[SpectroKid1]

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.)

Hi, I hope you're feelings better soon!
In answers to your questions:

I don't know the reagents, only that 1->2->3->4

I don't have more accurate peak data for the IR, only the spectra as photographed, I can approximate some of the major peaks if that would help, but it will only be to a similar accuracy as to you can do

Sorry about the issues with the photos, if there are any in particular that you'd like to be clearer let me know and I can redo them

I didn't run these spectra, I was just given them. I'm very frustrated with the quality of the spectra, the nmr is poorly resolved and the IR has a lot of spurious peaks. I'll be complaining about this when I speak to someone at the university.

Nope, don't expect a M+NH4 peak in the mass spec, that was only for number 2, as it specifically stated on the mass spec, but I had overlooked it at the time.

As always, any help you can provide is hugely appreciated! Once again, hope you're feeling better soon

[MOTOBALL]

Should I expect a M+NH4 peak in every MS?

Under CI (NH3) conditions,

if the gas phase basicity of NH3 is higher than that of M, you will generally see [M+NH4]+, while

if the gas phase basicity of NH3 is lower than that of M, you will generally see [M+H]+.

Under ESI (NH4OAc) conditions, you will generally see both [M+H]+ and [M+NH4]+; in fact the characteristic mass shifts of +17 (NH3), +22 (Na) and +38 (K) relative to [M+H]+ are used to confirm the MW.

[mjc123]

This is perplexing. The NMR of compound 4 (apart from a lone proton) looks very similar (but not identical) to the one given by Aldrich for 2-tetralone. But the MW is high (unless M⁺ is just absent for some reason) and where is the OH that the IR suggests is there? (Unless the sample is just wet of course.) But I don't see how this comes from benzaldehyde, or what 2 and 3 are.

[MOTOBALL]

SpectroKid1,

There are several rules associated with using this forum.

1.  We are not supposed to solve homework problems---merely nudge you in the right direction.

2. You are shooting yourself (and us) in the foot by not disclosing ALL of the analytical information.  For example, it is vitally important to know the ionizing conditions used to generate the MS data (see my post of Oct. 18) right at the outset.  You have also failed to take advantage of the C & H %-composition data provided on the mass spectrum.

That said, you are at least putting effort into the problems (which is nice to see) and are generally getting somewhere---but the devil is in the details, so tighten up your observational skills (point 2, above).  Do not be discouraged---no one of us was born knowing this spectral interpretation---it does have to be learned the hard way.

3.  The MS data for cpd. 2 contains some VERY characteristic m/z signals !!!  You need to consider the structure and reactions of benzaldehyde, as well as doing some reading on MS interpretation (see Interpretation of Mass Spectra by McLafferty & Frantisek).

Good Luck !

[SpectroKid1]

This is perplexing. The NMR of compound 4 (apart from a lone proton) looks very similar (but not identical) to the one given by Aldrich for 2-tetralone. But the MW is high (unless M⁺ is just absent for some reason) and where is the OH that the IR suggests is there? (Unless the sample is just wet of course.) But I don't see how this comes from benzaldehyde, or what 2 and 3 are.

Is it possible than the benzaldhye could react with an Azide (N3) and H+ to form a PhC(O)N3H type structure?

[SpectroKid1]

SpectroKid1,

There are several rules associated with using this forum.

1.  We are not supposed to solve homework problems---merely nudge you in the right direction.

2. You are shooting yourself (and us) in the foot by not disclosing ALL of the analytical information.  For example, it is vitally important to know the ionizing conditions used to generate the MS data (see my post of Oct. 18) right at the outset.  You have also failed to take advantage of the C & H %-composition data provided on the mass spectrum.

That said, you are at least putting effort into the problems (which is nice to see) and are generally getting somewhere---but the devil is in the details, so tighten up your observational skills (point 2, above).  Do not be discouraged---no one of us was born knowing this spectral interpretation---it does have to be learned the hard way.

3.  The MS data for cpd. 2 contains some VERY characteristic m/z signals !!!  You need to consider the structure and reactions of benzaldehyde, as well as doing some reading on MS interpretation (see Interpretation of Mass Spectra by McLafferty & Frantisek).

Good Luck !

Hi

I'm not looking for people to do my work, just to show me where to go, as for compound 2, 3 & 4 I've no idea where I'm going. For 2 the mass increase, but theres no new carbon environments and nothing particularly characteristic in the Hydrogen NMR.

Is it possible that it could be Ph-C(O)N3H, like an Azide attached to the carbonyl carbon? But then you'd expect a carbon slightly further downfield than we're seeing

I am providing you with all the information I have. I've attached all the spectra I've been given, there's nothing missing


What peaks should I be looking for? The one at 91 is presumably C7H7?

[MOTOBALL]

Yes, m/z 91 is C7H7+!!!!!!!!!!!, VERY characteristic of substd. phenyl.

What other low m/z signal signifies benzene ring ??

Let me give you a nudge, by telling you that m/z 149 does NOT contain nitrogen.  m/z 149 is VERY VERY characteristic of a certain class of organic plasticizer.  Once seen, never forgotten !!

[SpectroKid1]

Yes, m/z 91 is C7H7+!!!!!!!!!!!, VERY characteristic of substd. phenyl.

What other low m/z signal signifies benzene ring ??

Let me give you a nudge, by telling you that m/z 149 does NOT contain nitrogen.  m/z 149 is VERY VERY characteristic of a certain class of organic plasticizer.  Once seen, never forgotten !!

Are you talking about Phthalates? I found one with Mass 149 ( http://i.imgur.com/QLEiR8A.png ), but it doesn't fit with the carbon or the hydrogen NMR structures that I have provided. There are too few Carbon environment in the phthalate structure, compared to the NMR spectra I have provided, there are also too few hydrogen environments too. Also, I'm not sure how, or if you can go directly from a benzaldehyde to that structure?

[SpectroKid1]

I've been working on compound 3 and I now think it's phenylethylamine, can anyone check this? Not sure how I would go from Benzaldehyde-> X-> Phenylethylamine though?

[mjc123]

2-phenylethylamine or N-phenylethylamine?

[SpectroKid1]

2-phenylethylamine or N-phenylethylamine?

N-phenylethyleamine: Ph-(CH2)2NH2

[mjc123]

That's 2-phenylethylamine

[SpectroKid1]

That's 2-phenylethylamine

Well in that case I think Compound 3 is 2-phenylethylamine. Do you agree?

Out of curiosity, what is the structure of n-phenylamine? I though N- was the prefix denoting a straight chain molecule, i.e n-BuLi which is a straight Butane chain with an anion

[mjc123]

n- denotes a straight chain. N- denotes a group attached to nitrogen. N-phenylethylamine would be PhNHCH₂CH₃. 2-phenylethylamine would be more consistent with the nmr suggesting 2 CH₂ groups.

[SpectroKid1]

n- denotes a straight chain. N- denotes a group attached to nitrogen. N-phenylethylamine would be PhNHCH₂CH₃. 2-phenylethylamine would be more consistent with the nmr suggesting 2 CH₂ groups.

Thanks

Ok, so i think i've solved the sequence

Benzaldehyde -> B-Nitrostyrene -> Phenylethylamine -> Tetrahydroisoquinoline

The one thing I'm missing is reagents.

For 1->2 i'm guessing a base and nitromethane
2->3 possible Hydrogen and palladium on a carbon support
3->4 I'm not sure

Any chance you have an idea of the reagents/conditions required to carry out the reactions?