Nmr Definition and 199 Threads

Homework Statement It asks you to identify the shift and nature of the protons in the molecule. Picture: https://mailhost-6.tamu.edu/service/home/~/?auth=co&id=24393&part=2 Homework Equations none The Attempt at a Solution I cannot understand what makes C a multiplet...

Hello, I didn't know where else to post this so here it goes ... I have collected data from a pulsed NMR experiment to calculate the value of the spin-lattice relaxation time (T1). Now I'm asked to fit the data using a function of the form V(t) = V_0*(1 - 2*exp(-t/T1)). But I'm not really...

Homework Statement Determine the structure of the compound given the information belowHomework Equations Molecular Formula: C8H6O4 1H NMR: 1.57 (d, J=8.66 Hz, 1 H) 1.77 (d, J=8.66 Hz, 1 H) 3.51 (d, J=3.00 Hz, 1 H) 3.51 (d, J=3.00 Hz, 1 H) 3.60 (sc,J=7.56, 3.00 Hz, 1 H) 3.60 (sc, J=7.56, 3.00...

Hi, everyone. I am a junior student major in physics, and after an internship in a NMR lab this summer, I am really interested in this field, and I decided to learn it in my graduate program. Does anyone know any program of nmr, cos I find out that most of these programs are set up by medical...

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...

Hey, I did a small experiment to determine the electron, proton and fluorine nuclei g-factors using a teltron set up shown below. The experiment was set up to sweep the static magnetic field between 0 and 3.67 mT and to keep the frequency of the perpendicular high frequency field constant...

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...

Homework Statement Would anyone be able to tell me if I'm on the right track with determining the peaks on these NMR spectrums? We had to synthesize a product of Chalcone and then hydrogenate it to obtain an unknown product that we have to correctly identify. This had been quite a difficult...

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...

I'm trying to calculate the mass of a chemical (DMSO) and from a NMR spectrum of water and DMSO. I have the value of the total area under the spectrum and I have the value of the total area corrosponding to the DMSO peak and the total area corrosponding to water. I know that the total area of...

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

Hello, I've been working in an NMR lab for two years and am trying to gain a deeper understanding of the phenomenon. I started my work right out of freshman year before even taking organic chemistry or electromagnetism so my initial knowledge was practically zero and my projects were assigned...

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...

Hi, I need some help with nuclear magnet resonance (MRT). *) What defines the area of effect of nuclear magnetic resonance? Is it the magnetic field? the frequency? Or just the diameter of the coils? *) If the radiofrequency satisfies the larmor-frequency, which value has the magnetic...

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 ?...

Consider the following H1 NMR signal from the human brain obtained at 1.5 T S(t)= S(0) { 3 exp (-iw_NAA*t)* exp (-t/T2_NAA*) + exp(-iw_Cr*t)*exp(-t/T2_Cr*) + exp(-iw_Cho*t)*exp(-t/T2_Cho*)} where the 3 terms shown rep. the contributions from the major peaks of total...

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...

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 S(t) is given by: S(t)= S(0)exp (i*w_0*t)exp(-t/T2*), t>=0 S(t)=0 , t<0 You showed the spectrum G(w)...

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?

Suppose you acquire the 31P NMR signal from a region of muscle of a healthy subject using a 3 Tesla magnet. Assume that the signal has contributions from ATP,PCR, Pi, and from an unknown phosphorous containing biochemical. Assume that all decay shapes are exponential. Note: H1- 42.575 MHz/T...

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...