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CHEM 346 - EXAM 1 ANSWER KEY February 21, 2012 Name: Instructions: This is a one hour exam which you will have two hours to complete. You are only allowed to use molecular model kits, scratch paper, and your brain. Good luck!Chem 346 Exam 1 - 2012 Question 1: / 15 Question 2: / 24 Question 3: / 16 Question 4: / 10 Question 5: / 12 Question 6: / 13 Question 7: / 10 TOTAL: / 100 The following list of reagents may be of use to you for this exam: HNO3HClNaCNH2NNH2NaOHPd/C Pt/CZn(Hg)hνΔMg0Sn0CuBr CuCNCuClKICu(I)H2ONaNH2NaOCH3Br2Cl2AlCl3H2SO4NaNO2P2O5SOCl2H2KMnO4MnO2FeBr3FeCl3Pd(PPh3)4Na2Cr2O7H3PO2HBF4Et3NChem 346 Exam 1 - 2012 1. Describe each of the following transformations as an oxidation, reduction, or neither, and explain your designation based on labeling the oxidation levels of the carbons involved in the transformation. (3 points each) A. OII20 Reaction classification: reduction B. Br Br2200 Reaction classification: neither C. O OHH3CO OHH3COH210 0 Reaction classification: oxidation D. OOHOHOH1112 Reaction classification: reduction E. HOOCl ClH3COH3COH3COCH3OH133111 Reaction classification: neitherChem 346 Exam 1 - 2012 2. Predict the product(s) of the following transformations. (8 points each) A. OHO1. SOCl22.H3COAlCl33. KMnO4OHOH3COO1. acid chloride formation2. FC acylation (ortho to strongly activating group)3. oxidation of benzylic position B. 1. HNO3, cat. H2SO42. CH3CH2OH, cat. H+3. Cl2, FeCl3OHOOCH2CH3ONO2Cl1. nitration, meta-selective2. Fisher esterification3. chlorination, meta-selective C. FNO21. Br2, FeBr32. NaOCH33. Pd/C, H2H3CONH2Br1. bromination (ortho to fluorine, meta to nitro)2. nucleophilic aromatic sub.3. reduction of nitro to amineChem 346 Exam 1 - 2012 3. Provide reagents/conditions for executing the following synthetic sequence. You may assume that you can separate ortho and para isomers. Each arrow should have one set of reaction conditions (this doesn’t include workups). (8 points each) A. OHOCNClSOCl2NH3, Et3NP2O5Cl2, FeCl3 B. O OOOBr2, hνNaCNH2O, H+ClAlCl3Chem 346 Exam 1 - 2012 4. The following reaction was conducted, and two products of electrophilic aromatic substitution were observed. Based upon your knowledge of brominations, show the two products that were formed, with a clear explanation of the selectivity of these two molecules over all other potential EAS products. (10 points) OMeOMeBrOMeBrBr2 The question requires an analysis of the two groups to determine which may be the better atortho/para directing. In this case, one could also look at the conditions (Br2, no FeBr3) to notethat the group must be strongly activativing, which likely implicates the influence of the ether.OMeBr BrOMeHBrOMeHBrOMeHBrOHBrMeThe methoxy alkene group, through resonance forms, provides additional stabilization!OMeBr BrOMeBrHsame resonance effects hereOMeBr BrOMeHBrOMeHBrOMeHBrCan never use ether group to stabilize this cation. (Same effect whensubstituting at the other position.)OMeHBrChem 346 Exam 1 - 2012 5. Provide a synthesis of compound A from benzene (B) using reagents and conditions that we have discussed in lecture. You may assume that you can separate ortho and para isomers. (12 points) FNO2fromA B HNO3H2SO4NO2Sn, HClNH2NaNO2HClN2ClHBF4FClAlCl3HNO3H2SO4FFNO2Chem 346 Exam 1 - 2012 6. Provide an arrow-pushing mechanism for the following transformation. Writing “proton transfer” for the applicable processes is ok. (13 points) HOOOHOOOOOOOΔ HOOOHOOOOHOOOOOOOHBHOOOOOOOBHHOOOOOOOHHOOOOOOHO(writing "proton transfer" ok)OOOHOOprotontransferOOOOOHOHOOOOChem 346 Exam 1 - 2012 7. In class, we discussed the use of thionyl chloride (SOCl2) to convert carboxylic acids to acid chlorides. Another reagent that is capable of this same transformation is oxalyl chloride ((COCl)2, drawn below). Based upon your knowledge of the thionyl chloride reaction, provide an arrow-pushing mechanism for the reaction below, illustrating the effectiveness of this reagent for enabling this transformation. Writing “proton transfer” for the applicable processes is ok. (Hint: think about the byproducts.) (10 points) OHOClClOOClObyproducts(oxalyl chloride) With SOCl2, the reaction involves a "mixed anhydride", where chloride replaces the anhydride, and theleaving group irreversibly collapses to SO2 and chloride. The question here is what the comparative leavinggroup is and how does it irreversibly convert to something else.OHOClClOOOOHOClOClOOHOClOClOOOClOHClOOOClOHClOOOClOHClClOHOClOObyproductleaving groupOCOCO2COCOCO (carbonmonoxide)Cl- HClOThe byproducts of carbon monoxide and carbondioxide irreversibly form, leaving chloride as thelone counterion! Just like with


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CSU CHEM 343 - EXAM 1

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