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Unit-Two organic 1.pptx

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Unit-Two organic 1.pptx

  1. 1. Unit-Two Functional Groups in Organic Chemistry 1
  2. 2.  Classes of organic compounds can be distinguished according to functional groups they contain.  A functional group is a group of atoms that is largely responsible for the chemical behavior of the parent molecule. It is atom or a group of atoms within a molecule that are responsible for the characteristic reactions of a molecule. The chemistry of every organic molecule, regardless of size and complexity, is determined by the functional groups it contains. 2.1. Functional Groups 2
  3. 3. Cont’d • The concept of functional group is important organic chemistry for three reason:- • Functinal group serves as basic for nomenclature(naming organic compounds) • Functional group serve to classify organic compound in to classes (families). All families with the same functional group belong to the same class. • A functional group is the site of chemical reactivity in a molecule compound in the same class have similar chemical property. • NB A molecule can contain more than one functional group it is said to be poly-functional 3
  4. 4. 4
  5. 5. 5
  6. 6. 2.2 Nomenclature 2.2.1 Akanes (Paraffine) Alkanes are hydrocarbons in which all the bonds are single bonds Alkanes have no functional groups Alkanes are called saturated hydrocarbons  Open chain alkanes: - general formula, CnH2n+2 where n= 1, 2, 3,……  Cyclic alkanes (cycloalkanes):- general formula, CnH2n where n= 3,4,5,…  The formulas and structures of each successive compound differ from each other by one methylene group (CH2) is called homologous series.  E.g. CH3 _H, CH3 _CH2 _H, CH3 _ CH2 _CH2 _H  The names of alkanes are derived from the Greek prefixes that indicate the number of carbon atoms in the molecule, and ending with “ - ane ” . 6
  7. 7. Cont’d For examples  CH4 = methane, CH3-CH3 = ethane, CH3-CH2-CH3 = propane, CH3-CH2-CH2-CH3 = butane Naming of alkyl groups  Alkyl groups (R) are formed by removing one hydrogen atom from an alkane. They are named by dropping –ane from the name of the corresponding alkane, and adding the ending –yl. 7
  8. 8. Cont’d Naming of non-alkyl groups  A number of non-alkyl groups are used in naming organic compounds, some of their names are given below:  —Cl = Chloro —I = Iodo —NO2 = Nitro —OH = Hydroxy  —Br = Bromo —F = Fluoro —NH2 = Amino —NO = Nitroso 8
  9. 9. Naming system of alkanes IUPAC System  In general, organic compounds are given systematic names by using the order prefix–parent–suffix  Prefix indicates how many branching groups are present.  Parent indicates how many carbons are in the longest chain.  Suffix indicates the name of the family. The IUPAC rules for naming of alkanes are given below: 1. Select the longest continuous chain of carbon atoms; this chain determines the parent name for the alkane. 2. Number the longest chain beginning with the end of the chain nearer the substituent. 9
  10. 10. Cont’d 3. Use the numbers obtained by application of rule 2 to designate the location of the substituent group. 4. When two or more substituents are present, give each substituent a number corresponding to its location on the longest chain and list them alphabetically order. 5. When two or more substituents are identical, indicate this by the use of the prefixes di-,tri-,and so on. 10
  11. 11. Cont’d 6. When branching first occurs at an equal distance from either end of the longest chain, choose the name that gives the lower number at the first point of difference. Properties of Alkanes  The first four alkanes are gases. While pentane and higher alkanes ( heptadecane or C17H36 ) are liquids.  Alkanes are insoluble in water but soluble in non-polar solvents. Why?  Boiling point and melting point of alkanes show regular increases as molecular weight increases. E.g pentane has higher boiling point than butane. Why?  Alkanes react with oxygen with oxygen to produce CO2 and H2O and release large amount of energy. 11
  12. 12. Cont’d  Alkanes undergo a sequential substitution of the alkane hydrogen atoms by chlorine. Cycloalkane Nomenclature  Cycloalkanes are alkanes that contain a ring of three or more carbons.  They have the general formula CnH2n , n = 3, 4, 5…..  Cycloalkanes are named under the IUPAC system by adding the prefix cyclo to the name of the un branched alkane with the same number of carbons as the ring.  The smallest possible ring consists of cyclo propane, C3H6. 12
  13. 13. Cont’d  Note that in the condensed structural formulas, there is a carbon atom at each corner and enough hydrogen are assumed to be attached to give a total of four single bonds. 13
  14. 14. 2.2.2 Alkenes (Olefins)  Alkenes are hydrocarbons that contain a carbon-carbon double bond (C=C) in their molecule.  Alkenes have carbon-carbon double bond (C=C) functional groups  Alkenes are called unsaturated hydrocarbons - Acyclic alkenes: - general formula, CnH2n where n= 2, 3,…… e.g. CH3 CH2CH=CHCH3 = C5H10 - Cyclic alkenes ( cycloalkenes ):- general formula, CnH2n-2 where n= 3,4,5,.. 14
  15. 15. Naming system of alkenes IUPAC system 1. Select the parent name by selecting the longest chain that contains the double bond and change the ending of the name of the alkane of identical length from -ane to -ene. 2. Number the parent chain in the direction that gives the double bond carbons get lower numbers. 3. Indicate the locations of the substituent groups. Carbon–carbon double bonds take precedence over alkyl groups and halogens. 15
  16. 16. Cont’d 4. Hydroxyl groups are outranking the double bond. Compounds that contain both a double bond and a hydroxyl group use the combined suffix -en + -ol to signify that both functional groups are present. 5. When there are two or three double bonds in a molecule, the ending –ane of the corresponding alkane is replaced by –adiene or –atriene to get the name of the hydrocarbon. 16 H2C C CH2 Propadiene H2C CH CH CH2 1,3-Butadiene
  17. 17. Physical properties of alkenes  The first three alkenes (ethane, propene and butene) are gases at ordinary temperature.  C5- C14 members of alkenes are liquids.  More than C18 are solids.  All alkenes are colorless and odorless, except ethene which has a rather pleasant odor.  Alkenes are only slightly soluble in water but dissolve freely in organic solvents.  In general the boiling points and melting points of alkenes increases as the molecular weight increases. 17
  18. 18. Chemical properties of alkenes  The most important reactions of alkenes are the addition reactions. 1. Addition of Hydrogen (Hydrogenation of alkene)  Alkenes add hydrogen under pressure and in the presence of Ni, Pt, or Pd catalyst to produce saturated hydrocarbons.  A hydrogenation reaction carried in this manner is called Catalytical Hydrogenation. 2. Addition of Halogen  Halogens (Cl2 or Br2) react with alkenes in the presence of an inert solvent to form dihalogen derivatives.  This provides a useful test for unsaturation, the red (brown) color of the bromine being rapidly discharge as the colorless dibromo compound is formed. 18
  19. 19. 3. Addition of Halogen Acids  Alkenes react with halogen acids (HCl, HBr or HI) to form alkyl halides.  Addition of HX to unsymmetrical alkenes follows Markovnikov’s rule.  This rule states that when an unsymmetrical reagent (HBr) add to an unsymmetrical alkene, the positive part of the reagent (H) become attached to the double bonded carbon which has the most hydrogen atoms. 4. Oxidation with cold KMnO4 solution  An alkene can be oxidized to a 1,2-diol either by potassium permanganate (KMnO4) in a cold basic solution.  Since the bright purple color of KMnO4 disappears during the reaction; it is used as a test for presence of a double bond (Baeyer’s test). 19
  20. 20. 5. Oxidation with Ozone  Ozone reacts with the C=C bond is cleaved and an oxygen atom becomes doubly bonded to each of the original alkene carbons. 2.2.3 Alkynes  Alkynes are unsaturated hydrocarbons that contain carbon - carbon triple bond.  Alkynes have carbon-carbon triple bond (C≡C) functional groups  Alkynes are called unsaturated hydrocarbons  They have the general formula CnH2n-2 where n= 2,3,4,5,……  The simplest alkyne is C2H2 and is commonly known as acetylene. 20
  21. 21. Nomenclature of Alkynes  The IUPAC names of alkynes are obtained by dropping the ending –ane of the parent alkane and adding the suffix –yne.  Select the longest chain which contain C≡C bond as a parent chain.  Number the chain from the end closer to the C≡C bond.  Indicate the position of the C≡C bond by the number of the first carbon atom involved in the triple bond. Physical properties of Alkynes  The first three members are gases, next eight are liquids and the higher alkynes are solids.  They all are colorless and odorless except acetylene which has a garlic odor. 21
  22. 22. Cont’d  Their boiling points and melting points show a regular increase with the increase in molecular weights.  Alkynes generally have slightly higher boiling points than the corresponding alkenes.  They are only slightly soluble in water but dissolve readily in organic solvent such as benzene, acetone, and ethyl alcohol. Chemical properties of Alkynes 1. Addition of Hydrogen (Reduction)  In the presence of Ni, Pt , or Pd alkynes add up two molecules of hydrogen first forming the corresponding alkenes and finally alkanes. 22
  23. 23. Cont’d  The reduction can be stopped at the alkene stage by using Pd poisoned with BaSO4 + quinoline ( Lindlar’s catalyst). 2. Addition of Halogens  Halogens add to alkynes in two steps forming a dihalide and then a tetrahalide. 23
  24. 24. 3. Addition of Halogen Acids  Hydrogen halides add to alkynes to form alkenyl halides. The regioselectivity of addition follows Markovnikov’s rule.  A proton adds to the carbon that has the greater number of hydrogens, and halide adds to the carbon with the fewer hydrogens.  In the presence of excess hydrogen halide, geminal dihalides are formed by sequential addition of two molecules of hydrogen halide to the carbon– carbon triple bond. 4. Combustion  Alkynes are burnt in air to form CO2, H2O and heat energy. 24 2CH≡CH + 5O2 → 4CO2 + 2 H2O + heat energy
  25. 25. Aromatic hydrocarbons (Benzene and Aromaticity Characteristics of aromatic compounds 1. A delocalized conjugated π system, most commonly an arrangement of alternating single and double bonds : Conjugated 2. planar structure 3. Contributing atoms arranged in one or more rings (Cyclic) 4. A number of π delocalized electrons that is, 4n + 2 number of π electrons, where n=0, 1, 2, 3, and so on. This is known as Hückel's Rule.
  26. 26. Aromatic compounds N
  27. 27. Nomenclature of Aromatic Compounds 1. Monosubstituted Benzenes a. IUPAC name Cl CH2CH3 C(CH3)3 NO2 t-Butylbenzene Ethylbenzene Nitrobenzene Chlorobenzene CH2 Benzyl group C O O H CH=CH2 CH3 OH C O H Toluene Styrene Phenol Benzaldehyde Benzoic acid N H2 Aniline CH2 Cl Benzyl chloride b. Common name
  28. 28. 2. Disubstituted Benzenes All disubstituted benzenes, can give rise to three possible isomers. The differentiate between the isomers, the relative positions of the substituents are designated by number or, more commonly, by the prefixes ortho (o: 1,2), meta (m:1,3) or para (p:1,4). Br Br Br Br Br Br 1,2-Dibromobenzene 1,3-Dibromobenzene 1,4-Dibromobenzene o-Dibromobenzene m-Dibromobenzene p-Dibromobenzene When the substituents are different, they are listed in alphabetical order C2H5 Cl O2N Br F I 1-Chloro-2-ethylbenzene 1-Bromo-3-nitrobenzene 1-Fluoro-4-iodobenzene o-Chloroethylbenzene m-Bromonitrobenzene p-Fluoroiodobenzene
  29. 29. If one of the substituents is part of a parent compound, then the di substituted benzene is named as a derivative of the parent compound. OH Cl O2N C H3 COOH Br 2-Chlorophenol 4-Nitrotoluene 3-Bromobenzoic acid o-Chlorophenol p-Nitrotoluene m-Bromobenzoic acid Certain disubstituted benzenes are referred to by their common names. CH3 CH3 C H3 CH3 o-Xylene m-Xylene CH3 CH3 p-Xylene
  30. 30. Reactions of Benzene • Even though benzene is highly unsaturated, it does not • undergo any of the regular reactions of alkenes
  31. 31. Specific Electrophilic Aromatic : Substitution Reactions X2 , FeX3 Halogenation X + HX (X=Cl, Br) RCl, AlCl 3 Alkylation R + Cl H HONO2 , H2SO4 Nitration NO2 + O H2 SO3 , H2SO4 Sulfonation SO3H
  32. 32. Side-Chain Reactions of Aromatic Compounds a. Halogenation of an Alkyl Side Chain CH3 Br2 UV light Toluene CH2Br + Br H Benzyl Bromide b. Oxidation of an Alkyl Side Chain CH3 KMnO4 Toluene COOH Benzoic acid CH2CH3 KMnO4 COOH Benzoic acid + + O H2 CO2
  33. 33. Alcohols  Alcohols are compounds whose molecules have a hydroxyl group (-OH) attached to a saturated carbon atom.  General formula: R-OH  Compounds in which a hydroxyl group is attached to an unsaturated carbon atom of a double bond (i.e., C=C–OH) are called enols.  Compounds that have a hydroxyl group attached directly to a benzene ring are called phenol.  Alcohols are classified as primary (10), secondary (20), and tertiary (30) depending upon weather the –OH group is attached to a primary, a secondary, or a tertiary carbon. 33
  34. 34. Nomenclature of Alcohols (IUPAC System)  Parent Hydrocarbon is the longest continuous chain that contains the –OH  Change the name of the alkane corresponding to this chain by dropping the ending –e and adding the suffix –ol.  Number the chain in direction that gives functional group the lowest number  If both a substituent and a functional group are present, the functional group gets the lower number  If the functional group gets the same number when counted from both directions, use direction which gives the substituent the lower number  If there is more than one substituent, cite substituents in alphabetical order 34
  35. 35. Physical properties of alcohols  Lower alcohols are colourless, toxic liquids. They have a characteristics smell.  Boiling points of alcohols increase regularly with the increase in the number of carbon atoms.  Boiling points of alcohols are much higher than those of the corresponding alkanes.  Lower alcohols (C1 to C3) are completely soluble in water. As we go higher in the series, the water solubility falls rapidly. Chemical reactions of alcohols 1. Reaction with Active Metals  Alcohols react with sodium or potassium to form alkoxides with the liberation of hydrogen gas. 35
  36. 36. 2. Reaction with Hydrogen Halides  Alcohols react with hydrogen halides (HX) to form the corresponding alkyl halides. 3. Dehydration of Alcohols to Alkenes  Alcohols undergo dehydration reaction when they are treated with concentrated H2SO4 to an alkene. 36
  37. 37. Cont’d  Dehydration of secondary and teriary alcohols containing four or more carbon atoms give a mixture of two alkenes.  The alkene produced in greater abundance is indicated by Zaitsev’s rule.  It states that the alkene formed preferentially is the one containing the higher number of alkyl groups. 37
  38. 38. 4. Dehydration of Alcohols to Ethers  Primary alcohols are converted to ethers on heating in the presence of an acid catalyst, usually sulfuric acid.  This kind of reaction is called a condensation.  A condensation is a reaction in which two molecules combine to form a larger one while liberating a small molecule. 5. Reaction with Carboxylic Acid  Alcohols react with carboxylic acids to form esters, concentrated H2SO4 is used as a catalyst.  This reaction is called Esterification. 38
  39. 39. 6. Oxidation of Alcohols  Alcohols can undergo oxidation reaction and the nature of the product depends on the type of alcohol and the conditions of the reaction.  Most widely used oxidizing agents are KMnO4 + H2SO4 or Na2CrO7 + H2SO4.  Oxidation of alcohols can be used to distinguish between primary, secondary, and tertiary alcohols.  Primary alcohols are first oxidized to aldehydes then to carboxylic acids.  Secondary alcohols are oxidized to the corresponding ketones.  Tertiary alcohols are stable to oxidation under normal conditions. 39
  40. 40. Ethers • Ethers are a class of compounds which contain an oxygen atom bonded to two alkyl groups. They are further designated as symmetrical ethers or un symmertrical ethers according as the two alkyl groups attached to the oxygen are same or different. 40 CH3-O-CH3 Symmetrical ether or CH3-O-CH2CH3 Unsymmetrical ether
  41. 41. Cont’d Nomenclature of Ethers Common name • The two alkyl groups attached to oxygen are named in alphabetic order and the word ether is added. • If the two alkyl groups are same, the prefix di- is used. CH3-O-CH2CH3 CH3-O-CH3 Ethyl methyl ether Dimethyl ether IUPAC name • In this system, ethers are named Alkoxyalkanes. • The larger of the alkyl groups is considered to be the alkane. • The name of the alkane is prefixed by the name of the alkoxy group and position number. 41
  42. 42. Cont’d 42 •Names of some common alkoxy groups (RO-) are given below: CH3O- methoxy CH3CH2O- ethoxy CH3CH2CH2O- propoxy Physical properties of ethers Dimethyl ether and ethyl methyl ether are gases. All other are colorless liquids with pleasant odors. Lower ethers are highly volatile and very flammable. Boiling points of ethers show a gradual increase with the increase in molecular weight. Ethers are slightly soluble in water. This is because they can form hydrogen bonds with water. Ethers have lower boiling points than isomeric alcohols ? Why?
  43. 43. Cont’d This is because ether molecules cannot form hydrogen bonds with each other as they have no –OH groups. Chemical Reactions of Ethers Ethers are unreactive to many reagents used in organic chemistry, a property that accounts for their wide use as reaction solvents. Halogens, dilute acids, bases, and nucleophiles have no effect on most ethers. In fact, ethers undergoonly one truly general reaction—they are cleaved by strong acids. Aqueous HBr and HI both work well, but HCl does not cleave ethers. 43
  44. 44. Amines • Amines are organic derivatives of ammonia in which one or more of the hydrogens of ammonia have been replaced by alkyl groups. Classification of Amines • Amines are classified as primary, secondary, and tertiary amines. • The classification depends on how many alkyl groups are bonded to the nitrogen. • Primary amines have one alkyl group bonded to the nitrogen, secondary amines have two, and tertiary amines have three. 44
  45. 45. Cont’d 45 Amines are further divided into aliphatic, aromatic, and heterocyclic amines: Aliphatic amine: An amine in which nitrogen is bonded only to alkyl groups.
  46. 46. Cont’d • Aromatic amine: An amine in which nitrogen is bonded to one or more aryl groups. 46 NH 2 Heterocyclic amine: An amine in which nitrogen is one of the atoms of a ring. Pyrrole Piperidine Pyrrolidine Pyridine (heterocyclic aliphatic amines) (heterocyclic aromatic amines) N N N H H N H
  47. 47. Cont’d Nomenclature of Amines Common names • Amines are named as “ alkylamines ” • The entire name is written as one word. • Amines bearing two or three similar alkyl groups are indicated by the prefix di- or tri- • Amines bearing dissimilar alkyl groups are named as the N- substituted derivative of the larger alkyl group. • Aromatic amines are called Anilines 47
  48. 48. cont’d 48
  49. 49. Cont’d • IUPAC name • Amines are named just as we do alcohols, i.e. by dropping the final -e ending from the alkane name and adding the suffix -amine. • Amines have a lower priority than do alcohols, which in turn are lower than carbonyls when the amine is a substituent; it is termed an amino group. • 3-chloro-4-methyle-2pentanamine 49 NH 2 Cl 1 3 4 5 NH 2 O H 4-aminoheptanal
  50. 50. Cont’d • Physical properties amines – Low molecular-weight amines tend to have sharp, penetrating odors similar to ammonia. Higher molecular-weight amines often smell like rotting fish, and are often found in decaying animal tissues. – Primary amines (RNH2) & secondary amines (R2NH) possess N-H bonds & can thus form hydrogen bonds to each other, accounting for their higher boiling points: 50
  51. 51. Cont’d • Tertiary amines (R3N) have no N-H bonds, cannot form hydrogen bonds to each other, & thus, have lower boiling points than the other two classes of amines. 51 Amines that have fewer than six or seven carbon atoms are soluble in water. Primary and secondary amines are more soluble than tertiary because they have more H-bonding with water Chemical Reactions of Amines 1. Reaction of Amines with Alkyl Halides Alkylations of primary and secondary amines are difficult to control and often give mixtures of products, but tertiary amines are cleanly alkylated to give quaternary ammonium salts.
  52. 52. Cont’d 52 Reactions of Primary Amines with Aldehydes and Ketones Imines are formed by nucleophilic addition of a primary amine to the carbonyl group of an aldehyde or a ketone.
  53. 53. cont’d •Reactions of Secondary Amines with Aldehydes and Ketones Enamines are formed in the corresponding reaction of secondary amines with aldehydes and ketones. 53
  54. 54. Cont’d •Reaction of Amines with Nitrous Acid Nitrous acid (HNO2 or HONO) reacts with aliphatic amines in a fashion that provides a useful test for distinguishing primary, secondary and tertiary amines. 54 10 -Amine+HONO(coldacidicsolution) NitrogenGasEvolutionfromaClearSolution 20 -Amine +HONO(coldacidicsolution) AnInsolubleOil(N-Nitrosoamine) 30 -Amine +HONO(coldacidicsolution) AClearSolution(AmmoniumSaltFormation)
  55. 55. Aldehydes and Ketones • The carbonyl group (C=O) is found in aldehydes, ketones, and many other organic functional groups. • Aldehydes and ketones are simple compounds which contain a carbonyl group - a carbon-oxygen double bond. • In ketones, two carbon groups are attached to the carbonyl carbon, • while in aldehydes at least one hydrogen is attached to the carbon. • Nomenclature of Aldehydes and Ketones i. Some Common Names Aldehydes and Ketones 55
  56. 56. Cont’d •ii. IUPAC Names of Aldehydes Select the longest carbon chain containing the carbonyl carbon. The -e ending of the parent alkane name is replaced by the suffix -al. The carbonyl carbon is always numbered “1.” (It is not necessary to include the number in the name.) Name the substituents attached to the chain in the usual way. 5-hydroxy-4,6-dioxooctanal 2-hydroxy-3-oxohexa-5-en-al IUPAC : 2-pentanone 3-diethyl-2-heptanone Name COMMON: methylpropylketone name 56 H O O O 1 2 3 4 5 6 7 8 1 4 5 6 H O O O H
  57. 57. Cont’d 57 O OH Cl 1 2 3 4 5 6 7 8 OH O O 1 2 3 4 5 6-chloro-5-hydroxyoctan-2-one 3-hydroxy-penta-2,4-dione Physical Properties of Aldehydes and Ketones In general, aldehydes and ketones have higher boiling points than alkenes because they are more polar and the dipole–dipole attractive forces between molecules are stronger. But they have lower boiling points than alcohols because, unlike alcohols, two carbonyl groups can’t form hydrogen bonds to each other.
  58. 58. Cont’d 58 Aldehydes and ketones can form hydrogen bonds with the protons of OH groups. This makes them more soluble in water than alkenes, but less soluble than alcohols.
  59. 59. Carboxylic Acids and Their Derivatives • the presence of at least one carboxyl group (-COOH). • The general formula of a carboxylic acid is R-COOH OR R-CO2H. • A carboxyl group (-COOH) is a functional group consisting of a carbonyl (C=O) and a hydroxyl (-OH). • They are weak acids. Nomenclature of Carboxylic Acids i. Common system • The common names are usually derived from the Latin or Greek word that indicates the original source of the acid. They do not follow any rule except that all common names of acids end in –ic acid. 59
  60. 60. Example ii. IUPAC system  Simple carboxylic acids derived from open-chain alkanes are systematically named by replacing the terminal -e of the corresponding alkane name with -oic acid.  The -CO2H carbon atom is numbered C-1. • Cycloalkanes bonded to -COOH are named as cycloalkanecarboxylic acids. • Aromatic acids are named as benzoic acids. 60 HCOOH Formic acid CH3COOH Acetic acid CH3CH2CH2 COOH Butyric acid CH3(CH2)4COOH Caproic acid
  61. 61. Cont’d 61 Physical properties of carboxylic acids  Lower carboxylic acids (up to C-10) are liquids with sharp or disagreeable odor. Higher members are wax-like solids and almost odorless. • They have sour taste.  Carboxylic acids have higher boiling points than alcohols of similar molecular weight. • Smaller carboxylic acids (1 to 5 carbons) are soluble in water, whereas higher carboxylic acids are less soluble.
  62. 62. Cont’d Chemical properties of carboxylic acids 1. Esterification • In the presence of an acid catalyst, carboxylic acids and alcohols react to form esters. • The reaction is an equilibrium process but can be driven to favor the ester by removing the water that is formed. 62
  63. 63. Cont’d 2. Formation of acyl chlorides Thionyl chloride reacts with carboxylic acids to yield acyl chlorides. Reduction of Carboxylic Acids • Carboxylic acids are reduced to primary alcohols by the powerful reducing agent lithium aluminum hydride. 63
  64. 64. 3. Esters • The most widespread of all naturally occurring compounds. • Many simple esters are pleasant-smelling liquids that are responsible for the fragrant odors of fruits and flowers. • They are result from the combination of a carboxylic acid with an alcohol. Naming  First identifying the alkyl group attached to oxygen and then the - ic acid ending replaced by-ate or oate. O O H3CO OCH3 O O Ethyl butanoate Isopentyl acetate Isopentyl pentanoate Dimethyl malonate (isolated from mangoes) (used in synthetic banana flavor) (used in synthetic apple flavor) O O O O 64
  65. 65. 4. Amides • resulting from the replacement of the -OH of a carboxylic acid with an • 1o (Amides with an unsubstituted -NH2 group) are named by replacing the -oic acid or -ic acid ending with -amide, or by replacing the -carboxylic acid ending with -carboxamide. • The substituents are preceded by the letter N-(for 2o) or N,N- (3o) to identify them as being directly attached to nitrogen. -NH2 (1o), -NHR (2o amide), or -NR2 (3o amide) group. • Cyclic esters and amides are called lactones and lactams, respectively. 65

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