Elementary Organic Chemistry I

Organic Chemistry

Organic Chemistry Lab

Exam_2_S2018_KEY.pdf-CHEM 232 Spring 2018: Exam 2

7 18. ( 40 points) Fill the boxes with the necessary starting materials, reagent(s)/reaction conditions, intermediate products, or final products. Provide reagent(s)/reaction conditions that would produce the major product most efficiently. Assume acidic workups if needed . If multiple stereoisomers are formed, only draw one and show appropriate

CHM | 232 | Organic Chemistry | exam | 7 18. ( 40 points) Fill the bo

1. Consider the molecule below: a. What reaction will take place (SN2, E2, SN1/E1)? b. How will the rate change if an ethanol solvent is used instead of DMSO? c. How will the rate change if [-NH2] doubles? 2. Draw the arrow-pushing mechanism for the major organic product. 6 Aphotic solvents Bad Bulky - CHS F - Acetone LDA Ntlzc ⑦ Ott T but oxide DMF row , electro neg = bad LG DMFO HMPA Nitromethane Acetonitrile SN z → favors polar aphotic aphotic Far photic ( hydrogen bond ) , so Rate of rxn decreases rate of rxn doubles ( increase ) - ↳ more concentrated - N Rz → good Nu → strong base w NU ① LG → good LG 10 branched , no Ez bc B carbon ✓ substituted E ① LG ( good ) ✓ bulky base → E2 good Nu E Hoffman bc bulky Concerted ↳ less substituted ' I step T ETAH KIT → if → H H 3. Which alkene is the least stable? a. b. c. d. 4. Consider the reaction below: a. Calculate the Δ H of the reaction. b. According to the Hammond Postulate, does the rate-determining step have an early or late transition state? Endothermic or exothermic? c. Bromine uses the most stable radical to form the major product. T/F Terminal internal 3 3 2 30 -78 kglmol endo → late TS ↳ true ( Bromine is very selective ) ↳ low energy Brt 5 bonds broken - bonds formed ( 404 +190 ) - (368+304) = -78 5. Bromine is 28x more selective for 3° carbons versus 2° carbons. Based on the molecule below, what percentage of products will form at the secondary carbon? 6. Draw the SN1 arrow pushing mechanism for the starting materials in ethanol. How would the reaction rate change if the solvent was changed to acetone? I > a g - - e a t 30 2 ° 56+14--70 Stat 2 14 = 80 - l . Sei 28 1 70 exp 56 14 good LG = electronegativity , a lot of resonance ✓ ROH E , triflate poor Nu 5025-3 2- W weak base µ Nu of d ⑦ / E ¥ o , - ¥ . ^ ¥ one product Hydride shift ↳ NO stereo center - 7. Consider the following reaction: a. What does the transition state of the rate-determining step look like? b. What are the HOMO and LUMO of the reaction? 8. Which of the following is not a polar aprotic solvent? 04%0 ÷ Iwweeaakunbuase } SNHEI 1st step → RDS iii. " " t ' m Late Tst L endo ↳ look like HOMO CNU ) : O sp 's orbital carbocation Lumo CE ) : C p orbital gfn+dg* inter . ① t ←¥ %hF " " " " " ° " " " 9. Identify all components of the mechanism: a. i. The electrophile is (methyl/1°-unhindered/1°-branched/2°/3°): ii. Is the leaving group good? iii. Is it a strong/weak nucleophile? Is it a strong/weak base? iv. Dominant mechanism? b. i. The electrophile is (methyl/1°-unhindered/1°-branched/2°/3°): ii. Is the leaving group good? iii. Is it a strong/weak nucleophile? Is it a strong/weak base? iv. Dominant mechanism? ① LG ( Not good bc F ) HSR EL 5 # → good m → weak base NO good Nu , weak base No rxn ( bad CG ) ① LG ( good ) 2 ° H T OH - ↳ good ✓ base ✓ N U -0 E ↳ good N u yes strong base , good NU EZ due to strong base ↳ zaitev ( small NU )

CHM | 233 | Organic Chemistry Lab | exam | 1. Consider the molecule below

1 CHEM 232 Worksheet Naming Benzene Rings 1. Draw the following molecules: a. Phenol b. Aniline c. Benzoic acid d. Anisole e. Toluene f. Benzaldehyde g. Styrene 2. Provide a systematic name and a variant using ortho, meta, para designations for the molecules shown below. a. 1-bromo-2-iodobenzene, ortho-bromoiodobenzene, o-bromoiodobenzene b. 1-nitr

CHM | 232 | Organic Chemistry | homework | 1 CHEM 232 Worksheet Naming Be

1 CHEM 232 Worksheet Synthesis with Benzene 1. Consider the functional groups on the benzene rings shown below. Label each substituent as “electron-donating” or “electron-withdrawing” and “activating” or “deactivating,” and provide at least one resonance structure that demonstrates the electron-donating or electron- withdrawing nature of the su

All courses in CHM

Popular Documents