 Organic chemistry: -The branch of chemistry that deals with carbons compounds. Organic – derived from living organisms Study of compounds extracted from living organisms and their natural products. Examples: sugar, starch, urea, waxes, carbohydrates, fats and etc Human are composed of organic molecules – proteins in skin, lipid in cell membranes, glycogen in livers and the DNA in the nuclei of cells. ORGANIC CHEMISTRY

4 Chemistry of carbon: - Two stable isotops ( 13 C and 12 C) - electron configuration: 1s 2 2s 2 2p 2 - four valence electrons - can form more compounds than any other element - able to form single, double and triple carbon- carbon bonds, and to link up with each other in chains and ring structures

5 HOMOLOGUE SERIES AND FUNCTIONAL GROUPS Functional group: A group of atoms that is largely responsible for the chemical behavior of the parent molecule. Functional groups: - hydrocarbons - alcohols - aldehydes - ketones - carboxylic acids - alkyl halides

6 HYDROCARBONS Made up of only hydrogen and carbon

7 ALKANES General formula: C n H 2n+2, where n = 1, 2, …. Only single covalent bonds are present Known as saturated hydrocarbons because contain the maximum number of hydrogen atoms that can bond with the number of carbon atoms present. Can be assumed to be sp 3 -hydridized

8 Structures of the first four alkanes

9 The melting and boiling points of the straight-chain isomers of the first 10 alkanes

10 Homologous Series 1. Definition: A series of compounds in which each member differs from the next by a specific number and kind of atoms. 2. Alkanes: Differ only at number of (CH 2 ) 3. Series of compounds that has the same functional group.

11 INITIAL NAMES OF THE HOMOLOGOUS SERIES Number of carbon atoms, nName 1Meth 2Eth 3Prop 4But 5Pent 6Hex 7Hept 8Oct 9Non 10Dec

12 The general formula of an alkyl group is C n H 2n+1. Alkyl groups are used to name organic compounds. NAMING ALKANES R= C n H 2n+1 (any alkyl group) R = CH 3 methyl group R = CH 3 CH 2 ethyl group The letter R is often used in formulas to represent any of the possible alkyl groups.

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14 IUPAC RULES International Union of Pure and Applied Chemistry Consider all alkyl groups attached to it as branch chains or substituents that have replaced hydrogen atoms of the parent hydrocarbon. If two chains of equal length are found, use the chain that has the larger number of substituents attached to it. The alkanes name consists of the parent compounds name prefixed by the names of the alkyl groups attached to it. RULE 1. Select the longest continuous chain of carbon atoms as the parent compound.

15 This structure has 2 chains. This chain has 6 carbon atoms This chain has 4 carbon atoms

16 This is the longest continuous chain. Select this chain as the parent compound

17 It is a branch chain and can be considered to have replaced a hydrogen on the parent compound This is a methyl group.

18 The name of the compound is 3-methylhexane. 3 3

19 IUPAC RULES If the first subsitutent from each end is on the same- numbered carbon, go to the next substituent to determine which end of the the chain to start numbering. RULE 2. Number the carbon atoms in the parent carbon chain starting from the end closest to the first carbon atom that has an alkyl group substituted for a hydrogen atom.

20 If the chain is numbered left to right, the isopropyl group is on carbon 5. isopropyl group

21 If the chain is numbered right to left, the isopropyl group is on carbon 4. isopropyl group Use right to left numbering so that the isopropyl group is on the lowest numbered carbon. 4-isopropyloctane

22 IUPAC RULES RULE 3. Name each alkyl group and designate its position on the parent carbon chain by a number (e.g., 2-methyl means group attached to C-2) isopropyl pentane

23 2,3-dimethylpentane The methyl group appears twice RULE 4. When the same alkyl-group branch chain appears more than once, indicate this repetition by a prefix (di-, tri-, tetra- and so forth) written in front of the alkyl group name (e.g. dimethyl indicates two methyl groups). –The numbers indicating the alkyl-group positions are separated by a command and followed by a hyphen and are placed in front of the name (e.g., 2,3-dimethyl).

24 RULE 5. When several different alkyl groups are attached to the parent compound, list them in alphabetical order (e.g. ethyl before methyl in 3-ethyl-4-methyloctane). Prefixes are not included in alphabetical ordering (ethyl comes before dimethyl).

25 methyl ethyl ethyl-4-methyloctane

26 Alkanes can have many different types of substituents. For example:

27 CYCLIC HYDROCARBONS A hydrocarbon that contains carbon atoms joined to form a ring. Cycloalkanes – all carbons of the ring are saturated

28 NOMENCLATURE OF CYCLOALKANES Similar to that alkanes. For examples:

29 ISOMERISATION Structural isomers: - Molecules that have the same molecular formula, but different structure Three isomers of pentane (C 5 H 12 )

30 STRUCTURE ISOMERS FOR ALKANES NAMEMOLECULAR FORMULA TOTAL OF ISOMERS MethaneCH 4 1 EthaneC2H6C2H6 1 PropaneC3H8C3H8 1 ButaneC 4 H 10 2 PentaneC 5 H 12 3 HexaneC 6 H 14 5 HeptaneC 7 H 16 9 OctaneC 8 H NonaneC 9 H DecaneC 10 H 22 75

31 ALKENES Also called olefins Contain at least one carbon-carbon double bond (C=C) General formula, C n H 2n (n=2,3,…) Classified as unsaturated hydrocarbons (compound with double or triple carbon-carbon bonds that enable them to add hydrogen atoms. sp 2 -hybridized For example: C 2 H 4 - ethylene

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33 ALKYNES Alkynes contain at least carbon-carbon triple bond. General formula: C n H 2n-2, where n = 2, 3,…. Alkyne nomenclature: - Used suffix –yne - Same as alkene nomenclature

34 Naming Alkenes and Alkynes

35 IUPAC RULES RULE 1. Select the longest continuous carbon chain that contains a double or triple bond. This chain contains 6 carbon atoms

36 RULE 2. Name this compound as you would an alkane, but change –ane to –ene for an alkene and to –yne for an alkyne. This chain contains 8 carbon atoms This is the longest continuous chain. Select it as the parent compound. Name the parent compound octene.

37 This chain contains a triple bond. Name the parent compound octyne. RULE 2. Name this compound as you would an alkane, but change –ane to –ene for an alkene and to –yne for an alkyne.

38 RULE 3. Number the carbon chain of the parent compound starting with the end nearer to the double or triple bond. Use the smaller of the two numbers on the double- or triple-bonded carbon to indicate the position of the double or triple bond. Place this number in front of the alkene or alkyne name.

39 IUPAC RULES This end of the chain is closest to the double bond. Begin numbering here.

40 The name of the parent compound is 1-octene. IUPAC RULES

41 The name of the parent compound is 1-octyne. IUPAC RULES

42 RULE 4. Branched chains and other groups are treated as in naming alkanes. Name the substituent group, and designate its position on the parent chain with a number.

43 IUPAC RULES This is an ethyl group The ethyl group is attached to carbon ethyl-1-octene

44 IUPAC RULES The ethyl group is attached to carbon ethyl-1-octyne

45 must specify whether the molecule is cis or trans (geometric isomer) cis – two particular atoms (or groups of atoms) are adjacent to each other trans – the two atoms (or groups of atoms) are across from each other

46 CYCLOALKENES Contains C=C in the ring Nomenclature of cycloalkenes: - Similar to that alkenes - Carbons atoms in the double bond are designated C1 and C2

47 AROMATIC HYDROCARBONS Contain one or more benzene rings Benzene Kekulé Structure 3 double bonds 6 carbons in a ring

48 The corner of each hexagon represents a carbon and a hydrogen atom. The structure of benzene can be represented in two abbreviated ways.

49 Naming Aromatic Compounds

50 A substituted benzene is derived by replacing one or more of benzenes hydrogen atoms with an atom or group of atoms. A monosubstituted benzene has the formula C 6 H 5 G where G is the group that replaces a hydrogen atom. All hydrogens in benzene are equivalent. It does not matter which hydrogen is replaced by G.

51 Monosubstituted Benzenes

52 Some monosubstituted benzenes are named by adding the name of the substituent group as a prefix to the word benzene. The name is written as one word. nitrobenzene nitro group ethylbenzene ethyl group

53 Certain monosubstituted benzenes have special names. These are parent names for further substituted compounds. methyl group toluene hydroxy group phenol

54 carboxyl group benzoic acid aniline amino group

55 C 6 H 5 is the phenyl group. It is used to name compounds that cannot be easily named as benzene derivatives. diphenylmethane 4-phenyl-2-pentene

56 Disubstituted Benzenes

57 Three isomers are possible when two substituents replace hydrogen in a benzene molecule. The prefixes ortho-, meta- and para- (o-, m- and p-) are used to name these disubstituted benzenes.

58 ortho-dichlorobenzene (1,2-dichlorobenzene) mp –17.2 o C, bp o C ortho disubstituted benzene substituents on adjacent carbons

59 meta-dichlorobenzene (1,3-dichlorobenzene) mp –24.82 o C, bp 172 o C meta disubstituted benzene substituents on adjacent carbons

60 para-dichlorobenzene (1,4-dichlorobenzene) mp 53.1, bp o C para disubstituted benzene substituents are on opposite sides of the benzene ring

61 phenol m-nitrophenol When one substituent corresponds to a monosubstituted benzene with a special name, the monosubstituted compound becomes the parent name for the disubstituted compound.

62 toluene m-nitrotoluene

63 Tri- and Polysubstituted Benzenes

64 Numbering starts at one of the substituent groups. The numbering direction can be clockwise or counterclockwise. Numbering must be in the direction that gives the substituent groups the lowest numbers. When a benzene ring has three or more substituents, the carbon atoms in the ring are numbered.

65 clockwise numbering 1,4,6-trichlorobenzene 4-chloro 1-chloro 6-chloro

66 counterclockwise numbering 1,2,4-trichlorobenzene 4-chloro 1-chloro 2-chloro chlorine substituents have lower numbers

67 When a compound is named as a derivative of the special parent compound, the substituent of the parent compound is considered to be C-1 of the ring.

68 toluene ,4,6- trinitrotoluene (TNT)

69 ALCOHOLS Alcohols: Organic compounds containing hydroxyl (-OH) functional groups. Phenols: Compounds with hydroxyl group bonded directly to an aromatic (benzene) ring.

70 According to the type of carbinol carbon atom (C bonded to the –OH group). CLASSIFICATION Classes: i) Primary alcohol - -OH group attached to a primary carbon atom ii) Secondary alcohol - -OH group attached to a secondary carbon atom iii) Tertiary alcohol - -OH group attached to a tertiary carbon atom

71 TYPE STRUCTURE EXAMPLES i) Primary (1°) ii) Secondary (2°) iii) Tertiary (3°)

72 Alcohols that contain more than one OH group attached to different carbons are called polyhydroxy alcohols. Monohydroxy: one OH group per molecule. Dihydroxy: two OH groups per molecule. Trihydroxy: three OH groups per molecule. Polyhydroxy Alcohols

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74 Naming Alcohols

75 IUPAC RULES 1. Select the longest continuous chain of carbon atoms containing the hydroxyl group. 2. Number the carbon atoms in this chain so that the one bonded to the –OH group has the lowest possible number. 3. Form the parent alcohol name by replacing the final – e of the corresponding alkane name by –ol. When isomers are possible, locate the position of the –OH by placing the number (hyphenated) of the carbon atom to which the –OH is bonded immediately before the parent alcohol name. 4. Name each alkyl branch chain (or other group) and designate its position by number.

76 Select this chain as the parent compound. This is the longest continuous chain that contains an hydroxy group.

77 This end of the chain is closest to the OH. Begin numbering here.

78 methyl-2-butanol

79 Select this chain as the parent compound. This is the longest continuous chain that contains an hydroxy group.

80 This end of the chain is closest to the OH. Begin numbering here.

81 3-methyl-2-pentanol

82 EXAMPLE 1) Longest carbon chain = 4 carbons = root name: butanol 2) Position of –OH group = second carbon atom = 2-butanol 3) Name of substituents = 1-bromo = 3-methyl COMPLETE IUPAC NAME = 1-bromo-3,3-dimethyl-2-butanol

83 EXAMPLES OF POLYHYDROXY ALCOHOL

84 An ether has the formula ROR´. R and R´ can be the same or different groups. R and R´ can be saturated, unsaturated or aromatic. Saturated ethers have little chemical reactivity but are often used as solvents. Ethers

85 Alcohols and ethers are isomeric. They have the same molecular formula but different structural formulas. An alcohol and its isomeric ether have different chemical and physical properties.

86 CH 3 CH 2 OH ethanol B.P o C hydrogen bonds soluble in water C2H6OC2H6O CH 3 –O–CH 3 dimethyl ether B.P. –27.3 o C does not hydrogen bond insoluble in water C2H6OC2H6O

87 Naming Ethers

88 Common Names Common names of ethers are formed from the names of the groups attached to the carbon atom in alphabetical order followed by the word ether. CH 3 CH 2 CH 2 O CH 2 CH 3 propyl ethyl ethyl propyl ether ether

89 IUPAC RULES RO– is an alkoxy group. Ethers are named as alkoxy derivatives of the longest carbon-carbon chain in the molecule

90 IUPAC RULES 1. Select the longest carbon-carbon chain and label it with the name of the corresponding alkane. 2. Change the –yl ending of the other hydrocarbon group to –oxy to obtain the alkoxy group name. 3. Combine the names from steps 1 and 2, giving the alkoxy name first, to form the ether name.

91 ethyl Label it with the name of the corresponding alkane. Change the name of the other hydrocarbon group to –oxy. CH 3 CH 2 CH 2 O CH 2 CH 3 This is the longest carbon-carbon chain. propane ethoxy IUPAC name: ethoxypropane Trivial name: ethyl propyl ether

92 ALDEHYDES AND KETONES Functional group: carbonyl group Aldehyde: one hydrogen atom is bonded to the carbon in the carbonyl group. Ketone: the carbon atom in the carbonyl group is bonded to two hydrocarbon groups.

93 Naming Aldehydes

94 The IUPAC names of aldehydes are obtained by dropping the –e and adding -al to the name of the parent hydrocarbon. butanebutanal al

95 The parent hydrocarbon is the longest chain that carries the –CHO group This chain has 4 carbon atoms.

96 The parent hydrocarbon is the longest chain that carries the –CHO group This chain has 5 carbon atoms. 5

97 methylpentanal 1 The –CHO group is always at the beginning of the carbon chain. The carbonyl carbon is numbered as carbon 1. 1

98 The common names of aldehydes are derived from the common names of the carboxylic acids. butyric acidbutyraldehyde The –ic acid or –oic acid ending of the acid name is dropped and is replaced with the suffix –aldehyde.

99 Naming Ketones

100 The IUPAC name of a ketone is derived from the name of the alkane corresponding to the longest carbon chain that contains the ketone-carbonyl group. The parent name is formed by changing the –e ending of the alkane to -one. propanepropanone one

101 If the carbon chain is longer than 4 carbons, its numbered so that the carbonyl carbon has the smallest number possible, and this number is prefixed to the name of the ketone. This end of the chain is closest to the C=O. Begin numbering here.

102 3-hexanone

103 The common names of ketones are derived by naming the alkyl or aryl groups attached to the carbonyl carbon followed by the word ketone. ethyl propyl ketone ethyl propyl

104 ALKYL HALIDES General formula: C n H 2n+1 X where n = 1,2,… and X (halogen) Functional group: halogen, -X (X = F, Cl, Br, I) Naming alkyl halides: - same as nomenclature of alkanes

105 AMINES Functional group: Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pairorganic compoundsfunctional groupsbasicnitrogenatomlone pair Primary amineSecondary amineTertiary amine Classification of amines:

106 Primary (1 o ) amine: one hydrogen of ammonia is replaced by an alkyl or aryl group Secondary (2 o ) amine: two hydrogens of ammonia is replaced by an alkyl or aryl group Tertiary (3 o ) amine: three hydrogens of ammonia is replaced by an alkyl or aryl group Quaternary (4 o ) amine: an ion in which nitrogen is bonded to four alkyl or aryl groups and bears a positive charge

107 NAMING AMINES Common names: - formed from the names of the alkyl groups bonded to nitrogen, followed by the suffix –amine. - the prefixes di-, tri-, and tetra- are used to decribe two, three or four identical substituents.

108 NAMING AMINES IUPAC names: - similar to that alcohols. - the longest continuous chain of carbon atoms determine the root name. - the –e in alkane name is changed to –amine, and a number shows the position of the amino group along the chain. - other substituents on the carbon chain are given numbers, and the prefix N- is used for each substituent on nitrogen.

109 CARBOXYLIC ACIDS Functional group: carboxyl group, -COOH The carboxyl group can also be written as or

110 Open-chain carboxylic acids form a homologous series. homologous The carbonyl group ( ) is always at the beginning of a carbon chain. The carbonyl carbon atom is always designated as C

111 The IUPAC name of a carboxylic acid is derived from the name of the alkane corresponding to the longest carbon chain that contains the carboxyl group. The parent name is formed by changing the –e ending of the alkane to –oic acid. methanone oic acid methane

112 Examples of carboxylic acid

113 Organic acids are usually known by common names. These names usually refer to a natural source of the acid. ethanoic acid IUPAC name acetic acid common name methanoic acid IUPAC name formic acid common name

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115 CARBOXYLIC ACID DERIVATIVES Group replacing the –OH group of RCOOH Class of compound General formula Example -X (halogen)Acyl halide -OREster -NH 2 Amide Acid anhydride

116 Esters

117 carbonyl group OR´ bonded to a carbonyl carbon. An ester is an organic compound derived from a carboxylic acid and an alcohol. The ester functional group is –COOR.

118 Esterification is the reaction of an acid and an alcohol to form an ester. acetic acid (ethanoic acid) ethyl alcohol (ethanol) ethyl acetate (ethyl ethanoate)

119 According to the IUPAC system the alcohol part of the ester (R΄) is named first. ethyl IUPAC NAME

120 This is followed by the name of the acid where the –ic ending of the acid has been changed to –ate. ethanoate IUPAC NAME

121 According to the IUPAC system the alcohol part of the ester (R΄) is named first. This is followed by the name of the acid where the –ic ending of the acid has been changed to –ate. ethyl ethanoate IUPAC NAME

122 COMMON NAME The alcohol part is named first (derived from the common names of alcohol). The common names of esters are derived by adding –ate to the name of the acid. acetate acetic acid ethyl

123 ethyl acetate COMMON NAME The alcohol part is named first (derived from the common names of alcohol). The common names of esters are derived by adding –ate to the name of the acid.

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125 Amide Amide: a composite of a carboxylic acid and ammonia or an amine. Classification of amide: i) primary amide: RCONH2 (two H atoms bonded to N atom) ii) secondary amide: RCONHR (one H atoms bonded to N atom) iii) tertiary amide: RCONRR (no H atoms bonded to N atom)

126 NAMING AMIDE IUPAC name: i) primary amide - first name the corresponding acid. Drop the –ic acid or oic acid, and add the suffix –amide. ethanoic acidethanamide ammonia acetic acidacetamide IUPAC name Common name

127 NAMING AMIDE IUPAC name: i) secondary and tertiary amide - treat the alkyl groups on nitrogen as substituents, and specify their position by the prefix N-.

128 Acyl halide / acid halides Naming acid halides: - replacing the –ic acid suffix of the acid name with –yl and the halide name.

129 Acid anhydride Naming acid anhydride: - the word acid is changed to anhydride in both the common and the IUPAC name

130 FUNCTIONAL GROUPS OF ORGANIC COMPOUNDS

131 A polymer is a high molar mass molecular compound made up of many repeating chemical units. Naturally occurring polymers Proteins Nucleic acids Cellulose Rubber Synthetic polymers Nylon Dacron Lucite POLYMERS

132 The simple repeating unit of a polymer is the monomer. Homopolymer is a polymer made up of only one type of monomer ( CF 2 CF 2 ) n Teflon ( CH 2 CH 2 ) n Polyethylene ( CH 2 CH ) n Cl PVC

133 Copolymer is a polymer made up of two or more monomers Styrene-butadiene rubber ( CH CH 2 CH 2 CH CH CH 2 ) n

134 Formation of Polyethylene nCH 2 =CH 2 CH 2 CH 2 [CH 2 CH 2 ] n CH 2 CH 2 CH 2 CH 3 ethylene monomer polyethylene n = the number of monomer units. n ranges from 2,500 to 25,000

135 SOME MONOMERS AND THEIR COMMON SYNTHETIC POLYMERS

136 USES AND IMPORTANCE OF ORGANIC COMPOUNDS NYLON General reactions: Nylons are condensation copolymers formed by reacting equal parts of a diamine and a dicarboxylic acids, so that peptide bonds form at both ends of each monomer in a process analogous to polypeptides biopolymers. DiaminesDicarboxylic acids Nylon

137 Basic concepts of nylon production The first approach: - combining molecules with an acid (COOH) group on each end are reacted with two chemicals that contain amine (NH 2 ) groups on each end. - Form nylon 6,6, made of hexamethylene diamine with six carbon atoms and acidipic acid, as well as six carbon atoms. The second approach: - a compound has an acid at one end and an amine at the other and is polymerized to form a chain with repeating units of (-NH-[CH 2 ]n-CO-)x. - Form nylon 6, made from a single six-carbon substance called caprolactam.

138 Uses and important of nylon Apparel: Blouses, dresses, foundation garments, hosiery, lingerie, raincoats, ski apparel, windbreakers, swimwear, and cycle wear Home Furnishings: Bedspreads, carpets, curtains, upholstery Industrial and Other Uses: Tire cord, hoses, conveyer and seat belts, parachutes, racket strings, ropes and nets, sleeping bags, tarpaulins, tents, thread, monofilament fishing line, dental floss

139 AZO-DYES Azo compounds: - compounds bearing the functional group R-N=N-R', in which R and R' can be either aryl or alkyl. - N=N group is called an azo group - HNNH is called diimide Aryl azo compounds have vivid colors, especially reds, oranges, and yellows Yellow azo dye

140 Methyl orange - used as acid-base indicators due to the different colors of their acid and salt forms Artists paints – clays, yellow to red range Dye in food and textiles Uses and important of azo dye

141 E102: Tartrazine E107 : Yellow 2G E110 : Sunset Yellow E122 : Azorubine EXAMPLES OF AZO DYES USED IN FOOD

142 E123 : Amaranth E124 : Ponceau 4R E129 : Allura Red E151 : Brilliant Black

143 FUEL Any material that is burned or altered to obtain energy and to heat or to move an object Its energy can be stored to be released only when needed, and that the release is controlled in such a way that the energy can be harnessed to produce work Examples: Methane, petrol and oil. Application of energy released from fuels: - cooking - powering weapons to combustion - generation of electricity Fuel oil: generate heat or used in an engine for the generation of power


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