Nmr Definition and 199 Threads

I am trying to understand the theory behind nuclear magnetic resonance. I have been reading various explanations (some more detailed than others) but I still have several holes in my understanding and I hope that some of you can help clear them up. I realize there are quite a lot of...

CHM238L - Identifying Peaks of H NMR spectra Homework Statement The experiment is "Reducing Benzil using Sodium Borohydride". The experiment itself was simple enough and when I finished, I got a melting point of 134-136 C, which is indicative of benzoin (135-137) rather than...

I am attempting to identify an organic "mystery compound." Having run both IR and mass spectrometry, I conjecture that the compound has a molecular mass of ~130 amu and possesses at least one -OH group. C8H18O fits this profile nicely, but no isomers of which I can conceive are commensurate...

Hi all: I am confused about how far spin magnetic moment goes during a finite diffusion time (such as 100 ms). As we know, due to T2 relaxation mechanism in NMR, spin 1 and spin 2 can exchange magnetic moment but no energy transfer during this exchanging process due to dipole-dipole...

background: I have a HNMR spectra and I am trying to figure out what is coupled to what. There is a set of 4 doublets where it is know that there 2 sets of coupled doublets. the doublets have j-values of 8.8 @ 8.04ppm, 8.8@ 7.58ppm, 8.4@7.39ppm and 8.4@7.00ppm. While I may have assumed that...

Hello, I have been running spin evolutions with 8 spin 1/2 nuclei, but I am having issues increasing the number of spin 1/2 nuclei to 12. I get the following error message in command prompt. Firstly Spinevolution appears to be loading as normal, but then after a minute or so the simulation...

1. Homework Statement How many peaks will there be in the NMR spectrum of Malic Acid, HOOC CH2 CH(OH) COOH, WITHOUT D2O as the solvent (i.e. Hydrogens in Hydroxyl groups WILL have corresponding peaks)? 3. The Attempt at a Solution I thought the two -COOH groups will be identical...

Homework Statement How many peaks will there be in the NMR spectrum of Malic Acid, HOOC CH2 CH(OH) COOH, WITHOUT D2O as the solvent (i.e. Hydrogens in Hydroxyl groups WILL have corresponding peaks)? The Attempt at a Solution I thought the two -COOH groups will be identical Hydrogen...

Hello, The nutation frequency in NMR is given as \omega_{1} = - \gamma B_{1} Here gamma is the gyromagnetic ratio and B1 the radio frequency field. My problem is that this is all well and good, but what does omega 1 actually represent in an NMR experiment? What is its physical...

I'm reading a paper on NMR, and the authors keep referring to the operators I_x, I_y, I_z . What are these operators? I keep finding them mentioned in other papers, but no description of what they are.

Homework Statement I have attached the IR and NMR spectrum from lab. I have determined that there was a nitrogen present in the compound. There was no sulfur or halogens. The molecular weight was 138. The compound was solid and yellow color. It had a melting point between 124 and 134 C...

I have got myself very confused. I am trying to understand Nuclear Magnetic Resonance but am running into issues. The basic idea of NMR, resonant excitations between Zeeman split nuclear energy states, I understand. The semi-classical picture of precessing moments also makes some sense to me...

I've got the spectra for C5H8O2 (the spectral database confirms that it's ethyl acrylate) and treatment with hot aq. HCL causes the signals in the 1N NMR spectrum at d 1.3 and 4.2 to disappear. Does anyone know why this happens? Thanks!

Homework Statement I have a 3 compounds with the same formula: C6H12O2 I need to find the molecules by interpreting the H NMR spectroscopy http://aceorganic.pearsoncmg.com/epoch-plugin/tempfiles/1867_430.jpg http://aceorganic.pearsoncmg.com/epoch-plugin/tempfiles/1869_524.jpg...

Homework Statement Give the structure of C8H8O3.Homework Equations IR tells us that there is an OH group and a C=O group Degree of saturation = 5 --> Benzene ring + C=O H NMR spectrum shows: Peak at ~7.8ppm integrating for 1H and is a doublet Peak at ~7.45ppm integrating for 1H and is a...

Homework Statement I'm having a hard time understanding spectral data. It says that there is a compund with a sharp IR between 1700 and 1720 cm-1 and a strong broad absorption over the region 2500-3000 cm-1. 1H NMR: 2.49 (t, 2H), 2.80 (t, 2H), 3.72 (s, 3H), 6.78 (d, 2H), 7.11 (d, 2H)...

Learning about Nuclear Magnetic Resonance for a while. I have read than when the main field B0 is applied along the Z axis, it takes a time (T1) in the order of seconds for the M0 field to be created in the body we are studying. Yet we can apply a short (maybe in the order of one wave...

I have a real stumper for you guys. We have an 7T (300 MHz) NMR in our lab that recently quenched – the superconductors went normal and we lost all our helium. That is can be pretty bad for a magnet, but we think ours got through it without significant harm. We have been getting it back up and...

I have a molecule and I'm barely accostumed to H-NMR and C-NMR this has neither it's trifluorophosphine I have to predict the splitting, intensities and frequency the first two I think I have some idea about but I don't even know where to look on how I could calculate this it seems like if...

Homework Statement Does anyone understand the basic theory behind NMR experiments such as the one shown here http://www.ifw-dresden.de/institutes/imw/sections/22/laboratory-for-pulsed-high-magnetic-fields/nmr/nmr_exp.gif. If so I have questions.Homework Equations The Attempt at a Solution

Hey, I've recently started to revise for a spectroscopy test and had a random retardation moment where I asked myself "Why don't protons on a methyl group couple to eachover?" The answer seemed obvious, there all in the same chemical environment and all sigma bonded to whatever substituent you...

Using two pernament magnets, a transmitter coil and a pickup coil, we applied a match filter to find the resonant frequency (our sample was wrapped in the pickup coil with the trasmitter stationary wrt it: the magnets are the round type, ceramic I think). Using this frequency we can map the...

Good Morning, I have been carrying out some NMR relaxation measurements (T1 and T2), and have found that they have a dependence on the temperature of the sample, for example T1 is small at lower temperatures, and larger at higher temperatures. Can anyone explain why there is a dependence of...

I currently have a problem with having 2 small peaks, normally from what I would recall would correspond to 2 fully substituted carbons. (The molecule I have predicted is ethyl-3-bromobenzoate) With one carbon fully substitued at the '3 position of the benzene, the carbon of the carbonyl group...

[SOLVED] Sites with IR, 1H NMR, 13C NMR, and mass spectroscopy? I was wondering if anyone knew where I can look at IR, 1H NMR, 13C NMR, and mass spectroscopy (sites or programs). I'd like to be able to input the name of an organic compound and be able to see these spectra. Thanks.

1. What will be the multiplicity due to spin-spin splitting of the highlighted protons in the molecule: (C6H5)-CH2-CH2-CH2-OH? Homework Equations None The Attempt at a Solution I know that the ones surrounding the highlighted CH2 group are not equivalent. If they were, the...

NMR and MRI -- questions! I'm currently doing an experiment on nuclear magnetic resonance for an undergrad physics lab. Our experiment was based around determining the effects of proton concentration on spin-lattice and spin-spin relaxation times. We used two separate sets of ionic solutions...

I'm trying to teach myself the theory behind NMR spectroscopy, but I am having some trouble with some pchem/physics concepts that I have never seen before. The chapter I am currently on talks about the quantization of nuclear angular momentum. What I don't understand is, what is the...

Hi All; Long time reader, first time poster. Here's a tricky one. I have a solid state NMR set of data in 3D. Let's say the signal phases in the three dimensions are: exp(i*(A+B*C+C)t_1) exp(i*(A+B*C+C)t_2) exp(i*(A+B*C+C)t_3) given the information, one should be able to (in theory)...

Hi, We are using Varian Unity Inova 500 MHz NMR instrument.When we are taking 31P and 19F spectra we do not use any reference sample as like TMS etc. Our customer says us that they are not interpreting these spectras without reference. Which reference can we use for these spectras and how can...

When a 90 degree pulse is followed by a 180 degree pulse, a spin echo may be seen at a time tau later...i understand this in general terms, as the direction of precessional drift has been flipped about its own axis by the 180 pulse, which means the spins catch up and rephase in an echo etc...

Hi! Now I am doing an undergraduate program in molecular and biological physics. At the graduate stage I would like to take part in research in the area of modern scientific instruments like electronic microscopes and nuclear magnetic resonance tomographs/spectroscopes. I know there are...

I need to answer the following question: A simple energy level system has two energy levels. These are the energy levels matching the spin of a proton in a magnetic field. This is important for NMR. In that case the energy difference depends on the used magnetic field, but for a typical NMR...

We did a NMR analysis on acetylacetone (2,4 pentadiene) and I'm suppose to just use the spectrum and determine the equilibrium constant. I have no clue on how to start it and its no use on asking the professor because he's also NMR illiterate. Can someone try and explain to me how to calulate...

I am a bit confused with how to determine whether a set of hydrogens are enantiomers or diastereomers (and therefore how many different sets there are). [In attachment} I understand d, and e, since they both already have a chirality center, and replacing a hydrogen on the CH2 (which is a...

hey bio people, Im a physics student, but I am taking a class in biophysics with hopes to work in the space that the two disciplines share. Anybody do 3D NMR here... I'm looking at slices in the N direction of a 3D HNCA spectrum of a short protein (so the amide hydrogen and alpha carbon...

Acidic chemical shift--(NMR Question) *Well, the greater the deshielding on a proton, the greater the chemical shift (as measured I believe from Si\left( {CH_3 } \right)_4 ), with smaller electron density to reduce the effect of the external magnetic field on THAT proton Aside from organic...

Anybody who know something about the temperature dependency of the proton Larmor frequency say for protons in pure water? I am sure people with experience in NMR spectroscopy know. Any good articles/references? I am not asking about: -temperature dep of the proton density beeing...

Hello everyone. In the literature I come across spectra data as in the examples below: English example: 1H-NMR (CDCl3) δ: 1.09 (3H, t, CH3), 3.77 (3H, s, OCH3), 3.97-4.28 (2H, m, CH2), 4.28 (1H, s, CH) 6.41 (2H, t, pyrrole-H), 6.78 (2H, t, pyrrole-H), 7.13-7.21 (5H, m, ArH), 8.53 (1H, d...

NMR "Pople Notation" HELP! All the examples in my textbook show molecules that have only three sets of multiplets (AX, AB, ABX, or AMX first oder spin systems). But what if I have a molecule with more than 3 spin systems, for example in 1-bromobutane: CH3-CH2-CH2-CH2-Br (there is a triplet...

Could someone explain to me how to use and interpret C NMR? For proton NMR there are (fairly) simple coupling rules from which to deduce that there, e.g., are two protons on a carbon next to a CH3 group. Is there anything alike for multinuclear NMR? Titanium NMR would be fun to do also, or won't...

Hey guys I was wondering does anyone know of any papers about the 7-qubit quantum computer used to perform Shor's algorithm in 2001? Thanks

I was wondering if someone could please help me with my lab. We are synthesizing NMR shift reagents in order to determine what isomers are present in a mixture of xylenes. I have the NMR and I can't figure out how to determine which isomers are present. If I have the NMR of o,m,p-xylene by...

Okay I am lost. My Professor has given me the formula ( C4 H8 Br2) and the signals 3.8(s, 2H) and 1.8(s, 6H). How the hell am I suppose to compose a molecule from that?? Any ideas? :biggrin:

there is this one really good NMR spectra interpretation website out there... i think. i vaguely remember coming across one years ago. anybody know what I am talking about? anybody know the url?

Hello We conducted an experiment recently for our physics lab to determine the relaxation times for a solution of Fe3+ and Mn2+ ions we then had to compare the ratios of T1/T2 for the two solutions and we found that for Fe3+ ions the ratio came to ~1 and for Mn2+ ions it came to 4 (i.e >1)...

I know that a Nuclear Magnetic Resonance (NMR) machine consists of a magnet, radio transmitter, detector and a sample material. By using a NMR machine how are the spins of the nuclei in the sample material observed? The more detail the better. Thanks in advance.

I have an exam soon and i am having problems understanding hi-res n.m.r. both theory and analytical sides. i don't understand why it happens and what it shows and stuff. Can anyone help?

I would like to ask why a radio-wave pulse with defined frequency was used in NMR, why it can excited different proton in sample measured. Is it related to so-called "lifetime boarding" ?? Thx :frown: