Experiment 7

The behavior of esters and ketones in a reaction with a nucleophile is different because: 1) the carbonyl of the ketone is more positive. 2) the ester cannot form a tetrahedral intermediate. 3) the two oxygens of the ester sterically hinder the nucleophile attack. 4) there is a reasonable leaving group in the ester. O 2 O 4 O 1

A 3. Rank the following compounds in terms of reactivity with a good nucleophile. Br B NH₂ F D OH E CI

What is the major elimination product obtained from the following reaction? Br toons CH3 (CH3)3CO (CH3)3COH CH₂ Of-Bu || CH₂ Of-Bu III CH3 o IV CH3

Decide which compounds from the list below are best suited for nucleophilic addition reactions and which ones are more appropriate for nucleophilic substitution reactions.

In both examples below the reactants shown are combined to bring about a nucleophilic substitution (SN1, SN2) and/or elimination (E1, E2) reaction. What is the major reaction that takes place in each case? BrCH₂COCH3 CH3 CH3CH₂CCH3 NaCN CH3OH H₂O SN2 M

What major product will be formed when the shown Grignard reagent is combined with the shown organolithium reagent ? MgBr Li O1.C C O2B a 1:1 mixture of A and C 3. O 4. A O 5. Are you kidding us? Both the Grignard reagent and the organolithium are nucleophiles. They will not react with each other.

Br CH3OH + Br-Br H3CO The mechanism proceeds through a first cationic intermediate, intermediate 1. Nucleophilic attack leads to intermediate 2, which goes on to form the final product. In cases that involve a negatively charged nucleophile, the attack of the nucleophile leads directly to the product. +Br + CH3OH Br Intermediate 1 Intermediate 2 (product) In a similar fashion, draw intermediate 1 and intermediate 2 (final product) for the following reaction. OH + Br2 + HBr Br racemic mixture • Pay attention to the reactants, they may differ from the examples. In some reactions, one part of the molecule acts as the nucleophile. • You do not have to consider stereochemistry. • Draw one structure per sketcher. Add additional sketchers using the drop-down menu in the bottom right corner. Separate intermediate 1 and intermediate 2 using the → symbol from the dropdown menu.

Provide the correct sequence of the steps involved in the following reaction: H3C CH2 H3C Br2 HBr но Br Step 1 [Choose] Nucleophilic attack on Bromine Carbocation rearrangement Proton transfer to bromide ion Step 2 Nucleophilic attack by water Leaving group leaves Nucleophilic attack by hydroxide Step 3 Generation of bromonium ion Step 4 [ Choose ]

14. Draw the two reactants used to form the following compound, label the nucleophile and the electrophile, and using arrows show the points of attack of the nucleophile on the electrophile that enables the formation of the heterocyclic product. Na2CO3, H2O NH2 А. H CH3 H CH3H CH3

3. Which of the following are nucleophiles? 1 CH3NH2 2 CH3O 3 H3CC=CH

Rank the following reactions in order of increasing nucleophile strength: Cl-, H2O, CH3-, H2S, HS-, I-

A set of three nucleophilic displacement reactions is shown below: Br CH3 BRCH,CHCH,CH,CH,CH3 Br CH3CHCH,CH,CH,CH3 CH3CCH,CH2CH,CH3 CH3 A B H20, CH;CH,OH SN1 reaction Which reaction (A, B, or C) proceeds the fastest? Which reaction (A, B, or C) proceeds the slowest?

In nucleophilic acyl substitution what is true? V addition to the carbonyl by a nucleophile is followed by loss of the leaving group. O Tetrahedral intermediate is formed. O loss of the leaving group is followed by rearrangement of the carbocation. O an SN2 reaction occurs. O protonation of the carbonyl is followed immediately by loss of the leaving group. 4>A 144 & 7 8 R T Y

Rank the following nucleophiles in order from slowest SN2 reaction rate to fastest if DMSO is the solvent. ОН PH SH A B D E

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How does gold help to catalyze the reaction in the gold catalysis experiment? It deprotonates the methanol, making methanol a better nucleophile. оа. o b. It donates electron density to the alkyne, making the alkyne a better nucleophile. О с. It coordinates to the methanol, making methanol a better nucleophile. o d. It coordinates to the alkyne, making the alkyne a better electrophile.

What is the major product of the following nucleophilic ring-opening reaction (Hint: basic condition)? 1. Dimethyl ether CH3MgBr + H2C CHCH3 2. H2O+ ? 1. CH3CH2CHCH3 II. HOCH2CHCH3 III. HOCH2CHCH3 Он CH3 OH A | B III C None D II

Which of the following nucleophilic substitution reactions will take place?

Payalben

estion 8 nydrogen and the leaving group have to be antiperiplanar in which reaction? E2 Oinversion O SN1 O SN2 Question 9 The nucleophile approaches from the opposite side of the carbon with the leaving group in which reaction mechanism? SN1 O E2 O SN1 and SN2 O SN2 17 16 A- 14 5. OO O O

Which of the following nucleophilic substitution reaction will not likely to happen? NH2 + NH2 CH3 SCH3 + CI .CI + CHSCH, H,ö: OH + HI Na* -CN CN + Nal

SH OH + H20 Lewis Acid cat 1. What is the nucleophile is the reaction shown above? What part of the compounds structure indicates that it serves as a nucleophile in the above reaction? 2. What is the substrate (electrophile)? What part of the compounds structure indicates that it serves as an electrophile in the above reaction? 3. Is this an SN2 or SN1 reaction? Explain 117% CO Focus 品 三 Page 4 of 4 642 words