Qustion about leaving groups and bases

In summary, the speaker is asking if a nucleophile would attack the carbon bound to a bromide or the proton on a primary alcohol in a reaction involving isobutanol and benzene. The speaker also mentions the possibility of using AlCl3 catalysis instead of a bromide leaving group, but notes that it may result in a messy mixture. They question the need for this particular compound and suggest finding a more practical alternative.
  • #1
invain
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If I had a nucleophile, say the conjugate base of benzene, and a molecule with a bromide, and a primary alcohol. Would the nucleophile attack the carbon bound to the bromide, or the proton on the alcohol?

If it's hard to follow I can try to make a picture. Basically I want to add Isobutanol to benzene using a bromide leaving group. (2-bromo-2-methyl-propanol). Possible? I don't know if the alcohol would act like an acid or would the bromide leave first.
 
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  • #2
This doesn't work. First, as you suspect, the phenyl anion will pick up the proton from the alcohol and return to benzene. Two, if you protect the alcohol as e.g. a benzyl ether, it will still be too crowded around the bromine for this to work.
Maybe you could fish some of the correct structure out of you use AlCl3 catalysis instead but this reaction (Friedel-Crafts alkylation) is notorius for giving messy mixtures. And the alcohol group certainly doesn't help.
Why do you need this awkward compound? Can't you make something sensible?
 

FAQ: Qustion about leaving groups and bases

1. What is the purpose of leaving groups and bases in chemical reactions?

Leaving groups and bases are important functional groups in chemical reactions that help facilitate the formation of new bonds and the creation of new molecules. Leaving groups are typically electron-withdrawing groups that are able to easily detach from a molecule, leaving behind a positively charged site that can react with other molecules. Bases, on the other hand, are able to accept protons and participate in acid-base reactions, allowing for the formation of new bonds.

2. How do leaving groups and bases affect the rate of a chemical reaction?

The presence of leaving groups and bases can greatly influence the rate of a chemical reaction. Leaving groups that are more stable and easily detachable can increase the rate of a reaction by making it easier for the reaction to proceed. Similarly, strong bases can also increase the rate of a reaction by readily accepting protons and facilitating bond formation. On the other hand, weaker leaving groups and bases may slow down the rate of a reaction as they are less likely to participate in the reaction.

3. Can leaving groups and bases affect the selectivity of a chemical reaction?

Yes, leaving groups and bases can greatly impact the selectivity of a chemical reaction. Leaving groups that are more stable and easily detachable can promote the formation of specific products, while weaker leaving groups may result in different products or even side reactions. Similarly, the choice of base can also influence the selectivity of a reaction by promoting the formation of certain products over others.

4. Can leaving groups and bases be altered to improve the efficiency of a reaction?

Yes, leaving groups and bases can be modified or chosen strategically to optimize the efficiency of a reaction. For example, leaving groups can be substituted with more electron-withdrawing groups to increase their stability and reactivity, while bases can be chosen based on their strength and ability to promote specific reactions. The modification of leaving groups and bases can greatly impact the efficiency and success of a chemical reaction.

5. Are there any limitations to using leaving groups and bases in chemical reactions?

While leaving groups and bases are important functional groups in chemical reactions, there are some limitations to their use. For example, some leaving groups may be too stable and not reactive enough, while others may be too reactive and lead to side reactions. Similarly, some bases may be too strong and cause unwanted reactions, while others may not be strong enough to participate in the desired reaction. Careful consideration and selection of leaving groups and bases is needed to overcome these limitations and achieve successful reactions.

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