The widely used antioxidant and food preservative called BHA (butylated hydroxyanisole) is actually a mixture of 2-tert-butyl-4-methoxyphenol and 3-tert-butyl-4-methoxyphenol. BHA is synthesized from...
Provide a mechanism for the following reaction. NO2 SO NaOCH OH NO2 NO2
Account for the fact that the Dow process for the production of phenol produces both diphenyl ether (1) and 4-hydroxybiphenyl (2) as by-products: OH
Your laboratory instructor gives you a mixture of 4-methylphenol, benzoic acid, and toluene. Assume that you have available common laboratory acids, bases, and solvents and explain how you would...
Predict the products of each of the following reactions. (a) (b) (c) (d) OH Cl pyridine OH (1) NaH (2) CH2l HBr OH HNOg, H2SO4 H3C
(a) What products would be formed if salicin were treated with dilute aqueous HCl? (b) Outline a mechanism for the reactions involved in their formation.
(a) Would you expect d-glucitol to be optically active? (b) Write Fischer projection formulas for all of the d-aldohexoses that would yield optically inactive alditols.
Although d-fructose is not an epimer of d-glucose or d-mannose (d-fructose is a ketohexose), all three yield the same phenylosazone. (a) Using Fischer projection formulas, write an equation for the...
(a) What are the structures of L-(+)-threose and L-(+)-erythrose? (b) What aldotriose would you use to prepare them in a Kiliani-Fischer synthesis?
(a) Outline a Kiliani-Fischer synthesis of epimeric aldopentoses starting with D-(-)- erythrose (use Fischer projections). (b) The two epimeric aldopentoses that one obtains are D-(-)-arabinose and...
Arbutin, a compound that can be isolated from the leaves of barberry, cranberry, and pear trees, has the molecular formula C12H16O7. When arbutin is treated with aqueous acid or with a -glucosidase,...
(a) Would you expect d-glucaric acid to be optically active? (b) Write the open-chain structure for the aldaric acid (mannaric acid) that would be obtained by nitric acid oxidation of d-mannose. (c)...
Although monosaccharides undergo complex isomerizations in base (Section 22.5A), aldonic acids are epimerized specifically at C2 when they are heated with pyridine. Show how you could make use of...
A useful synthesis of sesquiterpene ketones, called cyperones, was accomplished through a modification of the following Robinson annulation procedure (Section 19.7B). Write a mechanism that accounts...
What products would you expect to obtain if each of the following terpenes were subjected to ozonolysis and subsequent treatment with dimethyl sulfide? (a) Myrcene (b) Limonene (c) a-Farnesene (d)...
Designate with asterisks the eight chirality centers of cholesterol.
What form of glutamic acid would you expect to predominate in
(a) Which amino acids in Table 24.1 have more than one chirality center? (b) Write Fischer projections for the isomers of each of these amino acids that would have the l configuration at the a...
(a) What product would you expect to obtain from treating tyrosine with excess bromine water? (b) What product would you expect to be formed in the reaction of phenylalanine with ethanol in the...
How would you convert stearic acid, CH3(CH2)16CO2H, into each of the following? (a) Ethyl stearate, (b) tert-Butyl stearate, (c) Stearamide, (d) N, N-Dimethylstearamide, (e) Octadecylamine, (f)...
(a) On the basis of the following sequence of reactions, Emil Fischer was able to show that L-(-)-serine and L-(+)-alanine have the same configuration. Write Fischer projections for the intermediates...
The guanidino group of arginine is one of the most strongly basic of all organic groups. Explain. NH NI NI
Starting with diethyl a-bromomalonate and potassium phthalimide and using any other necessary reagents, show how you might synthesize (a) dl-leucine, (b) dl-alanine, and (c) dl-phenylalanine.
(a) Write a reaction showing how 2, 4-dinitrofluorobenzene could be used to identify the N-terminal amino acid of VAG. (b) What products would you expect (after hydrolysis) when VKG is treated with...
Give the amino acid sequence of the following polypeptides using only the data given by partial acidic hydrolysis: (a) (b) S, O, P, T H2o STTO PS A, R, C, V, LAC + CR+RV +LA H20
The sense strand of a segment of DNA has the following sequence of bases: 5' . . . T G G G G G T T T T A C A G C . . . 3' (a) What mRNA sequence would result from this segment? (b) Assume that the...
(a) Mitomycin is a clinically used antitumor antibiotic that acts by disrupting DNA synthesis through covalent bondforming reactions with deoxyguanosine in DNA. Maria Tomasz (Hunter College) and...
As described in Section 25.5B, acid-base catalysis is believed to be the mechanism by which ribosomes catalyze the formation of peptide bonds in the process of protein translation. Key to this...
(a) There are approximately 3 billion base pairs in the DNA of a single human cell. Assuming that this DNA exists as a double helix, calculate the length of all the DNA contained in a human cell. (b)...
Analysis of a sample of polyacrylonitrile (see Table 16-3) shows that there are six lengths of chains, with the number of chains of each length shown in the table below. Determine (a) The weight...
A polymer component that needs to maintain a stress level above 10 MPa for proper functioning of an assembly is scheduled to be replaced every two years as preventative maintenance. If the initial...
A stress of 2500 psi is applied to a polymer serving as a fastener in a complex assembly. At a constant strain, the stress drops to 2400 psi after 100 h. If the stress on the part must remain above...
A stress of 1000 psi is applied to a polymer that operates at a constant strain; after six months, the stress drops to 850 psi. For a particular application, a part made from the same polymer must...
A polyethylene rope weighs 0.25 lb per foot. If each chain contains 7000 repeat units, calculate (a) The number of polyethylene chains in a 10-ft length of rope, and (b) The total length of chains in...
(a)Construct a hybrid orbital picture for the hydronium ion (H3O+) using oxygen sp3 hybrid orbitals. (b) How would you expect the H-O-H bond angles in hydronium ion to compare with those in water...
Although compounds are indexed by their IUPAC substitutive names, sometimes chemists give whimsical names to compounds that they discover. Assist these two chemists by providing substitutive names...
What is the dissociation constant of an acid that has a pKa of (a) 4 (b) 7.8 (c) -2
Arrange the compounds in each of the following sets in order of decreasing pKa, highest first. Explain your reasoning. (a) CLCH2CH2SH CH3CH2OH CH3CH2SH (b) CH,CH,OH (CH3),N-CH-CH,OH (CH3)N OH
Give the structure for each of the following: (a) 2-methylpropene (b) 5 -(3 -pentenyl)- 1, 3,6,8-decatetraene
Apply Hammond's postulate to decide which reaction is faster: addition of HBr to 2 methylpropene or addition of HBr to trans-2-butene. Assume that the energy difference between the starting alkenes...
A reaction has the reaction free-energy diagram shown in Fig. P4.55. (a) Which compound is present in greatest amount when the reaction comes to equilibrium? In least amount? (b) What is the...
Which of the following two reactions should have the greatest ÎH° change? Why? (1) (2) C(CH3) (CH3)Q C(CH3) H C CH3 H3C CH3
Although the addition of H-CN to an alkene could be envisioned to occur by a free-radical chain mechanism, such a reaction is not observed. Justify each of the following reasons with appropriate...
(a) Using lines, wedges, and dashed wedges as appropriate, draw perspective structures of the two stereoisomers of ibuprofen, a well-known non steroidal anti-inflammatory drug. (b) Only the S...
(a) The specific rotation of sucrose (table sugar) in water is 66.5 degrees mL g-1 dm-1. What is the observed optical rotation in a 1 dm path of a sucrose solution prepared from 5 g of sucrose and...
(a) When fumarate reacts with D2O in the presence of the enzyme fumarase only one stereoisomer of deuterated malate is formed, as shown in Fig. P7 .52.Is this a syn- or an ant I - addition ? Explain....
(a) What two diastereomeric products could be formed in the hydroboration-oxidation of the following alkene? (b) Considering the effect of the methyl group on the approach of the borane-THF reagent...
A widely used undergraduate experiment is the recrystallization of acetanilide from water. Acetanilide (see following structure) is moderately soluble in hot water, but much less soluble in cold...
Acetone (Table 8.2) has a significant dipole moment (2.7 D). Using structures, show the stabilizing interactions to be expected between acetone solvent molecules and (a) A dissolved potassium ion;...
Arrange the compounds in order of increasing (decreasing pka). Explain your choices. C1CH2CH2SH, C1CH2CH2OH, CH3CH2OH
Answer Problem 8.33 for all alcohols with the forrnula C4H9OH. (a) Give the structures of all alcohols with the molecular formula C5H13OH. (b) Which of the compounds in part (a) are chiral? (c) Name...
A student, Flick Flaskflinger, in his twelfth year of graduate work, needed to prepare ethylmagnesium brdmide from ethyl bromide and magnesium, but found that his laboratory was out of diethyl ether....
(a) Two isomeric S"2 products are possible when sodium thiosulfate is allowed to react with one equivalent of methyl iodide in methanol solution. Give the structures of the two oroducts. ...
(a) When propanol containing deuterium (D, or 2H; rather than hydrogen at the oxyger, CH3CH2CH2OD, is treated with an excess of H2O containing a catalytic amount of NaOH, 1-propanol is formed...
Arrange the following bonds in order of increasing stretching frequencies, and explain your reasoning. C=C C=C C=0 C-C
(a) You have found in the laboratory two liquids, C and D, in unlabeled bottles. You suspect that one is deuterated chloroform (CDC13) and the other is ordinary chloroform (CHC13). Unfortunately, the...
Analyze the splitting pattern for a set of equivalent b protons in the presence of three equivalent adjacent a protons. Include an analysis of the relative intensity of each line of the splitting...
Although this chapter has discussed only nuclei that have spin 1/2, several common nuclei such as 14N and deuterium (2H, or D) have a spin of 1. This means that the spin has three equally probable...
(a) Using the pKa values of the hydrocarbons and ammonia, estimate the equilibrium constant for (1) the reaction in Eq. 14.22 and (2) the analogous reaction of an alkane with amide ion. Eq. 14.22 (b)...
Give the structures of the products in each of the following reactions. CH,Ca C: Na+ + CH,CH,-| - Br( CH2)-Br + HC C: Na+ (excess) -
Give the principal products expected when 4-octyne or the other compounds indicated are treated with each of the following reagents: (a) H2, Pd/C catalyst (b) H2, Lindlar catalyst (c) Product of (b)...
A student consulted a well-known compilation of reference spectra for the proton NMR spectrum of propyne and was surprised to find that this spectrum consists of a single unsplit resonance at 51.8....
Assuming endo stereochemistry of the product, give the structure of the compound formed when l, 3-cyclohexadiene reacts with maleic anhydride. (The structure of maleic anhydride is shown in Eq....
Which d the following species should be aromatic by the Huckel 4n + 2 rule? (a) (b) (c) N: isoxazole C2Hs
Explain each of the following observations. The allene 2, 3-heptadiene can be resolved into enantionmers, but the cumulene 2, 3, 4-heptatriene cannot.
Explain why 4-methyl-1, 3-pentadiene is much less reactive as a diene in Diels-Alder reactions than (E)-1, 3-pentadiene, but its reactivity is similar to that of (Z)-1, 3-pentadiene.
Although aldehydes and ketones are weak acids, their a-hydrogens are rnore than 30 pKa units more acidic than the hydrogen's of alkanes. Using polar effects and resonance effects in your argument,...
Assume you have unlabeled samples of the compounds within each of the following sets. Explain how UV-vis spectroscopy could be used to distinguish each compound in the set from the other (s). (a) (b)...
A small amend of a by4roduct, gdibromobenzene, is also formed in the brorlination of benzene shown in Eq. 16.2. Write a curved-arrow mechanism for formation of this compound. Eq. 16.2 HBr FeBra or Fe...
Arrange the following compounds in order of increasing reactivity toward HNO3 in H2SO4. (The references to equations will assist you with nomenclature.) (a) Chlorobenzene, benzene, nitrobenzene (b)...
Give two Friedel-Crafts acylation reactions that could be used to prepare 4-methoxybenzophenone. Which reaction would be faster or occur under milder conditions? Explain. OCH3 4-methoxybenzophenone
A student Al Lillich has prepared a pure sample of 3-bromo-l-butene (A). Several weeks later he finds that the sample is contaminated with an isomer B formed by allylic rearrangement. (a) Give the...
Account for each of the following facts with an explanation. 1, 3-Cyclopentadiene is a considerably stronger carbon acid than 1, 4-pentadiene even though the acidic hydrogens in both cases are doubly...
A method for determining the structures of disubstituted benzene derivatives was proposed in 1874 by Wilhelm Korner of the University of Milan. Kdrner had in hand three dibromobenzenes, A, B, and C,...
(a) What are the two constitutionally isomeric cyclic acetals that could in principle be formed in the acid-catalyzed reaction of acetone and glycerol (1, 2, 3-propanetriol)? (b) Only one of the two...
What is the pH of a solution containing a buffer consisting of acetic acid and sodium acetate in which the actual [acetic acid]/[sodium acetate] ratio is (a) 1/3? (b) 3? (c) 1?
(a) Show that the two following compounds have the same conjugate base. (b) Which compound is more acidic? Explain your reasoning using an argument invoking the relative free energies of A and B. O-H...
A student, Cringe Labrack, has suggested each of the faulty synthetic procedures shown in Fig. P22.73. Explain why each one cannot be expected to work. NadEt CHAI NaOEt PhBt a) CH,CH CO,Et (c OH CH...
Analyze each of the following compounds and determine what starting materials would be required for its synthesis by a Claisen condensation. Then decide which if any of the possible Claisen...
Arrange the compounds in order of increasing C---N bond length. Explain your answers. , NH, . NH> HN=CH2
Alizarin yellow R is an azo dye that changes color from yellow to red between pH 10.2 and 12.2. (a) Outline a synthesis of alizarin yellow R from aniline, salicylic acid (o-hydroxybenzoic acid), and...
(1) 2,4 - dimethylbenzylamine (2) 2,4,6-trmethylaniline (3) NJV-dimethyl-p-methylaniline (4) 3,5-dimethyl-N-methylaniline (5) 4-ethyl-2,6-dimethylaniline 2.07 (6H, s), 2.16 (3H, s), 3.19
Assuming you knew the properties of the compound obtained in Problem 24.23, including its optical rotation, show how you could use periodate oxidation to distinguish methyl -D- galactopyranoside from...
Draw in detail the structure of a section of RNA four residues long that, from the 5'-end, has the following sequence of bases: A, U, C, G. Label the 3' and 5' ends.
There is evidence that alkylation at O-4 of thymine, like alkylation at O-6 of guanine, is another mutagenic event that can lead to cancer. Explain why 04 alkylation at thymine would disrupt...
Give the principal organic product(s) expected when 2- methylthiophene or other compound indicated reacts with each of the following reagents. (a) HNO3 (b) Dilute aqueous NaOH (c) Product of part (a)...
A process called sizing chemically modifies the cellulose in paper. As a result, the paper resists wetting (and thus prevent inks from running). In addition, sizing leaves the paper in a slightly...
Aromatic sulfonation can be reversed by hearting an arylsulfonic acid in steam: (a) Draw a curved-arrow mechanism for this transformation. (b) Explain why compound C cannot be synthesized in one step...
Although the synthesis of heterocyclic rings was not discussed in the text, many such syntheses employ reactions that are similar or identical to reactions in other parts of the text. Give...
A mixture of N-acetyl-Leu-Gly, Lys-Gly-Arg, and Lys-Gly-Leu is applied to a sulfonated polystyrene cation-exchange column at a buffer pH of 6.0. Predict the order in which these three peptides will...
After the coupling, he deprotects his resin-bound peptide with 20% piperidine in DMF, and then completes the synthesis in the usual way by coupling Fmoc-Gly, deprotecting the peptide, and removing it...
AQC-typtoptan is not shown in Fig. 26.3, in what general region of the chromatogram would you expect to find AQC-Trp if it ware preseirr? Explain.
Apeptide P has the sequence of amino acids E-R-G-A-N-I-K-K-H-E-M. what products would be formed if this peptide were subjected to trypsin-catalyzed hydrolysis?
Alloisoleucine is the diastereomer of isoleucine. Draw Fischer projections of L - allo- isoleucine and D-alloisoleucine.
A previously unknown amino acid, y-carboxyglutamic acid (Gla), was discovered to be a posttranslational modification in the amino acid sequence of the blood clotting protein prothrombin. This amino...
(a) Point out the ionizable groups of the amino acid tyrosine (Table 26.1). (b) What is the net charge on tyrosine at pH 6? How do you know? (c) Draw the structure of the major form(s) of tyrosine...
Although the stereochemistry of Eq. 27.39 cannot be determined from the reaction, what stereochemistry is expected from orbital symmetry considerations?
An all-suprafacial [3,3] sigma tropic rearrangement could in principle take place through either a chair-like or a boat-like transition statel When the terpene germacrone is distilled under reduced...
(a) What type of pericyclic reaction is required to form benzene from Dewar benzene? (b) Explain why Dewar benzene, although a very un-stable molecule, is not readily transformed to benzene....
After heating to 200 °C, the following compound is converted 95% yield into an isomer A that can be hydrogenated o cyclodecane. Give the structure of A, including its stereo chemistry.