Questions and Answers of Organic Chemistry 6th

Carv and Di Oxhide drive their family car about 12,000 miles per year with an average mileage of about 25 miles per gallon of gasoline. What is the “carbon footprint” (pounds of CO2 released into
The a-amino acids are the building blocks of proteins.Most have the following general structure:These amino acids differ only in their side chains —R.What functional groups are present in the side
Use the curved-arrow notation to derive a structure for the product of each of the following Lewis acid–base association reactions; be sure to assign formal charges. Label the Lewis acid and the
(a) Two amides are constitutional isomers and have the formula C4H9NO, and each contains an isopropyl group as part of its structure. Give structures for these two isomeric amides.(b) Draw the
Which of the following compounds can react with the Lewis base Cl– in a Lewis acid–base association reaction? H T H-C-H | H methane :CI: I :CI-AI-CI: aluminum chloride
For each of the following cases, give the product(s) of the transformation indicated by the curved-arrow notation. HỘI (a) HO: CH₂C: T CH3 (b) (CH3)₂C=C(CH3)2 H-Br: (c) H₂C H₂C :0
Gasoline consists mostly of alkanes. Explain why water is not usually very effective in extinguishing a gasoline fire.
In each part, match the melting point with the compound. (a) -109 °C, -56 °C, +100.7 °C: octane, 2-methylheptane, and 2,2,3,3-tetramethylbutane (b)-93 °C, +5.5 °C: benzene and toluene H H H
Give a general balanced reaction for (a) The complete combustion of an alkane (formula CnH2n+2).(b) The complete combustion of a cycloalkane containing one ring (formula CnH2n).
Given the boiling point of the first compound in each set, estimate the boiling point of the second. (a) CH₂CH₂CH₂CH₂CH₂CH₂Br (bp 155
Draw the structures and give the names of all isomers of octane with (a) Five carbons (b) Six carbons in their principal chains.
Label each carbon in the following molecules as primary, secondary, tertiary, or quaternary.(a)(b) Me
This problem illustrates how combustion can be used to determine the molecular formula of an unknown compound. A compound X (8.00 mg) undergoes combustion in a stream of oxygen to give 24.60 mg of
A hydrocarbon Y is found by combustion analysis to contain 87.17% carbon and 12.83% hydrogen by mass.(a) Use the procedure in Problem 2.44(b) and (c) to determine the molecular formula of Y.
Give the curved-arrow notation for the following reaction. + (CH3)3S: BÖH trimethylsulfonium hydroxide (CH3)2S: + H₂C-ÖH dimethyl sulfide methanol
Provide a curved-arrow notation for the following reaction in the left-to-right direction. CH₂OH-CH₂-CH-Br: I CH3 CH,Ö-H H₂C=CH L CH3 Br
Given the following two reactants and the curved-arrow notation for their reaction, draw the structure of the product. H₂N H co: CH3
For each of the following electron-pair displacement reactions, give the curved-arrow notation; identify the nucleophile, the nucleophilic center, the electrophile, the electrophilic center, and the
This problem refers to the reactions shown in Eqs. 3.12a and 3.12b. When equal numbers of moles of –OH, H—Br, and H3C—Br, are placed in solution together, what products are formed? leaving
A histidine residue (B), one of the functional groups in the structure of a certain enzyme, has a conjugate-acid pKa = 7.8. What is the fraction of each form (BH and B) present at physiological pH
In the following reactions, label the conjugate acid–base pairs and specify within each pair which is the acid and which is the base. Then draw the curved-arrow notation for these reactions in the
Write a Brønsted acid–base reaction in whichact as conjugate acid–base pairs. H₂Ö/-:ÖH and CH,ÖH/CH,Ö:-
Work Study Problem 3.5 for the reverse of each reaction 3.16a–c. CH3 H3C-C Br: I CH3 A CH3 H₂C-C+ B CH, H CH3 H3C-C-O -H I CH3 E H :0-H D F CH3 H₂C-C+ B T CH3 :Br C CH, H H3C-C-0-H CH3 E CH,
What is the pKa of an acid that has each of the following dissociation constants? (a) 10-3 (b) 5.8 × 10-6 x (c) 50
What is the dissociation constant of an acid that has each of the following pKa values?(a) 4 (b) 7.8 (c) –2
Using the pKa values in Table 3.1, calculate the equilibrium constant for each of the following reactions.(a) NH3 acting as a base toward the acid HCN (b) F– acting as a base toward the acid HCN
Write an equation for each of the following equilibria, and use Table 3.1 to identify the pKa value associated with the acidic species in each equilibrium.(a) Ammonia acting as a base toward the acid
The basicities of conjugate bases A– increase with increasing pKa of the conjugate acids AH. How do the basicities of conjugate bases A– change with increasing pKb?
(a) The pKa of acetic acid, CH3CO2H, is 4.67. What is the pKb of its conjugate base acetate, CH3CO2–?(b) Explain why an aqueous solution of acetic acid has an acidic pH, whereas an aqueous solution
Ibuprofen is a drug sold as a nonprescription anti-inflammatory medication.(a) What are the concentrations of ibuprofen and its conjugate base if 10–4 mole of ibuprofen is dissolved in an aqueous
Nicotine, a habit-forming compound found in tobacco, can be protonated twice:(a) Using intuition gained from this section, and using the pKa values shown above, sketch on the same set of axes,
(a) A reaction A + B ⇄ C has a standard free-energy change of –2.93 kJ mol–1 (–0.7 kcal mol–1) at 25 °C. What are the concentrations of A, B, and C at equilibrium if, at the beginning of
In each pair, which compound has the greater Brønsted acidity (smaller pKa)? + (a) : NH3 or NH4 (b) CH₂SH or + CH3SH2
Complete each of the following statements with a number. Assume that the temperature is 25°C (298 K).(a) Two reactions have equilibrium constants that differ by a factor of 10. Their standard free
In each of the following sets, arrange the compounds in order of decreasing pKa, and explain your reasoning. (a) CICH₂CH₂SH CICH₂CH₂OH CH3CH₂OH (b) (c) _CH_i_OH
Which of the following are electron-deficient compounds? Explain. (a) (c) (e) H₂C CH3 C* CH3 1+ H₂C-N-CH3 CH3 CH3 T CH 3 H₂C-N: (b) (d) H₂C H₂C CH3 CH3 CH3 B. CH3
(a) Although we normally think of acetic acid as an acid, it is amphoteric and can also act as a weak base. The conjugate acid of acetic acid is shown below. Using the curved-arrow notation, derive a
Calculate the standard free energy for dissociation of(a) Fluoroacetic acid (pKa = 2.66)(b) Acetic acid (pKa = 4.76)
Use the curved-arrow notation to indicate the flow of electrons in each of the transformations given in Fig. P3.41. (a) (b) (d) :O: H₂C- :S: -CH₂ + CN CH₂ CH₂
In each of the following processes, give the products and classify each of the atoms indicated by a colored label with one or more of the following terms: Brønsted base, Brønsted acid, nucleophilic
The examples of incorrect curved-arrow notation in Fig. P3.44 were found in the notebooks of Barney Bottlebrusher, a student who was known to have difficulty with organic chemistry. Explain what is
Naphthalene can be described by two resonance structures in addition to the following structure. Derive these structures with the curved-arrow notation. two additional structures naphthalene
Arrange the labeled bonds in the following molecule in order of increasing length, shortest first. Explain your reasoning. Ha H Η Η όξι Η H C=C H CH,CH,
Name the following compound using IUPAC substitutive nomenclature. HỌC=C−CH,CH,CH, I CH,CH,CH,CH,CH,
Which of the following alkenes can exist as double-bond stereoisomers? Identify the stereocenters in each. (a) H,C=CHCH,CH,CH, (b) CH,CH,CH=CHCH,CH, 1-pentene 3-hexene (c) H₂C=CH-CH=CH-CH3 (d)
Draw a conventional structure corresponding to the following skeletal structure, and then name it.
Give the structure for each of the following:(a) 2-methylpropene (b) 4-methyl-1,3-hexadiene (c) 1-isopropenylcyclopentene (d) 5-(3-pentenyl)-1,3,6,8-decatetraene
Name the following compounds. Ignore double-bond stereochemistry. (a) Me Me (b) CH3CH₂CH=CHCH₂CH₂CH3
What is the configuration of the following stereoisomer of 3-methyl-2-pentene? (The numbers are for reference in the solution.) H3C Н 2 3 c=c CH3 CH₂CH3
What is the configuration (E or Z) of the following alkene? (The numbers and letters are for reference in the solution.) H 2 H₂C C=C 02 CH₂CH₂CBr₂CH3 61
Give the structure of:(a) (E)-4-allyl-1,5-octadiene (b) (2E,7Z)-5-[(E)-1-propenyl]-2,7-nonadieneBe sure to read Study Guide Link 4.2 if you have difficulty with this problem.
Calculate the standard enthalpy difference between the cis and trans isomers of 2-butene. Specify which stereoisomer is more stable. The heats of formation are, for the cis isomer, 27.40 kJ mol–1,
Give the structure of an alkene that would give 2-bromopentane as the major (or sole) product of HBr addition.(The numbers are for reference in the solution.) an alkene + HBr 3 2
Calculate the unsaturation number for each of the formulas in parts (a) and (b) and each of the compounds in parts (c) and (d).(a) C3H4Cl4 (b) C5H8N2(c) Methylcyclohexane (d) 2,4,6-octatriene
Which of the following cannot be correct formula(s) for an organic compound? Explain.(a)(b) Draw constitutional isomers of compounds with the formula C4H8O that contain (1) An alcohol functional
A compound has the molecular formula C20H34O2. Certain structural evidence suggests that the compound contains two methyl groups and no carbon–carbon double bonds. Give one structure consistent
Which of the following two carboxylic acids is more acidic? Explain. H₂C=CH-CH₂- -OH 3-butenoic acid H3C-CH₂-CH₂- butanoic acid -OH
Which compound in each set should have the larger dipole moment? Explain.(a) Cis-2-butene or trans-2-butene (b) Propene or 2-methylpropene
(a) Calculate the enthalpy change for the hypothetical reaction 1-butene → 2-methylpropene. The heats of formation are 1-butene, 20.30 kJ mol–1 (20.07 kcal mol–1); 2 methylpropene, 217.3 kJ
(a) If the standard enthalpy change for the reaction 2-ethyl-1-butene → 1- hexene is 115.3 kJ mol–1 (13.66 kcal mol–1), and if ΔH°f for 1-hexene is 240.5 kJ mol–1 (29.68 kcal mol–1), what
Alkenes can undergo the addition of hydrogen in the presence of certain catalysts.The ΔH° of this reaction, called the enthalpy of hydrogenation, can be measured very accurately and can serve as a
The ΔH°f of CO2 is 2393.51 kJ mol–1 (294.05 kcal mol–1), and the ΔH°f of H2O is 2285.83 kJ mol–1 (268.32 kcal mol–1). Calculate the ΔH°f of 1-heptene from its heat of combustion,
Give the structure of the addition product formed when ethylene reacts with each of the following reagents:(a) H—I (b) Br2(c) BH3Each of the B—H bonds undergoes an addition to one molecule of
Classify the isomeric carbocations in each of the following parts as primary, secondary, or tertiary, and tell which is the most stable carbocation in each part and why.
Using the known regioselectivity of hydrogen halide addition to alkenes, predict the addition product that results from the reaction of:(a) H—Cl with 2-methylpropene (b) H—Br with
In each case, give two different alkene starting materials that would react with H¬Br to give the compound shown as the major (or only) addition product. (a) Br (b) Me Br
Which of the following carbocations is likely to rearrange? If rearrangement occurs, give the structures of the rearranged carbocations. @ H I + CH3 (b) CH3 CH3 T T CH3CH-C-CH3 + O
Only one of the following three alkyl halides can be prepared as the major product of the addition of HBr to an alkene. Which compound can be prepared in this way? Explain why the other two cannot be
Draw curved-arrow mechanisms and transition-state structures for each of the following two reactions. Each reaction occurs as a single step. (a) CH₂CH₂-Br: + FÖCH3 CH₂CH₂-ÖCH3 + :Br: (b)
(a) Draw the transition state for the reverse reaction of Eq. 4.30. Compare it with the transition state shown in Eq. 4.31.(b) What general statement can you make about the transition-state
(a) The standard free energy of activation of one reaction A is 90 kJ mol–1 (21.5 kcal mol–1). The standard free energy of activation of another reaction B is 75 kJ mol–1 (17.9 kcal mol–1).
Draw a reaction free-energy diagram for a reaction A ⇄ B ⇄ C that meets the following criteria: The standard free energies are in the order C < A < B, and the rate- limiting step of the reaction
Repeat Problem 4.30 for a case in which the standard free energies are in the order A , C , B, and the rate-limiting step of the reaction is A ⇄ B.Problem 4.30Draw a reaction free-energy diagram
Give the product formed when each of the following alkenes reacts with a large excess of hydrogen in the presence of Pd/C.(a) 1-pentene (b) (E)-1,3-hexadiene
(a) Give the structures of five alkenes, each with the formula C6H12, that would give hexane as the product of catalytic hydrogenation.(b) How many alkenes containing one double bond can react with
Give the mechanism for the reaction in Eq. 4.43. Show each step of the mechanism separately with careful use of the curvedarrow notation. Explain why the rearrangement takes place. H H₂C-C-CH=CH₂
Explain why the hydration of ethylene (Eq 4.44) is a very slow reaction. (Think about the structure of the reactive intermediate and apply Hammond’s postulate.) H₂C=CH₂ +
Give the structures and IUPAC substitutive names of the isomeric alkenes with molecular formula C6H12 containing five carbons in their principal chains.
Give the structures and the IUPAC substitutive names of the isomeric alkenes with the molecular formula C6H12 containing four carbons in their principal chain.
Which alkenes in Problem 4.41 give predominantly a single constitutional isomer when treated with HBr, and which give a mixture of isomers? Explain.Problem 4.41Give the structures and the IUPAC
Arrange the alkenes in Problem 4.40 in order of increasing heats of formation. (Some may be classified as “about the same.”)Problem 4.40Give the structures and IUPAC substitutive names of the
Give a structure for each of the following compounds.(a) Cyclobutene (b) 3-methyl-1-octene(c) 5,5-dimethyl-1,3-cycloheptadiene(d) 1-vinylcyclohexene
Classify each of the labeled bonds in the following structure in terms of the bond type (σ or π) and the component orbitals that overlap to form the bond. (For example, the carbon–carbon bond in
A confused chemist Al Keane used the following names in a paper about alkenes. Although each name specifies a structure, in some cases the name is incorrect. Correct the names that are wrong.(a)
Give the structures of all the alkenes containing one double bond that would give propylcyclohexane as the product of catalytic hydrogenation.
You have been called in as a consultant for the firm Alcohols Unlimited, which wants to build a plant to produce 3-methyl-1-butanol, (CH3)2CHCH2CH2OH. The research director, Al Keyhall, has proposed
A certain compound A is converted into a compound B in a reaction without intermediates. The reaction has an equilibrium constant Keq = [B]/[A] = 150 and, with the free energy of A as a reference
(a) Give the product X expected when methylenecyclobutane undergoes acid-catalyzed hydration.(b) The rate-limiting step is protonation of the double bond; use H3O+ as the acid catalyst. Draw the
Invoking Hammond’s postulate, draw the structure of the reactive intermediate that should most closely resemble the transition state of the rate-limiting step for the hydration of
The heat of formation of (E)-1,3-pentadiene is 75.8 kJ mol–1 (18.1 kcal mol–1), and that of 1,4-pentadiene is 106.3 kJ mol–1 (25.4 kcal mol–1).(a) Which alkene has the more stable arrangement
The ΔH° of hydrogenation is the heat liberated when a compound undergoes catalytic hydrogenation. Consider the ΔH° values for hydrogenation of the following three alkenes: 3-methyl-1-butene,
Make a model of cycloheptene with the trans (or E) configuration at the double bond. Now make a model of cis-cycloheptene. By examining your models, determine which compound should have the greater
The curved-arrow notation can be used to understand seemingly new reactions as simple extensions of what you already know. This is the first step in developing an ability to use the notation to
Using the curved-arrow notation, suggest a mechan ism for the reaction shown in Fig. P4.67.(1) Follow the problem-solving suggestions in Problem 4.65. (2) Use Hammond’s postulate to decide which
(a) Consider the second propagation step for peroxide-promoted HBr addition to an alkene (Eq. 5.52b). Calculate the ΔH° for this reaction.(b) Calculate the ΔH° for the same step using HCl instead
In a laboratory a bottle was found containing a clear liquid A. The bottle was labeled, “C10H16, Isolated from a lemon.” Because of your skills in organic chemistry, you have been hired to
Identify the asymmetric carbon(s) in 4-methyloctane: CH3 CH3CH₂CH₂CHCH₂CH₂CH₂CH3 4-methyloctane
State whether each of the following molecules is achiral or chiral. Cl H-C-Br -EL F (b) CI H-C-Br Cl H CH3 Cl (d) H I H₂C-NCH₂CH, Cl- T CH₂CH₂CH3
Determine the stereochemical configuration of the following enantiomer of 3-chloro-1-pentene: H₂C CH Cl I CH CH₂CH3
Ignoring specific markings, indicate whether the following objects are chiral or achiral. (State any assumptions that you make.)(a) A shoe (b) A book (c) A man or woman (d) A pair of shoes

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