Author Topic: Spectroscopic Analysis of Amines  (Read 3016 times)

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Methlaab

  • Guest
Spectroscopic Analysis of Amines
« on: November 08, 2004, 01:34:00 AM »
Spectroscopic Analysis
 

    * IR - The -N-H should be apparent. -NH one band, -NH2 two bands (symmetric and asymmetric)

      Absorbance (cm-1)      Interpretation
      3500 - 3100            NH stretch
      1350 - 1000              C-N stretch

           
    * 1H NMR - The -N-H proton(s) tend to be broad peaks. N is less electronegative than O so it deshields less.

      Resonance (ppm)                     Interpretation
      0.5 - 5.0 (broad, exchangeable)      -NH proton
      1.5 - 3.0                                    CH2-NR2

    * 13C NMR

      C-N typically 35 - 50 ppm (deshielding due to N)
      note: the deshielding is less than that observed in alcohols, C-O = 50 - 65 ppm)

    *   UV-VIS

       maxima due to  n®s* (190 nm)
          o n electron from N lone pair
          o s* antibonding C-N

    *   Mass Spectrometry

      Peak for the molecular ion, M+, is usually apparent.
      The nitrogen rule : compounds composed of only C, H, O have an even molecular weight.
      If a compound contains an odd number of N atoms will have an odd molecular weight. (the Nitrogen rule).
      Since N is very good at stabilising positive charge, cleavage at the b-carbon are common.




Methlaab

  • Guest
Chromatography
« Reply #1 on: November 08, 2004, 01:52:00 AM »
Good link to the The Coupling of Gas and Liquid Chromatography
with Mass Spectrometry

http://www.spectroscopynow.com/Spy/pdfs/JMS34157.pdf




methyl_ethyl

  • Guest
informative
« Reply #2 on: November 08, 2004, 03:23:00 AM »
Informative link, although somewhat dated.  I wonder what your reason for posting that link in this thread has to do with anything relevent. 

Thread: Spectroscopic Analysis of Amines

Your Post: GC/MS LC/MS Theory and Background

Does not mention anything about the analysis of amines. Then again neither does this post.  I guess I better dig up some information on the spectroscopic analysis of amines  ::)

sorry,

m_e


Methlaab

  • Guest
????
« Reply #3 on: November 08, 2004, 04:31:00 AM »
* IR - The -N-H should be apparent. -NH one band, -NH2 two bands (symmetric and asymmetric)

      Absorbance (cm-1)      Interpretation
      3500 - 3100            NH stretch
      1350 - 1000            C-N stretch

          
    * 1H NMR - The -N-H proton(s) tend to be broad peaks. N is less electronegative than O so it deshields less.

      Resonance (ppm)                     Interpretation
      0.5 - 5.0 (broad, exchangeable)      -NH proton
      1.5 - 3.0                                    CH2-NR2

    * 13C NMR

      C-N typically 35 - 50 ppm (deshielding due to N)
      note: the deshielding is less than that observed in alcohols, C-O = 50 - 65 ppm)

    *   UV-VIS

       maxima due to  n®s* (190 nm)
          o n electron from N lone pair
          o s* antibonding C-N

    *   Mass Spectrometry

      Peak for the molecular ion, M+, is usually apparent.
      The nitrogen rule : compounds composed of only C, H, O have an even molecular weight.
      If a compound contains an odd number of N atoms will have an odd molecular weight. (the Nitrogen rule).
      Since N is very good at stabilising positive charge, cleavage at the b-carbon are common.

____________________________________________________________
Don't understand your comment but for you i've marked everything red what is typical for amines, related to spectroscopic analysis


Nicodem

  • Guest
Politeness
« Reply #4 on: November 08, 2004, 12:15:00 PM »
I think Methyl_ethyl wanted to say that your two posts

Post 540278

(Methlaab: "Spectroscopic Analysis of Amines", Chemistry Discourse)
and

Post 540283

(Methlaab: "Chromatography", Chemistry Discourse)
are unrelated to each other and the second one is therefore off topic since the first one determines the topic of the thread. :P  Anyway, I'm sure he will explain it you much better.

But what I wanted to ask you is:
Why the hell do you post material found on the net inside the posts and without providing the link to the original location, thus not giving credit to the real authors?
That, at least in my personal view, is considered something like being very rude and lacking consideration for other people's work and effort. (Not to mention that on the original sites the formatting is better.)

So, next time you can simply post something like this:

{Insert here your comments on why is this important for The Hive "community" and your personal view on the subject.}

Amines: Spectroscopic Analysis

(http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch22/ch22-4.html)




The same goes for

Post 540145

(Methlaab: "Ritter and Grignard Reaction. An overview...", Chemistry Discourse) where you (still) did not provide the link to

Grignard Reaction / Grignard Reagents

(http://www.organic-chemistry.org/frames.htm?http://www.organic-chemistry.org/namedreactions/grignard-reaction.shtm) even though in another thread,

Post 540137

(Methlaab: "A short story about amines", Chemistry Discourse)
, I expressed you that, at least I, miss the link very much.