Nuclear Magnetic Resonance. This tag relates to NMR spectroscopy, the experimental technique of measuring the resonance and thus deducing the molecular structure of the given compound.

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How to predict the ³¹P NMR spectra?

What can I predict about the $\ce{^{31}P}$ spectra of $\ce{TiP2O7}$? To get the required information about the crystal structure of the compound, here is a screenshot from the ICSD website: Since ...
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29 views

Why do the two methylene protons in ethylbenzene have a chemical shift at 2-2.9?

The data sheet does not have any chemical shifts in this range for compounds containing only carbon and hydrogen
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Why do NMR coupling constants change with temperature?

Why do coupling constants change with temperature in NMR?
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60 views

Splitting across a double bond in ¹H NMR

Why do the Hs in the figure below split into doublets instead of staying as a singlet. Wouldn't they be isolated from each other since the double bond does not rotate?
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Spin spin coupling in a proton NMR of an ester?

I am learning about proton NMR and spin-spin coupling, and am confused about whether splitting occurs over an ester bond. Specifically, in the case of ethyl methanoate, HCOOCH2CH3, if I were to number ...
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1answer
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proton NMR deshielding

The protons alpha to the oxygen in methyl propionate are more shielded than their corresponding protons in ethyl propionate. . We can see from the NMR data that this is the case as well. My ...
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Could I get a hint on the structure of this molecule based on HNMR spectra?

Chemical formula is $\ce{C7H6O3}$. IR spectra has a peak at 3238, which I believe could be an alcohol, phenol, or carboxylic acid. There's an additional peak at 3015, which I believe is either an ...
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1answer
99 views

What does it mean in a Ni(II)complex if the HNMR spectrum appears unbroadened and unshifted & what does this tell you about the coordination geometry?

I am trying to work out the an unknown Ni(II) complex. I don't known the geometry and I have read that broad lines on the nmr spectrum indicate large compounds with symmetric environments. Does this ...
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45 views

NMR and pseudorotation

I think it has something to do with the fact that at high temp it interconverts and so all the coupling constants are the same hence quintet but at lower temps the frequency of the rotation is less ...
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80 views

7,7-dichlorobicyclo[4.1.0]heptane NMR solving

i made a synthesis of this material in the lab and now i got the H-NMR specta , and by litreture i know that i got the right product. im having trouble to match the hydrogens to the peaks,i tried to ...
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Interpreting the NMR spectrum of Wittig salt p-carboxybenzyl triphenylphosphonium bromide

I synthesized the Wittig salt p-carboxybenzyltriphenylphosphonium bromide. Below is the proton NMR spectrum I measured. I'm having a little problem of matching the peaks to the hydrogens, especially ...
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94 views

Why is there a doublet instead of a singlet in this Wittig reaction salt configuration NMR?

I did an NMR sample to my salt p-carboxybenzyl triphenylphosphonium bromide. I got a doublet at 5.26, and according to every article it belongs to the $CH_2$ next to $P^+$, but how come I didn't get a ...
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131 views

Suggest possible structures for the compound PF3(Ph)(NMe2) using the NMR data

use these data to suggest the possible structure for the compound PF3(Ph)(NMe2): 19F Spectrum, two signals: a doublet of doublets, J=56 and 819Hz, -39.5ppm, relative intensity 2 a doublet of ...
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137 views

1H NMR proton coupling

I had the opportunity to work with a NMR spectrometer and decided to learn some of the theory behind it. After finishing Clayden's chapter on $^{1}\textrm{H}$ NMR (Ch. 11) I'm still left with some ...
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1answer
162 views

Assigning 1H NMR spectrum and predicting peak coupling patterns

I have a the proton NMR of this molecule: There are 6 individual hydrogens and none of them are equivalent. In the spectrum I have been given there are only four peaks. I have been able to assign ...
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128 views

Which has the higher chemical shift E/Z alkene?

If you have a simple alkene for example 1-methyl-But-2-ene then you will have two methyl groups on one side of the double bond, which one of these will have the highest. Will the one on the same side ...
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2answers
97 views

Assigning Carbon NMR

I have a molecule and i need to assign the carbon NMR to each of the carbons My molecule is The peaks i have for the carbon NMR are shown below. I have also used the DEPT to work out if its a CH3, ...
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1answer
40 views

Are there some similarities between J-coupling and j,j-coupling?

I'm a bit confused having heard two different terms in different lecture parts: J-coupling There is the J-coupling (= indirect dipole dipole coupling = scalar coupling) which arises from a ...
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How to assign the signals in the H-NMR of Aspirin?

I need to assign the H-NMR of aspirin, below is aspirin with the H's labelled. The peaks I have are: 2.30ppm (I this is a singlet and would be F) 7.07ppm (I think this is E) 7.29ppm ...
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1answer
113 views

HNMR Assignment

I have a molecule and i need to assign the hnmr. I have a printed spectrum So far my answer is: chemical shift_______splitting pattern_______coupling constant ...
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241 views

What splitting pattern is this?

I am trying to find the structure of an unknown molecule. What is the splitting pattern of these sets of lines? I think my unknown molecule is butanol and the hydrogens this splitting pattern is ...
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2answers
295 views

Proton NMR signals and rings

Does pyridine or furan have the more shielded proton NMR signals? I know that both are aromatic, so both have rather deshielded signals due to ring current combining constructively with the applied ...
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1answer
60 views

Chemdoodle to mestranova

Is it possible to copy my chemdoodle displayed structure into mestranovea? I have tried simple dragging (mac) and all the various copy/paste options... any ideas?
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13C NMR peak location in butanone

The above is the correct $ ^{13}C $ NMR spectrum of butanone. In the $ ^{13}C $ NMR spectrum of butanone, I figure that the peak locations of the first and third carbons should be switched (27.3, ...
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39 views

Relation in the sign (+/-) for gyromagnetic ratio and magnetic susceptibility

Is there a relation (or formula) between the sign of the magnetic susceptibility and the gyromagnetic ratio of a nucleus in NMR?
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1answer
257 views

NMR: Most deshielded protons (electron withdrawal)

Of these two molecules, which one would be expected to have the most deshielded signal? First off, I think the wording of this question is wack because neither of these molecules has only one NMR ...
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Using MestReNova: An Introduction

Can anyone help me with a quick question regarding MestReNova 9.0. I have been fiddling with this thing all day and before you ask yes, I have consulted the users guide to no avail. I want to do ...
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Nuclear magnetic resonance : Difference between S and I

In the lecture our professor told us that nuclei with S>1/2 have a quadrupole and are therefore detected with NQR instead of NMR. The majority of all elements have nuclei with S>1/2. I wondered why ...
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1answer
284 views

para-dichlorobenzene - number of proton NMR signals

I am told that para-dichlorobenzene exhibits two proton NMR signals. This doesn't jibe with me; all the protons on the molecule are equivalent. Here is a book claiming the same thing. Am I wrong, or ...
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1answer
41 views

how to determine timescale with characterization methods?

There are as classified in the Atkins textbook 4 different timescales on material characterization: a)Time during which a quantum of radiation or a particle can interact with a molecule. b)Lifetime of ...
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197 views

Most negative and most positive value for proton chemical shifts

What are the most negative and the most positive values for proton chemical shifts recorded till present?
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288 views

How do I find out what benzene containing compound this is with IR and NMR?

I have the following IR and NMR of an unknown substance. Can someone tell me what is a possible structure of the compound or point me in the correct direction. So far I am thinking of a benzene ring ...
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3answers
324 views

Identifying an unknown compound(w/ NMR/IR)?

I need some help identifying the following unknown compound. Any suggestions or hints regarding the possible compound would be highly appreciated. So far I am thinking the broad peak on the IR is an ...
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3answers
170 views

What is the conformer distribution in monosubstituted fluoro bullvalene?

Bullvalene is a fluxional molecule able to interconvert any two carbon atoms through a series of degenerate Cope rearrangements (read the Stereodynamics section of this article if you would like more ...
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273 views

$\ce{^13}$C NMR of dimethyl 3,4,5,6-tetraphenylphthalate?

I am trying to assign the peaks here to dimethylphenylphatalate but all the benzene rings are throwing me off. All I can get is that the further most signal is the carbonyl carbon (168.71) and the ...
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261 views

Why is the para carbon in Benzaldehyde NMR more deshielded than the ortho and meta carbons?

Assuming this image is correct, why is the Carbon-3 more deshielded than Carbon-2 and Carbon-1? From what I understand, deshielding is the greatest when the Carbon atom is closer to electron ...
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1answer
108 views

How to construct NMR spectra from chemical shift tensors?

If I know the chemical shift tensor (from ab initio methods), $\sigma$, for each atom in my structure, is it possible to construct an NMR spectra for my system? If yes, how and what mathematical ...
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What other nuclei besides hydrogen and carbon 13 could be detected using NMR and is H1-NMR synonymus to NMR?

From my understanding NMR spectroscopy works by analyzing the resonance frequency of each structure around a hydrogen or carbon. Since every structure is unique and has unique resonance frequency it ...
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HNMR - Peak Splitting

If you have $\ce{CH3-\color{\red}{CH2}-CH2Br}$ Then the $\ce{CH2}$ (in red) would have a peak splitting of $12$ because $(n+1)(m+1)$ where $n$ for the $\ce{CH3}$ is $(3+1=4)$ and m for $\ce{CH2}$ is ...
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Hydrogen suspended in the center of an aromatic ring and NMR

My textbook (Organic Chemistry, 2nd Ed. Hornback, Joseph) states that if a hydrogen is located near the center of an aromatic ring it will experience an (often quite sizable) upfield shift, as seen in ...
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223 views

Identifying protons in NMR using the J values

When looking over an old organic midterm I came across this question. As you can see I got half of it right, but honestly I'm not sure how I got that one right or how you would answer this in ...
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How many signals would be seen in total in the 13C NMR spectrum

This is NanoBalletDancer. How many different carbon environments are there in NanoBalletDancer – i.e. how many signals would be seen in total in the 13C NMR spectrum? I counted 8 signals from ...
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2answers
59 views

Unexplained peak cluster in proton NMR trace?

I am working on a straight-forward NMR graph as part of my test prep. I have a pretty limited understanding of NMR, but I thoroughly read the chapter leading up to this practice question and am having ...
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144 views

1H-NMR and deducing structures

here is the data booklet we must refer too: Here is the exam paper solution: I dont understand how they conclude this. Peak areas and the chemical shifts seem to be different for me. For ...
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318 views

Why are NMR typically taken for a power of 2 scans?

Why do we typically take $n^2$ scans, even in the basic NMR experiment? I've heard various explanations, including that it helps the fast Fourier transform, and would like to know the real reason.
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227 views

rate determination by 1H NMR spectroscopy

Currently I investigate a reaction where a starting material A reacts with an excess of thiophenol B towards products C and D. As shown by recurrent TLC analysis of the reaction, the formation of D ...
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207 views

How do I overlay spectra in an ACD/NMR Processor, version 12.01?

I am having great difficulty getting spectra to overlay (the option doesn't even appear) after setting to new window mode and selecting each spectrum.
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11B NMR in a borosilicate tube

I'm just wondering, if one were to run a $\ce{^{11}B}$ NMR on a boron containing sample in a borosilicate tube, how could we separate the spectra of the tube and the sample? Apart from using a ...
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245 views

How to predict a COSY NMR spectra for an AMX spin system?

Does anyone know how to draw (predict) a hypothetical COSY NMR spectra for AMX spin system (the spin of A M X nuclei is 1/2)?
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Is aromaticity of the 4 aromatic amino acids affected by pH?

During a discussion of NMR, my lecturer told me to think about which amino acids contain protons in an aromatic ring, and whether any are likely to be affected by changes in pH. The 4 aromatic amino ...