1. Give the IUPAC name for the following structures: a) a) _________trans-4-isopropyl-2-octene__________________________ b) b) _____E-5-secbutyl-4-decene__________________ c) c) ________2-cyclopropyl pentane__________________________________
a) allyl fluoride a) _______________________________ b) ethylene b) __________________________________________ Z-5-methyl-4-isopropyl-4-decene c) __________________________________________
Draw the most stable conformation of 1,3-dichloro cyclohexane using the template below:
4. (3 points each, total of 12 points) What is the degree of unsaturation for each formula indicated? a) C2H4 b) C5H12O c) C11H20FCl d) C21H37N a) 1 b) 0 c) 1 d) 4
5. (5 points each) Give the reagent or product for the following reactions: (5 points each) Give the reagent or product for the following reactions:
6. Rank the following as nucleophiles: a) NH3 b) NH2 - c) NH4 + ____NH2-_______ > ____NH3_______ > _____NH4+________
7. Fill in the correct way to draw arrows for the following reaction... 7. Fill in the correct way to draw arrows for the following reaction...
8. (5 pts) Draw the best possible Newman projection for 1,2 dibromo ethane on the correct template below:
What type of reaction is the following? SN2 (conversion of propanol to propyl bromide) answer: ____substitution (specifically SN2)_________________
10. Rank the following carbocations in order of their stability (most stable on the left side of the arrows). 10. Rank the following carbocations in order of their stability (most stable on the left side of the arrows). ___b_______ > ____c______ > ____a
11. Which of the choices below best depicts the mechanism of the reaction between a grignard reagent and water to form an alkane (5 pts)?
12. Briefly state Markvonikov’s Rule and how it governs addition to a double bond. When adding to a double bond, when the carbocation forms, the more stable one is preferred. This (typically) means that the hydrogen has added to the less substituted carbon, and the nucleophile (which adds second) will be on the more substituted carbon. Therefore, overall, Markovnikov's rule is that in an addition reaction to a double bond, the more substituted product is formed.
13. Which is more stable, E-3-methyl-2-hexene or 2-hexene? Briefly explain why. The more substituted double bond is more stable. (Tetra > tri > trans > cis > di > mono > ethene)
14. Why is this probably the least stable of the 6 carbon sugars?
14. Why is this probably the least stable of the 6 carbon sugars? all of the groups are axial (least stable position).
15. If you had a mixture of ethanol, ethane, and ethane, which of the three spots (a, b, or c) would correspond to ethanol if the eluent for this TLC plate was hexane? answer: ____b (it is the most polar of the three spots)________
17. Using the diagram below, draw the energy diagram for the addition of HBr to an alkene. R+ is the carbocation
18. Draw the complete, detailed mechanism for the following reaction. Be sure to explain the regiochemistry (location) and stereochemistry (direction) of the product.
Topics for Exam: 1)Naming Alkenes 2)Degrees of Unsaturation 3)Organic Reactions & Mechanisms 4)Addition Reactions
Naming Alkenes The suffix is –ene The double bond has to be in the longest chain The double bond gets priority in the numbering If it is di substituted, include “cis” or “trans” in the prefix If it is tri or tetra substitued, include “E” or “Z” in the prefix after completing your ranking & determining the sides of the highest ranking groups according to the Cahn-Ingold-Prelog rules
Degrees of Unsaturation Cn H 2n+2 Know how to calculate for various types of formulas CH CHO CHX CHN
Organic Reactions & Mechanisms 1)Know the types of reactions a)Addition b)Elimination c)Substitution d)Rearrangement 2)Carbocation rearrangements 3)Recognize & draw nucleophiles & electrophiles 4)Recognize & draw mechanisms for some reactions
Addition Reactions There are 13 reactions for this exam. They are listed on the following pages in order from the reaction sheet.
Dehydrohalogenation Recognize that a strong base (like KOH) causes the alkyl halides to eliminate. We will discuss the mechanism later (exam 4)
Markovnikov addition of water to the double bond Needs the acid catalyst. Adds via a carbocation…so you get a mix of products, and the OH adds to the more substituted carbon of the double bond.
Markovnikov addition of an alkyl halide to the double bond Needs HBr to form the carbocation. Adds via a carbocation…so you get a mix of products, and the Br adds to the more substituted carbon of the double bond.
Trans formation of a dihalide Forms a bromonium ion. Backside attack of the nucleophile (in this case Br - ) causes inversion at the center and attack on the more substituted carbon.
Markovnikov addition of HOBr Forms a bromonium ion. Backside attack of the nucleophile (in this case OH - ) causes inversion at the center and attack on the more substituted carbon.
Markovnikov addition using NBS Forms a bromonium ion. Backside attack of the nucleophile (in this case H2O ) causes inversion at the center and attack on the more substituted carbon. The OH winds up attached to the more substituted carbon.
Anti Markovnikov addition of HBr using a radical initiator Recognize with the ROOR, that the Bromine adds to the least substituted carbon. Know the steps initiation (neutral to radicals) propogation (just changes where the radical is) termination (radicals to neutral The radicals mimic carbocation stability (tertiary > secondary > primary
Anti Markovnikov addition of water (hydroboration) Recognize the BH3 (it can be B2H6) Know that it adds syn (to give a cis product) The lesser substitued alcohol is the major product
Cis addition of Hydrogen to the double bond Recall that the Pt or Pd makes a “sheet” for the Hydrogens to add from They add cis because the alkene approaches the “sheet” from one side.
Formation of a cis diol Recall that the Manganese forms a 5 membered ring which is why the oxygens wind up cis in the product.
Ozonolysis Recall that the Ozone forms a 5 membered ring that is “bad” so it rearranges & breaks the carbon – carbon bond. Basically splits the alkene into two carbonyl containing structures.
Epoxide Formation Uses a “per” acid… a carboxylic acid with an extra oxygen in it. MCPBA is the most common reagent, but others can be used. Just look for the –OOH.
Less acidic Markovnikov addition of water Less acidic than straight H3O + Mercury forms a three membered ring with the alkene Just recognize that the final product is Markovnikov addition of water.