@Ivanneretin hi sir :-)

@Ivanneretin I don't know whether you are getting any notification of my messages or not.....but I have a question in chemistry.....so I am posting it here....if you get time please hsge a look at this

@Ivanneretin in dehydration of alchohol two mechanism are proposed. First one is E1 and second is E2. I have read that E2 are performed in case of primary alchohol and E1 are performed in case of secondary and tertiary alchohol. But I don't understand why some books uses E1 mechanism in all the alchohol , even in case of primary. Like in case of ethanol and butanol .....

@Ivanneretin firstly I thought that it would not create an difference in product formed, but in case when rearrangement occurs in E1 than we get different products if we follow E1 and E2. This is quite confusing to me. Please have a look at this.

@Ivannetetin and ping me every time if you reply....

I am waiting for your reply

Why wouldn't you ask this question on Chem.SE? True, it might get downvoted and kinda sneered upon, so what?

Now to the point. I believe that the first concept is true. It is E2 with primary alcohols and E1 otherwise.

As for the authors who use E1 for all alcohols, well, they just teach some entry-level chemistry and disregard rearrangements altogether. Without those, the result is the same.

That's what I think, @ronakjain

@IvanNeretin but sir the product I get from the two mechanism are different

When?

@IvanNeretin consider the case of butanol. If I proceed via E1 than a carbocation will be formed and than rearrangement will take place

Imagine a dumb dude who does not know that rearrangements exist.

To him, it is all the same.

Ya. But in actually they are different

Yes, actually they are.

And this question is from a reputed exam JEE ADVANCED.

It is confusing me because books use E2 mechanism and all websites show E2 for primary

And what is the sense of giving wrong knowledge to beginners ? It is not too difficult to learn two mechanism instead of one

@IvanNeretin even they are included in the exam syllabus

Even in reputed exams, sometimes you need to know two kinds of science: (1) what is it really like, and (2) what do they want from you.

Ok.

Did you look at the previous question that I posted in previous room which was blocked due to inactivity

The wrong knowledge is not necessarily wrong. It is simplified.

@IvanNeretin ok

What was that question?

@IvanNeretin I wanted to derive an equation....I am posting... please be online.....

It will take just a minute

@IvanNeretin can you tell me how to proof the first equation....

wait a sec

Ok

well, it is a consequence of dG/dT=-S

@IvanNeretin can you please explain

The whole derivation

I don't know where to start. Well, G = H - TS. Now, dG/dT = dH/dT - T * dS/dT - S.

Yes

We know that dH/dT = Cp, and dS/dT = Cp/T, so those two cancel out.

What remains is dG/dT=-S.

@IvanNeretin but the reaction is going in solution. Still dH = CpdT

@IvanNeretin so we came to the initial equation

So? I think that's what I said. You have dH/dT = Cp.

Ok. I thought it may not be true in case of aqueous phase

Solution or no solution, we don't care. If the things go at constant pressure, that's what you have.

Ok

Otherwise it could have turn out differently.

Ok

Now how to derive the equation ?

What equation? I thought we are done with (ii).

@IvanNeretin where we derived ? I want derivation of the highlighted equation

There are two highlighted equations. Are we done with (ii)?

@IvanNeretin using first, second can be derived easily. But how to derive the first equation

@IvanNeretin where did first equation come from ?

@IvanNeretin ok

@IvanNeretin I generally face a problem in organic chemistry. Sometime I think that mechanism are just like s foretell which predict the product

@IvanNeretin do you think that there actually happens step that we use in mechanism in reality ?

Who have seen atoms? Nobody. It is just a model. So are mechanisms.

@IvanNeretin do you have any idea that how can I predict mechanism at my level. I am a school student.

And just appearing for a entrance exam for college

@IvanNeretin I feel great difficulty in memorizing mechanism. And if I somehow manage to memorize than the question in exam are made in such a way that it uses all the concepts of organic

Learn many mechanisms. That seems to be the only way.

Ok. I will try

@IvanNeretin one last question....

@IvanNeretin can you tell me when a cyclic carbocation is formed in which one atom is a halogen or any atom which have lone pair.

@IvanNeretin and is it possible to have hydride , methyl shift in the case when it is formed

I am not qualified to answer this.

Ok. Thanks for help. I will ping you frequently because I am weak in physical chemistry, if you don't mind

Ping me, but I won't promise to be constantly online.

Ok. I will wait for your reply