Questions and Answers of Organic Chemistry 12th

For each of the following, identify the product (represented by A, B, and C) that would be formed through the indicated sequence of steps from the given starting material.
Develop a synthesis for the following molecule using only the indicated materials as sources for the carbon atoms that appear in the final product. As a hint, you will need to draw upon several
The first step in peptide synthesis is blocking (protection) of the amine functional group of an amino acid (a compound that contains both amine and carboxylic acid functional groups). Such a
For each of the following questions, please provide a route that could reasonably be expected to convert the starting material into the final product. In each case, more than one reaction is
Working backward, deduce the starting material that led to the indicated product through the defined reactions.(a)(b) (1) KOt-Bu, t-BuOH (2) 0₂ (3) Me,S (4) Cl₂.hv CI
For each of the following, identify the product (represented by A and B) that would be formed through the indicated sequence of steps from the given starting material.
Devise two syntheses for meso-2,3-butanediol starting with acetylene (ethyne) and methane. Your two pathways should take different approaches during the course of the reactions for controlling the
Evaluate the relative merits of your syntheses on the basis of selectivity and efficiency. (Decide which ones could be argued to be the “best” syntheses and which might be “poorer” syntheses.)
For each of the following, write a mechanism that accounts for the reaction shown.a)b)c)d) OH HA + НОН
The following reaction does not produce the product shown.(a) Predict the major product from the conditions shown above, and write a detailed mechanism for its formation.(b) What reaction conditions
For each of the following, identify the product (represented by A, B, and C) that would be formed through the indicated sequence of steps from the given starting material. Be careful to indicate the
Working backward, deduce the starting material that led to the indicated product through the defined reactions.(a)(b) (1) t-BUOK, t-BUOH (2) NBS, ROOR, A (3) Na = (racemic)
Provide a reasonable mechanism for each of the following reactions:(a)(b)(c) What other products would you expect from the reaction given in part (b)?(d) ОН H₂SO4, heat
Which member of these pairs is the more polar?(a) CHCl3 or CCl4(b) (c) CH3I or CH3Cl CI CI or CI CI
Describe how solubility could be used to distinguish between members of each of the following pairs of compounds:(a) 4-Chlorophenol and 4-chloro-1-methylbenzene(b) 4-Methylphenol and 4-methylbenzoic
Though they each contain only one type of chemical bond, the dipole moment of BF3 is 0 D but that of NF3 is 0.24 D. What does this indicate about their molecular shapes?
An alkane (A) with the formula C6H14 reacts with chlorine to yield three compounds with the formula C6H13Cl: B, C, and D. Of these only C and D undergo dehydrohalogenation with sodium ethoxide in
Compound Y (C10H18O5) exhibits one 1H NMR signal at δ 1.4 (a singlet), three signals in its broadband proton decoupled 13C NMR spectrum at δ 28, 87, and 151, and has the following IR spectrum
Dehalogenation of meso-2,3-dibromobutane occurs when it is treated with potassium iodide in ethanol. The product is trans-2-butene. Similar dehalogenation of either enantiomer of 2,3dibromobutane
Working backward, deduce the starting material that led to the indicated product through the defined reactions.(a)(b)(c) (1) BrMg :3 (2) H₂O¹ (3) MSCI, pyr. (4) KOt-Bu, t-BuOH (5) Lindlar's cat.,
For each of the following questions, please provide a route that could reasonably be expected to convert the starting material into the final product. In each case, more than one reaction is
Compound X (C5H10O) shows a strong IR absorption band near 1710 cm−1. The broadband proton-decoupled 13C NMR spectrum of X is shown in Fig. 2. Propose a structure for X.Fig. 2 220 C X,
There are nine stereoisomers of 1,2,3,4,5,6-hexachlorocyclohexane. Seven of these isomers are meso compounds and two are a pair of enantiomers.(a) Write structures for all of these stereoisomers,
When the following deuterium-labeled isomer undergoes elimination, the reaction yields trans-2-butene and cis-2-butene-2-d (as well as some 1-butene-3-d ).These compounds are not produced:How can you
Fluorination of (R)-2-fluorobutane yields a mixture of isomers with the formula C4H8F2.(a) How many different isomers would you expect to be produced? Write their structures.(b) If the mixture of
Elucidate the structures of compounds A through I in the following “road map” problem. Specify any missing reagents. A (C5H₂) Br., warm (1 molar equiv.) F CH,ONA (2 molar equiv.) G 1₁ HBr (no
Deduce the structures of compounds E–L in the roadmap below. E (C₂H13 Br) HBr (no peroxides) F (C8H₁4Br₂) meso + G (C₂H₁4Br₂) racemate
Synthesize 2-chloro-4-nitrobenzoic acid from toluene and any other reagents necessary. Begin by writing a retrosynthetic analysis.
The trifluoromethyl group is a meta director. Explain why this is so using resonance structures for the arenium ions that would result upon ortho, meta, and para bromination of trifluoromethyl
For each of the following questions, please provide a route that could reasonably be expected to convert the starting material into the final product. In each case, more than one reaction is
Use the S − A + 1 = N method to determine the number of rings in the cubane.
For each of the following, identify the product (represented by A, B, and C) that would be formed through the indicated sequence of steps from the given starting material(a)(b)(c) (1) NaNH,, EtBr (2)
Use the 1HNMR and IR data below to propose a stereochemical formula that is consistent with the data for the following compound: C2HXCly. ¹H NMR 8 (ppm) 6.3 Splitting S Integration
(a) Draw structures for all organic products that would result when an excess of cis-1,3-dimethylcyclohexane reacts with Br2 in the presence of heat and light. Use three-dimensional formulas to show
Consider the following information.(a) How many total 1HNMR signals would you expect for the molecule at the right?(b) Ha appears as a doublet of doublets (dd) at 1.32 ppm in the 1HNMR spectrum. Draw
The 1HNMR spectrum of a solution of 1,3-dimethylcyclopentadiene in concentrated sulfuric acid shows three peaks with relative areas of 6 : 4 : 1. What is the explanation for the appearance of the
Predict the products from each of the following reactions.(a)(b)(c)(d)(e)(f)(g) (1) Br₂, H₂O (2) NaOH (3) MeONa, MeOH
Draw a free-energy diagram (reaction progress versus free energy) for each of the following reactions. Be sure to label the axes,transition state(s), the energy of activation for each step, and ΔH,
The following is a synthesis of “musculature,” the sex-attractant pheromone of the common housefly. Give the structure of each intermediate and of musculature itself. the Br HC CNa A
A hydrocarbon (A) has the formula C7H10. On catalytic hydrogenation, A is converted to B (C7H12). On treatment with cold, dilute, and basic KMnO4, A is converted to C (C7H12O2). When heated with
Write structures for the diastereomers of 2,3-diphenyl-2-butene and assign each diastereomer its (E) or (Z) designation. Hydrogenation of one of these diastereomers using a palladium catalyst
Predict the products from each of the following reactions.(a)(b)(c)(d)(e)(f) (1) BH₂:THF (2) NaOH, H₂O₂
Provide the reagents needed to achieve each of the following transformations.(a)(b)(c) -OH Br
Predict the products of the following reactions.(a)(b) Eto OEt (1) EtMgBr (excess) (2) NH,CI, H₂O
When either enantiomer of 3-chloro-1-butene [(R) or (S)] is subjected to hydrolysis, the products of the reaction are optically inactive. Explain these results.
Dehydrohalogenation of Meso-1,2-dibromo-1,2-diphenylmethane by the action of sodium ethoxide in ethanol yields (E )-1-Bromo-1-2-diphenylmethane. Similar dehydrohalogenation of either enantiomer of
Give structures for A–C. Br EtONa EtOH A (CH₁₂) major product BH:THF B (C₂H₁3) ₂BH HẠO, HỌ C (C₂H₁O) 14
(R)-3-Methyl-1-pentene is treated separately with the following reagents and the products in each case are separated by fractional distillation. Write appropriate formulas for all of the components
Compound A (C8H15Cl) exists as a racemic form. Compound A does not react with either Br2 or dilute aqueous KMnO4. When A is treated with magnesium in dry ether followed by aqueous acid and the
Indicate the reagents needed for the following multistep transformation. HO гхе
Synthesize the following compound by a method that derives all carbon atoms from alcohols of five carbons or fewer. You may use any other reagents needed. OH
Provide three methods that employ Grignard reagents to synthesize the following compound. HO
List the bases you gave as answers to Problem 3.20 in order of decreasing basicity.Problem 3.20What is the conjugate base of each of the following acids?(a) NH3 (b) H2O (c)
Streptomycin is an antibiotic that is especially useful against penicillin-resistant bacteria. (a) Identify all of the chirality centers in the structure of streptomycin. (b) Assign the
Cortisone is a natural steroid that can be isolated from the adrenal cortex. It has anti-inflammatory properties and is used to treat a variety of disorders (e.g., as a topical application for common
List the substituents in each of the following sets in order of priority, from highest to lowest:(a) −Cl, −OH, −SH, −H(b) −CH3, −CH2Br, −CH2Cl, −CH2OH(c) −H, −OH, −CHO,
Consider the following compound:(a) Develop all reasonable retrosynthetic analyses for this compound (any diastereomer) that, at some point, involve carbon-carbon bond formation by alkylation of an
cis-4-Bromocyclohexanol t - Buo / t - Buohracemic C6H10O (compound C) Compound C has infrared absorption in the 1620–1680 cm−1 and in the 3590–3650 cm−1 regions. Draw and label the (R) and
Write a mechanism for the following reaction. cat. H₂SO4 CH₂OH OCH 3
Write a mechanism that shows how 2,3-dimethyl-2-butanol is formed in the acid-catalyzed hydration of 3,3-dimethyl-1-butene.
The relative chemical shifts of the doublet and triplet of 1,1,2-trichloroethane (Fig. 9.4) and 1,1,2,3,3-pentachloropropane (Fig. 9.12) are reversed. Explain this.Fig. 9.4Fig. 9.12 2H (a) A
Two compounds with the molecular formula C5H10O have the following 1H and 13CNMR data. Both compounds have a strong IR absorption band in the 1710–1740 cm−1 region. Elucidate the structure of
Given the following information, elucidate the structures of compounds A and B. Both compounds are soluble in dilute aqueous HCl, and both have the same molecular formula. The mass spectra of A and B
Working backwards, deduce the starting material that led to the indicated product through the defined reactions.(a)(b)(c) Br (1) NaNH,, Mel (2) Br, (1 equiv) A - Br
In one industrial synthesis of ethanol, ethene first undergoes an addition reaction with sulfuric acid, and this product undergoes hydrolysis to ethanol. Write a mechanism for the addition of
Deduce the structures of compounds A–D. Draw structures that show stereochemistry where appropriate: CgH1,04 D OH (optically inactive) (1) hot KMNO,, HO | (2) H,0+ CH18 (1) Li, EINH, (2) NH,CI H2,
Write a reasonable and detailed mechanism for the following transformation: concd H,SO, + H,O heat ÓH
(a) Synthesize (3S,4R)-3,4-dibromo-1-cyclohexylpentane (and its enantiomer, since a racemic mixture will be formed) from ethyne, 1-chloro-2-cyclohexylethane, bromomethane, and any other reagents
When 1-cyclobutylethanol (shown below) is treated with concentrated H2SO4 at 120 °C, one of the products that is formed is methylcyclopentene. Please write a mechanism that can account for the
Working backward, deduce the starting material that led to the indicated product through the defined reactions(A)(B) (1) NANH, (2 equiv) A (2) Li/NH,
For each of the following questions, please provide a route that could reasonably be expected to convert the starting material into the final product. In each case, more than one reaction is
Write a structural formula for each of the following:(a) 3-Methylcyclobutene(b) 1-Methylcyclopentene(c) 2,3-Dimethyl-2-pentene(d) (Z)-3-Hexene(e) (E)-2-Pentene(f) 3,3,3-Tribromopropene(g)
Each of the following names is incorrect. Give the correct name and explain your reasoning. (a) trans-3-Pentene(b) 1,1-Dimethylethene(c) 2-Methylcyclohexene(d) 4-Methylcyclobutene(e) (Z
Predict the products of the following acid-base reactions. If the equilibrium would not result in the formation of appreciable amounts of products, you should so indicate. In each case label the
Acid-catalyzed dehydration of either 2-methyl-1-butanol or 3-methyl-1-butanol gives 2-methyl-2-butene as the major product. Write plausible mechanisms that explain these results.
Write the structure(s) of the major product(s) obtained when 2-chloro-2,3-dimethylbutane reacts with (a) Sodium ethoxide (EtONa) in ethanol (EtOH) at 80 °C or (in a separate reaction)
Using the (E )–(Z ) designation [and in parts (e) and (f) the (R )–(S ) designation as well give IUPAC names for each of the following:(a)(b)(c)(d)(e)(f) Br H CI
Consider the solvolysis reaction of (1S,2R)-1-bromo-1,2-dimethylcyclohexane in 80% H2O/20% CH3CH2OH at room temperature.(a) Write the structure of all chemically reasonable products from this
Consider the following sequence of reactions, taken from the early steps in a synthesis of ω-fluorooleic acid, a toxic natural compound from an African shrub.(ω-Fluorooleic acid, also called
Shown below are Newman projection formulas for (R, R)-, (S, S)-, and (R, S)-2,3-dichlorobutane. (a) Which is which? (b) Which formula is a meso compound?(A)(B)(c) CH3 Н. CI CI H.
Write structural formulas for all of the stereoisomers of 1,3-dimethylcyclopentane. Label pairs of enantiomers and meso compounds if they exist. Shown below are Newman projection formulas for (R,R)-,
Assign (R ) and (S ) configurations for each pair of enantiomers given as answers to Practice Problem 5.4.Practice Problem 5.4Some of the molecules listed here have a chirality center; some do not.
Write the enantiomeric forms of bromochlorofluoromethane and assign each enantiomer it's correct (R) or (S) configuration.
Classify each of the following objects as to whether it is chiral or achiral:(a) A screwdriver (b) A baseball bat (c) A golf club(d) A tennis shoe(e) An ear(g) A car (h) A hammer(f) A
Construct hand-held models of the 2-butanols represented in Fig. 5.3 and demonstrate for yourself that they are not mutually superposable. (a) Make similar models of 2-bromopropane. Are they
d-Galactitol is one of the toxic compounds produced by the disease galactosemia. Accumulation of high levels of d-galactitol causes the formation of cataracts. A Fischer projection for d-galactitol
When 1,2-dimethylcyclohexene is allowed to react with hydrogen in the presence of a platinum catalyst, the product of the reaction is a cycloalkane that has a melting point of −50 °C and a boiling
Draw structural formulas for two compounds having molecular formula C5H10O that would be consistent with the number of signals in the 13C NMR spectrum shown in Fig. A.6.
Write bond-line formulas for the following:(a) cis-3-Octene(b) trans-2-Hexene(c) 2,4-Dimethyl-2-pentene(d) trans-1-Chlorobut-2-ene(e) 4,5-Dibromo-1-pentene (f)
Draw a structural formula for a compound with molecular formula C5H10O that is consistent with the 13CNMR spectrum shown in Fig. A.5. Assign signals in the spectrum to specific carbons in your
When cyclohexene is dissolved in an appropriate solvent and allowed to react with chlorine, the product of the reaction, C6H10Cl2, has a melting point of −7 °C and a boiling point (at 16 torr) of
Using Newman projections, depict the relative positions of the substituents on the bridgehead atoms of cis- and trans-decalin. Which of these isomers would be expected to be more stable and why?
Arrange the following in order of increasing basicity:(a) CH3NH2, CH3N+H3 + h3, CH3N-H(b) CH3CH=CH, CH3CH2(c) CH3CH=CH, CH3CH2C − H2, CH3C ≡C−
List the acids you gave as answers to Problem 3.22 in order of decreasing acidity.Problem 3.22 What is the conjugate acid of each of the following bases?(a) HSO4− (b) H2O (c)
Use a table of pKa values, such as Table 3.1, to estimate pKa values for any potentially acidic hydrogens in each of the species you listed in part 1 (or for the conjugate acid).Table 3.1 TABLE 3.1
Predict the outcome of the following reaction. NH,
Nitro groups have a large acid-strengthening effect on phenols. The pKa of 4-nitrophenol is 7.15, whereas that of phenol is 9.89, a factor of almost 1000. Account for the greater acidity
(a) What is the value of ΔG ° for a reaction where Keq = 1? (b) Where Keq = 10? (The change in ΔG ° required to produce a 10-fold increase in the equilibrium constant is a useful term to
(a) Explain, on the basis of polarities and solubility, why separate layers formed when aqueous sodium bicarbonate was added to the reaction mixture.(b) List the chemical species likely to be present
Formic acid (HCO2H) has Ka = 1.77 × 10−4. (a) What are the molar concentrations of the hydronium ion and formate ion (HCO2−) in a 0.1 M aqueous solution of formic acid?(b) What percentage

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