Orgo 11.1-11.5

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  1. Oxidation of alcohols leads to __, __, and _. These functional groups, in turn, undergo a wide variety of additional reactions. For these reasons, __ are some of the most common organic reactions.
    • ketones
    • aldehydes
    • carboxylic acids
    • alcohol oxidations
  2. In inorganic chemistry, we think of oxidation as __ and reduction as __. Most organic compounds are uncharged, and gain or loss of electrons is not obvious. Organic chemists tend to think of oxidation as the result of __ and reduction as the result of __.
    • loss of electrons
    • gain of electrons
    • adding an oxidizing agent
    • adding a reducing agent
  3. Explain: 
    oxidation: addition of O or O2; addition of X2 (halogens); loss of H2

    reduction: addition of H2; loss of O or O2; loss of X2

    neither: addition or loss of H+, -OH, H2O, HX, etc. is neither an oxidation nor a reduction
  4. How can we tell an oxidation or reduction of an alcohol has taken place? 

    Oxidation usually does what?

    A __ is more oxidized than an __ because the __ has one bond to oxygen, while the __ has no bonds to oxygen.
    by counting the number of C-O bonds to the carbon atom. 

    converts C-H bonds to C-O bonds

    primary alcohol


    carbinol carbon atom

  5. Oxidation of a primary alcohol gives an __ with a carbonyl carbon having __ bonds to oxygen. Oxidation of the __to an acid adds __ to oxygen, for a total of __. Further oxidation would require what to give four bonds to oxygen, the oxidation state of __.
    • aldehyde
    • two 
    • aldehyde
    • another bond
    • three
    • carbon dioxide
  6. Oxidation of a primary or secondary alcohol forms __ by the removal of two hydrogen atoms: one from __ and one from __.

    Why can't tertiary alcohols do this?
    • carbonyl groups
    • carbinol carbon
    • hydroxyl group
    • there is no hydrogen atom available on the carbinol carbon
  7. Primary and secondary alcohols are easily oxidized by a variety of reagents, including __, __, __, and even __. The choice of reagent depends on __. Many of the traditional oxidants are based on __ because they are highly toxic, and they are difficult to dispose of properly.
    • chromium oxides
    • permanganate
    • nitric acid
    • household bleach
    • amount and value of the alcohol 
    • chromium (VI) compounds
  8. All of the oxidizing agents have what and do what?
    • have an element (Cr, Cl, I or S) in a high oxidation state bonded to oxygen
    • they follow similar mechanisms
  9. What are the steps of oxidation of a secondary alcohol.
    • 1: forms an intermediate in which the alcohol oxygen replaces one of the oxidant's original bonds of oxygen
    • 2: a base (often water or other solvent) removes a proton from the carbinol carbon atom, giving it a double bond to oxygen, which leaves it oxidized; the oxidant leaves with fewer bonds to oxygen and one more pair of electrons, giving it a lower (reduced) oxidation state
  10. Secondary alcohols are easily oxidized to give excellent yields of __. The __ is often used for lab oxidations of secondary alcohols. The __ is prepared by dissolving __ in a mixture of __ and water. The active species in the mix is probably __ or the __. Adding __ to __ achieves the same result.
    • ketones
    • chromic acid reagent x2
    • sodium dichromate
    • sulfuric acid
    • chromic acid
    • acid chromate ion
    • chromium trioxide
    • dilute sulfuric acid
  11. The mechanism of chromic acid oxidation
    1: __
    2: __ gives the __.

    In the elimination, the carbinol carbon does what but loses what and gains what?
    • formation of a chromate ester
    • elimination of the chromate ester
    • ketone
    • retains its oxygen atom 
    • but loses its H
    • and gains a second bond to oxygen
  12. The __ formed reacts further to give the stable reduced form, __. Both __ and __ are orange, but __ is a deep blue.
    • chromium (IV) species
    • chromium (III)
    • sodium dichromate
    • chromic acid
    • chromic ion
  13. Oxidation of primary alcohols
    Oxidation of a primary alcohol initially forms an __. Unlike a __, however, an __ is easily oxidized further to give a __. 

    Obtaining the __ is often difficult, since most oxidizing agents strong enough to oxidize primary alcohols also oxidize __. __ generally oxidizes a primary alcohol all the way to a __.
    • aldehyde
    • ketone
    • aldehyde
    • carboxylic acid
    • aldehyde
    • aldehydes
    • chromic acid
    • carboxylic acid
  14. A better reagent for the limited oxidation of primary alcohols to aldehydes is __, a complex of chromium trioxide with pyridine and HCl. __ oxidizes most primary alcohols to aldehydes in excellent yields. Unlike most other oxidants, __ is soluble in nonpolar solvents such as __, which is an excellent solvent for most organic compounds. __ can also serve as a mild reagent for oxidizing secondary alcohols to ketones.
    • pyridinium chlorochromate (PCC) x3
    • dichloromethane
    • PCC
  15. Oxidation of tertiary alcohols is not important because what?
    they have no hydrogen atoms on the carbinol carbon atom, so oxidation must take place by breaking carbon-carbon bonds.
  16. The __ for primary and secondary alcohols exploits the resistance of __ to oxidation. When a __ or __ is added to the __, the orange color changes to green or blue. When a nonoxidizable substance is added to the reagent, no immediate color change occurs.
    • chromic acid test
    • tertiary alcohols
    • primary or secondary alcohol
    • chromic acid reagent
  17. The __ is a complex o chromium trioxide and pyridine, the original version of PCC. The __ is a milder form of chromic acid: a solution of diluted chromic acid in acetone.

    In many cases, simple oxidants such as household bleach can accomplish the same oxidations as chromic acid without using __ and without generating hazardous wastes.
    • Collins reagent
    • Jones reagent
    • heavy metals
  18. Oxidations using __ involve mildly acidic or basic conditions that may be better than chromic acid for acid-sensitive compounds. Two other strong oxidants are __ and __. Both are less expensive and produce less ehazardous. They both oxidize __ to __ and __ to __.
    • sodium hypochlorite
    • potassium permanganate and nitric acid
    • primary alcohols to carboxylic acids
    • secondary alcohols to ketones
  19. The __ uses dimethyl sulfoxide (DMSO) as the oxidizing agent to convert acohol to ketones and aldehydes. DMSO and oxalyl chlroide are added to the alcohol at low temp, followed by a hindered base such as triethylamine. The reactive species, formed in the solution, is thought to act as the __ in the __. __ are oxidized to __ and __ are oxidized only as far as the __. The byproducts of this reaction are all __ and are easily separated from the organic products.
    • Swern oxidation
    • oxidant
    • Swern oxidation
    • Secondary alcohols
    • ketones
    • primary alcohols
    • aldehyde
    • volatile
  20. Like the Swern oxidation, the __ reagent oxidizes primary alcohols to __ and secondary alcohols to __ without using chromium or other heavy-metal compounds. THe reaction with __ takes place under mild conditions and gives excellent yields. The __ reagent, which owes its oxidizing ability to a __, is a commercially available solid that is easily stored.
    • Dess-Martin periodinane (DMP)
    • aldehydes
    • ketones
    • DMP x2
    • high-valence iodine atom
  21. Although it is the least toxic alcohol, __ is still poisonous. To detoxify it, the liver produces an enzyme called __, which catalyzes an oxidation: __.
    • ethanol
    • alcohol dehydrogenase
    • the removal of two hydrogens from the alcohol
  22. The oxidizing agent is __, which exists in two forms: the oxidized __ and the reduced __

    A subsequent oxidation, catalyzed by __, converts acetaldehyde to acetic acid, a normal metabolite. These oxidations take place with most small __. Unfortunately, the oxidation products of some other alcohols are more toxic than __. Methanol is oxidized first to __ and then to __. Both of these compounds are more toxic than methanol itself.
    • NAD
    • NAD+
    • NADH
    • aldehyde dehydrogenase (ALDH)
    • primary alcohols
    • acetic acid
    • formaldehyde
    • formic acid
  23. Alcohols react as both __ and __. An alcohol is easily converted to a __ by forming its __. THe __ can attack a weaker __, such as an __.
    • nucleophiles
    • electrophiles
    • strong nucleophile
    • alkoxide ion x2
    • alkyl halide
  24. The O-H bond is broken when alcohols react as __, both when an __ reacts as a weak __, or when an alcohol is converted to its __ that then reacts as a __. In contrast, when an alcohol reacts as an __, the C-O bond is broken.
    • nucleophiles
    • alcohol
    • nucleophile
    • alkoxide
    • strong nucleophile
    • electrophile
  25. Why is an alcohol a weak electrophile? 

    The hydroxyl group becomes a good leaving group when __.

    The disadvantage of using a protonated alcohol is that a __ is required to protonate the alcohol. Although __ are stable in acid, few other good nucleophiles are stable in strongly acidic solutions.
    because the hydroxyl group is a poor leaving group

    it is protonated

    strongly acidic solution

    halide ions
  26. Most strong nucleophiles are also __ and will __. Once protonated, the reagent is no longer __. 

    How can we convert an alcohol to an electrophile that is compatible with basic nucleophiles?
    • basic
    • abstract a proton in acid
    • nucleophilic

    we can convert it to an alkyl halide or we can simply make its tosylate ester
  27. A __ is the product of condensation of an alcohol with p-toluenesulfonic acid (TsOH). The __ is an excellent leaving group, and __ undergo __ and __ much like alkyl halides. In many cases, a __ is more reactive than the equivalent alkyl halide.
    • tosylate ester
    • tosylate group
    • alkyl tosylates
    • sub
    • elim
    • tosylate
  28. __ are made from alcohols using __ in pyridine. This reaction gives much higher yields than the reaction with TsOH itself. The mechanism of __ formations shows that the C-O bond of the alcohol remains intact throughout the reaction, and the alcohol retains its __. __ serves as an organic base to remove the HCl formed in the reaction, preventing it from protonating the alcohol and causing side reactions.
    • Tosylates
    • tosyl chloride (TsCl)
    • tosylate formation
    • stereochemical configuration
    • pyridine
  29. The tosylate ion is a particularly __, with its negative charge delocalized over __.
    Like halides, the __ is displaced by a wide variety of nucleophiles. The __ is more commonly used than the __.
    • stable anion
    • three oxygen atoms
    • tosylate leaving group
    • Sn2
    • Sn1
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Orgo 11.1-11.5
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