|Problem Set #3||September 26, 1997|
1. The digitoxin derivative shown below is a metal chelating agent that is specific for ATPase and has potential use in radio-imaging.
(i) Identify the functional groups present in this compound.
(ii) Identify a methyl group, and a primary, secondary, or tertiary carbon (if there are any present).
(iii) Identify a primary, secondary, or tertiary alcohol (if any are present).
(iv) Identify a primary, secondary, or tertiary amide (if any are present).
2. Consider the following three organic molecules:
(a) Give the hybridization of each of the atoms (excluding hydrogens) in each molecule.
(b) In which direction do the lone pairs on the N atoms in the three structures point relative to the plane of the rings?
(c) A cyclic array of 6 electrons (or 6 electrons in overlapping 2p orbitals is said to be aromatic:
(i) Would you expect thymine, adenine, or imidazole to be
aromatic? If so, what resonance structures would you have to write in order to obtain 6 electrons in a cycle?
(ii) The first sites of protonation of adenine by a strong acid (e.g. HCl) are N(1), N(3), and N(7), NOT the NH2 group as one might expect. Write one or more resonance structures that would account for this.
3. Show the direction (LHS or RHS) that you would expect the following equilibria to lie:
(i) CH3CN + C6H5- [CH2CN]- + C6H6
(ii) CH2CH2 + OH- CH2CH- + H2O
(iii) OH- + CH3NH2 CH3NH- + H2O
(iv) CH3SH + CH3- CH3S- + CH4
(v) CH3CH2O- + C6H5COOH CH3CH2OH + C6H5COO-
(vi) (C2H5)2NH2+ + HCO2- (C2H5)2NH + HCO2H
4. The following equilibria all lie on the right hand side of the equation:
NH2- + CH3COOCH3 NH3 + -CH2COOCH3
-CH2COOCH3 + CH3COCH3 CH3COOCH3 + -CH2COCH3
-CH2COCH3 + CH3OH CH3COCH3 + CH3O-
CH3O- + CH3NO2 CH3OH + -CH2NO2
(i) Identify which compounds are weaker acids than methanol.
(ii) Identify which compounds are weaker bases than methoxide ion.
(iii) Identify which compounds are weaker acids than acetone (2-propanone).
(iv) Identify which compounds are weaker bases than acetone anion.
(v) Identify which is the strongest acid and which is the strongest base.
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