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All Textbook Solutions for Introduction to General, Organic and Biochemistry

17-69 Propanal (bp 49°C) and 1-propanol (bp 97°C) have about the same molecular weight, yet their boiling points differ by almost 50°C. Explain this fact.17-70 What simple chemical test could you use to distinguish between the members of each pair of com pounds? Tell what you would do, what you would expect to observe, and how you would interpret your experimental observation. (a) Benzaldehyde and cyclohexanone (b) Acetaldehyde and acetone 17.71P 17-72 The following molecule is an enediol; each carbon of the double bond carries an —OH group. Draw structural formulas for the hydroxyketone and the a-hydroxyaldehyde with which this enediol is in equilibrium.17-73 Alcohols can be prepared by the acid-catalyzed hydration of alkenes (Section 12-6B) and by the reduction of aldehydes and ketones (Section 17-4B). Show how you might prepare each of the following alcohols by (1) acid-catalyzed hydration of an alkene and (2) reduction of an aldehyde or a ketone. (a) Ethanol (b) Cyclohexanol (c) 2-Propanol (d) 1-Phenylethanol 17-74 Glucose, C6H12O6, contains an aldehyde group but exists predominantly in the form of the cyclic hemiacetal shown here. We will discuss this cyclic form of glucose in Chapter 20. A cyclic hemiacetal is formed when the —OH group of one carbon bonds to the carbonyl group of another carbon. (a) Which carbon in glucose provides the —OH group and which provides the —CHO group? (b) Draw the alternative chair confirmations of D-glucose and state which of the two is the more stable.17.75P 17.76P 17.77P 17-78 Complete the following equation for these reactions.17-79 Write an equation for each conversion. (a) 1-Pentanol to pentanal (b) 1-Pentanol to pentanoic acid (c) 2-Pentanol to 2-pentanone (d) 2-Propanol to acetone (e) Cyclohexanol to cyclohexanone 18.1P 18.2P 18.3P 18-4 Answer true or false. (a) The functional groups of a carboxylic acid are a carbonyl group bonded to a hydroxyl group. (b) The VSEPR model predicts bond angles of 180° about the carbonyl carbon of a carboxyl group. (c) The VSEPR model predicts bond angles of 109.5° about the oxygen of the OH group of a carboxyl group. (d) The carbonyl carbon of a carboxyl group can be a stereocenter, depending on its location within a molecule. (e) Carboxylic acids can be prepared by chromic acid oxidation of primary alcohols and of aldehydes. (f) The product of chromic acid oxidation of hexanoic acid is 1-hexanol.18.5P 18-6 Name and draw structural formulas for the four carboxylic acids with the molecular formula C5H10O2. Which of these carboxylic acids are chiral?18-7 Write the IUPAC name for each carboxylic acid.18-8 Write the IUPAC name for each carboxylic acid. CCl3COOH 18.9P 18.10P 18.11P 18.12P 18.13P 18-14 Answer true or false. (a) Carboxylic acids are polar compounds. (b) The most polar bond of a carboxyl group is the C—O single bond. (c) Carboxylic acids have signi?cantly higher boiling points than aldehydes, kebones, and alcohols of comparable molecular weight. (d) The low-molecular-weight carboxylic acids (formic, acetic, propanoic, and butanoic acids) are in?nitely soluble in water. (e) The following compounds are arranged in order of increasing boiling point:18-15 Draw a structural formula for the dimer formed when two molecules of formic acid interact by hydrogen bonding.18-16 Propanedioic (malonic) acid forms an intramolecular hydrogen bond in which the H of one COOH group forms a hydrogen bond with an O of the other COOH group. Draw a structural formula to show this internal hydrogen bonding. (There are two possible answers.)18-17 Hexanoic (caproic) acid has a solubility in water of about 1 g/100 mL water. Which part of the molecule contributes to water solubility, and which part prevents solubility?18-18 Propanoic acid and methyl acetate are constitutional isomers, and both are liquids at room temperature. One of these compounds has a boiling point of 141°C; the other has a boiling point of 57°C. Which compound has which boiling point? Explain.18-19 The following compounds have approximately the same molecular weight: hexanoic acid, heptanal, and 1-heptanol. Arrange them in order of increasing boiling point.18.20P 18.21P 18.22P 18-23 Characterize the structural features necessary to make a good synthetic detergent.18.24P 18.25P 18-26 Answer true or false. (a) Carboxylic acids are weak acids compared to mineral acids such as HCI, H2SO4, and HNO3. (b) Phenols, alcohols, and carboxylic acids have in common the presence of an —OH group. (c) Carboxylic acids are stronger acids than alcohols but weaker acids than phenols. (d) The order of acidity of the following carboxylic acids is: (e) The order of acidity of the following carboxylic acids is: (f) The reaction of benzoic acid with aqueous sodium hydroxide gives sodium benzoate. (g) A mixture of the following compounds is extracted in order with (1) 1 M HCI, (2) 1 M NaOH, and (3) diethyl ether. Only compound II is extracted into the basic layer. (h) Conversion of compound I to compound II is best accomplished by reduction with NaBH4. (i) The following ester can be prepared by treating benzoic acid with 1-butanol in the presence of a catalytic amount of H2SO4: (j) Thermal decarboxylation of this ((-ketoacid gives benzoic acid and carbon dioxide: (k) Thermal decarboxylation of this (-ketoacid gives 2-pentanone and carbon dioxide.18.27P 18-28 Arrange these compounds in order of increasing acidity: benzoic acid, benzyl alcohol, phenol.18-29 Complete the equations for these acid—base reactions. (a) (b) (c) (d) (e)18-30 Complete the equations for these acid-base reactions.18-31 Formic acid is one of the components responsible for the sting of biting ants and is injected under the skin by bee and wasp stings. The pain can be relieved by rubbing the area of the sting with a paste of baking soda (NaHCO3) and water, which neutralizes the acid. Write an equation for this reaction.18.32P 18.33P 18.34P 18.35P 18.36P 18.37P 18-38 Which is the stronger base: CH3CH2NH2 or CH3CH2COO? Explain.18.39P 18.40P 18-41 Complete these examples of Fischer esterification. In each case, assume an excess of the alcohol.18.42P 18.43P 18.44P 18.45P 18-46 Procaine (its hydrochloride salt is marketed as Novocaine) was one of the ?rst local anesthetics developed for in?ltration and regional anesthesia. It is synthesized by the following Fischer esteri?cation: (a) Draw the structural formula of Procaine. (b) Which of the two nitrogen atoms in Procaine is the stronger base? (c) Draw the structural formula of Novocaine (the hydrochloride salt of Procaine). (d) Would you predict Procaine or Novocaine to be more soluble in blood?18-47 Methylparaben and propylparaben are used as preservatives in foods, beverages, and cosmetics. Show how each of these preservatives can be prepared from 4-aminobenzoic acid.18-48 4-Aminobenzoic acid is prepared from benzoic acid by the following two steps. Show reagents and experimental conditions to bring about each step.18.49P 18.50P 18.51P 18.52P 18.53P 18.54P 18.55P 19.1P Problem 19-2 Complete the equation for each hydrolysis reaction. Draw all products as they are ionized under these experimental conditions.19.3P 19.4P Write the IUPAC name for each compound.19.6P 19.7P 19.8P 19.9P 0 Complete the equations for these reactions.19.11P 19.12P 19.13P 19.14P 19.15P 6 Why are Dacron and Mylar referred to as polyesters?7 What type of structural feature do the anhydrides of phosphoric acid have in common with carboxylic acids?19.18P 19.19P 0 Show how triphosphoric acid can form from three molecules of phosphoric acid. How many moles of H2O are produced per mole of triphosphoric acid?1 Write an equation for the hydrolysis of trimethyl phosphate to dimethyl phosphate and methanol in aqueous base. Show each product as it would be ionized in this solution.2 (Chemical Connections 19A) Locate the ester group in pyrethrin I and draw a structural formula for chrysanthemic acid, the carboxylic acid from which this ester is derived.19.23P 19.24P 19.25P 19.26P 19.27P 8 (Chemical Connections 19C) Once it has been opened, and particularly if it has been left open to the air, a bottle of aspirin may develop a vinegar-like odor. Explain how this might happen.19.29P 19.30P 19.31P 19.32P 19.33P 4 (Chemical Connections 19F) Why do Lactomer stitches dissolve within 2 to 3 weeks following surgery?19.35P 19.36P 19.37P 8 In Chapter 22, we will discuss a class of compounds called amino acids, so named because they contain both an amino group and a carboxyl group. Following is a structural formula for the amino acid alanine. What would you expect to be the major form of alanine present in aqueous solution (a) at pH 2.0, (b) at pH 5—6, and (c) at pH 11.0? Explain.19.39P 19.40P 19.41P 19.42P 19.43P 19.44P 19.45P 19.46P 19.47P 19.48P 19.49P 20.1P 20.2P 20.3P 20.4P 20.5P 20.6P 20.7P 20.8P 20.9P 20.10P 20.11P 20.12P 20.13P 20.14P 20.15P 20.16P 20.17P 20.18P .19 What is an amino sugar? Name the three amino sugars most commonly found in nature.20.20P 20.21P 20.22P 20.23P 20.24P 20.25P 20.26P 20.27P 20.28P 20.29P 20.30P 20.31P 20.32P 20.33P 20.34P 20.35P 20.36P 20.37P 20.38P 20.39P 20.40P 20.41P 20.42P 20.43P 20.44P 20.45P 6 Where is glycogen stored in the human body?20.47P 8 How is it possible that cows can digest grass but humans cannot?20.49P 20.50P 1 Hyaluronic acid acts as a lubricant in the synovial fluid of joints. In rheumatoid arthritis, inflammation breaks hyaluronic acid down to smaller molecules. Under these conditions, what happens to the lubricating power of the synovial fluid?2 The anticlotting property of heparin is partly due to the negative charges it carries. (a) Identify the functional groups that provide the negative charges. (b) Which type of heparin is a better anticoagulant, one with a high degree or a low degree of polymerization?20.53P 20.54P 20.55P 20.56P 20.57P 20.58P 20.59P 20.60P 20.61P 2 In making candy or sugar syrups, sucrose is boiled in water with a little acid, such as lemon juice. Why does the product mixture taste sweeter than the initial sucrose solution?20.63P 20.64P 20.65P 20.66P 20.67P 20.68P 20.69P 0 What are the structural differences between vitamin C and sugars? Do these structural differences play a role in the susceptibility of this vitamin to air oxidation?20.71P 20.72P 20.73P 20.74P 20.75P 20.76P 20.77P 20.78P 20.79P 20.80P 20.81P 20.82P 20.83P 20.84P 20.85P 20.86P 20.87P 20.88P 20.89P 21.1P 21-2 Why are fats a good source of energy for storage in the body?21-3 Proteins, nucleic acids, and carbohydrates are grouped by common structural features found within their group. What is the basis for grouping substances as lipids?21.4P 21.5P 21.6P 21-7 For the diglycerides in Problem 21-6, predict which two will have the highest melting points and which two will have the lowest melting points.21-8 Predict which acid in each pair has the higher melting point and explain why. (a) Palmitic acid or stearic acid (b) Arachidonic acid or arachidic acid 21.9P 21.10P 21.11P 21.12P 21-13 Rank the following in order of increasing solubility in water (assuming that all are made with the same fatty acids): (a) triglycerides, (b) diglycerides, and (c) monoglycerides. Explain your answer.21.14P 21-15 Name the products of the saponification of this triglyceride:21.16P 21.17P 21.18P 21.19P 21.20P 21.21P 21.22P 21.23P 21-24 In what sense is the active transport of K+ selective? How does K+ pass through the transporter?21.25P 21.26P 21.27P 21.28P 21-29 Name all the groups of complex lipids that contain ceramides.21.30P 21.31P 21.32P 21.33P 21.34P 21.35P 21.36P 21.37P 21.38P 21-39 How does VLDL become LDL?21.40P 21.41P 21.42P 21.43P 21-44 Describe the difference in structure between the male hormone testosterone and the female hormone estradiol.21.45P 21.46P 21.47P 21-48 List all of the functional groups that make taurocholate water-soluble.21-49 Explain how the constant elimination of bile salts through the feces can reduce the danger of plaque formation in atherosclerosis.21.50P 21.51P 21-52 What are the chemical and physiological functions of the COX-2 enzyme?21-53 How does aspirin, an anti-inflammatory drug, prevent strokes caused by blood clots in the brain?21.54P 21.55P 21.56P 21.57P 21.58P 21.59P 21-60 (Chemical Connections 21C) Why were Mark McGwire and Floyd Landis not given the same penalties for taking steroids in their sports?21.61P 21.62P 21.63P 21.64P 21.65P 21.66P 21.67P 21-68 What is the role of taurine in lipid digestion?21.69P 21-70 How many different triglycerides can you create using three different fatty acids (A, B, and C)?21.71P 21.72P 21.73P 21.74P 21.75P 21-76 Which part of LDL interacts with the LDL receptor?21.77P 21.78P 21.79P 21.80P 21.81P 21-82 Suggest a reason why the same protein system moves both sodium and potassium ions into and out of the cell.21.83P 21.84P 21-85 Which of the following statements is (are) consistent with what is known about membranes? (a) A membrane consists of a layer of proteins sandwiched between two layers of lipids. (b) The compositions of the inner and outer lipid layers are the same in any individual membrane. (c) Membranes contain glycolipids and glycoproteins. (d) Lipid bilayers are an important component of membranes. (e) Covalent bonding takes place between lipids and proteins in most membranes.21.86P 21-87 Which statements are consistent with the fluid mosaic model of membranes? (a) All membrane proteins are bound to the interior of the membrane. (b) Both proteins and lipids undergo transverse (flip-flop) diffusion from the inside to the outside of the membrane. (c) Some proteins and lipids undergo lateral diffusion along the inner or outer surface of the membrane.21.88P 21.89P 21-90 To what extent do lipids and carbohydrates play structural roles in living organisms? Do these roles differ in plants and in animals?21.91P 21.92P 21.93P 21.94P 21.95P 21.96P

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