p 37 James Sindelar Kelly I 23 points a Indicate the hybridization that is expected at each of the indicated atoms in the structure of ethynylestradiol shown to the right You should consider any possible resonance forms in your assignments H H3C O 1 C C H 1 1 1 H O ethynylestradiol 1 b Now for the bonds indicated by arrows and labels in the structure below rank them according to the relative bond lengths by putting the corresponding label in the boxes as directed H H3C O C B D E A H O C C H shortest longest c How many units of unsaturation are in a molecule of ethynylestradiol see above for structure d Using the pKa table provide estimated pKa values for the indicated hydrogens in this compound Answers acceptable within 1 pKa units 5 3 H H3C O 1 1 C C H 1 H O H H 1 1 e Finally which of the following bases when 1 molar equivalent is used would deprotonate the most acidic site in ethynylestradiol with an equilibrium constant greater than 100 Mark an X in the appropriate box H2O NaSCH3 NaC N NaH CH3NH2 YES it can NO it cannot 5 5 Name Page 2 p 38 authors unknown II 22 points Some metals like iron Fe behave in a way that is very similar to boron they are considered open shelled The following transformation involves a complexation Lewis acid base reaction followed by a decomplexation The complete transformation yields a resonance stabilized organic product called Look at the entire problem before answering the questions Provide the an acylium ion and FeCl4 missing information Be sure to follow the precise directions for each box a Provide the curved arrow mechanism for the complexation reaction you predict will occur based on the other information provided b Provide complete Lewis structure s for the product s of this reaction and then draw the curved arrow mechanism for the decomplexation step that results in the products indicated O C H H C H Cl Fe Cl Cl Cl 2 c Draw the other resonance contributor for the acylium ion all atoms should have closed shells d Given that there are no other valence electrons on Fe to worry about predict the VSEPR electronic geometry of the Fe atom in the product shown O C H H C H FeCl4 3 acylium ion e Assuming the hybridization model for all atoms and considering both resonance contributors above provide an accurate and complete three dimensional orbital picture for the acylium ion contributor that was drawn for you As always you should use lines dashes wedges p orbitals lone or overlapping to show the direction of all electrons or empty orbitals All bond angles should reflect the appropriate geometry and hybridization chosen for your drawing f Draw the product s that would result from the following transformation complete Lewis structure s 5 2 6 4 Li H H C H O C Cl H H C H 6 page 42 all Name Page 1 I 22 points A Restless Leg Syndrome RLS has been a disorder that has only recently made the news One of the most commonly prescribed drugs for RLS is ropinirole sold as Requip Analyze the structure and potential reactivity of this compound considering all other closed shell resonance contributors in your evaluations Requip ropinirole BOND A N BOND C Atom 4 a For each of the atoms indicated with an arrow provide the atom s most reasonable hybridization as well as its electronic geometry VSEPR and observable geometry shape no partial credit Hybridization observable geometry Electronic VSEPR geometry BOND D Atom 1 N H BOND E O Atom 2 BOND B Atom 3 b List the bonds indicated in Requip above in order of their lengths if any are predicted to be exactly the same length put them together in the same box no partial credit longest shortest 5 Atom 1 Atom 2 Atom 3 Atom 4 circle one Yes No Requip would be in this form at pH 7 c Your bloodstreamhas a fairly constant pH of about 7 If Requip was placed in your bloodstream would it exist in the form shown above circle Yes or No Explain BRIEFLY indicating specific atom s in Requip to justify your answer d Two of the major buffer systems present in your bloodstream are derived from phosphoric acid and carbonic acid both are shown in their fully protonated forms below Given the pKa information provided draw the form s of these molecules that would predominate in your blood at pH 7 0 predominant form s that exist in blood at pH 7 i phosphoric acid 3 acidic protons pKas 2 7 and 12 H O H O P O O H ii Carbonic acid 2 acidic protons pKas 6 5 and 10 2 O C H O O H predominant form s that exist in blood at pH 7 2 2 2 2 3 3 3 7 pg 46 II Problem A changkit reedscot kbgar II 19 points Name Page 2 A Provide structural information and or explanations as required a Like other third row elements silicon atoms can exist in hypervalent 10e forms which means they can behave as open shell atoms Predict the product that forms from the following combination show the balanced equation O O Si O CH3 O CH3 CH3 CH3 N CH3 F CH3 CH3 tetramethylammonium fluoride J Org Chem 1999 64 1684 6 b c d What is the hybridization of the nitrogen atom in the tetramethylammonium cation in part a The tetramethylammonium cation in part a is analogous to the ammonium cation NH4 Provide a three dimensional representation for the ammonium NH4 cation 2 3 Tetramethylammonium fluoride is prepared by a simple acid base reaction between hydrofluoric acid and another substance The complete set of reaction products is shown below Provide the missing starting material H F 4 F CH3 N CH3 CH3 CH3 H O H B The structure of the following ionic substance was determined experimentally J Org Chem 1999 64 1039 In the observed structure there are two equivalent hydrogen bonds proposed to exist between two different and distinct pairs of atoms Draw a representation for the structure of this ionic substance that includes these two hydrogen bonds depict hydrogen bonds with dashed lines H2C H2C CH2 CH2 N C CH2 CH2 N H N H F F B F F 4 8 p 49 Rula Mualla Ashley Turner Name Page 3 III 21 points a Nitrile oxides are very reactive compounds that are useful in organic syntheses One Lewis structure a minor contributor for a simple nitrile oxide is shown below Provide the other two major resonance contributors for this compound all atoms must be closed shell formal charges between 1 and 1 Form A Form B H H C C N O H a nitrile oxide b Which of your drawings above contributes most to the actual structure circle one Form A Form B Forms A and B contribute an equal amount 3 3 2 c Assuming the hybridization model for all atoms and considering the resonance contributors …