J
john t
Guest
I've been revising some topics and the following questions have been annoying me a little bit. Please note that these questions don't link seamlessly with eachother, as these ARE NOT from the same test paper/ question sheet. These are questions that have stumped me and that I've compiled together for my understanding. Any help would be much appreciated!:
1) Explain why non- polar bromine molecules are able to react with the double bonds in alkenes.
Would it be that an instantaneous dipole is formed, leaving one side slightly positive and therefore making it attract to the area of negative charge around the double bond?
2) Explain how geometric isomerism arises.
note: this question focuses around alkenes.
I wrote: "Through the random nature of reaction- sometimes E is formed, and sometimes Z"... though this is wrong, as I've heard.
3) Complete and balance the following equation for the reaction of ammonia with bromomethane. Give the name of the organic product of this reaction.
CH3Br + NH3 ----> __________ + NH4Br
I want to know how this reacts, also, as I'm not sure how the mechanism works. My guess, however, is that the product is a positive molecule: methylamine, with molec. form. CH3NH2...?
4) Bromomethane reacts with bromine by a free radical substitution mechanism to dorm dibromomethane, CH2Br2
The reaction mechanism is similar to that form the reaction of chlorine with methane.
a) Write equations for the following steps in the mechanism for the reaction of bromine with CH3Br to form CH2Br2
i)initiation step?
My guess is that It's Br2 ----> Br.2 (with the dot being an electron)
ii) First propagation step?
iii) Second propagation step?
b) The bromination of bromomethane will produce a micture of products including dibromomethane, tribromomethane and tetrabromomethane.
i) Write an over all equation for the conversion of bromomethane into tetrabromomethane (CBr4).
I wrote: CH3Br +Br2 ---> CBr4 +HBr
Although I know that's unbalanced, is it otherwise correct? I don't understand which mechanism this uses (how would I know this anyway). Also note: when I talk about mechanisms, I'm talking about nucleophillic substitution, elimination and electrophillic addition- the three we've studied.
c) State how the reaction conditions would have to be adusted to produce the highest possible yield of tetrabromomethane.
I wrote "exposure to UV light". Although, it could be use of catalyst or high temperatures. It's only 1 mark, so that often means there's one thing that they're looking for.
5) Some bromine solution was shaken with a sample of but-2-ene and a reaction occurred.
i) state what would be seen during the reaction.
This isn't on our syllabus, but I thought I read somewhere that it turns from brown to red. Why would this colour change be the case (if it IS the correct colour change)?
ii) Draw the structural formula of the product of this reaction, and name this product.
Well, I drew a diagram of CH3CH2CH2CHBrCH3, though it's wrong. The name of what I drew is, of course, 2-bromobutane. Again, I'm not sure what mechanism this question relates to.
Thanks so much to anybody that is kind enough to help me with these!
1) Explain why non- polar bromine molecules are able to react with the double bonds in alkenes.
Would it be that an instantaneous dipole is formed, leaving one side slightly positive and therefore making it attract to the area of negative charge around the double bond?
2) Explain how geometric isomerism arises.
note: this question focuses around alkenes.
I wrote: "Through the random nature of reaction- sometimes E is formed, and sometimes Z"... though this is wrong, as I've heard.
3) Complete and balance the following equation for the reaction of ammonia with bromomethane. Give the name of the organic product of this reaction.
CH3Br + NH3 ----> __________ + NH4Br
I want to know how this reacts, also, as I'm not sure how the mechanism works. My guess, however, is that the product is a positive molecule: methylamine, with molec. form. CH3NH2...?
4) Bromomethane reacts with bromine by a free radical substitution mechanism to dorm dibromomethane, CH2Br2
The reaction mechanism is similar to that form the reaction of chlorine with methane.
a) Write equations for the following steps in the mechanism for the reaction of bromine with CH3Br to form CH2Br2
i)initiation step?
My guess is that It's Br2 ----> Br.2 (with the dot being an electron)
ii) First propagation step?
iii) Second propagation step?
b) The bromination of bromomethane will produce a micture of products including dibromomethane, tribromomethane and tetrabromomethane.
i) Write an over all equation for the conversion of bromomethane into tetrabromomethane (CBr4).
I wrote: CH3Br +Br2 ---> CBr4 +HBr
Although I know that's unbalanced, is it otherwise correct? I don't understand which mechanism this uses (how would I know this anyway). Also note: when I talk about mechanisms, I'm talking about nucleophillic substitution, elimination and electrophillic addition- the three we've studied.
c) State how the reaction conditions would have to be adusted to produce the highest possible yield of tetrabromomethane.
I wrote "exposure to UV light". Although, it could be use of catalyst or high temperatures. It's only 1 mark, so that often means there's one thing that they're looking for.
5) Some bromine solution was shaken with a sample of but-2-ene and a reaction occurred.
i) state what would be seen during the reaction.
This isn't on our syllabus, but I thought I read somewhere that it turns from brown to red. Why would this colour change be the case (if it IS the correct colour change)?
ii) Draw the structural formula of the product of this reaction, and name this product.
Well, I drew a diagram of CH3CH2CH2CHBrCH3, though it's wrong. The name of what I drew is, of course, 2-bromobutane. Again, I'm not sure what mechanism this question relates to.
Thanks so much to anybody that is kind enough to help me with these!