Chem 225b

Comprehensive Organic Chemistry

Problem Set 7

Chapter 8

Due: Monday, March 24, 2008


We have discussed Degree of Unsaturation (D.U.) as it relates to hydrocarbons. How do you find the D.U. if other atoms are present? Fear not! There is an html document and an independent, different Powerpoint presentation on this topic. The subject of oxidation levels of organic compounds is a useful concept. Check it out here Oxidation Levels.The alcohol module in ORGO will give you a good review of some of the fundamental reactions discussed in class and in Chapters 8 and 9.

1. How many grams of K2Cr2O7 in aqueous H2SO4 are required to oxidize 20 grams of cyclohexanol to cyclohexanone? [This is a redox reaction from Gen. Chem. Derive the balanced equation and show your work.]

 

Victor Grignard (1871-1935)

Co-Nobel Prize in Chemistry (1912)


2. Two bottles on a shelf have had their labels fall on the desktop. Both of the labels read "C5H11Br". A student decides to run some reactions on the contents of bottle A and B to determine the structures of the two compounds. She also has access, as do you, to heats of formation. From the flow chart below, determine the structure of A and B and identify C-I. [Note: The mixture C and D is derived from A.] Show your reasoning.


3. Predict the products in each of the following examples. Justify your answer.

 


4. When organometallic reagents add to aldehydes and ketones, there is only one addition. Aldehydes give secondary alcohols and ketones afford tertiary alcohols. Esters (RCO2CH3), which are derivatives of carboxylic acids and are at the same oxidation level, undergo addition of an organometallic reagent (R'M) twice to yield a tertiary alcohol, RR'2COH. The reaction cannot be stopped after the first addition. It is also true that carboxylic acids are at a higher oxidation level than aldehydes by two electrons. Provide an explanation for these results and provide a mechanism for the process.