[helper]

Hello,

my question is attached.
I AM ASKING ABOUT THE TRANSITION STATE IN A REACTION BETWEEN NH3 AND CH3I.

Thank you ahead:)

[Dan]

What do you think at this point (and why)?

Note: You must show you have attempted the question, this is a Forum Rule.

Also, please refrain from using ALL CAPS.

[helper]

hi,

I attempted to solve the question. the question which is written under the picture is what I wrote. I is not the original question.
I tend to think that the second picture represent more the transition state because NH3 is not charged molecule therefore it can not be charged negatively. it can be charged positively because as I said before when it approaches the C which is charged half positively, the electrons tend to C and therefore NH3 became charged positively.

Is it  a good assumption?

Thank you ahead, and sorry for Caps.

[camptzak]

hi,

I attempted to solve the question. the question which is written under the picture is what I wrote. I is not the original question.
I tend to think that the second picture represent more the transition state because NH3 is not charged molecule therefore it can not be charged negatively. it can be charged positively because as I said before when it approaches the C which is charged half positively, the electrons tend to C and therefore NH3 became charged positively.

Is it  a good assumption?

Thank you ahead, and sorry for Caps.

the δ+ and δ- are not formal charges, NH₃ can be negatively charged by the removal of a proton NH₂^-...not that it applies here, I'm just saying.

I would say that during the transition state, NH₃ and Iodine should both be denoted with a δ-

only because as the Iodine leaves only a nucleophile (a group with a δ-) can displace it.

but you are correct in thinking that once the the NH₃ connects to the carbon it will have a formal ⁺ charge, but Iodine or the solvent will remove the proton.

I am not sure on this, I am only making an educated guess

[Dan]

I tend to think that the second picture represent more the transition state because NH3 is not charged molecule therefore it can not be charged negatively. it can be charged positively because as I said before when it approaches the C which is charged half positively, the electrons tend to C and therefore NH3 became charged positively.

Is it  a good assumption?

I agree with you. The incoming nucleophile becomes more positive (= less negative) in the transition state (TS). So if the nucleophile starts as an anion it goes from ^- to δ^- (becomes less negative), and if it starts neutral (as it does here) then it becomes δ⁺ (more positive) in the TS.

A quick check is to look for charge balance: if the reactants are overall neutral, then the TS should be overall neutral (δ⁺ cancels δ^-).

[Benzene]

I tend to think that the second picture represent more the transition state because NH3 is not charged molecule therefore it can not be charged negatively. it can be charged positively because as I said before when it approaches the C which is charged half positively, the electrons tend to C and therefore NH3 became charged positively.

Is it  a good assumption?

I agree with you. The incoming nucleophile becomes more positive (= less negative) in the transition state (TS). So if the nucleophile starts as an anion it goes from ^- to δ^- (becomes less negative), and if it starts neutral (as it does here) then it becomes δ⁺ (more positive) in the TS.

A quick check is to look for charge balance: if the reactants are overall neutral, then the TS should be overall neutral (δ⁺ cancels δ^-).

but the nucleophile is not an anion, its neutral.

[helper]

Thank you all!
Have a nice day.

[Dan]

I tend to think that the second picture represent more the transition state because NH3 is not charged molecule therefore it can not be charged negatively. it can be charged positively because as I said before when it approaches the C which is charged half positively, the electrons tend to C and therefore NH3 became charged positively.

Is it  a good assumption?

I agree with you. The incoming nucleophile becomes more positive (= less negative) in the transition state (TS). So if the nucleophile starts as an anion it goes from ^- to δ^- (becomes less negative), and if it starts neutral (as it does here) then it becomes δ⁺ (more positive) in the TS.

A quick check is to look for charge balance: if the reactants are overall neutral, then the TS should be overall neutral (δ⁺ cancels δ^-).

but the nucleophile is not an anion, its neutral.

I know that (see highlight). I was describing both scenarios.