Download Chapter 10 - UCSB CLAS

CLAS – Chem 109 B - Ch. 10
e-mail: [email protected]
website: http://clas.sa.ucsb.edu/staff/terri/
drop-in: T/R 2-3 and F 11-1 (SRB 3274)
I. Alcohols ⇒ for this chapter you’ll see alcohols undergoing nucleophilic substitution, elimination and oxidation.
1° alcohol
2° alcohol
3° alcohol
benzyl/allyl
alcohol
HI or HBr
SN2
SN1
SN1
SN1
HCl / ZnCl2
SN2
SN1
SN1
SN1
PBr3 or PCl3 /
pyridine
SN2
SN2
SN1
SOCl2 / pyridine
SN2
SN2
SN1
RSO2Cl in pyridine
ex TsCl
pre - SN2
pre - SN2
pre - E2
H2SO4 / Δ
E2
E1
E1
E1
POCl3 / pyridine,
cold
E2
E2
E2
E2
H2CrO4 or K2Cr2O7
/ H2SO4
Oxidation ⇒
carboxylic acid
Oxidation ⇒ Ketone
N/A
1° ⇒ carboxylic acid
2° ⇒ ketone
PCC / CH2Cl2
Oxidation ⇒
Aldehyde
Oxidation ⇒ Ketone
N/A
1° ⇒ aldehyde
2° ⇒ ketone
NaOCl / CH3COOH
cold
Oxidation ⇒
Aldehyde
Oxidation ⇒ Ketone
N/A
1° ⇒ aldehyde
2° ⇒ ketone
‘Swern’
1. Me2SO, C2O2Cl2
cold
2. triethylamine
Oxidation ⇒
Aldehyde
Oxidation ⇒ Ketone
N/A
1° ⇒ aldehyde
2° ⇒ ketone
Reagent
1° or 2° ⇒
SN2
3° ⇒ SN1
1° or 2° ⇒
SN2
3° ⇒ SN1
1° or 2° ⇒
pre-SN2
3° ⇒ pre E2
II. Ethers ⇒ In this chapter you will see ethers undergoing nucleophilic substitution reactions with HI or HBr producing
an alkyl halide (substituted product) and an alcohol (leaving group) - since the oxygen in the ether is bonded to 2
carbons your primary concern is to determine which one will be substituted – SN1 is preferred over SN2 because
the ether is in acidic solution – therefore the order of preference is…
benzylic/allylic (SN1) > 3° (SN1) > methyl (SN2) > 1° (SN2) > 2° (SN2)
III. Epoxides ⇒ In this chapter you will see epoxides undergoing nucleophilic substitution (only SN2) reactions aka ring
opening reactions - epoxides are ethers with lots of ring strain – the strain allows them to react with a large
number of nucleophiles unlike typical ethers which only react with HI or HBr – similar to typical ethers your
primary concern is to determine which carbon will be substituted – for epoxides the carbon that is substituted
depends on if the epoxide is in acidic verses basic conditions
Acidic (SN1-ish) ⇒ 3° > 2° > 1°
Basic or Neutral (SN2) ⇒ 1° > 2° > 3°
IV. Arene Oxides ⇒ In this chapter you will see arene oxides undergoing either nucleophilic substitution reactions same
as epoxides in basic/neutral conditions or rearrangement reactions to produce phenol (primary focus) – since
there’s a carbocation formed in the rearrangement reaction this will determine which carbon gets the OH – any
additional substituents that can stabilize a carbocation (electron donating) will speed up rearrangement
V. Amines ⇒ In this chapter you will see amines primarily acting as bases or nucleophiles – since the leaving group
of amines are such a strong bases they cannot undergo substitution or elimination reactions
VI. Quaternary ammonium hydroxides ⇒ In this chapter you will see quaternary ammonium hydroxides
undergoing Hoffmann (aka anti-Zaitsev) elimination reactions (only E2)– there are four carbons bonded to
the nitrogen and therefore there can be up to twelve β-carbons to choose from – however in an anti-Zaitsev
elimination the order of preference is benzylic/allylic > 1° > 2° > 3°
VII. Sulfur functional groups ⇒ In this chapter you will see thiols reacting as a nucleophile to produce sulfides aka thio
esters – thio esters can also react as nucleophiles to produce sulfonium ions – sulfonium ions can undergo SN2
reactions
Chapter 10 Practice
1.
2.
7.
8.
3.
9.
4.
10.
5.
11.
6.
12.
13.
26.
14.
27.
28.
15.
29.
16.
CH3CH2CH2CH2CH2CH2OH
17.
18.
19.
30.
31.
32.
20.
33.
21.
34.
22.
35.
23.
36.
1. RCO3H
24.
2. HO-, H2O
37.
25.
1. OsO4
2. H2O2, H2O
38.
41.
39.
42.
40.
43.
H3C
N
H
CH3
44. Rank the following alcohols in order of increasing rate of dehydration in the presence of sulfuric acid.
45. Which primary amine will form the following product when undergoing 2 successive Hoffman degradations?
46. Indicate how the following compound could be synthesized using the given starting material and any necessary
reagents.
47. What is the major product of rearrangement for the following arene oxide?
48. What is the major product of rearrangement for the following arene oxides? Which arene oxide is more likely to be
carcinogenic?
49. Explain why elimination of 2-bromopentane produces 2-pentene whereas elimination of the quaternary ammonium
ion produces 1-pentene.
OH