Chapter 25 Summary - Amides and Amines PDF

Chapter Outline Chapter 7 Amides and Amines: Organic Nitrogen Compounds Nylon is one of the materials used to give these colorful sails their strength and Introduction to General, Orga...

Chapter Outline Chapter 7 Amides and Amines: Organic Nitrogen Compounds Nylon is one of the materials used to give these colorful sails their strength and Introduction to General, Organic, and Biochemistry, 10e durability. John Wiley & Sons, Inc Morris Hein, Scott Pattison, and Susan Arena  Chapter Amides: Nomenclature and Physical Outline Properties Amides are neutral nitrogen-containing compounds. They are not acidic or basic (neutral) and exist as molecules both in aqueous solution and as pure substances. These compounds contain carbonyl groups. The carbonyl group is directly connected to a nitrogen atom. 2  Chapter Amides: Nomenclature and Physical Outline Properties Amides are prepared when a carboxylic acid is heated in the presence of ammonia. 3  Chapter Amides: Nomenclature and Physical Outline Properties Ammonium salts of carboxylic acids can also be converted to amides by heating. 4  Chapter Amides: Nomenclature and Physical Outline Properties IUPAC Rules for Naming Amides 1. Name the longest continuous carbon chain containing the amide group. The carbonyl carbon atom is the #1 carbon atom. 2. Drop –oic from the corresponding carboxylic acid and add the suffix –amide. 5  Chapter Amides: Nomenclature and Physical Outline Properties IUPAC names for amides are formed from the IUPAC names of carboxylic acids. Here are two examples. 6  Chapter Amides: Nomenclature and Physical Outline Properties 3. Use a capital N (italicized) as the prefix if alkyl groups or other groups are attached directly to the amide nitrogen atom. 7  Chapter Amides: Nomenclature and Physical Outline Properties The common names for amides are formed from the common names of carboxylic acids. 8  Chapter Amides: Nomenclature and Physical Outline Properties IUPAC and common names of some amides are on Table 25.1 on the next slide... 9  Chapter Outline 10  Chapter Outline Your Turn! Write formulas for N-methylpentanamide and N,N- diethyl-2-methylhexanamide. 11  Chapter Outline Your Turn! Write formulas for N-methylpentanamide and N,N- diethyl-2-methylhexanamide. O O CH3CH2CH2CH2CHC N(CH2CH3)2 CH3CH2CH2CH2C NHCH3 CH3 N-methylpentanamide N,N-diethyl-2-methylhexanamide 12  Chapter Amides: Nomenclature and Physical Outline Properties Physical Properties of Amides The physical properties of amides are determined largely by hydrogen bonding. 13  Chapter Amides: Nomenclature and Physical Outline Properties High water solubility and high melting and boiling are the result of hydrogen bonding. A table summarizing the physical properties of amides is on the following slide... 14  Chapter Amides: Nomenclature and Physical Outline Properties Property Description Polarity Polar Solubility Low molar mass amides are soluble in water M.P./B.P. Both m.p. & b.p. are high due to hydrogen bonding Physical Colorless/odorless solids at State/Appearance room temperature except formamide. 15  Chapter Outline Chemical Properties of Amides An important reaction of amides is hydrolysis. Amides undergo acidic and basic hydrolysis producing a carboxylic acid or carboxylate salt. Acidic Hydrolysis Basic Hydrolysis 16  Chapter Outline Your Turn! Write the equations for the acidic and basic hydrolysis of the following amide. O CH3CH2CH2CH2C NH2 17  Chapter Outline Your Turn! Write the equations for the acidic and basic hydrolysis of the following amide. O O + CH3CH2CH2CH2C NH2 + H2O + H+ CH3CH2CH2CH2C OH + NH4 Acidic hydrolysis O O CH3CH2CH2CH2C NH2 + NaOH CH3CH2CH2CH2C O- + NH3 Basic hydrolysis 18  Chapter Outline Polyamides: Condensation Polymers Polyamides are condensation polymers that contain repeating amide linkages as shown here. 19  Chapter Outline Polyamides: Condensation Polymers Polyamides are either synthetic like Nylon-66 or are biological like the protein chymotrypsin. The structure of chymotrypsin is shown below. 20  Chapter Outline Polyamides: Condensation Polymers The structure of synthetic Nylon-66 is shown here. 21  Chapter Outline Urea Urea is a simple diamide that is excreted in urine. Urea is the metabolite the body uses to excrete toxic ammonia. Urea is a white solid that melts at 133 C. It is very soluble in water. 22  Chapter Outline Urea Urea is a common commercial product. It is widely used in fertilizers to add nitrogen to the soil and as a starting material in the production of plastics and barbiturates like barbituric acid. 23  Chapter Amines: Nomenclature and Physical Outline Properties Classification of Amines Amines are basic nitrogen-containing compounds that are derivatives of ammonia. Amines are classified as: Primary (the nitrogen atom has one hydrocarbon group directly attached) Secondary (the nitrogen atom has two hydrocarbon groups directly attached) Tertiary (the nitrogen atom has three hydrocarbon groups directly attached). 24  Chapter Amines: Nomenclature and Physical Outline Properties Examples of primary (1o), secondary (2o) and tertiary (3o) amines are shown here. 25  Chapter Outline Your Turn! Classify the following amines as 1o, 2o or 3o. CH3 NH2 NHCH3 CH3CH2CHCH3 N(CH3)2 26  Chapter Outline Your Turn! Classify the following amines as 1o, 2o or 3o. CH3 NH2 NHCH3 CH3CH2CHCH3 N(CH3)2 O O O 1 3 2 27  Chapter Amines: Nomenclature and Physical Outline Properties IUPAC Rules for Naming Amines 1. Name the longest continuous carbon chain containing the amine group. The carbon atom attached to the amine group is the #1 carbon atom. 2. Drop –e from the corresponding alkane and add the suffix –amine. 28  Chapter Amines: Nomenclature and Physical Outline Properties Here are some examples of primary amines. 29  Chapter Amines: Nomenclature and Physical Outline Properties 3. Use a prefix with a capital N (italicized) if the amine nitrogen atom has an alkyl group or other group attached (2o and 3o amines). 30  Chapter Amines: Nomenclature and Physical Outline Properties 4. In naming diamines, the final -e of the alkane name is not omitted. 31  Chapter Amines: Nomenclature and Physical Outline Properties Simple amines are most often referred to by their common names. The common names for aliphatic amines are formed by naming the alkyl group or groups attached to the nitrogen atom, followed by the ending –amine. 32  Chapter Amines: Nomenclature and Physical Outline Properties The common names of some amines are shown here. 33  Chapter Amines: Nomenclature and Physical Outline Properties The most important aromatic amine is aniline (C6H5NH2). Derivatives are named as substituted anilines. 34  Chapter Amines: Nomenclature and Physical Outline Properties When a group is substituted for a hydrogen atom in the ring, the resulting ring substituted aniline is named as we have previously done with aromatic compounds. 35  Chapter Outline Your Turn! Give names for the following amines. CH3 N CH2CH3 NH2 CH2CH2CH3 CH3CH2CHCH2CH3 IUPAC and common names IUPAC name 36  Chapter Outline Your Turn! Give names for the following amines. CH3 N CH2CH3 NH2 CH2CH2CH3 CH3CH2CHCH2CH3 IUPAC: N-ethyl-N-methyl-1-propanamine IUPAC name: 3-pentanamine Common: ethylmethylpropylamine 37  Chapter Amines: Nomenclature and Physical Outline Properties Heterocyclic Compounds Heterocyclic compounds are ring compounds which have two or more atoms in the ring that are different. O, N, and S are common heteroatoms found in heterocyclic compounds. Nitrogen-based heterocyclic compounds like those shown on the next slide are found in DNA... 38  Chapter Amines: Nomenclature and Physical Outline Properties Some heterocyclic amines. 39  Chapter Amines: Nomenclature and Physical Outline Properties Physical Properties of Amines Amines are capable of hydrogen bonding with water. As a result, the aliphatic amines with up to six carbons are quite soluble in water. Methylamine and ethylamine are flammable gases with a strong ammoniacal odor. Trimethylamine has a “fishy” odor. 40  Chapter Amines: Nomenclature and Physical Outline Properties Amines are responsible for the strong odors of decaying flesh which are produced by bacterial decomposition. Two of these compounds are actually diamines as shown here. 41  Chapter Outline Preparation of Amines Amines are prepared by: 1. Alkylation of ammonia and amines 2. Reduction of amides 3. Reduction of nitriles 4. Reduction of aromatic nitro compounds 42  Chapter Outline Preparation of Amines Alkylation of Ammonia and Amines Ammonia can be alkylated producing primary, secondary and tertiary amines in successive reacctions. 43  Chapter Outline Preparation of Amines Four successive alkylations of ammonia eventually yields a quaternary ammonium salt as seen in the last reaction. 44  Chapter Outline Preparation of Amines Reduction of Amides Lithium aluminum hydride (LiAlH4) reduces amides to an amines. 45  Chapter Outline Preparation of Amines Reduction of Nitriles Nitriles are reduced to amines using hydrogen gas and a metal catalyst. 46  Chapter Outline Preparation of Amines Reduction of Aromatic Nitro Compounds Nitrobenzene is reduced to aniline which is a common aromatic amine. 47  Chapter Outline Your Turn! Write the structure of an amide and a nitrile that when reduced would form 2-methyl-1-butanamine. 48  Chapter Outline Your Turn! Write the structure of an amide and a nitrile that when reduced would form 2-methyl-1-butanamine. O reduction CH3CH2CHCH2 NH2 CH3CH2CHC NH2 CH3 CH3 2-methyl-1-butanamine reduction CH3CH2CHC N CH3 49  Chapter Outline Chemical Properties of Amines Alkaline Properties of Amines Amines resemble ammonia in their reactions. Amines are bases, and like ammonia, produce OH- ions in water 50  Chapter Outline Chemical Properties of Amines The ions formed in the reaction of amines with water are substituted ammonium ions. 51  Chapter Outline Chemical Properties of Amines Amines are weak bases. Compare the pH of the following amines with the pH of ammonia. A 0.1M solution of NH3 has a pH of 11.1 CH3NH2 is more basic at a pH of 11.8. An aromatic amine like aniline is less basic at a pH of 8.8. 52  Chapter Outline Chemical Properties of Amines Amines are much more basic than amides and the body uses this fact to convert toxic ammonia into urea as shown here. 53  Chapter Outline Chemical Properties of Amines Amines also are a source of positive charges on biological molecules under physiological conditions. The neurotransmitters dopamine and serotonin are typical examples of these charged amines. 54  Chapter Outline Chemical Properties of Amines Salt Formation Because amines are weak bases, they react with strong acids to form ammonium salts. Methylamine for example reacts with strong acid yielding the corresponding methylammonium salt. 55  Chapter Outline Chemical Properties of Amines Methylammonium chloride is a white crystalline solid made up of methylammonium ions, CH3NH3+, and chloride ions, Cl-. Many amines or amino compounds are more stable in the form of the hydrochloride salt. When the free amine is wanted, the HCl is neutralized to liberate the free amine. 56  Chapter Outline Chemical Properties of Amines Formation of Amides Amides are produced when primary and secondary amines react with acid chlorides. 57  Chapter Outline Your Turn! Show the products of the following reaction. O CH3CH2C Cl + H2NCH2CH3 58  Chapter Outline Your Turn! Show the products of the following reaction. O O CH3CH2C Cl + H2NCH2CH3 CH3CH2C NCH2CH3 + HCl 59  Chapter Sources and Uses of Selected Outline Amines Nitrogen compounds are found throughout the plant and animal kingdoms. Amines, substituted amines, and amides occur in every living cell. Many of these compounds have important physiological effects. 60  Chapter Sources and Uses of Selected Outline Amines Biogenic amines are derived from amino acids and act as neurotransmitters and hormones in animals. GABA (γ-aminobutyric acid) slows nerve action and can bring relaxation. Norepinephrine shown below affects our focus and concentration. 61  Chapter Sources and Uses of Selected Outline Amines Biogenic amines that act as hormones include the “fight-or- flight” hormone epinephrine (also a catecholamine) as well as histamine, an important component in allergic reactions. 62  Chapter Sources and Uses of Selected Outline Amines Amphetamines are designed to mimic the action of biogenic amines and act as stimulants. They are used to treat depression, narcolepsy, and obesity. The most widely abused amphetamine is methamphetamine, commonly called “speed.” 63  Chapter Sources and Uses of Selected Outline Amines Barbiturates are another class of drugs that are amines. These drugs are classified as sedatives and depress the activity of brain cells. An example is pentobarbital. 64  Chapter Sources and Uses of Selected Outline Amines Basic compounds that are derived from plants and show physiological activity are known as alkaloids. These substances are usually amines. Nicotine, an alkaloid derived from tobacco leaves, acts to stimulate the nervous system. 65  Chapter Sources and Uses of Selected Outline Amines Coffee beans and tea leaves contain caffeine, an alkaloid stimulant. 66  Chapter Sources and Uses of Selected Outline Amines The opium alkaloids are often called opiates and include both compounds derived from the opium poppy and synthetic compounds that have morphine-like activity. These compounds are sleep-inducing and have analgesic properties. 67  Chapter Sources and Uses of Selected Outline Amines These drugs are classified as narcotics because they produce physical addiction, and they are strictly regulated by federal law. An example is methadone. 68  Chapter Sources and Uses of Selected Outline Amines Another common narcotic alkaloid, cocaine, is obtained from the leaves of the coca plant. 69  Chapter Outline Chapter 25 Summary Carboxylic acids react with ammonia to form salts. Amides are neutral, nonionic compounds. The IUPAC naming of amides follows a similar process to that used for other organic molecules. Strong intermolecular hydrogen bonding accounts for the amides’ high melting, boiling points and water solubility. 70  Chapter Outline Chapter 25 Summary Amide hydrolysis uses water to split an amide into a carboxylic acid portion and a nitrogen-containing portion. Polyamides form when a carboxylic acid from one monomer reacts with an amine from a second monomer. Urea is a simple diamide of the structure. Animals excrete nitrogen in the form of urea. Urea is also a valuable fertilizer and industrial chemical. 71  Chapter Outline Chapter 25 Summary An amine is a substituted ammonia molecule bonded to at least one alkyl or aryl group. Many simple amines are referred to by their common names. The most important aromatic amine is aniline. Heterocyclic compounds are ring structures where the atoms forming the ring are not all alike. 72  Chapter Outline Chapter 25 Summary Intermolecular hydrogen bonding accounts for the amines’ high water solubility. Alkylation of ammonia (with alkyl halides) will successively form primary, secondary, and tertiary amines. Reduction of several different nitrogen-containing compounds will form amines. 73  Chapter Outline Chapter 25 Summary Amines are bases. Amines react with strong acids to form salts. Primary and secondary amines react with acid chlorides to form amides. Proteins are polymers of amino acids linked by amide bonds. Biogenic amines are derived from amino acids and act as neurotransmitters and hormones in animals. 74  Chapter Outline Chapter 25 Summary Many powerful drugs act by changing the biochemistry of biogenic amines. Basic compounds that are derived from plants and show physiological activity are known as alkaloids. 75