Page 1 2. 12 Points. (a) Name or write a structure for the following compounds (IUPAC nomenclature). Be sure to pay attention to stereochemistry! Note that most of these questions are taken directly from the end of chapter problems of the textbook! Cl Cl C 2 3 C C 2 C 3 cis-1-(bromomethyl)-2-(2-chloroethyl)cyclobutane Meso-1,2,3,4,butanetetraol (show as a Fischer projection) (1R,2R)-2-(2-hydroxyethyl)cyclopentanol
Page 2 2. 12 Points (a) ow many stereoisomers are possible for the compound below? Answer: 3 C 3 C C 3 C 3 (b) raw a Fischer projection for the compound below using the template to the right. Note that the stereochemistry of some C atoms is specified (R) (S) (R) C C C C 2 Cl Cl C 3 C 2 (c) Circle any compound below that is identical to compound A (shown in Fischer projection) C 3 C 3 C 3 C 3 C 3 C 3 Compound A (d) Choosing amongst the compounds below circle TW that are enantiomers C 3 C 3 3 C 3 C C 3 C 3 3 C 3 C 3 C C 3
Page 3 3. 12 Points. (a) A distracted student measured the boiling point (bp) of four organic molecules as 38 C, 82 C, 118 C, and 157 C but forgot to write these values next to the name of the molecules. Given the known trends for boiling points, write in the boxes below the bp value that matches each of the individual compounds named below: 1-hexanol pentane 2-methyl-2-propanol 1-butanol bp = bp = bp = bp = (b) Write the structure of two different alkyl magnesium chlorides (Grignard Reagents) that would react with water to produce propane. (c) raw the structure of the chiral alkane with the lowest molecular mass (no isotopes are allowed) (d) In a famous experiment carried out in 1848, Pasteur discovered the optically active enantiomers of tartaric acid. raw their structures in Fisher projections. C C C C Tartaric acid (e) Another stereoisomer of tartaric acid was discovered in 1906. raw its structure in Fischer projection
Page 4 4. 14 Points Complete the reactions below showing all the missing reagents and solvents as appropriate. If several steps are involved, show the first step above the arrow and the next below the arrow numbering the steps 1, 2, etc The reagents chosen must be such that the product shown is the major product of the reaction Et 3 C I Et C 3 Et 3 C SC 3 (Et = C 2 C 3 ) 3 C S C 3 N 3 C 3 C 3 3 C C C 3 C 2 C 2 Cl 3 C C C 3 C 2 C 2 C C 3 C 3 C 2 C 2 C 2 C 2 C 3 C 2 C 2 C 2 C 3 C C C 3 C 3 C 3 3 C C 3 C 3 C
Page5 5. 10 Points. Complete the following equations by showing the structure of the major product obtained (no mechanism needed). Note that structures are shown in Fischer projections where relevant C 2 Cr 3 2 Ph Ph Ph = C 3 C 3 C 2 Na in C 3 C 2 3 C C 3 C 3 C 2 NC MF C 3 Ph C 3 C 2 Na Ph in C 3 C 2 3 C C 3 C 2 C 3 1) NaB4 2) + 2
Page 6 6. 10 Points. Propose a step-by-step synthesis of the following compounds from the starting material(s) indicated. Show all reagents & solvents needed for each step. No mechanism is needed. (a) C 3 -C 2 --C 2 -C 3 from C 3 -C 2 - as the sole source of C atoms in the final product. (b) C 2 C 2 from cyclohexane and any other reagent with 4 C atoms or less
Page 7 7. 10 Points (a) Explain the observation that compound (A) undergoes rapid substitution in water but compound (B) is unreactive despite the fact both are primary halides. (Your answer should show key structures or mechanisms) (A) (B) C 3 C 2 Cl C 3 C 2 C 2 Cl 2 2 C 3 C 2 + Cl No Reaction (b) When dissolved in ethanol, the compound below reacts rapidly, (i) Show the structure of the product, (ii) write a mechanism explaining its formation, and (iii) write an expression for the rate of this reaction. 2 N-C 2 -C 2 -C 2 -C 2 - (i) structure of product (ii) Mechanism: (iii) Rate =
Page 8 8. 10 Points. (a) When 2 bromopropane C 3 -C-C 3 is dissolved in methanol and an equimolar amount of sodium iodide Na + I - is added, the concentration of iodide ion [ I - ] quickly decreases then slowly returns to its original value. Explain with equations showing the various processes that take place sequentially. (b) Explain why compound (C) exists mostly in a chair conformation with axial while compound () prefers a chair conformation with equatorial (C) ()
Page 9 9. 10 Points. Show the structures of ALL the products obtained in the solvolysis of 2-bromo-1,1- dimethylcyclopentane in ethanol. Also show the structure(s) of the key intermediate(s) involved in this reaction. 3 C C 3 Et Answer: structure(s) of the key intermediate(s) Answer: Structure of the PRUCTS