2,4,6-trinitro-N,N-dimethylaniline (A) is about 40,000 more basic than 2,4,6-trinitroaniline (B): show that this result is consistent with the existence of intramolecular hydrogen bonding and with the possibility of conjugation between the NH2 group and the aromatic ring in compound B; Specify what kind of effect may be at the origin of the prevention of this conjugation in compound A. NO2 NH2 NO2 O2N NO2 NO2

2,4,6-trinitro-N,N-dimethylaniline (A) is about 40,000 more basic than 2,4,6-trinitroaniline (B): show that this result is consistent with the existence of intramolecular hydrogen bonding and with the possibility of conjugation between the NH2 group and the aromatic ring in compound B; Specify what kind of effect may be at the origin of the prevention of this conjugation in compound A. NO2 NH2 NO2 O2N NO2 NO2

Organic Chemistry

8th Edition

ISBN:9781305580350

Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Publisher:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Chapter19: Enolate Anions And Enamines

Section: Chapter Questions

Problem 19.63P

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Arrange the members of each group in order of decreasing basicity: (a) Ammonia, aniline, methylamine (b) Acetanilide, aniline, N-methylaniline (c) 2,4-Dichloroaniline, 2,4-dimethylaniline, 2,4-dinitroaniline (d) 3,4-Dichloroaniline, 4-chloro-2-nitroaniline, 4-chloro-3-nitroaniline (e) Dimethylamine, diphenylamine, N-methylaniline
4. Each of the following is a much weaker base than aniline. Present a resonance argument to explain the effect of the substituent in each case. (a) o-cyanoaniline (b) C6H5NHCOCH3 (c) p-aminoacetophenone
if the pKa value for p-nitrophenol is 7.08, what fraction of it exists in its ionized form at (a) pH 7, and (b) pH 9?
An amine of unknown structure contains one nitrogen and nine carbon atoms, as well as at least one six-membered ring. The 13C-NMR spectrum shows only five signals, all between 20 and 60 ppm. Three cycles of Hofmann elimination sequence (1. CH3I, 2. Ag20, H20, 3. Heat) give trimethylamine and 1,4,8-nonatriene. Propose a structural formula for the amine. Justify your answer.
11. Which compound is the strongest base? (A) m-nitroaniline (B) aniline (C) 4-methylaniline (D) 3-bromo-5-nitroaniline (E) 2,4-dimethylaniline 13 Which of the following compounds has the 12. Which compound is the strongest acid? (A) benzoic acid (B) 4-amino-2-methylbenzoic acid (C) p-nitrobenzoic acid (D) 2,4-dinitroabenzamide (E) 3,5-dinitrobenzoic acid 14 How many H atoms are in the compound:
The 1H- and 13C-NMR data of an ester of molecular formula C6H10O2 are given below. Also shown are the COSY and HETCOR NMR spectra of the ester. Draw the structure of the ester, explaining how you reach your conclusion. 1H-NMR: 7.20-6.90 (1H), 5.85 (1H), 4.16 (2H), 1.88 (3H), 1.31 (3H) ppm 13C-NMR: 166.7, 144.5, 123.0 , 60.2, 18.0, 14.3 ppm
Show how to prepare the following aromatic amines by aromatic nitration, followed by reduction. You may use benzene andtoluene as your aromatic starting materials. (c) m-bromoaniline (d) m-aminobenzoic acid
Molecules of 6,6-dinitrobiphenyl-2,2-dicarboxylic acid have no tetrahedral chiral center, and yet they can be resolved to a pair of enantiomers. Account for this chirality.
An amine of unknown structure contains one nitrogen and nine carbon atoms. The 13C-NMR spectrum shows only five signals, all between 20 and 60 ppm. Three cycles of Hofmann elimination sequence [(1) CH3I; (2) Ag2O, H3O; (3) heat] give trimethylamine and 1,4,8-nonatriene. Propose a structural formula for the amine.
2. (a) This problem deals with the acidity of amines, not their basicity (or the acidity of their conjugate acids). While cyclohexylamine is a normal amine and is an extremely weak acid (pKa ~36), aniline (Ph-NH2) is somewhat more acidic, with a pKa of ~28. Explain this observation by comparing both ơ- and Tt-effects on the acidity of these two amines. (b) Similar to phenols, substituted derivatives of aniline have explainable shifts in pKa. Explain the following pKas based on the o- and t-effects of the -OCH3 substituent. o-Methoxyaniline: 26 m-Methoxyaniline: 26 p-Methoxyaniline: 29 Here are the pKas (for the N-H bond, not O-H) for the hydroxyanilines: o-Hydroxyaniline: 33 m-Hydroxyaniline: 29 p-Hydroxyaniline: 30 (c) Briefly explain why all three of these pKas are above 28. (d) Explain why the o- isomer is the highest. (e) Make predictions for the pKas of the three cyano-anilines, and provide explanations. Use actual numbers, but only the trend and your explanations will be graded.…
Without looking at a table of pKa data, rank the following compounds in order of increasing acidity. (a) Benzoic acid, p-methylbenzoic acid, p-chlorobenzoic acid (b) p-Nitrobenzoic acid, acetic acid, benzoic acid Explain in each case your choice for the highest acidity.
The gas-phase basicity of triphenylamine (876.4 kJ mol-1) is less thanthat of triphenylphosphine (940.4 kJ mol-1). Write an equation torepresent each reaction. Do you expect electronic or steric factors tocontribute more to this difference? Explain