CHEM 322/520 Midterm Exam 4-Organic Chemistry II/Survey of Organic Chemistry

CHEM 322/520Midterm Exam 412/15/15ProblemPointsPart I (50)_____Part II (50)_____Part III (25)Organic Chemistry II/Survey of Organic Chemistry Name:__________________Fall 2015Take-Home Exam: Due on or before Tuesday December 18 at 5:30 pm._____Total (125) ________________________________________________________________________________________Directions: 1. Make sure there are 5 numbered exam pages and 3 parts to this take-home midtermexam. 2. Print your name (last name first first name second) on this page of the exam only. 3. Signyour name below acknowledging that you will honor the pledge. 4. Read each question carefully. Markyour answers concisely and legibly and show all your work where required in order to receive partialcredit; however write the answer only in the space provided except where noted. You may use theback of each page as scratch paper but it will not be graded. This exam is open book notes handouts models etc. I require that your answers represent your own individual effort. You MUST NOT work ingroups or collaborate with others on this exam. Good luck!Pledge: On my honor I will not receive or give aid on this examination.___________________________________________________________________________________Kasey Kangaroo says “The following information may be useful”:Rings and Double Bonds/Double Bond Equivalents (DBE) formula: R = (n 1) – [(x-t)/2] where n =number of carbon atoms; x = number of (hydrogen halogen) atoms; t = number of nitrogen atoms.1 Part I. Predict the Product (50 pts)A. Instructions: Give the expected major product or products in each of the following transformations.Clearly show the stereochemistry where appropriate (i.e. with the use of wedged or dashed lines orother unambiguous convention). Assume the appropriate standard work-up conditions (i.e. acid workup or base work-up) that give the final neutral product. If no reaction is expected write “NR”.01.CHOCH3CHOOH-02.OCH32OH-03.O(CH3)2CuLi04.O2H3Ci) CH3CH2OOCH2CH3ii) H 05.OOOCH2CH3 H3Ci) CH3CH2OOCH2CH3ii) H 06.OH3CH2COOOCH2CH3 i) CH3CH2Oii) H 07.ONPhCH3 H 2 08.CHO HHH3CH2CO2CCH3CH2O-CO2CH2CH309.H3CCH2H3CHBrROOR(peroxides)light10.Br2lightPart II. Mechanisms and Spectroscopy (50 pts)A. When epoxy carboxylic acids are heated in the presence of pyridine an aldehyde is formed via arearrangement with the loss of CO2. Using the electron-pushing formalism show the mechanism for thistransformation. (10 pts)R1CO2HR1heatR2 O HR2 HO CO2HNB. Treating a solution of cis-1-decalone with base causes an isomerization to take place. At equilibrium the solution is found to contain about 95% trans-1-decalone and about 5% cis-1-decalone. Write amechanism to account for this isomerization (05 pts). Why is the trans isomer favored? (05 pts).HOHbaseHH3O C. Aldehydes that have no a-hydrogens cannot undergo the aldol condensation. When these compoundsare treated with base (e.g. hydroxide) they undergo instead an intermolecular oxidation-reductionrection called the Cannizzaro reaction as shown below. Using the electron-pushing formalism show themechanism for this transformation. (10 pts)OCHOOH-2OHH2OO- D. Shown below is an alternative mechanism for the photochemical chain radical chlorination ofmethane:Cl2 CH4CH3Cl HClStep 1 (initiation):2 Cl•Cl2Step 2 (propagation part 1):Cl• CH4CH3Cl H•Step 3 (propagation part 2):H• Cl2HCl Cl•1. Using the data provided below (bond dissociation energies BDE) calculate ?H° for each of the twopropagation steps of the alternative mechanism (10 pts). BDE: C-H bond 104 kcal/mol; C-Cl bond 83kcal/mol; Cl-Cl bond 58 kca/mol; H-Cl bond 103 kcal/mol.?H° (step 2) = _______________?H° (step 3) = _______________2. Based on this information will this alternative mechanism be: a) better; b) worse; or c) about thesame as the one discussed in your Jones text page 569 (circle one choice a b or c)? (05 pts) Justifyyour answer. (05 pts)4 Part III. Synthesis (25 pts)A. The structure of the analgesic Darvon is shown below. Starting with phenyl ethyl ketone and usingany reagents reactions or other materials we used in this course devise a synthesis of Darvon. Partialsyntheses will earn partial credit so be sure to write any steps you know. (25 pts)CH2CH3CH3OOOseveralsteps5N(CH3)2Darvon