[shafaifer]

In this IR-spec. the peak at 3490 tells a secondary amine. The molecular ion = 140 g/mol = equal number of nitrogens present in the compound, this means at least 2 nitrogens. The peaks at 1757 and 1191 tell me an aromatic ester (there must be a benzene ring due to peaks at 3070, 1618 and 1487). I would say the ring is substituted: 1, 3, 5.

Am I right in any og this at all? Right direction?

Yours sincerely,

S 

[mjc123]

If MW = 140, you haven't got enough mass for a benzene ring, 2 nitrogens and an ester. Are you sure about the MS?

[Irlanur]

No full MS and/or NMR?

IR are not too reliable for positive statements...

[shafaifer]

No, sorry. This is for student exercising and IR only. Yes, I am into MS now. The molecule in question must be benzoyl chloride.

[OrgXemProf]

From a molecule with two nitrogen atoms to benzoyl chloride would seem to be quite a segué!

I believe that you were misled by the peak at 3490 cm^-1, which you ascribed to the N-H stretch in a secondary amine, R₂N-H.

Note that the IR spectrum was run with the sample present at a relatively high concentration, so much so that the very intense C=O absorption peak at 1757 cm^-1 runs "off the chart". In this situation, one frequently observes "ovetones" in the spectrum that otherwise might be too weak to notice.

Note also that the errant (and much less intense) 3490 cm^-1 absorption (overtone) is roughly twice the frequency of the fundamental absorption (1754 cm^-1).

The situation is similar with musical overtones. As an example: With your right index finger hold down the piano key that corresponds to the C above middle C (i. e., simply lift the hammer off the piano string, thereby leaving that string free to vibrate). Then, with your left index finger strike the middle C piano key sharply. If the piano is in relative tune, along with the fundamental (261.6 Hz) you will hear the first overtone (frequency = 2 x 261.6 Hz).  With both musical and spectroscopic examples the overtone is not as intense as the fundamental due to exponential decay.

[Corribus]

The situation is similar with musical overtones. As an example: With your right index finger hold down the piano key that corresponds to the C above middle C (i. e., simply lift the hammer off the piano string, thereby leaving that string free to vibrate). Then, with your left index finger strike the middle C piano key sharply. If the piano is in relative tune, along with the fundamental (261.6 Hz) you will hear the first overtone (frequency = 2 x 261.6 Hz).  With both musical and spectroscopic examples the overtone is not as intense as the fundamental due to exponential decay.

Not exactly a perfect analogy. A better one I think would be to compare to overtones resonating on the same piano string, which is responsible for the timbre of an instrument.

http://en.wikipedia.org/wiki/Timbre

The vibrations on nearby strings would be more akin to coupled molecular vibrations, as we would measure in 2D IR spectroscopy.

http://en.wikipedia.org/wiki/Two-dimensional_infrared_spectroscopy

This is why a digitally sampled instrument will be hard pressed to match the richness of a good acoustic. But I digress...

[OrgXemProf]

Ah, Corribus, I stand corrected.

But.....I chose the imperfect analogy because it accounts for an overtone at twice the frequency of the fundamental...kinda like the overtone in the IR spectrum that distracted shafaifer.

Next time I get the urge to go off on a tangent I shall make a decided effort to confine my analogies to chemistry.

PS: These days, most sampling is done with live instruments under concert-hall conditions as, e. g., with East West/Quantum Leap virtual instruments (EWQLSO), thereby capturing the rich acoustic sound.

[Corribus]

Don't abandon your analogies. They make science more fun. I'm partial to food and cooking ones myself, and, likewise, they are rarely perfect.

These days, most sampling is done with live instruments under concert-hall conditions as, e. g., with East West/Quantum Leap virtual instruments (EWQLSO), thereby capturing the rich acoustic sound.

Having been raised on a Steinway baby grand and currently playing a very nice digital Kawai, I can verify that this is true... provided I'm listening to the digital through a pair of very good quality headphones. Played through the digital's speakers and filling a room, I think it's still no comparison to the real thing. But I'm willing to admit that might be my artistic sentiment trumping my scientific one.

[shafaifer]

I thank both Corribus and OrgZemProf, your great exellencies.