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Questions and Answers of
Organic Chemistry
The formation of imines, oximes, hydrazones, and related derivatives from carbonyl compounds is reversible. Write a detailed mechanism for the acid-catalyzed hydrolysis of cyclohexanone semicarbazone
Formulate a plausible mechanism for the following reaction. The product is a precursor of mediquox (shown in the margin), an agent used to treat respiratory infections in chickens (no, we are not
The two isomeric compounds below are naturally occurring insect pheromones. The isomer on the left attracts the male olive fruit fl y; the one on the right, the female. (a) What kind of isomeric
Explain the results of the following reactions by means of mechanisms. (a)(b)(c) Explain why hemiacetal formation may be catalyzed by either acid or base, but acetal formation is catalyzed only
Overoxidation of primary alcohols to carboxylic acids is caused by the water present in the usual aqueous acidic Cr(VI) reagents. The water adds to the initial aldehyde product to form a hydrate,
Formulate the mechanism of the BF3-catalyzed reaction of CH3SH with butanal.
Formulate detailed mechanisms for (a) the formation of the hemiacetal of acetaldehyde and methanol under both acid- and base-catalyzed conditions and (b) the formation of the intramolecular
Give the expected product(s) of each of the following reactions. (a)(b)(c)(d)(e)(f) + excess CH,OH HO-
Give the expected products of reaction of 4-acetylcyclohexene with each of the reagents in Problem 34. Data From Problem 34(a) LiAlH4, (CH3CH2)2O, then H+, H2O (b) CH3CH2MgBr, (CH3CH2)2O,
Give the expected products of reaction of 2-pentanone with each of the reagents in Problem 34. Data From Problem 34(a) LiAlH4, (CH3CH2)2O, then H+, H2O (b) CH3CH2MgBr, (CH3CH2)2O, then H+,
Give the expected products of reaction of butanal with each of the following reagents. (a) LiAlH4, (CH3CH2)2O, then H+, H2O (b) CH3CH2MgBr, (CH3CH2)2O, then H+, H2O (c) HOCH2CH2OH,
For each of the following groups, rank the molecules in decreasing order of reactivity toward addition of a nucleophile to the most electrophilic sp2 -hybridized carbon. (a)(b)(c) BrCH2COCH3,
Write the expected products of ozonolysis (followed by mild reduction—e.g., by Zn) of each of the following molecules. (a) CH3CH2CH2CH=CH2(b) (c)(d)
Indicate which reagent or combination of reagents is best suited for each of the following reactions. (a)(b)(c)(d)(e)(f) OH
Reaction review. Without consulting the Reaction Road Map on pp. 816 –817, suggest reagents to convert each of the starting materials below into 3-hexanone. (a)(b)(c)(d)(e)(f)(g)(h)page
Following are spectroscopic and analytical characteristics for an unknown compound. Propose a structure. Empirical formula: C8H16O. 1H NMR: δ = 0.90 (t, 3 H), 1.0 – 1.6 (m, 8 H), 2.05 (s, 3 H),
The compounds described in Problem 27 have very different ultraviolet spectra. One has λmax(ϵ) = 232(13,000) and 308(1450) nm, whereas the other has λmax(ϵ) = 272(35,000) nm and a weaker
The following spectroscopic data are for two carbonyl compounds with the formula C8H12O. Suggest a structure for each compound. The letter “m” stands for the appearance of this particular part of
Name or draw the structure of each of the following compounds. (a)(b)(c)(d)(e)(f)(e) (Z )-2-Acetyl-2-butenal(f) trans-3-Chlorocyclobutanecarbaldehyde (CH3),CHCCH(CH;)2
Draw structures and provide IUPAC names for each of the following compounds. (a) Methyl ethyl ketone; (b) ethyl isobutyl ketone; (c) methyl tert-butyl ketone; (d) diisopropyl
The 1H NMR spectrum of 2,4-pentanedione indicates the presence of an enol tautomer of the dione. What is its most likely structure? H;C, c=c=c_ ОН ОН OH OH OH (а) (b) (с) (d) Но CH3
The aqueous hydroxide-promoted reaction of the compound shown in the margin with (CH3)3CCHO yields exclusively one compound. Which one is it? (a)(b)(c)(d) H;CC -CH;
How would you best classify the following reaction? (a) Wittig reaction; (b) Cyanohydrin formation; (c) Conjugate addition; (d) Aldol addition. H. NC -> H2C=CHCH=N H.
When 3-methyl-1,3-diphenyl-2-butanone is treated with excess D2O in the presence of catalytic acid, some of its hydrogens are replaced by deuterium. How many? (a) One; (b) Two; (c)
When 2-methylcyclopentanone is treated with the bulky base triphenylmethyllithium under the two sets of conditions shown, the two possible enolates are generated in differing ratios. Why is this
Write reagents (a, b, c, d, e) where they have been omitted from the following synthetic sequence. Each letter may correspond to one or more reaction steps. This sequence is the beginning of a
Devise reasonable plans for carrying out the following syntheses. Ignore stereochemistry in your strategies. (a)(b) CH3 |, starting from cyclohexanone CN
The following steroid synthesis contains modified versions of two key types of reactions presented in this chapter. Identify these reaction types and give detailed mechanisms for each of the
A somewhat unusual synthesis of cortisone-related steroids includes the following two reactions.
Treatment of cyclopentane-1,3-dione with iodomethane in the presence of base leads mainly to a mixture of three products. (a) Give a mechanistic description of how these three products are
Using the following information, propose structures for each of these compounds. (a) C5H10O, NMR spectrum A, UV λmax(e) 5 280(18) nm; (b) C5H8O, NMR spectrum B, UV lmax(e) 5 220(13,200),
Would you expect addition of HCl to the double bond of 3-buten-2-one (shown in the margin) to follow Markovnikov’s rule? Explain your answer by a mechanistic argument. CH;CCH=CH, 3-Buten-2-one
Propose syntheses of the following compounds by using Michael additions followed by aldol condensations (i.e., Robinson annulation). Each of the compounds shown has been instrumental in one or more
Write the final products of the following reaction sequences. (a)(b)(c)(d) Write a detailed mechanism for reaction sequence (c). NaOCH, CH,OН, Д O + CH2=CHCCH3
Write the products of each of the following reactions after aqueous work-up. (e) Write the results that you expect from base treatment of the products of reactions (c) and (d). LDA, THE (a)
Give the expected product(s) of each of the following reactions. 1. LDA, THF 2. BICH,COCH, H 1. LDA, THF 2. CH.CH Br, HMPA (a) CH,CCH,CH,CH3 (b) 0:
Write the expected major product of reaction of each of the carbonyl compounds (i) – (iii) with each of the reagents (a) – (h). CH2CH,CH3 (i) (ii) CH;CH=C. (iii) CH || (а) Н, Pа,
The distillate from sandalwood is one of the oldest and most highly valued fragrances in perfumery. The natural oil is in short supply and, until recently, synthetic substitutes have been difficult
A number of highly conjugated organic compounds have found use as sunscreens. One of the more widely used is 4-methylbenzylidene camphor (4-MBC), whose structure is shown in the margin. This compound
Reaction review III. Without consulting the Reaction Road Maps on pp. 818 – 819, suggest reagents to convert 3-buten-2-one into each of the following compounds. Page 818-819 (а) (b) (с) (d)
Reaction review II. Without consulting the Reaction Road Maps on pp. 818 – 819, suggest reagents to convert acetophenone into each of the following compounds. ОН (b) C,H5 CCI3 (c) C,H5 (a) C,H5
Reaction review. Without consulting the Reaction Road Maps on pp. 818 – 819, suggest reagents to convert butanal into each of the following compounds. (а) H. (b) (с) H. H. Br Br H. (d) H.
Aldol condensations may be catalyzed by acids. Suggest a role for H1 in the acid-catalyzed version.
For each of the three crossed aldol reactions described in Problem 47, indicate which, if any, of the multiple possible products should predominate in the reaction mixture and explain why. Data From
Write all possible products of the base-catalyzed crossed aldol reactions between each pair of reaction partners given below. (Multiple products are possible in every case; be sure to include
Rotundone (margin) is the natural product responsible for the peppery aroma in peppers, many herbs, and red wines. What cyclic diketone will give rotundone upon intramolecular aldol
Give the likely products for each of the following aldol addition reactions. NaOH, H,O (а) 2 -CH,CHO NaOH, H,O (b) -СНО + (СH3)СНCHO СНО NaOH, H,O CH3 NaOH, H,O (с) Н H3C (d) CH3
Formulate a detailed mechanism for the reaction that you wrote in (c) of Problem 43. Data From Problem 43(c) 2,2-dimethylcyclopentanone.
Write the structures of the expected major products of crossed aldol condensation at elevated temperature between excess benzaldehyde and (a) 1-phenylethanone(b) acetone; (c)
Write the structures of the aldol condensation products of (a) pentanal; (b) 3-methylbutanal; (c) cyclopentanone.
Formulate a mechanism for the acid-catalyzed hydrolysis of the pyrrolidine enamine of cyclohexanone (shown in the margin). + H,O H+ 'N' H
Would the use of an enamine instead of an enolate improve the likelihood of successful alkylation of a ketone by a secondary haloalkane?
The problem of double compared with single alkylation of ketones by iodomethane and base is mentioned in Section 18-4. Write a detailed mechanism showing how some double alkylation occurs even when
Give the product(s) of the following reaction sequences. 1. Н, Н* 2. 1. Н, Н* 2. (CH),С—СНCH.CI 3. Н', Н.О CH,Br 3. H., Н.О (а) CH,CНO (b) CH2CHO
Give the product(s) that would be expected on reaction of 3-pentanone with 1 equivalent of LDA, followed by addition of 1 equivalent of (а) CH,СH,Br (b) (CH),СНCI (с) (CH)-СНCH,OS- CH3
Propose a mechanism for the following reaction. (Take note of all of the products that are formed and base your answer on the mechanism for acid-catalyzed bromination of acetone shown below) CI
Describe the experimental conditions that would be best suited for the efficient synthesis of each of the following compounds from the corresponding nonhalogenated ketone. (a)(b)(c) Br O
What product(s) would form if each carbonyl compound in Problem 32 were treated with (a) alkaline D2O; (b) 1 equivalent of Br2 in acetic acid; (c) excess Cl2 in aqueous base? Data From Problem
Write the structures of every enol and enolate ion that can arise from each of the carbonyl compounds illustrated in Problem 32. Data From Problem 32 H;C. CH3 (a) CH;CH,CH,CH3 (b) CH;CCH(CH3)2
Underline the a-carbons and circle the a-hydrogens in each of the following structures. H;C. CH3 (a) CH;CH,ČCH,CH, (b) CH,CCH(CH,h (c) CH, H,C. CH3 CHO CH, (d) (e) (g) (CH3);CCH (h) (CH3),CCHCH
Among the following choices, the group that activates the benzene ring toward electrophilic aromatic substitution is (a) –NO2; (b) 2CF3; (c) –CO2H; (d) –OCH3; (e) –Br.
A volume of 135 mL of benzene was treated with excess Cl2 and AlCl3 to yield 50 mL of chlorobenzene. Given the atomic weights of C 5 12.0, H 5 1.00, and Cl 5 35.5, and the densities of benzene, 0.78
The 1H NMR spectrum of an unknown compound shows absorptions at (no multiplicities given) δ = 7.3 (5H), 2.3 (1 H), and 0.9 (6 H) ppm. One of the following five structures satisfies these data. Which
The intermediate cation A in the sequence C6H6 + E+ → A → C6H5E + H+ is best shown as H H E H E (а) (b) (с) ЕН (d) `E
Which of the following reactions is an electrophilic aromatic substitution? Se, 300° Cl, hv (a) C,H12 (b) C,H;CH3 CH;CH,CI BF,, 60°C Mg. ether (c) C,H, + (CH,),CHOH C,H,CH(CH;), (d) CH,Br
Polystyrene (polyethenylbenzene) is a familiar polymer used in the manufacture of foam cups and packing beads. One could, in principle, synthesize polystyrene by cationic polymerization with acid.
Typical conditions for nitrosation are illustrated in the following equation. Propose a detailed mechanism for this reaction. OH OH ОН NO NANO,, HCI, H0 NO
The nitroso group, –NO, as a substituent on a benzene ring acts as an ortho, para– directing group but is deactivating. Use the Lewis structure of the nitroso group and its inductive and
Although methoxy is a strongly activating (and ortho, para–directing) group, the meta positions in methoxybenzene (anisole) are actually slightly deactivated toward electrophilic substitution
Although methoxy is a strongly activating (and ortho, para–directing) group, the meta positions in methoxybenzene (anisole) are actually slightly deactivated toward electrophilic substitution
Electrophilic substitution on the benzene ring of benzenethiol (thiophenol, C6H5SH) is not possible. Why? What do you think happens when benzenethiol is allowed to react with an electrophile?
Sulfonation of naphthalene at 808C gives almost entirely 1-naphthalenesulfonic acid, whereas the same reaction at 1608C gives 2-naphthalenesulfonic acid. Propose an explanation.
Write the expected product(s) of each of the following reactions. CH3 LOCH3 Cl,, CCl, A HNO, Conc. H,SO, A (a) (b) NO2 CH,CCI, AICI,, CS, Br,, FeBr, (d) (e)
Predict the major mononitration product of each of the following disubstituted naphthalenes. (a) 1,3-Dimethylnaphthalene; (b) 1-chloro-5-methoxynaphthalene; (c)
Catalytic hydrogenation of naphthalene over Pd–C results in rapid addition of 2 moles of H2. Propose a structure for this product.
The NMR and IR spectra for four unknown compounds A through D are presented below and on the next two pages. Possible empirical formulas for them (not in any particular order) are C6H5Br, C6H6BrN,
The science of pain control has evolved dramatically in the past several years. The body deals with pain by releasing anandamide (see Section 20-6). Anandamide binds to the cannabinoid receptor, the
(4-Methoxyphenyl)methanol (anisyl alcohol) (see margin) contributes both to the fl avor of licorice and to the fragrance of lavender. Propose a synthesis of this compound from methoxybenzene
Propose a reasonable synthesis of each of the following multiply substituted arenes from benzene. CH3 CH,CH3 NO2 NO2 (а) (d) CI S,H CH3 Br CH3 NO2 Cl. Br CI Br. Br (f) (h) O,N NO,
(a) When a mixture containing one mole each of the three dimethylbenzenes (o-, m-, and p-xylene) is treated with one mole of chlorine in the presence of a Lewis acid catalyst, one of the three
Give the expected major product(s) of each of the following reactions. NO2 COOH CH,CH; Cl, FeCI, So,, H,SO, HNO,, H,SO, (а) (b) CH3 NHCH, SO,H CH3 Brs, FeBr, Br,, FeBr, SO, H;SO, (d) (e) CH
Reaction review. The preparation of the following compounds requires more than one step. As in Problem 41, suggest a monosubstituted benzene as starting material and the reagents for all the steps
Reaction review. Without consulting the Reaction Road Map, suggest a combination of reagent and monosubstituted benzene that would give each of the following compounds. Refer to Table 16-2 for
Give the expected major product(s) of each of the following electrophilic substitution reactions. N(CH3)2 CI CCH,CH, CH.CCI, AICI, Br,, FeBr, HNO,. H,SO, (a) (b) H;C CH; CH CH;0 NO2 SO,, H,SO,
Draw appropriate resonance forms to explain the activating ortho, para-directing character of the phenyl substituent in biphenyl Biphenyl
Do you agree with the following statement? “Strongly electron-withdrawing substituents on benzene rings are meta directing because they deactivate the meta positions less than they deactivate the
Draw appropriate resonance forms to explain the deactivating meta-directing character of the SO3H group in benzenesulfonic acid.
Write the structure(s) of the major product(s) that you expect from each of the following electrophilic aromatic substitutions. (a) Sulfonation of methoxybenzene (anisole); (b) bromination of
Write the structure(s) of the major product(s) that you expect from each of the following electrophilic aromatic substitutions. (a) Nitration of methylbenzene (toluene); (b) sulfonation of
Halogenation of 1,3-dimethylbenzene (m-xylene) takes place 100 times faster than halogenation of either its 1,2- or 1,4-isomers (o- or p-xylene). Suggest an explanation.
Rank the compounds in each of the following groups in order of decreasing reactivity toward electrophilic aromatic substitution. Explain your answers. CH3 СООН СООН (а) (b) ČH; СООН ČH3
Specify whether you expect the benzene rings in the following compounds to be activated or deactivated. СООН NO2 OH (a) (b) 'NO2 CH3 COOH NH2 SO-H Но HO C(CH3)3 (d) (e) (f) 'NO2 ČH3
The rate of nitration of (chloromethyl)benzene, shown below is 0.71 relative to the rate of nitration of benzene (=1). The (chloromethyl)nitrobenzene product mixture that results contains 32% ortho,
Rank the compounds in each of the following groups in order of decreasing reactivity toward electrophilic substitution. Explain your rankings. || OCCH3 CH3 CHCI, CH,CI OCH; O Na+ (а) (b) CH,CH;
Rank the compounds in each of the following groups in order of decreasing reactivity toward electrophilic substitution. Explain your rankings. || OCCH3 CH3 CHCI, CH,CI OCH; O Na+ (а) (b) CH,CH;
One of the compounds shown here contains carbon – carbon bonds that are 1.39Å long. Which one? CH3 (а) (b) (с) -CH3 (d) (e) H;CC=CCH; CH3
Which set of reagents will best carry out the conversion shown? (a) HBr, peroxides; (b) Br2, FeBr3; (c) Br2 in CCl4; (d) KBr Br
When compound A (shown in the margin) is treated with dilute mineral acid, an isomerization takes place. Which of the following compounds is the new isomer formed? CHCH3 CHCH3 A
The species that is not aromatic according to Hückel’s rule is (а) (b) (с) (d)
o-Iodoaniline is the common name of which of the following compounds? NH2 CH3 NH2 NH2 (a) (b) (d) CH3
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