December 22, 2024, 12:08:48 PM
Forum Rules: Read This Before Posting


« previous next »
Pages: [1]   Go Down

Topic: Naming of benzene derivatives  (Read 12006 times)

0 Members and 1 Guest are viewing this topic.

Hong Luen

  • Guest
Naming of benzene derivatives
« on: December 19, 2005, 04:04:30 AM »
Hi all, I have problems in naming the attached compounds. I believe they are called butenyl-semi-benzene or so. Please kindly teach me how to name each of them correctly. Thank you very much.
Logged

Offline GSR

  • Regular Member
  • ***
  • Posts: 48
  • Mole Snacks: +9/-1
  • Gender: Male
  • Have Courage and Follow Your Own Path!
Re:Naming of benzene derivatives
« Reply #1 on: December 19, 2005, 05:25:35 AM »
hi,
here is an attempt to name  your compunds

for compound (23) it is: 3-((E)-But-2-enyl)-1,2,3,4,5-penta
methyl-6-methylene-cyclohexa-1,4-diene.

for compound (24) it is: 1-((E)-But-2-enyl)-2,3,4,5,6-penta
methyl-benzene.

for compound (25) it is: 1,2,3,4,5-Pentamethyl-6-(1-methyl-a
llyl)-benzene.

GSR

Logged

Hong Luen

  • Guest
Re:Naming of benzene derivatives
« Reply #2 on: December 19, 2005, 09:23:23 PM »
Dear GSR,

1. What is meant by (E) in the 3-((E)-But-2-enyl)-?
Is (E)-3-(But-2-enyl)- the same as 3-((E)-But-2-enyl)-?

2. For #23, is it a must to put the methylene at position 6?
Is it because the methylene is unsaturated as compared to the five methyl groups?
Alternatively, is it because that gives the smallest number 1,4 for the cyclohexa-diene?

3. Can we name #25 as 1-(But-3-en-2-nyl)-2,3,4,5,6-pentamethylbenzene?

4. What is the structure of "semi-benzene"?

Thank you very much.

Hong Luen
Logged

Offline GSR

  • Regular Member
  • ***
  • Posts: 48
  • Mole Snacks: +9/-1
  • Gender: Male
  • Have Courage and Follow Your Own Path!
Re:Naming of benzene derivatives
« Reply #3 on: December 20, 2005, 04:27:08 AM »
hi,

you are right perhaps.
the compound 25 can also be named as: 1,2,3,4,5-pentamethyl-6-(1-methylprop-2-enyl)benzene.
about the semi-benzene structures, as for as I know these are dimers(head-to-tail or head-to-head) of benzyl radicals. but I am not sure.
Logged

Offline Albert

  • Lonely Wanderer
  • Retired Staff
  • Sr. Member
  • *
  • Posts: 1050
  • Mole Snacks: +112/-22
  • Gender: Male
  • Half Decent Pharmaceutical Chemist
Re:Naming of benzene derivatives
« Reply #4 on: December 20, 2005, 05:42:57 AM »
Quote from: Hong Luen on December 19, 2005, 09:23:23 PM
1. What is meant by (E) in the 3-((E)-But-2-enyl)-?

In a nutshell, E-Z nomenclature stands for cis-trans one, every time there are alkenes with different groups. Instead of two couples of groups, you have different groups (3 or 4) with different 'importance' (you know what I mean, don't you?).

As you can see below, E is to trans as Z is to cis.

E comes from German entgegen, which means (more or less) 'contrary to'; Z from zusammen, 'together'.
« Last Edit: December 20, 2005, 05:44:20 AM by Albert »
Logged

Offline movies

  • Organic Minion
  • Retired Staff
  • Sr. Member
  • *
  • Posts: 1973
  • Mole Snacks: +222/-21
  • Gender: Male
  • Better living through chemistry!
Re:Naming of benzene derivatives
« Reply #5 on: December 20, 2005, 12:57:43 PM »
E/Z nomenclature is always better than cis/trans!  E/Z will always get you to the right compound, but with cis/trans you need to know which groups are cis or trans to one another.  With E/Z the priority is built in.
Logged

Offline Albert

  • Lonely Wanderer
  • Retired Staff
  • Sr. Member
  • *
  • Posts: 1050
  • Mole Snacks: +112/-22
  • Gender: Male
  • Half Decent Pharmaceutical Chemist
Re:Naming of benzene derivatives
« Reply #6 on: December 20, 2005, 01:17:43 PM »
I agree with you, movies. However, cis-trans nomenclature is still extremely common and it is good for simple alkenes with two couples of different substituents.
« Last Edit: December 20, 2005, 01:20:33 PM by Albert »
Logged

Offline movies

  • Organic Minion
  • Retired Staff
  • Sr. Member
  • *
  • Posts: 1973
  • Mole Snacks: +222/-21
  • Gender: Male
  • Better living through chemistry!
Re:Naming of benzene derivatives
« Reply #7 on: December 20, 2005, 03:36:38 PM »
Quote from: Albert on December 20, 2005, 01:17:43 PM
I agree with you, movies. However, cis-trans nomenclature is still extremely common and it is good for simple alkenes with two couples of different substituents.

Very true.  You can still use it for disubstituted alkenes and everyone will know what you are talking about.  I always try to encourage the use of E/Z though, to avoid future confusion!
Logged

Hong Luen

  • Guest
Re:Naming of benzene derivatives
« Reply #8 on: December 20, 2005, 10:06:19 PM »
Thanks for Albert's explanation on E/Z nonmenclature.

Back to naming of #25, I have question on the "1-methylprop-2-enyl" that GSR suggested.
If it is 1-methyl attached to propene, it should be a butene, isn't it?
Then, it should be a butenylbenzene.

 ???
Logged

Offline ATMyller

  • Chemist
  • Full Member
  • *
  • Posts: 223
  • Mole Snacks: +31/-6
Re:Naming of benzene derivatives
« Reply #9 on: December 28, 2005, 07:42:34 AM »
It's "1-methylprop-2-enyl" because with benzene derivatives you start the numbering from the carbon connected to the benzene ring.
If you consider it as a butene group it becomes 1-butene-3(1,2,3,4,5-pentamethylbenzene) which is a butene derivative.
Logged
Chemists do it periodically on table.

Offline moussa

  • Regular Member
  • ***
  • Posts: 33
  • Mole Snacks: +3/-15
  • Gender: Male
Re:Naming of benzene derivatives
« Reply #10 on: December 28, 2005, 11:10:22 AM »
i don't think that E & Z have interference with 23
you can simply find carbon numcber one and start naming from there
following  IUPAC rules
http://www.acdlabs.com/iupac/nomenclature/
Logged
earth is larger than a molecule

Hong Luen

  • Guest
Re:Naming of benzene derivatives
« Reply #11 on: December 28, 2005, 09:00:19 PM »
Can we name compound #25 as 1-(But-3-en-2-nyl)-2,3,4,5,6-pentamethylbenzene?
Logged
Pages: [1]   Go Up
« previous next »
Sponsored Links