Benzene Reactions - Video Tutorials & Practice Problems
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Benzene Reactions Concept 1
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Now, we've seen benzene a few times within this chapter. Now, benzene itself is what we call an aromatic compound. And aromatic compounds have an unusually or uniquely stable condition. Benzene possesses pie bonds. But because of its aromatic and its unique stability, it doesn't undergo additional reactions like we would expect benzene undergoes substitution reactions instead. And that's unlike alkenes and al Kines, which do addition because they have pie bonds but they're not uniquely stable. Now, here we're gonna cover two types of substitution reactions that benzene undergo one being halogen reactions where we're substituting in a halogen onto the benzene ring and then fried craft alkyl, we're substituting an alke group onto the benzene ring. So just remember benzene is pretty special, it's aromatic and very stable. It's gonna do substitution reactions instead of addition reactions because it wants to maintain this very highly stable form that it possesses
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concept
Halogenation Reactions Concept 2
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In this video, we're gonna take a look at the halogen nation of benzene. Here, benzene would react with either BR two or CL two in this reaction, one of the hydrogen atoms on the benzene is substituted with an X which stands in for either bromine or chlorine. Here, we'd say that a catalyst in a form of FEX three where X three is either BR three or CL three must be used and has to contain the same halogen as the reagent. So basically what I mean by this is if X two here is cl two, then this has to be fecl three. If X two here is BR two, then this has to be Febr three. So if we take a look here at this benzene halogen reaction example, we have our benzene with its six hydrogens on it. Remember X here equals either bromine or chlorine. What happens is that one of these hydrogens gets replaced, hydrogens gets replaced by this halogen here. One of them. So here the H is now gone. And instead in its place, we put one of the halogens that halogen could be chlorine or bromine. This is a way that we can substitute in a halogen at the expense of losing a hydrogen on benzene.
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example
Halogenation Reactions Example 1
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Which of the following is a correct product of benzene substitution reaction with VR two. So remember here, we have the brominated of benzene where we're going to substitute out a hydrogen benzene for a bromine. A doesn't work because we substituted in somehow an iron which doesn't work. B doesn't work because we only substitute in one bromine. Not two C doesn't work because the age is still there. The answer here is D because there was an H here and we substituted it out to get the bromine there creating Bromma benzene as our answer. So here, option D is the correct answer.
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Problem
Problem
Name the product of the following benzene halogenation reaction.
A
chlorobenzene
B
1,1-dichlorobenzene
C
1,2-dichlorobenzene
D
1,4-dichlorobenzene
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concept
Friedel Craft Alkylation Concept 3
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In this video, we're gonna take a look at Fried craft alkyl here in this reaction, benzene reacts with an alk hale. And what happens is that one of the hydrogens on the benzene ring is substituted with an alkyl group to do this. A catalyst of lum X three must be used and has this has to contain the same halogen as the reagent. So basically what we mean by this, if we take a look at this frutal craft reaction down below, this is CH three X, this X could represent either bromine or chlorine. If it's bromine, then this has to be a lbr three. If this X is chlorine, then this has to be a LCL three. So the halogens have to match between these two. Now, in this reaction, all that happens is that one of the hydrogens on benzene gets substituted out and the alko portion of our alko haid comes in the alko portion of our alal hale here would be methyl. So we wind up making methyl benzene as our final answer.
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example
Friedel Craft Alkylation Example 2
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Name the major product of the following Friedel Crafts alky reaction. All right. So here we have our benzene and we know we're still gonna have benzene at the end. So we can redraw it. And we know that essentially what happens is one of the hydrogens on benzene gets substituted out with the alkyl group portion of my alkyl halle. So here we have ethyl chloride and we have aluminum chloride as the catalyst. So here we're going to attach ethyl to my benzene. This would be my major product form and its name would be ethyl benzene. So just remember with Freedom Crafts alkyl, we're just substituting out an H and bringing in an alke group.
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Summary of Benzene Reactions Concept 4
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So here we have a summary of our benzene reactions. We have halogen nation in it. We have the reagent of X two which could represent BR two or CL two. We use our catalyst to get things going. In essence, what happens is that we substitute out one of the hydrogens on benzene with one of these halogens here. If this is BR two, then this has to be Febr three. If this is CL two and this has to be fecl three. At the end, the H is substituted out the halogen comes in. Next, we have fried crafts alkyl here we use as an our and Alkyl Haid X again, could be CL or BR but now we're using the catalyst of aluminum and it could be either aluminum chloride or aluminum bromide. Here we substitute out our hydrogen and bring in our alkyl group here. If the X is CL, then this is aluminum chloride. If the X here is bromine, then this is aluminum bromide. So remember both of these reactions are quite similar. They use similar types of catalysts and they're just substituting out in H this one substitutes in a halogen. This one here in Alko group.
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Problem
Problem
Provide a complete reaction of benzene Friedel Crafts alkylation with 2-bromo-2-methylpropane and name the product.
A
B
C
D
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Problem
Problem
Fill in the missing reagent for the provided reaction.
A
B
C
D
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