[SpectroKid1]

Hi guys

As part of my degree I have to do a spectroscopy course which includes identifying organic compounds from their spectra.

I'm a little stuck so was hoping for some advice

Here's the spectra i have http://imgur.com/a/MkPvt
So from the DEPT 13C NMR i inferred the the 3 or 4(?) peaks at the left hand side of the spectra are quaternary carbons. The peak at ~77 is due to the solvent CDCl3. The peak at 0 is due to TMS

The IR, i thought the band at 3000 was due to an aromatic compound. But other than that i'm stumped

From the Mass Spec. Even Mass indicated even number of Nitrogen atoms. Absence of any M+2 peaks shows no Br, S or Cl. I was really confused by the lack of any sort of alkane branches. I thought maybe the loss of 31 came from lost of an alcohol group? Also, using the relative abundance of the M+1 peak as being ~9% I used the relative abundance of 13C (1.1) to calculate there are 8 carbons in the structure

Any help is greatly appreciated
Thanks

[mjc123]

Well, the 3600 cm-1 band tells you there's OH there. Given that, juggling with the numbers to get 112 suggests perhaps fluorophenol - the simplicity of the nmr would suggest para.

[SpectroKid1]

Well, the 3600 cm-1 band tells you there's OH there. Given that, juggling with the numbers to get 112 suggests perhaps fluorophenol - the simplicity of the nmr would suggest para.

Excellent! I thought it might be some kind of phenol but kept blanking out on the 19 m/z I was missing. Would you be able to give me a hand on a couple more, if you don't mind?

[mjc123]

I can try; I promise nothing.

[SpectroKid1]

I can try; I promise nothing.

Hi again

Could you have a look at this please?

http://imgur.com/a/oVNYe

Strong IR band at ~1700 indicates presence of carbonyl oxygen. In a Spectroscopy book I've got from the library, the band at ~1200 is supposedly indicative of a saturated ester. The band at ~2900 also suggests an ester

In the mass spec. The molecular ion peak is 154, with an M+2 showing a +2 isotope is present. The 3:1 peak ratio shows its Chlorine due to the 75:25 relative abundances of 35Cl& 37Cl. The peak at 118 is indicative of loss of HCl

There is a peak at 43 which I thought what a C-H group with two methyl groups and a C=O group attached. This is because there is a multiplet peak in the 1H NMR with 7 peaks and an integration of 1. So that would come from the H atom coupling to the two equivalent methyl groups.

The 13C NMR shows which environments are CH3, CH2, CH and quaternary C environments.

This is what I've got so far, so any help would be great
 

[mjc123]

This has got me stumped. Are you certain that 154 is the molecular ion?
I'm virtually certain there's an isobutyl group; (CH₃)₂CH-CH₂- is consistent with the fragment 57 (and 43), and with the NMR. Likewise, 63/65 is consistent with COCl, and the frequency of ca. 1800 cm^-1 is consistent with an acid chloride. The band at ca. 1200 must be C-O or C-F. But how to fit them together, and make up a MW of 154, I can't see.

[SpectroKid1]

This has got me stumped. Are you certain that 154 is the molecular ion?
I'm virtually certain there's an isobutyl group; (CH₃)₂CH-CH₂- is consistent with the fragment 57 (and 43), and with the NMR. Likewise, 63/65 is consistent with COCl, and the frequency of ca. 1800 cm^-1 is consistent with an acid chloride. The band at ca. 1200 must be C-O or C-F. But how to fit them together, and make up a MW of 154, I can't see.

I think 154 is the molecular ion, given the evidence that there's Cl there, that's the only thing that makes sense for a Mass.

I agree with the isobutyl group, and the C=O. I was thinking that maybe it was an eater and then an alkyl halide, is there anything that suggests this isn't the case?

[mjc123]

Carbonyl frequency looks too high for an ester, C-O too high for an ether. Can you get a hemicarbonate chloride (dunno what the proper name would be) RO-CO-Cl?
Still have a problem getting 154/6. Are you sure that's the highest? How far up was the MW search extended?

[SpectroKid1]

Carbonyl frequency looks too high for an ester, C-O too high for an ether. Can you get a hemicarbonate chloride (dunno what the proper name would be) RO-CO-Cl?
Still have a problem getting 154/6. Are you sure that's the highest? How far up was the MW search extended?

Everything that I've been given is what's attached in that post. I'm struggling to make it fit 154 too. I wouldn't worry about it though. I'll keep chipping away

If you could check this for me, that would be great

I think this is Benzaldehyde: http://imgur.com/a/uJCEf

C=O band in the IR, 1H peak at 10ppm aromatic carbons and a quaternary aromatic carbon too. Would you agree?

If Benzaldehyde is compound 1, compound 2 is a product of a reaction of compound 1 (if that makes sense) I can't figure out what it is. Here's the spectra i've got: http://imgur.com/a/fnpM1

So far I've got: must contain nitrogen, as the mass number is odd. The Aldehyde peak has disappeared from the 1H NMR so that suggests the reaction has occurred at the aldehyde site

[Dan]

Carbonyl frequency looks too high for an ester, C-O too high for an ether. Can you get a hemicarbonate chloride (dunno what the proper name would be) RO-CO-Cl?
Still have a problem getting 154/6. Are you sure that's the highest? How far up was the MW search extended?

A chloroformate. 154/6 might be isobutyl chloroformate + water. Could that be an artefact of MS? I don't know enough about EI to be sure, but maybe if there's water in the system you could see isobutyl carbonic acid.HCl.

[SpectroKid1]

Carbonyl frequency looks too high for an ester, C-O too high for an ether. Can you get a hemicarbonate chloride (dunno what the proper name would be) RO-CO-Cl?
Still have a problem getting 154/6. Are you sure that's the highest? How far up was the MW search extended?

A chloroformate. 154/6 might be isobutyl chloroformate + water. Could that be an artefact of MS? I don't know enough about EI to be sure, but maybe if there's water in the system you could see isobutyl carbonic acid.HCl.

I suspect you might be right. The carbon and hydrogen nmrs match what I would expect from that compound. Cheers for that! Any help with the benzaldehyde spectra in the post above?

[mjc123]

1 is benzaldehyde. For 2, I can think of a handful of things that would match 149, e.g. PhCONMe₂, but not without introducing hydrogens that ought to appear in the IR and NMR, but don't.

[SpectroKid1]

1 is benzaldehyde. For 2, I can think of a handful of things that would match 149, e.g. PhCONMe₂, but not without introducing hydrogens that ought to appear in the IR and NMR, but don't.

That's where my confusion is coming from too. Obviously the aldehyde is the reaction site as the 10ppm 1H peak disappears. The only new Hydrogen environment that appears is the double with an integration of 1 at ~8ppm.

Here's the spectra for compound 3 and 4, so it might be possible to work backwards, since the reaction is 1->2->3->4

Unknown 3: http://imgur.com/a/tLYtK
Unknown 4: http://imgur.com/a/Di4EV

These seem to indicate more significant changes to the compound


Also, i realised where the extra mass was coming from from the fact NH3 was used as the ionising gas, so there was an M+NH4 adduct in the spectra, hence +18

[SpectroKid1]

Carbonyl frequency looks too high for an ester, C-O too high for an ether. Can you get a hemicarbonate chloride (dunno what the proper name would be) RO-CO-Cl?
Still have a problem getting 154/6. Are you sure that's the highest? How far up was the MW search extended?

A chloroformate. 154/6 might be isobutyl chloroformate + water. Could that be an artefact of MS? I don't know enough about EI to be sure, but maybe if there's water in the system you could see isobutyl carbonic acid.HCl.

I suspect you might be right. The carbon and hydrogen nmrs match what I would expect from that compound. Cheers for that! Any help with the benzaldehyde spectra in the post above?

I think the M+18 peak arises because NH3 is used as the ionising gas, so there will be an M +NH4+ ion peak.

Could you take a look at the benzaldhye reaction sequence sectra?

Benzaldehyde -> 2 -> 3 -> 4

2: http://imgur.com/a/fnpM1
3: http://imgur.com/a/tLYtK
4: http://imgur.com/a/Di4EV

Any ideas on what these could be?

[mjc123]

I've been off sick for a while but I'll look at these when I've time. In the meantime:
Do you know what the reagents were?
Can you annotate the IR spectra with the frequencies of the major peaks? It's hard to read them off to better than 50-100 cm^-1.
If you're going to post any more of these, please take care when scanning to get the original as flat as possible to avoid the plots appearing curved.
Did you run these spectra, or were you just given them? Better quality IR spectra, without all those negative peaks, would help.
Should I expect a M+NH₄ peak in every MS? (I'm not an MS expert.)