Report: 1993-06-00 (Part 2) Determination of Key Organic ...
Organic CA15 Key
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Class Activity 15 Oxidation and Reduction 1 by Suzanne Ruder, PhD Class Activity 15 Oxidation and Reduction Model 1: Reduction Reactions Questions: 1. For the reduction reactions, from left to right, shown in Model 1: (a). The number of C-H bonds for Eq. A is (circle one) increased / decreased / same (b). The number of C-H bonds for Eq. B is (circle one) increased / decreased / same (c). The number of C-H bonds for Eq. C is (circle one) increased / decreased / same 2. For the reduction reactions, from left to right, shown in Model 1: (a). The number of C-O bonds for Eq. A is (circle one) increased / decreased / same (b). The number of C-O bonds for Eq. B is (circle one) increased / decreased / same (c). The number of C-O bonds for Eq. C is (circle one) increased / decreased / same 3. Using the above information, reduction of organic compounds can be described as an increase in the bonds to __H__ or a decrease in the bonds to __O__. 4. Consider the reduction reaction CH 3 CHBrCHBrCH 3 CH 3 CH=CHCH 3 . (a). The number of C-H bonds is (circle one) increased / decreased / same (b). The number of C-Br bonds is (circle one) increased / decreased / same (c). Compare the effect of halogens to that of oxygen (#2 above) in a reduction reaction. Halogens are classified in (circle one) the same / differently with regards to reduction compared to oxygen. (d). Explain why this reaction is a reduction reaction. Since the number of bonds to halogen Br has been decreased, this is a reduction reaction. 5. Consider the reaction RCHBrCH 3 RCH=CH 2 + HBr (a). The number of C-H bonds is (circle one) increased / decreased / same (b). The number of C-Br bonds is (circle one) increased / decreased / same (c). Would this reaction be considered a reduction reaction? (circle one) yes / no Explain. Although C-Br bonds have been decreased, C-H bonds have also been decreased, so it is not considered a reduction reaction. Reducing Reagents [Red]: Strong Reducing Reagent: LiAlH 4 Weak Reducing Reagent: NaBH 4
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Transcript of Organic CA15 Key
Class Activity 15 Oxidation and Reduction 1
by Suzanne Ruder, PhD
Class Activity 15
Oxidation and Reduction
Model 1: Reduction Reactions
Questions: 1. For the reduction reactions, from left to right, shown in Model 1:
(a). The number of C-H bonds for Eq. A is (circle one) increased / decreased / same
(b). The number of C-H bonds for Eq. B is (circle one) increased / decreased / same
(c). The number of C-H bonds for Eq. C is (circle one) increased / decreased / same
2. For the reduction reactions, from left to right, shown in Model 1:
(a). The number of C-O bonds for Eq. A is (circle one) increased / decreased / same
(b). The number of C-O bonds for Eq. B is (circle one) increased / decreased / same
(c). The number of C-O bonds for Eq. C is (circle one) increased / decreased / same
3. Using the above information, reduction of organic compounds can be described as an increase in the bonds to __H__ or a decrease in the bonds to __O__.
4. Consider the reduction reaction CH3CHBrCHBrCH3 CH3CH=CHCH3. (a). The number of C-H bonds is (circle one) increased / decreased / same
(b). The number of C-Br bonds is (circle one) increased / decreased / same
(c). Compare the effect of halogens to that of oxygen (#2 above) in a reduction reaction.
Halogens are classified in (circle one) the same / differently with regards to reduction
compared to oxygen.
(d). Explain why this reaction is a reduction reaction. Since the number of bonds to halogen
Br has been decreased, this is a reduction reaction.
5. Consider the reaction RCHBrCH3 RCH=CH2 + HBr (a). The number of C-H bonds is (circle one) increased / decreased / same
(b). The number of C-Br bonds is (circle one) increased / decreased / same
(c). Would this reaction be considered a reduction reaction? (circle one) yes / no
Explain. Although C-Br bonds have been decreased, C-H bonds have also been
decreased, so it is not considered a reduction reaction.
Reducing Reagents [Red]: Strong Reducing Reagent: LiAlH4 Weak Reducing Reagent: NaBH4
Class Activity 15 Oxidation and Reduction 2
by Suzanne Ruder, PhD
6. Reducing reagents can be classified as strong or weak as shown in Model 1. Compare the starting carbonyl compound to the product in each of the following reactions: Carbonyl LiAlH4 Reductions NaBH4 Reductions
Acids RCO2H + LiAlH4 RCH2OH RCO2H + NaBH4 RCO2H
Esters RCO2CH3 + LiAlH4 RCH2OH RCO2CH3 + NaBH4 RCO2CH3
Ketones RCOR + LiAlH4 RCH(OH)R RCOR + NaBH4 RCH(OH)R
Aldehydes RCHO + LiAlH4 RCH2OH RCHO + NaBH4 RCH2OH (a). Which carbonyls undergo reduction with LiAlH4? (circle) acid / ester / ketone / aldehyde
(b). Which carbonyls undergo reduction with NaBH4? (circle) acid / ester / ketone / aldehyde
(c). Are any of the reducing reagents unable to reduce some carbonyl compounds?
(circle one) yes / no
If so, list the reagent and the carbonyl group(s) that is not reduced by the reagent.
NaBH4 does not reduce acids or esters.
(d). Once everyone in your group agrees on the above concepts, determine the reducing
reagents that will accomplish the following transformations:
Model 2: Oxidation
Questions: 7. For the oxidation reactions, from left to right, shown in Model 2:
(a). The number of C-H bonds for Eq. D is (circle one) increased / decreased / same
(b). The number of C-H bonds for Eq. E is (circle one) increased / decreased / same
(c). The number of C-H bonds for Eq. F is (circle one) increased / decreased / same
8. For the oxidation reactions, from left to right, shown in Model 2: (a). The number of C-O bonds for Eq. D is (circle one) increased / decreased / same
(b). The number of C-O bonds for Eq. E is (circle one) increased / decreased / same
(c). The number of C-O bonds for Eq. F is (circle one) increased / decreased / same
Oxidizing Reagents [Ox]: Strong Oxidizing Reagents:
Na2Cr2O7, H2SO4 or KMnO4
Weak Oxidizing Reagents:
CrO3-Py-HCl (PCC) or (COCl)2, Et3N, DMSO (Swern)
Class Activity 15 Oxidation and Reduction 3
by Suzanne Ruder, PhD
9. Using the above information, oxidation of organic compounds can be described as an increase in the bonds to _O___ or a decrease in the bonds to __H___.
10. For the oxidation reaction CH3CH=CHCH3 CH3CHBrCHBrCH3 (a). The number of C-H bonds is (circle one) increased / decreased / same
(b). The number of C-Br bonds is (circle one) increased / decreased / same
(c). Compare the effect of halogens to that of oxygen (#8 above) in an oxidation reaction.
Halogens are classified in (circle one) the same / differently with regards to oxidation
compared to oxygen.
11. Oxidizing reagents can be classified as strong or weak as shown in Model 2. Compare the
starting compound to the product in each of the following reactions: Compound Strong [Ox] Reagents Weak [Ox] Reagents
1 ROH RCH2OH + [Ox] RCO2H RCH2OH + [Ox] RCHO
2 ROH R2CHOH + [Ox] RCOR R2CHOH + [Ox] RCOR
3 ROH R3COH + [Ox] R3COH R3COH + [Ox] R3COH
Aldehydes RCHO + [Ox] RCO2H RCHO + [Ox] RCHO (a). Strong [Ox] convert primary alcohols to ___carboxylic acids_______.
(b). Weak [Ox] convert primary alcohols to _______aldehydes_______.
(c). Strong [Ox] convert secondary alcohols to _____ketones________. Compare the
oxidation of secondary alcohols with weak [Ox]. Are there any differences? (circle one)
Yes or no. Explain. .The same product is obtained (ketone) with either reagent.
(d). Strong [Ox] convert aldehydes to _____ carboxylic acids _______. Compare the
oxidation of aldehydes with weak [Ox]. Are there any differences? (circle one) Yes or
no. Explain. Weak oxidizing reagents do not oxidize aldehydes to carboxylic acids
(e). Are there any compounds not oxidized by either strong or weak [Ox]? (circle one) yes /
no. If so what compounds? Tertiary alcohols are not oxidized by any of the reagents
listed.
(f). Once everyone in your group agrees on the above concepts, choose the reagents that will accomplish the following transformations:
Reflection: on a separate sheet of paper. As a group, write three concepts your group has learned from this activity and the one most important unanswered question about this activity that remains with your group. Turn this in before leaving class.
Class Activity 15 Oxidation and Reduction 4
by Suzanne Ruder, PhD
Additional Questions: 12. Classify each of the following reactions as either oxidation, reduction or neither. (a).
oxidation
(b).
oxidation
(c).
reduction
(d).
neither 13. Shown below are some important cellular processes. Identify whether they are oxidation or reduction reactions. (a).
oxidation
(b).
reduction 14. Determine whether the reactions below are oxidation or reduction. List all of the reagents that will accomplish the transformations shown. (a).
oxidation using strong [Ox] like Na2Cr2O7/H2SO4 or KMnO4
(b).
reduction using LiAlH4 or NaBH4 (c).
oxidation using weak [Ox] like PCC or Swern
(d).
reduction using LiAlH4
