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organic chemistry
Organic Chemistry 1st edition David R. Klein - Solutions
Propose a mechanism for the following transformation: Н Н н Нeat H.
When 2-methoxy-1,3-butadiene is treated with 3-buten-2-one, there are two potential regiochemical outcomes for the Diels-Alder reaction that occurs:Nevertheless, only one of these products is obtained. Draw resonance structures for the diene and the dienophile, and use these resonance structures to
Propose a plausible mechanism for the following transformatio.
Would you expect nitroethylene to be more or less reactive than ethylene in a Diels-Alder reaction? Ethylene Nitroethylene
In each of the following pairs of compounds identify the compound that liberates the most heat upon hydrogenation.(a)(b)
Treatment of 1,2-dibromocycloheptane with excess potassium tert-butoxide yields a product that absorbs UV light. Identify the product.
Draw all possible conjugated dienes with molecular formula C6H10, taking special care not to draw the same compound twice.
α-Terpinene is a pleasant-smelling compound present in the essential oil of marjoram, a perennial herb. Upon hydrogenation with a metal catalyst, α-terpinene reacts with two equivalents of hydrogen gas to produce 1-isopropyl-4-methylcyclohexane. Ozonolysis of
Predict the product for each of the following reactions:(a)(b)(c) ? Heat
Predict the product for each of the following reactions:(a)(b)(c) Heat Heat
When trans-3,4-dimethylcyclobutene is heated, conrotatory ring opening can produce two different products, yet only one is formed. Draw both products, identify which product is formed, and then explain why the other product is not formed.
Predict which side of the following equilibrium is favored, and explain your choice. Heat
Predict the product for each of the following electrocyclic reactions:(a)(b)(c)(d) Нeat hv
Propose a method for achieving the following transformation:
Propose a plausible mechanism for the following transformation: D D Нeat
When 5-deutero-5-methyl-1,3-cyclopentadiene is warmed to room temperature, it rapidly rearranges, giving an equilibrium mixture containing the original compound as well as two others. Propose a plausible mechanism for the formation of these other two compounds. Me Me Me D 25°C 25°C
Predict the expected λmaxof the following compound:
Which of the following compounds below do you expect to have a longer λmax?
Rank the following compounds in order of increasing λmax:
Compound A (C7H10) exhibits a λmaxof 230 nm in its UV absorption spectrum. Upon hydrogenation with a metal catalyst, compound A will react with two equivalents of hydrogen gas. Ozonolysis of compound A yields the following two compounds. Identify two possible structures for compound A.
Cylopentadiene reacts very rapidly in Diels-Alder reactions. In contrast, 1,3-cyclohexadiene reacts more slowly and 1,3-cycloheptadiene is practically unreactive. Can you offer an explanation for this trend?
Chlordane is a powerful insecticide that was used in the United States during the second half of the twentieth century. Its use was discontinued in1988 in recognition of its persistence and accumulation in the environment. Identify the reagents you would use to prepare chlordane via a Diels-Alder
The following triene reacts with excess maleic anhydride to produce a compound with molecular formula C14H12O6. Draw the structure of this product (ignoring stereochemistry). Maleic anhydride (excess) C14H1208
Starting with 1,3-butadiene as your only source of carbon atoms, and using any other reagents of your choice, design a synthesis of the following compound:
Identify the reagents you would use to prepare each of the following compounds via a Diels-Alder reaction:(a)(b)(c)(d)(e)(f)(g)(h) COOH COOH
Predict the products for each of the following Diels-Alder reactions:(a)(b)(c)(d)(e)(f) HOOC, НООС. COOH
Predict the products for each of the following Diels-Alder reactions:(a)(b)(c)(d)(e)(f) НООС. СООН НООC CN
The absorbance spectrum of 1,3-butadiene displays an absorption in the UV region (λmax = 217 nm), while the absorption spectrum of 1,2-butadiene does not display a similar absorption. Explain.
Rank the following dienophiles (from least reactive to most reactive) in terms of reactivity in a Diels-Alder reaction:
Each of the following compounds does not participate as a diene in a Diels-Alder reaction. Explain why in each case.(a)(b)(c)(d)
After performing the reaction from Problem 17.38, the reaction flask is heated to 40ºC and two of the products become the major products. When the flask is then cooled to 0ºC, no change occurs in the product distribution. Explain why an increase in temperature causes a change in the product
Draw all four products obtained when 2-ethyl-3- methyl-1,3-cyclohexadiene is treated with HBr at room temperature, and show the mechanism of their formation.
Draw the major product expected when 1,3-butadiene is treated with one equivalent of HBr at 40ºC, and show the mechanism of its formation.
Draw the major product expected when 1,3-butadiene is treated with one equivalent of HBr at 0ºC, and show the mechanism of its formation.
Identify the structure of the conjugated diene that will react with one equivalent of HBr to yield a racemic mixture of 3-bromocyclohexene.
For each of the following pairs of compounds determine whether the two compounds would be at equilibrium at room temperature or whether they could be isolated from one another:(a)(b)(c)
Circle each compound that has a conjugated π system:
Draw the structure of each of the following compounds:(a) 1,4-Cyclohexadiene(b) 1,3-Cyclohexadiene(c) (Z)-1,3-Pentadiene(d) (2Z,4E)-Hepta-2,4-diene(e) 2,3-Dimethyl-1,3-butadiene
Use the color wheel in the following figure.(a) Identify the color of a compound that absorbs orange light.(b) Identify the color of a compound that absorbs blue-green light.(c) Identify the color of a compound that absorbs orange-yellow light. Violet Red Blue Orange Green Yellow
Identify which of the following compounds is expected to have a larger λmax:
Use Woodward-Fieser rules to estimate the expected λmax for each of the following compounds:(a)(b)(c)(d)
Draw a plausible mechanism for the following transformation: Нeat
Predict the product for each of the following reactions.(a)(b)(c)(d) ? Heat
Predict the product for each of the following reactions.(a)(b)(c)(d) Heat Нeat
Consider the structure of cis-1, 2-divinylcyclopropane:This compound is stable at low temperature but rearranges at room temperature to produce 1, 4-cycloheptadiene.(a) Draw a mechanism for this transformation.(b) Using brackets and numbers, identify the type of sigmatropic rearrangement taking
For each of the following reactions, use brackets and two numbers to identify the type of sigmatropic rearrangement taking place:(a)(b) Heat
For each of the following reactions, use brackets and two numbers to identify the type of sigmatropic rearrangement taking place:(a)(b) Heat Н TH. Heat
Identify whether the product obtained from each of the following reactions is a meso compound or a pair of enantiomers:(a) Irradiation of (2E,4Z,6Z )-4,5-dimethyl-2,4,6-octatriene with UV light(b) Subjecting (2E,4Z,6Z )- 4,5-dimethyl-2,4,6-octatriene to elevated temperature(c) Irradiation of
Draw the structure of cis-3,4-diethylcyclobutene.(a) Conrotatory ring opening produces only one product. Draw the product and determine whether its formation is best achieved under thermal conditions or photochemical conditions.(b) Disrotatory ring opening can produce two possible products, but
Predict the product for each of the following reactions:(a)(b)(c) Light Light
Predict the major product(s) for each of the following thermal electrocyclic reactions:(a)(b)(c) Heat Heat
Consider the following [4+4] cycloaddition process. Would you expect this process to occur through a thermal or photochemical pathway? Justify your answer with MO theory. +
Predict the products for each of the following reactions:(a)(b)(c)(d)(e)(f) NC CN CN NC
Rank the following dienes in terms of reactivity in Diels- Alder reactions (from least reactive to most reactive):
Consider the following two isomers of 2,4-hexadiene. One isomer reacts rapidly as a diene in a Diels-Alder reaction, and the other does not. Identify which isomer is more reactive, and explain your choice. (2E,4E)-Hexadiene (22,4Z)-Hexadiene
Propose a mechanism for the following transformation:
Predict the product(s) obtained when benzoquinone is treated with excess butadiene: O: (Excess)
Predict the products for each of the following reactions:(a)(b)(c)(d)(e)(f)(g)(h)(i) OMe OMe
Predict the products for each of the following reactions:(a)(b)(c)(d)(e)(f)(g)(h)(i) OMe OMe .COOH СООН
What monomer should be used to make each of the following polymers:(a)(b) ZEU ZEU- ZEU
When 1,3-cyclopentadiene is treated with HBr, the temperature does not have an influence on the identity of the major product. Explain.
When 1,4-dimethylcyclohepta- 1,3-diene is treated with HBr at elevated temperature, the 1,2- dduct predominates, rather than the 1,4-adduct. Explain this result. HBr 40°C Br
Predict the products for each of the following reactions, and in each case, determine which product will predominate:(a)(b)(c) HBr 40°C HCI 0°C
Propose the structure of a conjugated diene for which 1,2-addition of HBr produces the same product as 1,4-addition of HBr.
Consider the following two dienes. When treated with HBr, one of these dienes yields four products, while the other diene yields only two products. Explain.
Predict the products for each of the following reactions, and propose a mechanism that explains the formation of each product:(a)(b)(c)(d)(e)(f) HCI HCI HCI
Draw an energy diagram showing the relative energy levels of the MOs for 1,3,5,7- octatetraene and identify the HOMO and LUMO for both the ground state and the excited state.
Identify the most stable compound:
Compare the following three isomeric dienes:(a) Which compound will liberate the least heat upon hydrogenation with 2 mol of hydrogen gas? Why?(b) Which compound will liberate the most heat upon hydrogenation with 2 mol of hydrogen gas? Why?
Rank the three C-C bonds of 1-butene in terms of bond length (from shortest to longest).
Identify reagents necessary to convert cyclohexane into 1,3-cylohexadiene: Notice that the starting material has no leaving groups and cannot simply be treated with a strong base. You must first introduce functionality into the starting material.
For each of the following compounds, identify whether each C R C Ï€ system is cumulated, conjugated, or isolated:(a)(b)(c)(d) HO HO- он О cis-Aconitic acid Plays a role in the citric acid cycle
Compare the chemical shifts of the carbon atoms in the13C NMR spectra of the following compounds:This is exactly what we would expect. Each chlorine atom withdraws electron density via induction, which deshields the carbon atom. The greater the number of chlorine atoms, the stronger the deshielding
Consider the two methyl groups shown in the following compound. Explain why the methyl group on the right side appears at lower chemical shift. CH3 0.8 ppm 1.0 ppm H;C.
Consider the structure of phenol:The chemical shift of the hydroxyl proton is found to be sensitive to the concentration of phenol. In a concentrated solution, the hydroxyl proton produces a signal at 7.5 ppm. However, in a dilute solution, the hydroxyl proton produces a signal at 4.5 ppm. Can you
Consider the structure of N,N-dimethylformamide (DMF):We might expect the two methyl groups to be equivalent; however, both the proton and carbon NMR spectra of DMF show two separate signals for the methyl groups. Propose an explanation for the nonequivalence of the methyl groups. Would you expect
Deduce the structure of a compound with molecular formula C5H10O that exhibits the following IR,1H NMR, and13C NMR spectra. Data from the mass spectrum are also provided. 100 Mass Spec. Data relative mz abund. 15 23 26 27 29 20 61 92 30 20 31 39 47 41 100 45 10 57 82 58 86 86 12 20 4000 3500 3000
For each of the following compounds, determine whether the two protons shown in red are homotopic, enantiotopic, or diastereotopic:(a)(b)(c)(d)(e)Discuss. OMe Н. Н CI H,
Deduce the structure of a compound with molecular formula C5H10O that exhibits the following IR,1H NMR, and13C NMR spectra. Data from the mass spectrum are also provided. 100 Mass Spec. Data relative mz abund. 15 23 26 27 29 20 61 92 30 20 31 39 47 41 100 45 10 57 82 58 86 86 12 20 4000 3500 3000
Deduce the structure of a compound with molecular formula C8H10O that exhibits the following IR,1H NMR, and13C NMR spectra. 100 80 60 40 20 2500 2000 Wavenumber (cm-1) 1000 4000 3500 3000 1500 % Transmittance 3 Proton NMR 3 2 2 Chemical Shift (ppm) Carbon NMR There are two, unresolved lines at 130
Deduce the structure of a compound with molecular formula C6H14O2that exhibits the following IR,1H NMR, and13C NMR spectra. 100 80 60 40 20 4000 3500 3000 2500 2000 1500 1000 Wavenumber (cm-1) Proton NMR 4.5 2.0 Chemical Shift (ppm) 4.0 3.5 3.0 2.5 1.5 1.0 0.5 Carbon NMR 100 80 60 40 20 Chemical
Deduce the structure of a compound with molecular formula C6H14O2that exhibits the following IR,1H NMR, and13C NMR spectra. 100 80 60 40 20 3000 2500 Wavenumber (cm-1) 4000 3500 2000 1500 1000 % Transmittance my Proton NMR 2 2 4.5 3.0 2.0 2.5 Chemical Shift (ppm) 4.0 3.5 1.5 1.0 0.5 Carbon NMR 100
Determine the structure of an alcohol with molecular formula C6H14O that exhibits the following DEPT-135 spectrum: DEPT-135 70 60 50 40 Chemical Shift (ppm) 30 20 10
Propose the structure of a compound consistent with the following data:(a) C5H10O, broadband-decoupled 13C NMR: 7.1, 34.6, 210.5 δ(b) C6H10O, broadband-decoupled 13C NMR: 70.8, 116.2, 134.8 δ
Deduce the structure of a compound with molecular formula C9H10O2that produces the following1H NMR spectrum and13C NMR spectrum: Proton NMR 10 Chemical Shift (ppm) Carbon NMR - 128.4 128.8- 35.8 -126.8 -30.7 140.4 -179.9 180 160 100 140 120 80 60 40 20 Chemical Shift (ppm)
Deduce the structure of a compound with molecular formula C9H12that produces the following1H NMR spectrum: Proton NMR Chemical Shift (ppm)
A compound with molecular formula C8H10O produces six signals in its13C NMR spectrum and exhibits the following1H NMR spectrum. Deduce the structure of the compound. Proton NMR Chemical Shift (ppm) -00
Propose the structure of a compound that exhibits the following 1H NMR data:(a) C5H10O1.09 δ (6H, doublet)2.12 δ (3H, singlet)2.58 δ (1H, septet)(b) C5H12O0.91 δ (3H, triplet)1.19 δ (6H, singlet)1.50 δ (2H, quartet)2.24 δ (1H, singlet)(c) C4H10O0.90 δ (6H, doublet)1.76 δ (1H,
A compound with molecular formula C4H6O4 produces a broad signal between 2500 and 3600 cm-1 in its IR spectrum and produces two signals in its 1H NMR spectrum (a singlet at 12.1 ppm with a relative integration of 1 and a singlet at 2.4 ppm with a relative integration of 2). Deduce the structure of
A compound with molecular formula C3H8O produces a broad signal between 3200 and 3600 cm-1 in its IR spectrumand produces two signals in its 13C NMR spectrum. Deduce the structure of the compound.
A compound with molecular formula C8H10 produces three signals in its 13C NMR spectrum and only two signals in its 1H NMR spectrum. Deduce the structure of the compound.
A compound with molecular formula C13H28 exhibits a 1H NMR spectrum with two signals: a septet with an integration of 1 and a doublet with an integration of 6. Deduce the structure of this compound.
Assuming a 300 MHz instrument is used, calculate the difference between the frequency of absorption (in hertz) of TMS and the frequency of absorption of a proton with a δ value of 1.2 ppm.
Compare the structures of ethylene, acetylene, and benzene. Each of these compounds produces only one signal in its1H NMR spectrum. Arrange these signals in order of increasing chemical shift. Н Н Н- -н Н H.
How many signals will be expected in the1H NMR spectrum of each of the following compounds?(a)(b)(c)(d)(e)(f)(g)(h) `NO2
When 1-methylcyclohexene is treated with HCl, a Markovnikov addition is observed. How would you use 1H NMR spectroscopy to determine that the major product is indeed the Markovnikov product?
Predict the expected number of signals in the13C NMR spectrum of each of the following compounds. For each signal, identify where you expect it to appear in the13C NMR spectrum:(a)(b)(c)
Rank the signals of the following compound in terms of increasing chemical shift. Identify the proton(s) giving rise to each signal: CI. Н. но
How many signals do you expect in the1H NMR spectrum of each of the following compounds:(a)(b)(c) ОН Geraniol Isolated from roses and used in perfumes но. NH2 но Dopamine A neurotransmitter that is deficient in Parkinson's disease
A compound with molecular formula C9H18 exhibits a 1H NMR spectrum with only one signal and a 13C NMR spectrum with two signals. Deduce the structure of this compound.
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