Question: Propose a mechanism of formation for each

> There are two vacancies in a certain university statistics department. Five individuals apply. Two have expertise in linear models, and one has expertise in applied probability. The search committee is instructed to choose the two applicants randomly. (a

> A nationwide survey of college seniors by the University of Michigan revealed that almost 70% disapprove of daily pot smoking, according to a report in Parade. If 12 seniors are selected at random and asked their opinion, find the probability that the nu

> A random variable X that assumes the values x1, x2, . . . , xk is called a discrete uniform random variable if its probability mass function is f(x) = 1 k for all of x1, x2, . . . , xk and 0 otherwise. Find the mean and variance of X.

> Using the data in Table 6.1, predict the sign and magnitude of ΔH° for each of the following reactions. In each case, identify whether the reaction is expected to be endothermic or exothermic: From in Table 6.1: Br (а) + Bra +

> Identify the systematic name as well as the common name for each of the following compounds:

> Sigma bonds experience free rotation at room temperature: In contrast, π bonds do not experience free rotation. Explain. (Hint: Compare Figures 1.24 and 1.29, focusing on the orbitals used in forming a σ bond and the orbitals used

> Draw a Lewis dot structure for each of the following atoms: a. Carbon b. Oxygen c. Fluorine d. Hydrogen e. Bromine f. Sulfur g. Chlorine h. Iodine

> Indolizomycin is a potent antibiotic agent produced by a microorganism, called SK2-52. Of particular interest is the fact that SK2-52 is a mutant microorganism that was created in a laboratory from two different strains, Streptomyces teryimanensis and St

> Consider the structure of formaldehyde: a. Identify the type of bonds that form the C=O double bond. b. Identify the atomic orbitals that form each C−H bond. c. What type of atomic orbitals do the lone pairs occupy?

> Identify the electron configuration for each of the following ions: a. A carbon atom with a negative charge b. A carbon atom with a positive charge c. A nitrogen atom with a positive charge d. An oxygen atom with a negative charge

> a. Consider the figure shown in Problem 7.90. Compound 3 is most easily purified via recrystallization in water. As such, the product would have to be thoroughly dried in order to utilize IR spectral analysis to verify the conversion of 1 to 3. Explain w

> Pladienolide B is a macrocyclic (large ring) natural product isolated from an engineered strain of the bacterium Streptomyces platensis. An enantioselective, 31-step synthesis of it was reported18 in 2012—an improvement over a previousl

> Draw a Lewis structure of a carbon atom that is missing one valence electron (and therefore bears a positive charge). Which second-row element does this carbon atom resemble in terms of the number of valence electrons?

> Using E-Z designators, identify the configuration of each C=C double bond in the following compound:

> Consider the following four energy diagrams: a. Which diagrams correspond with a two-step mechanism? b. Which diagrams correspond with a one-step mechanism? c. Compare energy diagrams A and C. Which has a relatively larger Ea? d. Compare

> Consider the following reaction: a. Use Table 6.1 to estimate ΔH for this reaction. b. ΔS of this reaction is positive. Explain. c. Determine the sign of ΔG. d. Is the sign of ΔG dependent on temperatur

> In each of the following cases compare the bonds identified in red, and determine which bond you would expect to have the largest bond dissociation energy

> The following reaction gives a product with the molecular formula C4H8O2. Draw the structure of the product.

> George Olah was awarded the 1994 Nobel Prize in Chemistry for his research involving carbocations. An interesting series of carbocation rearrangements studied by Olah is shown below. Each of these rearrangements is accomplished via the migration of a met

> Which value of ΔG corresponds with Keq = 1? a. +1 kJ/mol b. 0 kJ/mol c. −1 kJ/mol

> Several natural products have been isolated from the flowering plant Sarcostemma acidum, which has been used in folk medicine as a cough suppressant. During efforts to make these compounds in the laboratory, it was discovered that one of the natural prod

> For each of the following multistep reactions, read the curved arrows and identify the sequence of arrow–pushing patterns:

> Most fabrics do a good job at protecting skin from exposure to sunlight, but addition of UV-absorbing compounds to clothing can further reduce the amount of ultraviolet light that passes through the fabric. The following transformation takes place upon a

> For each of the following cases, read the curved arrows and identify which arrow-pushing pattern is utilized:

> Name one element that you would expect to exhibit bonding properties similar to boron. Explain.

> Assign a systematic (IUPAC) name for each of the following compounds:

> Draw an energy diagram of a reaction with the following characteristics: a. A one-step reaction with a negative ΔG b. A one-step reaction with a positive ΔG c. A two-step reaction with an overall negative ΔG, where the intermediate is higher in energy

> Consider the following SN2 reaction: a. Assign the configuration of the chiral center in the substrate. b. Assign the configuration of the chiral center in the product. c. Does this SN2 process proceed with inversion of configuration? Explain. Br C

> (R)-(−)-Carvone is responsible for the characteristic minty odor and flavor of spearmint oil, and it can also serve as a useful chiral starting material for organic synthesis. A carbon-carbon π bond is normally nucleophilic,

> Identify all of the electrophilic centers in each of the following compounds: HO. (a) (b) Arachidonic acid A precursor in the biosynthesis of many hormones 2-Heptanone Used to control the population of Varroa mites in honey bee colonies

> For each of the following cases use the information given to determine whether or not the equilibrium will favor products over reactants: a. A reaction with Keq = 1.2 b. A reaction with Keq = 0.2 c. A reaction with a positive ΔG d. An exothermic rea

> Compare the Lewis dot structure of nitrogen and phosphorus and explain why you might expect these two atoms to exhibit similar bonding properties.

> Identify all of the nucleophilic centers in each of the following compounds: OH (a) 'Li (b) NH2 (c) (d)

> Consider the relative energy diagrams for four different processes: a. Compare energy diagrams A and D. Assuming all other factors (such as concentrations and temperature) are identical for the two processes, identify which process will occur more rapid

> In each of the following cases, use the data given to determine whether the reaction favors reactants or products: a. A reaction for which ΔG = +1.52 kJ/mol b. A reaction for which Keq = 0.5 c. A reaction carried out at 298 K, for which ΔH = +33 kJ/mol

> At room temperature, molecules spend most of their time in lower energy conformations. In fact, there is a general tendency for any system to move toward lower energy. As another example, electrons form bonds because they “prefer” to achieve a lower ener

> For each of the following reactions predict the sign of ΔG. If a prediction is not possible because the sign of ΔG will be temperature dependent, describe how ΔG will be affected by raising the temperature. a. An endothermic reaction for which the syste

> 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 ΔS for the reaction (ΔSsys) 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 ΔS for the reaction. In other words, will ΔSsys be positive (an increase in entropy) or negative (a decrease in entropy)? || - (a) (b) (c) Br 0-H (d) (e) (f) OH

> (−)-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 δ+ and δ− 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

> 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 “redox 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. Consider the possibilities for preparation of this compound, by evaluating the construction of a new bond

> Identify the sole product of the following reaction: Br NaOE!

> 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 ΔG 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 plant’s medicinal properties. Identify the chiral centers in 11-acetoxy-Δ9 -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