Identify the sole product of the following reaction:
> For each of the following carbocations determine if it will rearrange, and if so, draw the carbocation rearrangement with a curved arrow: (b) (c) (d) (f) (h) (6)
> For each of the following reactions determine whether Î”S for the reaction (Î”Ssys) will be positive, negative, or approximately zero: Br HBr (a) HCI (b) + H20 + HCI (c) он (d) (е)
> For each of the following processes predict the sign of Î”S for the reaction. In other words, will Î”Ssys be positive (an increase in entropy) or negative (a decrease in entropy)? || - (a) (b) (c) Br 0-H (d) (e) (f) OH
> (âˆ’)-Cameroonanol has been isolated from the essential oil of Echinops giganteus (globe thistle) plants and it is associated with a strong woody fragrance. Its structure, including relative stereochemistry, was confirmed when it was made
> Draw the curved arrows that accomplish each of the following transformations: H O-H H. (а) H 0-H он H H 0-H HOH (Ь) (c)
> Bromotriphenylmethane (compound 1) can be converted to 2a or 2b or 2c upon treatment with the appropriate nucleophile. a. Draw a mechanism for the conversion of 1 to 2b. b. In all three cases, conversion of 1 to 2 is observed to be nearly instantaneous
> Upon treatment with a strong base (such as NaOH), 2-naphthol (compound 1) is converted to its conjugate base (anion 2), which is then further converted into compound 3 upon treatment with butyl iodide. a. Draw the structure of 2, including a mechanism f
> For each of the following compounds, identify any polar covalent bonds by drawing Î´+ and Î´âˆ’ symbols in the appropriate locations: H :F: H H-C-0-c--ċ-ö-c-H H-C-CI: H-C-Mg-Br: (a) H HH H (Ь) H (c) H H 10: H H
> The following reaction sequence was part of a stereocontrolled synthesis of cyoctol, used in the treatment of male pattern baldness. The third step in this process employs an uncharged nucleophile, affording an ion pair as the product (anion and cation).
> When you look up thermodynamic values in a table, such as bond dissociation energies or heats of combustion, did you ever wonder where all the numbers come from? You can thank the physical organic chemists whose research involves studying chemical reacti
> Control of stereochemistry is always an important consideration when designing a synthesis. Several techniques exist to invert the stereochemistry of secondary alcohols, and a newly developed method was used in the example shown below. Provide reagents t
> When a new synthetic method is developed, it is applied to a series of compounds to explore its utility. 4-Fluorophenylacetonitrile was used as a substrate in a synthetic methodology research paper. Provide a synthesis for 4-fluorophenylacetonitrile usin
> Propose a mechanism of formation for each of the following products: EIOH Нeat Br OEt OEt
> Consider the reaction below. The rate of this reaction is markedly increased if a small amount of sodium iodide is added to the reaction mixture. The sodium iodide is not consumed by the reaction and is therefore considered to be a catalyst. Explain how
> Which of the following reactions is expected to exhibit a faster rate? Explain CH;CH,Br Nal/EIOH CH;CH2I + Br NaCI / EIOH CH;CH,Br CH;CH;CI + Br
> Consider the reaction below, which involves both a dehydrogenation (removal of two neighboring hydrogen atoms) and a Diels-Alder reaction (which we will learn about in Chapter 16). Utilizing a specially designed catalyst, the achiral starting materials a
> The following compound can react rapidly via an SN1 process. Explain why this primary substrate will undergo an SN1 reaction so rapidly. OTs
> When butyl bromide is treated with sodium iodide in ethanol, the concentration of iodide quickly decreases, but then slowly returns to its original concentration. Identify the major product of the reaction.
> When (1R,2R)-2-bromocyclohexanol is treated with a strong base, an epoxide (cyclic ether) is formed. Suggest a mechanism for formation of the epoxide: OH Strong base 'Br An epoxide
> If you are having trouble paying attention during a long lecture, your levels of acetylcholine (a neurotransmitter) may be to blame. Identify any formal charges in acetylcholine. HH H HHC H III. H-C-C-0-c-C-N-C-H H H H H HC HHH Acetylcholine
> When the following ester is treated with lithium iodide in DMF, a carboxylate ion is obtained: a. Draw a plausible mechanism for this reaction. b. When a methyl ester is used as the substrate (instead of an ethyl ester), as shown below, the reaction oc
> When 2-bromo-2-methylhexane is treated with sodium ethoxide in ethanol, the major product is 2-methyl-2-hexene. a. Draw a mechanism for this process. b. What is the expected rate equation for this process? c. What would happen to the rate if the conce
> Consider the following substitution reaction: a. Determine whether this reaction proceeds via an SN2 or SN1 process, and draw a complete mechanism. b. What is the expected rate equation for this process? c. Would the process occur at a faster rate if
> Predict the major product for each of the following reactions. ? DBN ? NaSH Br (a) (b) Br ? ? NaOH H,0 H20 heat (c) (d) ? Br -BUCK NaOMe MEOH (e) Br I-BUOK (g)
> 77. All of the following are significant resonance structures of the phenyl carbocation, EXCEPT: 78. Which of the following resonance structures is the greatest contributor to the resonance hybrid? 79. Which of the following structures exhibits an sp3
> Substitution vs. Elimination: Identify the major and minor product(s) for each of the following reactions: ? ? I-BUOK NaOH (a) Br Br ? ? NaOE! NaOEI (c) (d) Br NaOEI EIOH ? (e) Br NaOE EIOH ? (f) Br Br ? ? 1-BUOK NaOMe (h) OH conc. H,SO4 ? ? Нeat NaO
> In 2010 the structure of the compound (+)-trigonoliimine A (isolated from the leaves of a plant in the Yunnan province of China) was reported as shown below. In 2011, a synthesis of the reported structure was accomplished, although it was observed to be
> Therearetwostereoisomersof1-tert-butyl-4-chloro-cyclohexane. One of these isomers reacts with sodium ethoxide in an E2 reaction that is 500 times faster than the reaction of the other isomer. Identify the isomer that reacts faster, and explain the differ
> Which of the following reactions is expected to produce 1-propanol (CH3CH2CH2OH) at a faster rate? Explain. NaOH/ H,0 OH NaOH/ DMSO OH +
> (S)-1-Bromo-1,2-diphenylethane reacts with a strong base to produce cis-stilbene and trans-stilbene: a. This reaction is stereoselective, and the major product is transstilbene. Explain why the trans isomer is the predominant product. To do so, draw the
> 74. What is the configuration of the stereocenter in the following compound? a. R b. S c. Z d. Depends on T 75. What is the relationship between the following two compounds? a. Enantiomers b. Diastereomers c. Constitutional isomers d. Resonance f
> Draw a structure for each of the following ions; in each case, indicate which atom possesses the formal charge: a. BH4– b. NH2– c. C2H5+
> 74. Which is the correct hybridization state and geometry for the carbon atom in HCN? a. sp, linear b. sp2, trigonal planar c. sp3, tetrahedral d. None of the above 75. Which of the following is a constitutional isomer of cyclobutane? 76. Which o
> Predict which of the following substrates will undergo a solvolysis reaction more quickly. Explain your choice. Br Br
> Identify the reagents you would use to achieve each of the following transformations: (а) OTs он (b) он CN (c) HO. Br CI SH (d)
> When the following optically active alcohol is treated with HBr, a racemic mixture of alkyl bromides is obtained. Draw a mechanism for this process, and explain the stereochemical outcome. OH Br HBr H20 Racemic mixture
> 71. All of the following are representations of cis-1,2-dimethylcyclohexane, EXCEPT: 72. All of the following are representations of 2-methylpentane, EXCEPT 73. Which of the following is expected to have the largest heat of combustion? 74. Which of th
> Chiral catalysts can be designed to favor the formation of a single enantiomer in reactions where a new chiral center is formed. Recently, a novel type of chiral copper catalyst was developed that is â€œredox reconfigurableâ€&#
> Draw a plausible mechanism for each of the following transformations: -OH conc. H,SO, heat (a) conc. H,SO4 heat (b) OH EIOH (c) NaOEI (d) EIOH
> Explain why the following reaction yields the Hofmann product exclusively (no Zaitsev product at all) even though the base is not sterically hindered: Br EIOH
> 1-Bromobicyclo[2.2.2]octane does not undergo an E2 reaction when treated with a strong base. Explain why not.
> Melphalan is a chemotherapy drug used in the treatment of multiple myeloma and ovarian cancer. Melphalan is an alkylating agent belonging to the nitrogen mustard family. Draw a likely mechanism for the alkylation process that occurs when a nucleophile re
> Indicate whether you would use sodium ethoxide or potassium tert-butoxide to achieve each of the following transformations. Br Br (a) (b)
> Identify any formal charges in the structures below: H H H-AI-H H-C-H (а) (b) (с) H (d) H H. (е) H :či: H H H-C-H H-C-CEO: H-N-C (f) H (g) (h) (i) H H
> Draw the transition state for the reaction between tert-butyl chloride and sodium hydroxide.
> 66. What is the strongest base that is present after methyl magnesium bromide (CH3MgBr) is treated with water? 67. Which side of the following equilibrium is favored? a. The right side. b. The left side. c. Depends on temperature. d. Cannot determine
> In each of the following cases, draw the structure of an alkyl halide that will undergo an E2 elimination to yield only the indicated alkene. ? ? E2 E2 (a) (b) ? ? E2 E2 (c) (d)
> Predict the major product for each of the following reactions: ? NaOH (a) Br ? -BUOK (Ь) Br
> In an effort to develop molecular surfaces with interesting electronic properties, compounds such as the one below were prepared.â€‰Consider the possibilities for preparation of this compound, by evaluating the construction of a new bond
> Predict the stereochemical outcome for each of the following E2 reactions. In each case, draw only the major product of the reaction. ? NaOH (a) Br ? NaOH (b) CI
> Draw the major product that is obtained when (2S,3S)-2-Bromo3-phenylbutane is treated with sodium ethoxide, and explain the stereochemical outcome of this reaction.
> How many different alkenes will be produced when each of the following substrates is treated with a strong base? a. 1-Chloropentane b. 2-Chloropentane c. 3-Chloropentane d. 2-Chloro-2-methylpentane e. 3-Chloro-3-methylhexane
> 54. For a reaction with Î”G a. The reaction must be exothermic b. The reaction must be endothermic c. Keq > 1 d. None of the above 55. Which of the following can serve as a nucleophile? 56. In the following energy diagram showing the p
> One class of anti-viral drugs, called protease inhibitors, has been studied for the treatment of hepatitis C. A series of related compounds, represented by structure 2 (with varying R groups) were prepared from compound 1. Several of the compounds under
> Over 100 cannabinoid compounds, including the one shown below, have been isolated from the marijuana plant in order to explore the plantâ€™s medicinal properties. Identify the chiral centers in 11-acetoxy-Î”9 -tetrahydrocannabi
> There are many forms of cancer, all of which involve abnormal cell growth. The growth and production of cells, called cell proliferation, is known to involve an enzyme called protein farnesyltransferase (PFTase). It is thought that inhibitors of PFTase m
> When 3-bromo-2,4-dimethylpentane is treated with sodium hydroxide (NaOH), only one alkene is formed. Draw the product and explain why this reaction has only one regiochemical outcome.
> Coibacin B is a natural product that exhibits potent antiinflammatory activity and potential activity in the treatment of leishmaniasis, a disease caused by certain parasites: a. Assign the configuration of each chiral center in coibacin B. b. Identify
> The following compound, whose central ring is referred to as a 1,2,4-trioxane, is an anticancer agent that demonstrates activity against canine osteosarcoma. Assign the configuration of each chiral center and then draw all possible stereoisomers of this
> The following compound is optically inactive. Explain why H,C" CH3
> The following compound is known to be chiral. Draw its enantiomer and explain the source of chirality. CH, H,C H
> For each of the following pairs of compounds, determine the relationship between the two compounds: Et H. H (a) Me Me (E)
> How many stereoisomers do you expect for the following compound? Draw all of the stereoisomers. OH но. OH
> There are four constitutional isomers with the molecular formula C3H9N. Draw a Lewis structure for each isomer and determine the number of lone pairs on the nitrogen atom in each case.
> There are only two stereoisomers of 1,4-dimethylcyclohexane. Draw them and explain why only two stereoisomers are observed.
> In Chapter 9, we will see that an acetylide ion (formed by treatment of acetylene with a strong base) can serve as a nucleophile in an SN2 reaction: This reaction provides a useful method for making a variety of substituted alkynes. Determine whether th
> Draw a Fischer projection for each of the following compounds, placing the âˆ’CO2H group at the top: он он но он HO OH (а) (Ь) ÕH ÕH он но HO. (c) он OH
> A total synthesis of the marine natural product aldingenin C in the laboratory resulted in a significant revision of its proposed structure. The synthesis involved the conversion of compound 1 to compound 2, which is an intramolecular SN2-type process. T
> In the presence of a Lewis acid, compound 1 rearranges, via intermediate 2, to afford compound 3. a. Draw curved arrows showing how 1 is transformed into 2. Note that the Lewis acid has been left out for simplicity. b. Draw curved arrows showing how 2
> Compound 1 undergoes a thermal elimination of nitrogen at 250Â°C to form nitrile 4. One proposed (and subsequently refuted) mechanism for this transformation involves intermediates 2 and 3: a. Draw curved arrows that show the conversion of 2 t
> There are many examples of carbocation rearrangements that cannot be classified as a methyl shift or hydride shift. For example, consider the following rearrangement that was employed in the synthesis of isocomene, a tricyclic compound isolated from the
> The specific rotation of vitamin C (using the D line of sodium, at 20°C) is +24. Predict what the observed rotation would be for a solution containing 0.100 g of vitamin C dissolved in 10.0 mL of ethanol and placed in a sample cell with a length of 1.00
> Identify whether each of the following compounds is chiral or achiral: он (a) (b) (c) (d) OH он (e) Он (f) OH (h) он он (1) (k) (1)
> The specific rotation of (S)-carvone (at +20°C) is +61. A chemist prepared a mixture of (R)-carvone and its enantiomer, and this mixture had an observed rotation of −55°. a. What is the specific rotation of (R)-carvone at 20°C? b. Calculate the % ee of
> Strychnine (6), a notorious poison isolated from the strychnos genus, is commonly used as a pesticide in the treatment of rodent infestations. The sophisticated structure of strychnine, first elucidated in 1946, served as a tantalizing goal for synthetic
> Borane (BH3) is very unstable and quite reactive. Draw a Lewis structure of borane and explain the source of the instability.
> (+)-Aureol is a natural product that shows selective anticancer activity against certain strains of lung cancer and colon cancer. A key step in the biosynthesis of (+)-aureol (how nature makes the molecule) is believed to involve the conversion of carboc
> The following sequence was utilized in a biosynthetically inspired synthesis of preussomerin, an antifungal agent isolated from a coprophilous (dung-loving) fungus. a. Draw curved arrows for each step of the mechanism. b. Include an explanation for the
> Smoking tobacco with a water pipe, or hookah, is often perceived as being less dangerous than smoking cigarettes, but hookah smoke has been found to contain the same variety of toxins and carcinogens (cancer-causing compounds) as cigarette smoke. Draw a
> (S)-2-Iodopentane undergoes racemization in a solution of sodium iodide in DMSO. Explain.
> Compound 1 has been prepared and studied to investigate a novel type of intramolecular elimination mechanism. The proposed mechanistic pathway for this transformation is presented below. Complete the mechanism by drawing curved arrows consistent with the
> Under basic conditions (catalytic MeOâˆ’ in MeOH), compound 1 rearranges through the mechanistic sequence shown below to a propellane-type isomer 5. Note that MeOâˆ’ is catalytic in that it is consumed in the first step of
> As seen in Problem 6.18, carbocation rearrangements can occur via the migration of a carbon atom other than a methyl group. For example, carbocation 1 was observed to rearrange to give carbocation 2. a. Identify the carbon atom that is migrating, and dr
> Draw the curved arrows that accomplish the following transformation: H. POH Me Me Me NEN
> When an amine is protonated, the resulting ammonium ion is not electrophilic: However, when an imine is protonated, the resulting iminium ion is highly electrophilic: Explain this difference in reactivity between an ammonium ion and an iminium ion.
> Consider the following reaction. Predict whether an increase in temperature will favor reactants or products. Justify your prediction. ||
> In the presence of a special type of catalyst, hydrogen gas will add across a triple bond to produce a double bond: The process is exothermic. Do you expect a high temperature to favor products or reactants? Catalyst H2
> Draw a Lewis structure for each of the following compounds: a. C2H6 b. C2H4 c. C2H2 d. C3H8 e. C3H6 f. CH3OH
> Identify whether each of the following factors will affect the rate of a reaction: a. Keq b. ΔG c. Temperature d. ΔH e. Ea f. ΔS
> When (R)-3-bromo-2,3-dimethylpentane is treated with sodium hydroxide, four different alkenes are formed. Draw all four products and rank them in terms of stability. Which do you expect to be the major product?
> Consider the following reaction: The following rate equation has been experimentally established for this process Rate = k[HOâˆ’][CH3CH2Br] An energy diagram for this process is shown on the right: a. Identify the two characteristic ar
> Predict whether each of the following carbocations will rearrange. If so, draw the expected rearrangement using curved arrows. (a) (b) (c) (d) (e) (f) (g)
> Draw the transition state for the substitution reaction that occurs between ethyl iodide and sodium acetate (CH3CO2Na).
> Draw curved arrows for each step of the following mechanism: HÖ: H HÖ: H-O: OH HÖ: sÖH :OH -O: H HÖ: H HÖ: ÖH HỘ: -H20
> Draw curved arrows for each step of the following mechanism: H :ÖH HO H H, 7 :ÖH I-o. I-z:
> Draw curved arrows for each step of the following mechanism: [email protected] :0-H нӧ. TH. TH. TH. H :ÖH :ÖH HÖ но. HO OH HÖ OH H. H. TH. H
> Draw curved arrows for each step of the following mechanism: OH но. CH,SO, NO2 NO2
> For the following mechanism, identify the sequence of arrow-pushing patterns: :ÖH :ÖH OR H R H. R :ÖR R ÖR ÖR
> For the following mechanism, identify the sequence of arrow-pushing patterns: :0 :OH H R R- R R" R R R R R
> Lithium salts have been used for decades to treat mental illnesses, including depression and bipolar disorder. Although the treatment is effective, researchers are still trying to determine how lithium salts behave as mood stabilizers. a. Draw a Lewis st