General orrganic and biological chemistry structures off liffe 5th by karen timberlake18 worked examples

Sample Problem 18.1 IUPAC Names for Amines Give the IUPAC name for the following amine: Solution Step Name the longest carbon chain bonded to the N atom by replacing the e of its alkane name with amine The longest carbon chain bonded to the N atom has four carbon atoms, which is named by replacing the e in the alkane name with amine to give butanamine Step Number the carbon chain to show the position of the amine group and other substituents The N atom in the amine group is attached to carbon of butanamine General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.1 IUPAC Names for Amines Continued Step Any alkyl group attached to the nitrogen atom is indicated by the prefix N- and the alkyl name, which is placed in front of the amine name Alkyl groups attached to the N atom are listed alphabetically Study Check 18.1 Draw the condensed structural formula for N-ethyl-1-propanamine Answer General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.2 Common Names of Amines Give a common name for each of the following amines: Solution a This amine has one ethyl group attached to the nitrogen atom; its name is ethylamine b The common name for an amine with three methyl groups attached to the nitrogen atom is trimethylamine Study Check 18.2 Draw the condensed structural formula for butyldimethylamine Answer General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.3 UPAC Names for Compounds with Two Functional Groups Give the IUPAC name for the following compound, which is used in the production of methadone: Solution Step Identify the functional group with the highest priority and use the longest carbon chain to give the compound name Because the hydroxyl group has a higher priority than the amine group, the compound is named as an alcohol Step Number the carbon chain, and give the position and name of the main group and the substituent group on the carbon chain General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.3 UPAC Names for Compounds with Two Functional Groups Continued Study Check 18.3 Draw the condensed structural formula for 3-aminopentanal Answer General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.4 Classifying Amines Classify each of the following amines as primary (1°), secondary (2°), or tertiary (3°): Solution a b c d This is a primary (1°) amine because there is one alkyl group (cyclohexyl) attached to the nitrogen atom This is a tertiary (3°) amine There are three alkyl groups (two methyls and one ethyl) attached to the nitrogen atom This is a secondary (2°) amine with two carbon groups, methyl and phenyl, bonded to the nitrogen atom The nitrogen atom in this line-angle structural formula is bonded to two alkyl groups, which makes it a secondary (2°) amine General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.4 Classifying Amines Continued Study Check 18.4 Classify the following amine as primary (1°), secondary (2°), or tertiary (3°): Answer tertiary (3°) General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.5 Boiling Points and Solubility of Amines The compounds trimethylamine and ethylmethylamine have the same molar mass Why is the boiling point of trimethylamine (3 °C) lower than that of ethylmethylamine (37 °C)? Solution With polar N—H bonds, ethylmethylamine molecules form hydrogen bonds with each other Thus, a higher temperature is required to break the hydrogen bonds and form a gas However, trimethylamine, which is a tertiary amine, does not have N—H bonds and cannot hydrogen bond with other trimethylamine molecules It does not need as high a temperature to form a gas Study Check 18.5 Answer Hydrogen bonding makes amines with six or fewer carbon atoms soluble in water When there are seven or more carbon atoms in the alkyl portions of an amine, the longer nonpolar hydrocarbon chains diminish the solubility effect of the polar amine group General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.6 Reactions of Amines Write a balanced chemical equation that shows ethylamine: a acting as a weak base in water b neutralized by HCl Solution a CH3—CH2—NH2 + H2O b CH3—CH2—NH2 + HCl + CH3—CH2—NH3 + OH− + CH3—CH2—NH3 Cl− Study Check 18.6 Draw the condensed structural formula for the ammonium salt formed by the reaction of trimethylamine and HCl Answer General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.7 Heterocyclic Amines Identify the heterocyclic amines that are part of the structure of nicotine Solution Nicotine contains two heterocyclic rings The 6-atom ring with one N atom and three double bonds is pyridine, and the 5-atom ring with one N atom and no double bonds is pyrrolidine The N atom in the pyrrolidine ring is bonded to a methyl group (—CH3) General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.7 Heterocyclic Amines Continued Study Check 18.7 Sedamine is used as a sleep aid Identify the heterocyclic amine that is part of the structure of sedamine Answer piperidine General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.8 Place the following in order of occurrence for nerve impulses: a b c d e f Neurotransmitters diffuse across synapse to receptors on dendrites Neurotransmitters move away from receptors An electrical signal reaches the axon terminal of a nerve cell Reuptake moves neurotransmitters into the vesicles for storage Vesicles release neurotransmitters into the synapse of nearby nerve cells Neurotransmitters stimulate receptors to send new nerve impulse Solution c, e, a, f, b, d Study Check 18.8 How does an excitatory neurotransmitter send a nerve impulse at the receptor? Answer When the neurotransmitter attaches to the receptor, ion channels open and positive ions flow to nearby nerve cells creating new electrical impulses General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.9 Amidation Draw the condensed structural formula for the amide product in each of the following reactions: Solution The condensed structural formula for the amide product can be drawn by attaching the carbonyl group from the acid to the nitrogen atom of the amine The —OH group is removed from the acid and —H from the amine to form water General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.9 Amidation Continued Study Check 18.9 Draw the condensed structural formulas for the carboxylic acid and amine needed to prepare the following amide (Hint: Separate the N and C O of the amide group, and add —H and —OH to give the original amine and carboxylic acid.) Answer General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.10 Naming Amides Give the IUPAC name for the following amide: Solution Step Replace oic acid (IUPAC) or ic acid (common) in the carboxyl name with amide Step Name each substituent on the N atom using the prefix N- and the alkyl name General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.10 Naming Amides Continued Study Check 18.10 Draw the condensed structural formula for N,N-dimethylbenzamide Answer General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.11 Hydrolysis of Amides Draw the condensed structural formulas and give the IUPAC names for the products of the hydrolysis of N-methylpentanamide with NaOH Solution In hydrolysis, the amide bond is broken between the carboxyl carbon atom and the nitrogen atom When NaOH is used, the products are the carboxylate salt and an amine General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample Problem 18.11 Hydrolysis of Amides Continued Study Check 18.11 Draw the condensed structural formulas for the products obtained from the hydrolysis of N-methylbutyramide with HBr Answer General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc  ... carbon chain, and give the position and name of the main group and the substituent group on the carbon chain General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake... receptor, ion channels open and positive ions flow to nearby nerve cells creating new electrical impulses General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016... ammonium salt formed by the reaction of trimethylamine and HCl Answer General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Sample