1 a) Name the following substances with the used common names or according to IUPAC (4p):

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1 EGLIS VESI Exam rganic Chemistry 2 (3B1760) Tuesday August 28, 2007, Allowed answering aids: molecular models Periodic system and tables of bond energies, pk a -values and M-shifts are attached after the questions Total of 10 questions, each worth 10p (total 100p). Minimum requirement 50p, for grade 4 at least 66p and for grade 5 at least 83p. Answer every question on separate sheets to facilitate grading write name, programme and year on each sheet Motivate your answers, normally both text and figures are necessary Please observe that the questions are not necessarily organized in order of difficulty (question 10 is not essentially the most difficult!) Good luck! lof amström 1 a) ame the following substances with the used common names or according to IUPAC (4p): 2 b) Draw detailed structures of one example each of the following ions. Indicate possible free electron pairs and reasonable resonance forms (6p): - enolate ion - acylium ion - allyl anion 2 a) Draw the π-orbital levels for benzene (use for example the Frost circle as a guide). Indicate how many electrons there are in each orbital and what orbitals constitute the M and the LUM, respectively (4p). b) What orbital in benzene reacts with the electrophile in a typical EAS reaction (2p) c) Draw the mechanism for a typical EAS reaction (4p). 1 (9)

2 EGLIS VESI 3 a) ow would you perform the following transformation (any number of steps) o mechanisms required (4p). 2 b) Amides are considerably more stable than acid chlorides. Explain briefly why (4p). c) Explain briefly the reason for the difference below (2p). Fast rotation Slow rotation 4 a) Indicate what is formed in the following reactions. o mechanisms required (2p per reaction). 2 E + (1 equivalent) 2 /Pt high pressure long time 2 2 /Pt atmospheric pressure short time b) What is formed in the following reactions, and why is there a difference o mechanisms required (4p). (I) + Δ (II) + Δ 2 (9)

3 EGLIS VESI 5 a) Indicate reagent(s) for step A, and the products 1 and 2 in the reaction sequence below. An excess of D 2 S 4 is used in the final step (4p). b) Sketch out the 1 -M spectrum for ethyl benzene. Indicate approximate shifts, integrals and coupling patterns (4p). c) Sketch out the 1 -M spectrum for product 2. Indicate approximate shifts, integrals and coupling patterns here too. (2p). A 1 Zn(g) D 2 S 4 + D Complete the following reactions. o mechanisms required (2p per reaction). -Li (excess) Li a a (C ) a a - 2 Δ 3 (9)

4 EGLIS VESI 7 The enzyme CAL-B is a lipase from the microorganism Candida antarctica that is used extensively in the organic synthesis of esters. A particular advantage of using the enzyme is that it often gives products that are stereochemically pure (for example only one enantiomer) A reaction sequence is indicated in the example below where CAL-B is used to synthesize product 4. 1 A 3 CAL-B B a) What reaction types are step A and step B, respectively (2p) b) Explain how step A proceeds with mechanism (4p). c) Propose how step B proceeds with a plausible mechanism. o consideration to stereochemistry necessary. What is the byproduct 5 (4p) 8 onazepam is the active substance in the drug Iktoviril, which is used as therapy for different forms of epilepsy. The substance belongs to the group of compounds known as benzodiazepines, and prevents signal transmission in the brain during a seizure. The seizure becomes attenuated and new seizures less likely. A way to synthesize clonazepam is described below (J. d. Chem. 1963, 6, 261). Br A a B b 2 onazepam a) Indicate the names of the functional groups marked a and b (2p). b) Indicate reactants 1 and 2 (2p). c) Describe with mechanisms how the reactions A and B proceed. Simplify preferentially the molecule in order to make the mechanisms easier to write (6p). 4 (9)

5 EGLIS VESI 9 Assume that you just became employed at Poly-Poolen AB, a small company specializing in tailor-making polymers for other companies. The Chief Scientific fficer in the company, Dr. P.-. Lyman, has asked you to design synthesis methods for the polymers below. You need to use the company's extensive collection of dicarboxylic acids with six or less carbon atoms. therwise you can choose freely. ow would you go about Describe the syntheses in detail with mechanisms (5p per polymer). n n 10 A quite complex benzophenone structure was used as a starting material in the synthesis of onazepam in problem 7 (substance 5 below). ne method to synthesize 5 is to start from substance 1, and then couple this to substance 3 according to the reaction sequence below (J. d. Chem. 1991, 34, 1545). C 1 A B 2 4 C a) Propose a possible synthetic method to substance 1 starting from benzene and other reagents of your choice. o mechanisms required, but indicate all reagents in each step. Indicate also potential problems that may arise in the suggested steps (6p). b) Indicate conditions/reagents for steps A, B, C and the intermediate product 2. o mechanisms required (4p). 5 (9)

6 6 (9) EGLIS VESI

7 EGLIS VESI Average Bond Strengths Bond Dissociation Energies (BDE) Average Bond Dissociation Energies (kcal/mol) C F Si S Br I a C b 73 c 86 d 116 e 72 f c h a 86 d 53 h F e Si f S Br I a b c d e f Average value. Approximately 103 kcal/mol for alchols and 119 kcal/mol for water C=C 146 kcal/mol C C 200 kcal/mol C= 147 kcal/mol C 213 kcal/mol C= 176 kcal/mol for aldehydes and 179 kcal/mol for ketones C=Si 111 kcal/mol = 111 kcal/mol 226 kcal/mol elease of strain energy upon ring opening Cyclopropane 27 kcal/mol Cyclobutane 26 kcal/mol Epoxide 25 kcal/mol Aromatization energy Benzene 36 kcal/mol Pyridine 28 kcal/mol Delocalization of lone pair Carboxylic ester ~7 kcal/mol Carboxylic amide 17 kcal/mol ydrogen bonds 4-10 kcal/mol (usually) 7 (9)

8 EGLIS VESI SME APPXIMATE pk a VALUES C -10 Strong Mineral Acids <0 F 3 C 12 (C) 3 C C CF 3 C 2 C S 2 3 C C C C C 25 S 11 2 ~30 9 (C 6 5 ) 3 PC 3 35 S (I-Pr) 2 C > (9)

9 EGLIS VESI CAACTEISTIC PT CEMICAL SIFTS* Type of Proton Structure Chemical Shift, ppm Tetramethylsilane (TMS) (C 3 ) 4 Si 0 Cyclopropane C Primary -C Secondary 2 -C Tertiary 3 -C 1-2 Amino ydroxylic -C- 1-6 Allylic C=C-C Esters -C-C Acids -C-C 2-3 Carbonyl Compounds -C-C= 2-3 Acetylenic C C- 2-3 Benzylic Ar-C- 2-3 Iodides -C-I 2-4 Bromides -C-Br Alcohols -C- 3-4 Ethers -C- 3-4 Chlorides -C- 3-4 Esters C-C Vinylic C=C- 4-6 Fluorides -C-F Phenolic Ar Aromatic Ar- 6-9 Aldehydic -(-)C= 9-10 Enolic C=C Carboxylic C * Fritt modiferad från: 9 (9)

Carboxylic Acid Derivatives and Nitriles

Carboxylic Acid Derivatives and itriles Carboxylic Acid Derivatives: There are really only four things to worry about under this heading; acid chlorides, anhydrides, esters and amides. We ll start with