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All Textbook Solutions for Organic Chemistry
Which of the following compounds have the same oxidation level, and which have different levels?Tell whether each of the following reactions is an oxidation, a reduction, or neither:34APAlkylbenzenes such as toluene (methylbenzene) react with NBS to give products in which bromine substitution has occurred at the position next to the aromatic ring (the benzylic position). Explain, based on the bond dissociation energies in Table 6-3 on page 170.36AP37AP38AP39AP40APThe syntheses shown here are unlikely to occur as written. What is wrong with each?Why do you suppose its not possible to prepare a Grignard reagent from a bromo alcohol such as 4-bromo-1-pentanol? Give another example of a molecule that is unlikely to form a Grignard reagent.43APIdentify the reagents a–c in the following scheme:45AP46AP47APThe relative rate of radical bromination is 1;82;1640 for 1;2;3 hydrogens, respectively. Draw all of the monobrominated products that you might obtain from the radical bromination of the compounds below. Calculate the relative percentage of each. (a) methylcyclobutane (b) 3,3-dimethylpentane (c) 3-methylpentane49APPredict the product and provide the entire catalytic cycle for the Suzuki–Miyaura reactions below.1P2P3P4P5PRank the following compounds in order of their expected reactivity toward SN2 reaction: CH3Br, CH3OTos, (CH3)3CCl, (CH3)2CHClOrganic solvents like benzene, ether, and chloroform are neither protic nor strongly polar. What effect would you expect these solvents to have on the reactivity of a nucleophile in SN2 reaction?8P9P10PRank the following substances in order of their expected SN1 reactivity:3-Bromo-1-butene and 1-bromo-2-butene undergo SN1 reaction at nearly the same rate, even though one is a secondary halide and the other is primary. Explain.13PReview the mechanism of geraniol biosynthesis shown in Figure 11-15, and propose a mechanism for the biosynthesis of limonene from linalyl diphosphate.15PWhat alkyl halides might the following alkenes have been made from?17P18P19P20P21VCFrom what alkyl bromide was the following alkyl acetate made by SN2 reaction? Write the reaction, showing all stereochemistry.23VC24VC25MP26MP27MP28MP29MP30MP31MP32MPMetabolism of S-adenosylhomocysteine (Section 11-6) involves the following sequence. Propose a mechanism for the second step.Reaction of iodoethane with CN- yields a small amount of isonitrile, CH3CH2N≡C, along with the nitrile CH3CH2N≡N, as the major product. Write electron-dot structures for both products, assign formal charges as necessary, and propose mechanisms to account for their formation.One step in the urea cycle for ridding the body of ammonia is the conversion of argininosuccinate to the amino acid arginine plus fumarate. Propose a mechanism for the reaction, and show the structure of arginine.36MP37MPPropose a mechanism for the following reaction, an important step in the laboratory synthesis of proteins:39APThe following Walden cycle has been carried out. Explain the results, and indicate where Walden inversion occurs.41APWhich reactant in each of the following pairs is more nucleophilic? Explain. (a) -NH2 or NH3 (b) H2O or CH3CO2- (c) BF3 or F- (d) (CH3)3P or (CH3)3N (e) I- or Cl- (f) -C≡N or -OCH343AP44AP45AP46AP47AP48APPropose structures for compounds that fit the following descriptions: (a) An alkyl halide that gives a mixture of three alkenes on E2 reaction (b) An organohalide that will not undergo nucleophilic substitution (c) An alkyl halide that gives the non-Zaitsev product on E2 reaction (d) An alcohol that reacts rapidly with HCl at 0 CWhat products would you expect from the reaction of 1-bromopropane with each of the following? (a) NaNH2 (b) KOC(CH3)3 (c) NaI (d) NaCN (e) NaCCH (f) Mg, then H2O51AP52AP53AP54AP55APOrder each of the following sets of compounds with respect to SN1 reactivity:Order each of the following sets of compounds with respect to SN2 reactivity:58AP59APEthers can often be prepared by SN2 reaction of alkoxide ions, RO-, with alkyl halides. Suppose you wanted to prepare cyclohexyl methyl ether. Which of the two possible routes shown below would you choose? Explain.Show the stereochemistry of the epoxide (see Problem 11-31) you would obtain by formation of a bromohydrin from trans-2-butene, followed by treatment with base.62APIn addition to not undergoing substitution reactions, the alkyl bromide shown in Problem 11-32 also fails to undergo an elimination reaction when treated with base. Explain.The tosylate of (2R, 3S)-3-phenyl-2-butanol undergoes E2 elimination on treatment with sodium ethoxide to yield (Z)-2-phenyl-2-butene. Explain, using Newman projections.65AP66AP67AP68AP69AP(S)-2-Butanol slowly racemizes on standing in dilute sulfuric acid. Explain.Reaction of HBr with (R)-3-methyl-3-hexanol leads to racemic 3-bromo-3-methylhexane. Explain.Treatment of 1-bromo-2-deuterio-2-phenylethane with strong base leads to a mixture of deuterated and nondeuterated phenylethylenes in an approximately 71 ratio. Explain.73AP74APIn light of your answer to Problem 11-74, explain why one of the following isomers undergoes E2 reaction approximately 100 times as fast as the other. Which isomer is more reactive, and why?76APCompound X is optically inactive and has the formula C16H16Br2. On treatment with strong base, X gives hydrocarbon Y, C16H14. Compound Y absorbs 2 equivalents of hydrogen when reduced over a palladium catalyst and reacts with ozone to give two fragments. One fragment, Z, is an aldehyde with formula C7H6O. The other fragment is glyoxal, (CHO)2. Write the reactions involved, and suggest structures for X, Y, and Z. What is the stereochemistry of X?When a primary alcohol is treated with p-toluenesulfonyl chloride at room temperature in the presence of an organic base such as pyridine, a tosylate is formed. When the same reaction is carried out at higher temperature, an alkyl chloride is often formed. Explain.79APAmines are converted into alkenes by a two-step process called Hofmann elimination. SN2 reaction of the amine with an excess of CH3I in the first step yields an intermediate that undergoes E2 reaction when treated with silver oxide as base. Pentylamine, for example, yields 1-pentene. Propose a structure for the intermediate, and explain why it readily undergoes elimination.The antipsychotic drug flupentixol is prepared by the following scheme:1PTwo mass spectra are shown in FIGURE 12-8. One spectrum is that of 2-methyl-2-pentene; the other is of 2-hexene. Which is which? Explain.What are the masses of the charged fragments produced in the following cleavage pathways? (a) Alpha cleavage of 2-pentanone (CH3COCH2CH2CH3) (b) Dehydration of cyclohexanol (hydroxycyclohexane) (c) McLafferty rearrangement of 4-methyl-2-pentanone [CH3COCH2CH(CH3)2] (d) Alpha cleavage of triethylamine [(CH3CH2)3N]4P5P6PWhat functional groups might the following molecules contain? (a) A compound with a strong absorption at 1710 cm-1 (b) A compound with a strong absorption at 1540 cm-1 (c) A compound with strong absorptions at 1720 cm-1 and 2500 to 3100 cm-1How might you use IR spectroscopy to distinguish between the following pairs of isomers? (a) CH3CH2OH and CH3OCH3 (b) Cyclohexane and 1-hexene (c) CH3CH2CO2H and HOCH2CH2CHO9PWhere might the following compounds have IR absorptions?Where might the following compound have IR absorptions?12VCShow the structures of the fragments you would expect in the mass spectra of the following molecules:Propose structures for compounds that fit the following mass-spectral data: (a) A hydrocarbon with M+=132 (b) A hydrocarbon with M+=166 (c) A hydrocarbon with M+=84Write molecular formulas for compounds that show the following molecular ions in their high-resolution mass spectra, assuming that C, H, N, and O might be present. The exact atomic masses are: 1.007 83 (1H), 12.000 00 (12C), 14.003 07 (14N), 15.994 91 (16O). (a) M+=98.0844 (b) M+=123.0320Camphor, a saturated monoketone from the Asian camphor tree, is used among other things as a moth repellent and as a constituent of embalming fluid. If camphor has M+=152.1201 by high-resolution mass spectrometry, what is its molecular formula? How many rings does camphor have?The nitrogen rule of mass spectrometry says that a compound containing an odd number of nitrogens has an odd-numbered molecular ion. Conversely, a compound containing an even number of nitrogens has an even-numbered M+ peak. Explain.In light of the nitrogen rule mentioned in Problem 12-17, what is the molecular formula of pyridine, M+=79?Nicotine is a diamino compound isolated from dried tobacco leaves. Nicotine has two rings and M+=162.1157 by high-resolution mass spectrometry. Give a molecular formula for nicotine, and calculate the number of double bonds.The hormone cortisone contains C, H, and O, and shows a molecular ion at M+=360.1937 by high-resolution mass spectrometry. What is the molecular formula of cortisone? (The degree of unsaturation for cortisone is 8.)Halogenated compounds are particularly easy to identify by their mass spectra because both chlorine and bromine occur naturally as mixtures of two abundant isotopes. Recall that chlorine occurs as 35Cl (75.8%) and 37Cl (24.2%); and bromine occurs as 79Br (50.7%) and 81Br (49.3%). At what masses do the molecular ions occur for the following formulas? What are the relative percentages of each molecular ion? (a) Bromomethane, CH3Br (b) 1-Chlorohexane, C6H13Cl22APPropose structures for compounds that fit the following data: (a) A ketone with M+=86 and fragments at m/z=71 and m/z=43 (b) An alcohol with M+=88 and fragments at m/z=73, m/z=70, and m/z=592-Methylpentane (C6H14) has the mass spectrum shown. Which peak represents M1? Which is the base peak? Propose structures for fragment ions of m/z=71, 57, 43, and 29. Why does the base peak have the mass it does?Assume that you are in a laboratory carrying out the catalytic hydrogenation of cyclohexene to cyclohexane. How could you use a mass spectrometer to determine when the reaction is finished?What fragments might you expect in the mass spectra of the following compounds?How might you use IR spectroscopy to distinguish among the three isomers 1-butyne, 1, 3-butadiene, and 2-butyne?Would you expect two enantiomers such as (R)-2-bromobutane and (S)-2-bromobutane to have identical or different IR spectra? Explain.Would you expect two diastereomers such as meso-2, 3-dibromobutane and (2R, 3R)-dibromobutane to have identical or different IR spectra? Explain.Propose structures for compounds that meet the following descriptions: (a) C5H8, with IR absorptions at 3300 and 2150 cm-1 (b) C4H8O, with a strong IR absorption at 3400 cm-1 (c) C4H8O, with a strong IR absorption at 1715 cm-1 (d) C8H10, with IR absorptions at 1600 and 1500 cm-1How could you use infrared spectroscopy to distinguish between the following pairs of isomers? (a) HC≡CCH2NH2 and CH3CH2C≡N (b) CH3COCH3 and CH3CH2CHO32APAt what approximate positions might the following compounds show IR absorptions?How would you use infrared spectroscopy to distinguish between the following pairs of constitutional isomers?At what approximate positions might the following compounds show IR absorptions?Assume that you are carrying out the dehydration of 1-methylcyclohexanol to yield 1-methylcyclohexene. How could you use infrared spectroscopy to determine when the reaction is complete?Assume that you are carrying out the base-induced dehydrobromination of 3-bromo-3-methylpentane (Section 11-7) to yield an alkene. How could you use IR spectroscopy to tell which of three possible elimination products is formed, if one includes E/Z isomers?38APCarvone is an unsaturated ketone responsible for the odor of spearmint. If carvone has M+=150 in its mass spectrum and contains three double bonds and one ring, what is its molecular formula?40APThe mass spectrum (a) and the infrared spectrum (b) of an unknown hydrocarbon are shown. Propose as many structures as you can.The mass spectrum (a) and the infrared spectrum (b) of another unknown hydrocarbon are shown. Propose as many structures as you can.Propose structures for compounds that meet the following descriptions: (a) An optically active compound C5H10O with an IR absorption at 1730 cm-1 (b) A non-optically active compound C5H9N with an IR absorption at 2215 cm-14-Methyl-2-pentanone and 3-methylpentanal are isomers. Explain how you could tell them apart, both by mass spectrometry and by infrared spectroscopy.Grignard reagents undergo a general and very useful reaction with ketones. Methylmagnesium bromide, for example, reacts with cyclohexanone to yield a product with the formula C7H14O. What is the structure of this product if it has an IR absorption at 3400 cm-1?Ketones undergo a reduction when treated with sodium borohydride, NaBH4. What is the structure of the compound produced by reaction of 2-butanone with NaBH4 if it has an IR absorption at 3400 cm-1 and M+=74 in the mass spectrum?Nitriles, R–=C≡N, undergo a hydrolysis reaction when heated with aqueous acid. What is the structure of the compound produced by hydrolysis of propanenitrile, CH3CH2C≡N, if it has IR absorptions from 2500–3100 cm-1 and at 1710 cm-1, and has M+=74?The infrared spectrum of the compound with the mass spectrum shown below lacks any significant absorption above 3000 cm-1. There is a prominent peak near 1740 cm-1 and another strong peak near 1200 cm-1. Propose a structure consistent with the data.The infrared spectrum of the compound with the mass spectrum shown below has a medium-intensity peak at about 1650 cm-1. There is also a C-H out-of-plane bending peak near 880 cm-1. Propose a structure consistent with the data.50AP1P2P3PThe following 1H NMR peaks were recorded on a spectrometer operating at 200 MHz. Convert each into δ units. (a) CHCl3; 1454 Hz (b) CH3Cl; 610 Hz (c) CH3OH; 693 Hz (d) CH2Cl2; 1060 HzWhen the 1Η NMR spectrum of acetone, CH3COCH3, is recorded on an instrument operating at 200 MHz, a single sharp resonance at 2.1 δ is seen. (a) How many hertz downfield from TMS does the acetone resonance correspond to? (b) If the 1Η NMR spectrum of acetone were recorded at 500 MHz, what would the position of the absorption be in δ units? (c) How many hertz downfield from TMS does this 500 MHz resonance correspond to?Each of the following compounds has a single 1H NMR peak. Approximately where would you expect each compound to absorb?Identify the different types of protons in the following molecule, and tell where you would expect each to absorb:How many peaks would you expect in the 1H NMR spectrum of 1, 4-dimethyl- benzene (para-xylene, or p-xylene)? What ratio of peak areas would you expect on integration of the spectrum? Refer to Table 13-3 for approximate chemical shifts, and sketch what the spectrum would look like. (Remember from Section 2-4 that aromatic rings have two resonance forms.)Predict the splitting patterns you would expect for each proton in the following molecules:Draw structures for compounds that meet the following descriptions: (a) C2Η6Ο: one singlet (b) C3H7Cl: one doublet and one septet (c) C4H8Cl2O; two triplets (d) C4H8O2: one singlet, one triplet, and one quartetThe integrated 1H NMR spectrum of a compound of formula C4H10O is shown in FIGURE 13-11. Propose a structure.Identify the indicated sets of protons as unrelated, homotopic, enantiotopic, or diastereotopic:How many kinds of electronically nonequivalent protons are present in each of the following compounds, and thus how many NMR absorptions might you expect in each? (a) CH3CH2Br (b) CH3OCH2CH(CH3)2 (c) CH3CH2CH2NO2 (d) Methylbenzene (e) 2-Methyl-1-butene (f) cis-3-HexeneHow many absorptions would you expect (S)-malate, an intermediate in carbohydrate metabolism, to have in its 1H NMR spectrum? Explain.3-Bromo-1-phenyl-1-propene shows a complex NMR spectrum in which the vinylic proton at C2 is coupled with both the C1 vinylic proton (J = 16 Hz) and the C3 methylene protons (J = 8 Hz). Draw a tree diagram for the C2 proton signal, and account for the fact that a five-line multiplet is observed.How could you use 1H NMR to determine the regiochemistry of electrophilic addition to alkenes? For example, does addition of HCl to 1-methylcyclohexene yield 1-chloro-l-methylcyclohexane or l-chloro-2-methylcyclohexane?17PPropose structures for compounds that fit the following descriptions: (a) A hydrocarbon with seven lines in its 13C NMR spectrum (b) A six-carbon compound with only five lines in its 13C NMR spectrum (c) A four-carbon compound with three lines in its 13C NMR spectrum19P20P21P22P23PInto how many peaks would you expect the 1H NMR signals of the indicated protons to be split? (Green = Cl.)How many absorptions would you expect the following compound to have in its 1H and 13C NMR spectra?Sketch what you might expect the 1H and 13C NMR spectra of the following compound to look like (green = Cl):How many electronically nonequivalent kinds of protons and how many kinds of carbons are present in the following compound? Dont forget that cyclohexane rings can ring-flip.Identify the indicated protons in the following molecules as unrelated, homotopic, enantiotopic, or diastereotopic.29AP30APWhen measured on a spectrometer operating at 200 MHz, chloroform (CHCl3) shows a single sharp absorption at 7.3 δ. (a) How many parts per million downfield from TMS does chloroform absorb? (b) How many hertz downfield from TMS would chloroform absorb if the measurement were carried out on a spectrometer operating at 360 MHz? (c) What would be the position of the chloroform absorption in δ units when measured on a 360 MHz spectrometer?32AP33APHow many types of nonequivalent protons are present in each of the following molecules?The following compounds all show a single line in their 1H NMR spectra. List them in order of expected increasing chemical shift: CH4, CH2Cl2, cyclohexane, CH3COCH3, H2C=CH2, benzene36APPropose structures for compounds with the following formulas that show only one peak in their 1H NMR spectra: (a) C5H12 (b) C5H10 (c) C4H8O2Predict the splitting pattern for each kind of hydrogen in the following molecules: (a) (CH3)3CH (b) CH3CH2CO2CH3 (C) trans-2-ButenePredict the splitting pattern for each kind of hydrogen in isopropyl propanoate, CH3CH2CO2CH(CH3)2.Identify the indicated sets of protons as unrelated, homotopic, enantiotopic, or diastereotopic:Identify the indicated sets of protons as unrelated, homotopic, enantiotopic, or diastereotopic:The acid-catalyzed dehydration of 1-methylcyclohexanol yields a mixture of two alkenes. How could you use 1H NMR to help you decide which was which?How could you use 1H NMR to distinguish between the following pairs of isomers?Propose structures for compounds that fit the following 1H NMR data: (a) C5H10O 0.95 (6 H, doublet, J=7 Hz) 2.10 (3 H, singlet) 2.43 (1 H, multiplet) (b) C3H5Br 2.32 (3 H, singlet) 5.35 (1 H, broad singlet) 5.54 (1 H, broad singlet)Propose structures for the two compounds whose 1H NMR spectra are shown.46APHow many absorptions would you expect to observe in the 13C NMR spectra of the following compounds? (a) 1,1-Dimethylcyclohexane (b) CH3CH2OCH3 (c) tert-Butylcyclohexane (d) 3-Methyl-l-pentyne (e) cis-1,2-Dimethylcyclohexane (f) Cyclohexanone48APHow could you use 1H and 13C NMR to help distinguish the following isomeric compounds of the formula C4H8?How could you use 1H NMR, 13C NMR, and IR spectroscopy to help you distinguish between the following structures?Assign as many resonances as you can to specific carbon atoms in the 13C NMR spectrum of ethyl benzoate.Assume that you have a compound with the formula C3H6O. (a) How many double bonds and/or rings does your compound contain? (b) Propose as many structures as you can that fit the molecular formula. (c) If your compound shows an infrared absorption peak at 1715 cm-1, what functional group does it have? (d) If your compound shows a single 1H NMR absorption peak at 2.1 , what is its structure?The compound whose 1H NMR spectrum is shown has the molecular formula C3H6Br2. Propose a structure.The compound whose 1H NMR spectrum is shown has the molecular formula C4H7O2Cl and has an infrared absorption peak at 1740 cm-1. Propose a structure.Propose structures for compounds that fit the following 1H NMR data: (a) C4H6Cl2 2.18 (3 H, singlet) 4.16 (2 H, doublet, J=7 Hz) 5.71 (1 H, triplet, J=7 Hz) (b) C10H14 1.30 (9 H, singlet) 7.30 (5 H, singlet) (c) C4H7BrO 2.11 (3 H, singlet) 3.52 (2 H, triplet, J=6 Hz) 4.40 (2 H, triplet, J=6 Hz) (d) C9H11Br 2.15 (2 H, quintet, J=7 Hz) 2.75 (2 H, triplet, J=7 Hz) 3.38 (2 H, triplet, J=7 Hz) 7.22 (5 H, singlet)Long-range coupling between protons more than two carbon atoms apart is sometimes observed when bonds intervene. An example is found in 1-methoxy-l-buten-3-yne. Not only does the acetylenic proton, Ηa, couple with the vinylic proton Hb, it also couples with the vinylic proton Hc, four carbon atoms away. The data are: Construct tree diagrams that account for the observed splitting patterns of Ηa, Hb, and Hc.The 1H and 13C NMR spectra of compound A, C8H9Br, are shown. Propose a structure for A, and assign peaks in the spectra to your structure.Propose structures for the three compounds whose 1H NMR spectra are shown.The mass spectrum and 13C NMR spectrum of a hydrocarbon are shown. Propose a structure for this hydrocarbon, and explain the spectral data.Compound A, a hydrocarbon with M+=96 in its mass spectrum, has the 13C spectral data given below. On reaction with BH3, followed by treatment with basic H2O2. A is converted into B, whose, 13C spectral data are also given below. Propose structures for A and B. Compound A Broadband-decoupled l3C NMR: 26.8, 28.7, 35.7, 106.9, 149.7 DEPT-90: no peaks DEPT-135: no positive peaks; negative peaks at 26.8, 28.7, 35.7, 106.9 Compound B Broadband-decoupled 13C NMR: 26.1, 26.9, 29.9, 40.5, 68.2 DEPT-90: 40.5 DEPT-135: positive peak at 40.5 ; negative peaks at 26.1, 26.9. 29.9, 68.2Propose a structure for compound C, which has M+=86 in its mass spectrum, an IR absorption at 3400 cm-1, and the following, 13C NMR spectral data: Compound C Broadband-decoupled l3C NMR: 30.2, 31.9, 61.8, 114.7, 138.4 DEPT-90: 138.4 DEPT-135: positive peak at 138.4 ; negative peaks at 30.2, 31.9, 61.8, 1 14.762GPPropose a structure for compound E, C7H12O2, which has the following, 13C NMR spectral data: Compound E Broadband-decoupled 13C NMR: 19.1, 28.0, 70.5, 129.0, 129.8, 165.8 DEPT-90: 28.0, 129.8 DEPT-135: positive peaks at 19.1, 28.0, 129.8 ; negative peaks at 70.5, 129.0Compound F, a hydrocarbon with M+=96 in its mass spectrum, undergoes reaction with HBr to yield compound G. Propose structures for F and G, whose 13C NMR spectral data are given below. Compound F Broadband-decoupled 13C NMR: 27.6, 29.3, 32.2, 132.4 DEPT-90: 132.4 DEPT-135: positive peak at 132.4 ; negative peaks at 27.6, 29.3, 32.2 Compound G Broadband-decoupled 13C NMR: 25.1, 27.7, 39.9, 56.0 DEPT-90: 56.0 DEPT-135: positive peak at 56.0 ; negative peaks at 25.1, 27.7, 39.93-Methyl-2-butanol has five signals in its 13C NMR spectrum at 17.90, 18.15, 20.00, 35.05, and 72.75 . Why are the two methyl groups attached to C3 nonequivalent? Making a molecular model should be helpful.A 13C NMR spectrum of commercially available 2,4-pentanediol, shows five peaks at 23.3, 23.9, 46.5, 64.8, and 68.1 . Explain.Carboxylic acids (RCO2H) react with alcohols (ROH) in the presence of an acid catalyst. The reaction product of propanoic acid with methanol has the following spectroscopic properties. Propose a structure. MS: M+=88 IR: 1735 cm-1 1H NMR: 1.11 (3 H, triplet, J=7 Hz); 2.32 (2 H, quartet, J=7 Hz); 3.65 (3 H, singlet) 13C NMR: 9.3, 27.6, 51.4, 174.668GPThe proton NMR spectrum is shown for a compound with the formula C5H9NO4. The infrared spectrum displays strong bands at 1750 and 1562 cm-1 and a medium-intensity band at 1320 cm-1. The normal carbon-13 and the DEPT experimental results are tabulated. Draw the structure of this compound.The proton NMR spectrum of a compound with the formula C5H10O is shown. The normal carbon-13 and the DEPT experimental results are tabulated. The infrared spectrum shows a broad peak at about 3340 cm-1 and a medium-sized peak at about 1651 cm-1. Draw the structure of this compound.The proton NMR spectrum is shown for a compound with the formula C7H12NO2. The infrared spectrum displays strong bands at 1738 cm-1 and a a weak band at 1689 cm-1. The normal carbon-13 and the DEPT experimental results are tabulated. Draw the structure of this compound.1PGive the structures of both 1, 2 and 1, 4 adducts resulting from reaction of 1 equivalent of HCl with 1,3-pentadiene.3PGive the structures of both 1, 2 and 1, 4 adducts resulting from reaction of 1 equivalent of HBr with the following compound:5P6PPredict the product of the following Diels–Alder reaction:8PWhich of the following dienes have an s-cis conformation, and which have an s-trans conformation? Of the s-trans dienes, which can readily rotate to s-cis?Predict the product of the following Diels–Alder reaction:11P12P13P14PWhich of the following compounds would you expect to show ultraviolet absorptions in the 200 to 400 nm range?16VCShow the product of the Diels–Alder reaction of the following diene with 3-buten-2-one, H2C = CHCOCH3. Make sure you show the full stereochemistry of the reaction product.18VC19VC20MP21MPIn light of your answer to Problem 14-21 propose mechanisms for the reactions below.Luminol, which is used by forensic scientists to find blood, fluoresces as a result of Diels–Alder-like process. The dianion of luminol reacts with O2 to form an unstable peroxide intermediate that then loses nitrogen to form a dicarboxylate and emit light. The process is similar to that in 14-21 and 14-22. Propose a mechanism for this process.24MPGive IUPAC names for the following compounds:26AP27APElectrophilic addition of Br2 to isoprene (2-methyl-1, 3-butadiene) yields the following product mixture: Of the 1, 2-addition products, explain why 3, 4-dibromo-3-methyl-1- butene (21%) predominates over 3, 4-dibromo-2-methyl-1-butene (3%).29AP30APPredict the products of the following Diels–Alder reactions:2,3-Di-tert-butyl-1,3-butadiene does not undergo Diels–Alder reactions. Explain.33AP34AP35AP36APRank the following dienophiles in order of their expected reactivity in the Diels–Alder reaction.38AP39AP40APAlthough the Diels–Alder reaction generally occurs between an electronrich diene and an electron-deficient dienophile, it is also possible to have inverse-demand Diels–Alder reactions between suitable electrondeficient conjugated double bonds and electron-rich alkenes. These reactions are particularly useful because they allow for the incorporation of heteroatoms into the new six-membered ring. Predict the products of each inverse-demand Diels–Alder reaction below. Be sure your products reflect the correct stereochemistry. If more than one regioisomer is possible, draw both.42APTires whose sidewalls are made of natural rubber tend to crack and weather rapidly in areas around cities where high levels of ozone and other industrial pollutants are found. Explain.44AP45AP46APWould you expect allene, H2C = C = CH2, to show a UV absorption in the 200 to 400 nm range? Explain.The following ultraviolet absorption maxima have been measured: 1,3-Butadiene 217 nm 2-Methyl-1,3-butadiene 220 nm 1,3-Pentadiene 223 nm 2,3-Dimethyl-1,3-butadiene 226 nm 2,4-Hexadiene 227 nm 2,4-Dimethyl-1,3-pentadiene 232 nm 2,5-Dimethyl-2,4-hexadiene 240 nm What conclusion can you draw about the effect of alkyl substitution on UV absorption maxima? Approximately what effect does each added alkyl group have?49AP-Ocimene is a pleasant-smelling hydrocarbon found in the leaves of certain herbs. It has the molecular formula C10H16 and a UV absorption maximum at 232 nm. On hydrogenation with a palladium catalyst, 2,6-dimethyloctane is obtained. Ozonolysis of -ocimene, followed by treatment with zinc and acetic acid, produces the following four fragments: (a) How many double bonds does -ocimene have? (b) Is -ocimene conjugated or nonconjugated? (c) Propose a structure for -ocimene. (d) Write the reactions, showing starting material and products.Draw the resonance forms that result when the dienes below are protonated. If the resonance forms differ in energy, identify the most stable one.52APTreatment of 3,4-dibromohexane with strong base leads to loss of 2 equivalents of HBr and formation of a product with formula C6H10. Three products are possible. Name each of the three, and tell how you would use 1H and 13CNMR spectroscopy to help identify them. How would you use UV spectroscopy?54AP55AP56AP57AP58APHydrocarbon A, C10H14, has a UV absorption at λmax = 236 nm and gives hydrocarbon B, C10H18, on catalytic hydrogenation. Ozonolysis of A, followed by zinc/acetic acid treatment, yields the following diketo dialdehyde: (a) Propose two possible structures for A. (b) Hydrocarbon A reacts with maleic anhydride to yield a Diels–Alder adduct. Which of your structures for A is correct? (c) Write the reactions, showing the starting material and products.60AP61AP62AP63AP64APThe double bond of an enamine (alkene + amine) is much more nucleophilic than a typical alkene double bond. Assuming that the nitrogen atom in an enamine is sp2hybridized, draw an orbital picture of an enamine, and explain why the double bond is electron-rich.66AP1PGive IUPAC names for the following compounds:3PPyridine is a flat, hexagonal molecule with bond angles of 120°. It undergoes substitution rather than addition and generally behaves like benzene. Draw a picture of the π orbitals of pyridine to explain its properties. Check your answer by looking ahead to section 15-55PDraw the five resonance structures of the cyclopentadienyl anion. Are all carbon-carbon bonds equivalent? How many absorption lines would you expect to see in the 1H NMR and 13C NMR spectra of the anion?7P8P9P10P11PHow many electrons does each of the four nitrogen atoms in purine contribute to the aromatic π system?Give IUPAC names for the following substances (red = O, blue = N):