University:
Amherst College
Course:
CHEM 221 | Organic Chemistry I
Academic year:

2021
Views:

63

Pages:

4
Author:

Wesley Woods

Chem 21 Homework set 11 End-of-chapter problems from Hornback: Ch 11: 32 - 37, 38 (of course, your syntheses must (not "may") produce racemic mixtures), 39 - 54. 1. Draw the products of the following reactions, showing stereochemistry where necessary. Label any products that are enantiomers or diastereomers. As a general rule, don't draw products formed in insignificant amounts, don't draw the same product twice, and don't write mechanisms. Of course you should always keep the mechanism in mind — that’s the best way to predict products. (a) (b) HBr HCl (c) (d) HCl HI (e) Suppose you combined 1 mole of isobutylene (aka 2-methylpropene) and 1 mole of 1-butene then added 1 mole of HBr. (of course, 2 moles would be needed to use up all of both alkenes, but we're only adding 1 mole here.) What compounds would you find when the reaction was over? Draw their structures below. (f) (g) How is part f similar to part e? HI (1 equiv) 2. Draw the products of the following reactions. Show stereochemistry where relevant, and label any products that are enantiomers or diastereomers. (a) (b) Br2 (c) Cl2 (d) Cl2 Br2 H2O H2O (e) (f) Hg(OAc)2 NaBH4 Hg(OAc)2 H2O NaBH4 D2O (g) (h) Hg(OAc)2 Hg(OAc)2 NaBD4 H2O NaBH4 Et–OH 3. Draw the organic products of the following reactions. Show stereochemistry where relevant, and indicate any products that are enantiomers or diastereomers. (a) (b) BH3 BH3 H2O2 H2O2 HO– , H2 O HO– , H2 O (c) (d) BD3 H2O2 1. OsO4 – HO , H2 O 2. aq. Na2SO3 (e) (f) 1. OsO4 1. OsO4 2. aq. Na2SO3 2. aq. Na2SO3 4. Write mechanisms for the reactions below, showing each step clearly with curved arrows, as always. Although they may look completely alien at first, they are just slight variations on the reactions you've recently learned. So what's the best approach? (i) panic and forget everything you've learned about skeletal structures, valence, and assigning charges, then draw a swarm of arrows, wave your hands over the page, and say “poof”; or (ii) pay careful attention to the electrons and charges, and shift electrons in logical, familiar ways. (hint: pick ii! pick ii!) (a) O H+ OH H2O (b) OH Br2 H2O O Br Chem 21 Fall 2009 HW set 11 30 points; due Wed, Dec 2 Name _________________________________________ 1. Draw the products of the 8 reactions below, including stereochemistry where appropriate. (Please do not use wedge/dash notation when you're only showing conformation.) H2 Pd D2 Br2 Pd D2O 1. Hg(OAc)2, H2O 1. OsO4 2. NaBH4 2. aq. Na2SO3 HCl 1. BH3 2. H2O2 H2O, HO– 1. Hg(OAc)2 CH3CH2OH 2. NaBH4 2. The following reaction goes via the usual mechanism. Explain why the first product is formed instead of the second. (A good answer will likely include more structures than words.) O H+ ROH O O R not R 3. Write a mechanism to account for the following reaction. O H+ OH H2O (racemic) 4. Suggest synthetic routes that could be used to carry out the following conversions in good yield. Please do not write mechanisms. Just write the sequence of reactions — starting material, reagents, and final product — that you would carry out in the lab. (a) OCH3 Br (b) (racemic) Br OH

Chemistry 21 Homework set 11

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