1. Ethyl is C2H6. Why why C2H5 is called that here ?

2. Aniline means benzenamine (C₆H₅NH₂) but NH2 is at 1. So it can also be written as 1-amino-4-Ethyl-2-methybenzene ?

1. No, C2H6 is called ethane, C2H5 is Ethyl, the naming is correct.

2. Is possible, but Aniline is a trival name .

1 hour ago, chenbeier said:

Aniline is a trival name

According to Wikipedia, aniline is the preferred IUPAC name.

@KJW I understand 4-Ethyl-2-methylaniline is the correct name but Is 1-amino-4-Ethyl-2-methybenzene wrong ?

No， but aniline is preferred as already mentioned.

7 hours ago, HbWhi5F said:

@KJW I understand 4-Ethyl-2-methylaniline is the correct name but Is 1-amino-4-Ethyl-2-methybenzene wrong ?

That's hard to say. Writing chemical names is much harder than reading chemical names because there are many possible ways of naming a particular chemical structure, and not all of them obey the rules of nomenclature. I have forgotten many of the finer points of chemical nomenclature.

I believe 1-amino-4-ethyl-2-methybenzene is incorrect. The parent compound, methylbenzene, has only one isomer. Therefore, one would not have a number in front of it. And the methyl group would be in the 1 position in this case. Thus, it would be 2-amino-5-ethylmethylbenzene. By why not ethylbenzene as the parent compound? In this case, it would be 4-amino-3-methylethylbenzene. But no, the parent compound is (using the systematic IUPAC name) benzenamine. So, the correct name in this case is 4-ethyl-2-methylbenzenamine (or 4-ethyl-2-methylaniline using the preferred IUPAC name, aniline, for the parent compound). And note that it's 4-ethyl-2-methyl... and not 2-methyl-4-ethyl... because ethyl occurs before methyl alphabetically.

@KJW Is there a parent compound priority list?

Also thanks for the reply I am being boycotted on the forum. I know I take sometime to reply but somehow that make fellow scholars racist.

1 hour ago, HbWhi5F said:

@KJW Is there a parent compound priority list?

Also thanks for the reply I am being boycotted on the forum. I know I take sometime to reply but somehow that make fellow scholars racist.

Don't say things like that. Chucking accusations of racism around is pretty unpleasant. I explained the reason I stopped responding to you, which you have now addressed on another thread.

3 hours ago, HbWhi5F said:

Also thanks for the reply I am being boycotted on the forum.

"Boycotted" is the wrong word. We have rules, and reminding you of them is NOT abstaining from discussion with you.

4 hours ago, HbWhi5F said:

I know I take sometime to reply but somehow that make fellow scholars racist.

"Racist" is the wrong word. I'm not sure if you've ever shared information regarding your "race", but the frustration you're seeing is not about that at all.

You seem to have a good grasp of the science you're asking questions about, and your posts usually give a bit of your thinking with regard to the problem you're trying to solve. You normally don't ask the question straight from the book, and that's always appreciated. When you don't understand something, you ask follow up questions, and that's great as well.

It would also be nice to get a few words from you when you DO understand something the other members have shown you. It doesn't matter how much time it takes you to reply. The issue is more a matter of discussion vs classroom. We like to discuss, like a conversation, instead of lecturing, like a classroom. Does that make sense to you?

9 hours ago, Phi for All said:

"Racist" is the wrong word. I'm not sure if you've ever shared information regarding your "race", but the frustration you're seeing is not about that at all.

Actually 1 wrote "It would be good if some of your countrymen would step in here and tell you that it doesn't hurt to respond to those who have genuinely put themselves out to help you."

Many be I am reading it wrong but what is "countrymen" about ?

7 hours ago, HbWhi5F said:

Actually 1 wrote "It would be good if some of your countrymen would step in here and tell you that it doesn't hurt to respond to those who have genuinely put themselves out to help you."

Many be I am reading it wrong but what is "countrymen" about ?

I missed any reference to your actual country. Unless you mentioned it, or your coursework indicates the country of origin, I don't think anyone outside of staff could know from where you're posting.

In any event, science discussion should be attacking ideas and concepts, not people. We're not face-to-face, but it's good to imagine we're sitting around a table talking about science.