Nmr Definition and 181 Threads

Is it true that only a NMR test is able to detect the effectiveness, quality, quantity of a product? That it is able to detect wrong raw material, over-reaction, or isomers occurring during synthesis? But what about the other tests like GC/MS, HPLC/GC, HCLtitration, meltingpoint test. Is one...

Hi, Question: we have a magnetization M_x that varying as M_x(t)=M_x e^{-t}.Threre is a coil on the x axe. The magnetization will induce a current in the coil. How can get value of this current. This situation happen in NMR device. I try to caculate magnetic flux and then voltage (v=-N...

Hello everyone, I'm having a really confusing time trying to get my head around these concepts, so I will try to explain what I can... So, in proton NMR we have nuclei that can be in either spin-up or spin-down states. Nuclei align with an external magnetic field but precess. (This precession...

Hello, I am writing an appendix to my thesis where i try to explain how nmr works but i am having trouble understanding something. Suppose that we have a sample with many nuclei with 1/2 spin precessing around an external magnetic field \vec{B_0} aligned with the z axis. At Boltzmann...

What determines the tilt angle of a precessing proton in a magnetic field? Is it a constant the assuming no additional magnetic forces? In an NMR a perpendicular magnetic field is applied which rotates the precessing magnetic moment into the X-Y plane. After this perpendicular magnetic...

Hi, long time user, first time poster. A while back someone posted a great question https://www.physicsforums.com/showthread.php?t=33584 To paraphrase, can you explain on a spin-by-spin level exactly how a 181* pulse is possible? You always hear this really intuitive explanation of...

So my question pertains to a question about 13C NMR. The figure in question is below, the stars indicate the carbons in question. http://imageshack.us/photo/my-images/841/updownd.jpg/ In class, the professor said that the carbon on the left would be upfield, while the carbon on the right...

Homework Statement Butane, CH3CH2CH2CH3 has two proton environments would the splitting be 3, 6 OR 3,4 Homework Equations The Attempt at a Solution The 3 splitting would be because the CH3 group is next to a carbon with 2 hydrogens (n+1 --> 2+1 = 3) Now the 6 would be because...

I can't figure out how aromatic substituents effect aromatic rings. I can think of it in a couple ways: Is the group ortho or meta directing? When we learned about aromatic electrophilic substitution, we obviously learned about these groups. When an aromatic proton is lost, it will be...

In the Nuclear Magnetic Resonance, do the applied magnetic and electromagnetic fields correspond linearly to the heat generated? If not, how do they vary? Gracias

Homework Statement It is supposed to be a glycol with a formula of C6H14O2. The H NMR integrations are 6H and 1H as indicated on the H NMR. The IR: http://imageshack.us/photo/my-images/90/18155707.jpg/ The H NMR: http://imageshack.us/photo/my-images/155/hnmr.jpg/ Homework...

Homework Statement Last week in organic chem lab, we were provided with an H NMR spectrum of an unknown compound with the formula C7H5NO3. I'm not terribly good at analyzing these spectra, but I've managed to figure out that I'm looking at 4-nitrobenzaldehyde. The only thing that's bothering...

I'm currently in an advanced laboratory for physics majors, and I'm conducting a pulsed NMR experiment. My partner and I decided that we we're going to measure the T1 and T2 times of Epoxy. The idea is to explore the relationship between curing epoxy and changing T1 and T2 times. We have results...

Homework Statement Which isomer with formula C6H12O2 has the following NMR spectrum? http://aceorganic.pearsoncmg.com/epoch-plugin/tempfiles/1869_4119.jpg [b]3. The Attempt at a Solution It's hard (and probably unhelpful) to list all the tries I've had at this.

I am a junior molecular biology major. I plan to go into graduate school and currently my #1 topic of interest is using solid state NMR to determine molecular structure. I am doing research on the unrelated topic of bacteriophage genomics but do not want to change labs because I am well...

[PLAIN]http://img585.imageshack.us/img585/362/nmrs.jpg I had to identify an unknown in the lab and it was a UV active acid with a melting point of 133C-135C. Sodium fusion test revealed no heteroatoms so the only compound that fits the criteria is cinnamic acid but although the IR matches that...

Homework Statement How many types of protons are present? Homework Equations compound 1: CH3CH2OCH2CH2CH2CH2CH3 and compound 2: CH3CH2CO2CH2CH3 The Attempt at a Solution Compound 1: Arbitrarily assigning hydrogens which see a unique environment, left to right...

Homework Statement I'm having a bit of difficulty interpreting the spectrum. I've given it a shot but I think I might be missing something. The compound contains only C,H,O and any assistance would be appreciated. The molecular weight is 116g/mol. Homework Equations none The Attempt...

Homework Statement Draw the skeletal structure of the compound with molecular formulaC3H4Cl4 whose proton NMR spectrum contains a down-field triplet and an up-field triplet with relative integration of 2:2. 2. Rationale for Solution Integration ratio of 2:2 means CH2-CH2, after this one carbon...

Hello all, I have questions regarding my understanding of NMR and the mathematics of it. If anyone would take the time to read this, I would very much appreciate it. Please bear with me, I am a beginner. Thank you! First, there is the question on how to model this phenomenon. Up till now I...

When a molecule, let's say butane is placed in an external magnetic field and its hydrogens align parallel or antiparallel to the direction of the magnetic field, do 50% of the H atoms align parallel to the B field and the other 50% align antiparallel or what? If so, when they radio waves are...

Hi My basic understanding of NMR is that the nucleus of an atom is like a little bar magnet and when placed in a magnetic field this magnet can align with the magnet (low energy state) or oppose the magnet (high energy). The nucleus can enter the opposed state when radio frequency radiation...

Hi Are there any protons that do not show up on proton NMR as I am analysing an NMR spec (of a known molecule but I don't know what it is!) and I can't get my integration to equal the number of Hs in the empirical formula of the molecule Many thahks

Why are sp2 carbons more downfield than sp3 carbons? Is it because the bond length of sp2 carbons is shorter (electrons are more localized-thus more shielded)?

Hi all, I am currently self studying a chapter on Modern Analytical Chemistry. One part talks about interpreting NMR graphs and I understand the basic gist of it, however, I don't understand how to find the integrated peaks. I've looked extensively online and I now understand that you have to...

Homework Statement OK. So I've been given a uni lab report to write up but we were only told yesterday how to read proton NMR, and it's due in on Monday. I'm not terrible at deciphering it, but the compound I've been given the NMR for doesn't make sense (to me). I have to look at the proton...

Each proton has it's own magnetic field so it should effect the magnetic field of all nearby proton whether it is homologous (equivalent) or not. I don't understand how this discrimination arise? How a proton understand - "that proton is like me so I shoudn't ... ... ... " I mean it's...

Homework Statement Determine the chemical shift, integrated intensity, proton type, multiplicity, J (Hz), and # of protons on the adjacent atoms for this spectra given a 400 MHz NMR. http://img411.imageshack.us/img411/7629/chem262lnmr1.png Homework Equations (n+1) rule? (n+1) x...

Homework Statement Hi, I'm taking a Chemistry NMR & MRI class and were going over the part where the time domain graph is converted to the frequency domain graph by way of the Fourier Transform. I took Applied Mathematics last semester and we spent a week on the Fourier Transform but no time...

Homework Statement Propose a structure that is consistent with the data. C15H14O singlet 2.20 (3H) singlet 5.08 (1H) multiplet 7.25 (10H) Homework Equations None The Attempt at a Solution The multiplet is giving me trouble. I don't know how to interpret...

The NMR spectrum of CH3 CH2 OH consists of 3 bunches of spectral lines. the number of spectral lines in the bunch correspoding to CH2 group is ...? Answer is 4...how to do this ?...

Suppose that you obtain a one dimension magnetic resonance image from two water-filled cubic shaped containers arranged as shown below. This diagram is a cross-section of the cubic containers in the x-y plane. figure description: -one of cube's is 2 cm wide, the other is 1 cm wide, and...

The "Free Induction Decay signal" (FID) is a particular type of NMR signal observed in both MRI and MRS. An idealized representation of the signal Sf(t) is given by Sf(t)= Sf(0) exp (-i2pi(f_0)(t))*exp(-t/T2*) t>=0 Sf(t)= 0 it was proven that Gf(f) corresponding to this signal is given...

NMR NOESY spectrum -- Please help! "trans-9-(2-phenylethenyl) anthracene" Here is the NOESY spectrum: http://img109.imageshack.us/img109/5708/wittiggosy.jpg Here is the Proton NMR and the structure of the molecule: http://img40.imageshack.us/img40/1774/wittigprotont.jpg )...

Hi all, I was struggling in solving this question which is a part of a practice exam, and I need you to be patient with me and teach me step by step how to figure out the structure and how to read and analyze the spectra. I attached the two 1H NMR & IR spectra so you will be able to know...

Hi all! I only have a short question concerning nuclear magnetic resonance: the basic principle is that we apply an external magnetic field, the protons (the core of H^1) is split into two energy levels (depending on the alignment of its spin) and we can apply an external high-frequency pulse...

is it possible to detect the presence of enantiomeric exess of one enantiomer over the other using 1H nmr in a 400 mhz instrument without the use of any chiral agent?

Fourier Transform NMR Physics... Work Shown... Please Help! Suppose you would like to detect the NMR signal from water within an area of the brain using a 2 Tesla Magnet. Intially, the magnetization from the protons in water has a magnitude (length) represented by Mo and oriented in a direction...

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...

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!