³¹Phosphorus NMR

The 1D ³¹Phosphorus NMR experiment is much less sensitive than Proton (¹H) but more sensitive than ¹³Carbon. ³¹Phosphorus is a medium sensitivity nucleus that yields sharp lines (fig. 1) and has a wide chemical shift range. It is usually acquired with ¹Hdecoupling (fig. 2) means that spin-spin couplings are seldom observed. This greatly simplifies the spectrum and makes it less crowded. Where there are one-bond ³¹P-¹H couplings present then the decoupling power needs to be at lest twice that needed for ¹³C because of the large coupling constant.

Fig. 1. Typical ³¹P-NMR spectrum of a mixture of organic phosphates

Integration is inaccurate (almost useless when there is one-bond coupling to ¹H) in a regular decoupled ³¹P NMR spectrum because of uneven NOE enhancement of the signals by decoupling and long longitudinal relaxation times (T₁'s). Quantitative spectra may be obtained by inverse gated decoupling.

Gated decoupling may be used in order to observe proton couplings (fig. 4). If coupling constants are required then a phosphorus coupled proton spectrum (fig. 5) is much more sensitive than the phosphorus spectrum although the reduced chemical shift range may cause overlapping that make analysis more difficult. One-bond couplings are typically 600 to 700 Hz, two-bond 20 to 30 Hz, three-bond 5 to 10 Hz and four-bond <1 Hz. Couplings may be observed with other nuclei such as ¹⁹Fluorine.

Fig. 2. ³¹P-NMR spectrum of diethylphosphite with ¹H decoupling

Fig. 3. Molecular structure of deithylphosphite

Fig. 4. spectrum of diethylphosphite showing one-bond and three-bond coupling to ¹H

Fig. 5. ¹H-NMR spectrum of diethyl phosphite showing coupling to ³¹P

A typical analysis of a ³¹P NMR spectrum consists of matching expected chemical shifts to the expected moieties. Each type of signal has a characteristic chemical shift range (fig. 6).

Fig. 6. Chemical shift ranges of phosphorus according to their chemical environment

Choose the structure that most closely represents the phosphorus in question. R = alkyl or H.

The heteronuclear coupling patterns between phosphorus and proton can be used to assign the proton spectrum (figs. 7, 8).

Fig. 7. ¹H-NMR spectrum of sphingomyelin showing the effects of ³¹P coupling

Fig. 8. ³¹P-NMR spectrum of sphingomyelin showing the effects of ¹H coupling

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Properties of ³¹P

(Click here for explanation)

Property	Value
Spin	½
Natural abundance	100%
Chemical shift range	430 ppm, from -180 to 250
Frequency ratio (Ξ)	40.480742%
Reference compound	85% H3PO4 in H2O = 0 ppm
Linewidth of reference	1 Hz
T1 of reference	0.5 s
Receptivity rel. to 1H at natural abundance	6.63 × 10-3
Receptivity rel. to 1H when enriched	6.63 × 10-3
Receptivity rel. to 13C at natural abundance	37.7
Receptivity rel. to 13C when enriched	37.7

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PAGE CREATED BY DR ANTHONY MELVIN CRASTO M.SC, Ph.D (ORGANIC CHEMISTRY,24+ years experience in the field of research and development, currently with Glenmark-Generics Ltd, Navi Mumbai,  India

Ентоні  アンソニー  Αντώνιος  安东尼    แอนโทนี   Энтони   אַנטאַני  Антхони  एंथनी  안토니  أنتوني

NAME: DR. ANTHONY MELVIN CRASTO.  Principal scientist, GLENMARK-GENERICS LTD Navi mumbai, INDIA Email  amcrasto@gmail.com MOBILE+91-9323115463 TWITTER-   @amcrasto web links       http://in.linkedin.com/in/amcrasto     https://sites.google.com/site/amcrasto/     https://sites.google.com/site/anthonycrastomycv/ Anthony in different languages   安东尼    Энтони    एंथनी  안토니   Anthony in different languages アンソニー    安东尼    Энтони    एंथनी  안토니       أنتوني This presentation requires the Flash plug-in for proper viewing. Download the player FREE. This presentation requires the Flash plug-in for proper viewing. Download the player FREE.

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Methyl 2-(4-oxochroman-3-yl)acetate

 Methyl 2-(4-oxochroman-3-yl)acetate

1H NMR (500 MHz, CDCl₃):

δ = 2.44 (dd, J = 17.0, 8.1 Hz, 1H), 

2.95 (dd, J = 17.0, 5.0 Hz, 1H), 

3.31-3.37 (m, 1H), 3.74 (s, 3H), 

4.30 (dd, J = 12.0, 11.2 Hz, 1H), 

4.60 (dd, J = 11.2, 5.3 Hz, 1H), 

6.98 (d, J = 8.4 Hz, 1H), 

7.03 (apparent triplet, J = 7.5 Hz, 1H), 

7.48 (apparent triplet, J = 8.4 Hz, 1H), 

7.89 (d, J = 7.8 Hz, 1H)

13C NMR (125 MHz, CDCl₃): δ = 30.1, 42.5, 52.0, 70.2, 117.8, 120.4, 121.5, 127.3, 136.0, 161.7, 171.8(C=0), 192.5(C=0)

GC-MS: (EI) 220 (M+, 2%), 189 (17), 147 (100), 120 (58), 92 (33)

---

References

Yoshikai, K.; Hayama, T.; Nishimura, K.; Yamada, K.; Tomioka, K. J. Org. Chem., 2005, 70, 681-683.
Santoso, H.; Casana, M. I.; Donner, C. D. Org. Biomol. Chem., 2014, 12, 171-176.

1. Roberts, B. P. Chem. Soc. Rev., 1999, 28, 25-35.

2. Aitken, H. M.; Schiesser, C. H.; Donner, C. D. Aust. J. Chem., 2011, 64, 409-415.

5-morpholino-1-indanone.......NMR

1H NMR: 

(CDCl₃) δ ppm 

2.59-2.62 (m, 2H), 

3.01 (t, J=5.7 Hz, 2H), 

3.30 (t, J=5.0 Hz, 4H), 

3.83 (t, J=4.7 Hz, 4H), 

6.78 (m, 6.78-6.79, 1H),

6.83-6.86 (m, 1H), 

7.61 (d, J=8.8 Hz, 1H).

13C NMR:  

(CDCl₃) δ ppm 25.8, 36.3, 47.6, 66.4, 109.7, 114.0, 124.9, 128.2, 155.8, 157.7, 204.9

GCMS EI [M+]  Predicted: 217.2, Actual: 217

---

Chern, C.-Y.; Yek, Y.-L.; Chen, Y.-L.; Kan, W.-M. J. Chin. Chem. Soc. 2008, 55, 846–853.

Dinges, J.; Albert, D.H.; Arnold, L.D.; Ashworth, K.L.; et al J. Med Chem. 2007, 50, 2011-2029


HELP TO INTERPRET USING RELATED MOLECULES.....U CAN LEARN

The resonance assignment of 2-ethyl-1-indanone 

ORGANIC SPECTROSCOPY.........SOLVED PROBLEM CARVONE

NMR

Interpretation at the end of page

1H-NMR

Expansion

table

Peak List Date: 23.07.2000 Time: 19:18
File Name: c: \ mydocu ~ 1 \ carvone \ picccarv \ 001001.1R
Peak Results saved in File: -
Peak Picking Parameter:
Peak constant PC: 1.00
Noise: 32624
Sens. Level: 130495
Peak Picking region:
Start (ppm) Start (Hz) End (ppm) End (Hz) MI (%) MAXI (%)
3999.5 643.0 8.00 1.29 2.53 100.00
Peak Picking results:
Nr. Data Point Frequency PPM Intensity% Int.
 1 27,086,716 8.7 6.6736 3337.67 14 963
 2 14 968 11.3 3336.44 6.6711 35.30668 million
 6.6687 37,279,372 14 973 3 11.9 3335.21
 6.6657 34,489,456 4 14 979 11.0 3333.73
 6.6623 33,366,342 14 986 5 10.7 3332.01
 6 14 992 11.3 3330.53 6.6593 35.16274 million
 7 14 997 11.0 3329.30 6.6569 34.35534 million
 3327.82 15 003 8 26,249,558 8.4 6.6539
 4.7102 62,156,552 9 18 953 19.9 

13C-NMR (COM, DEPT)

also use the table, and type of carbon chemical shift (CH ₃ , CH _two , CH, quaternary) complete case distinctions. The peaks are very close to the chemical shift is going to document what you duty.

DEPT

Carbon than the sum of protons, C10 H14 (134 formula weight), and 16 out of 150 molecular weight. δ199.4 carbonyl signal (C = O) is estimated to be, can be determined with the molecular formula C10H14O. Degree of unsaturation (C +1- H / 2) = 4 and is estimated to carbon double bond and two of four from 110.3 δ146.5, leaving one degree of unsaturation together with one carbonyl According to the ring can be estimated.

COSY

 

The one-dimensional 1H spectra in the side-swing write a letter to the peak of the NMR spectra, summarized in the table the correlation. Ground shaking in alphabetical HMQC spectra see the next section. If you do the same if drawn in order to analyze only the low-field COSY.

Here, they reveal the following partial structure.

1. j (CH3) - c (CH) (estimated from the δ-allyl coupling we value and c J)
2. i (CH3) - e '(CH2) (estimated from the δ-allyl coupling we value and c J). That i (CH3) - (C) = e '(CH2)
3. Structure, including the first part, j (CH3) - (C) = c (CH) - h, h '(CH2) - g (CH) - f, f' (CH2)

Only from COSY and 1H-NMR, the structure of some compounds can be estimated. Identification is performed to obtain the data or preparation at the time of construction was estimated. Compounds are also present here can be estimated ccarvone would continue as a unknown compound below.

HMQC

 

1. A low magnetic field side of the carbon, b, c. ... and shake the alphabet.
2. Alphabetical shake directly linked to the proton. If the methylene protons of the inequality is correlated with higher magnetic field back out of two protons and one carbon "'" give.

This spectrum becomes incomplete decoupling c-axis across the carbon peak is completely decoupled j is not.

HMBC

  

Fill in the spectrum of the same alphabet shaken by HMQC.

Between protons and carbon through the binding of two or three there is a coupling of a few Hz (coupling distance, long-rangecoupling,, LRJCH ,2-3JCH). Similar peaks are not involved in measuring HMQC "turn phase" and "gradient pulse" so that off with a caution because it may appear Upon analysis of the spectrum . There may appear to be direct correlation between carbon and proton, which do not divide by 1JCH carbon decoupling (e, j, i). If you have a location just one proton, the observed correlation and unerring attention to this remote. Create a correlation table shown below, to be analyzed. Direct proton - carbon position in the Q, HMBC correlations will fill O. If you can not determine whether it has given not correlate with chemical shift is close to f and g of carbon length across the circle to fill in the table below it. Focus on the correlation structure connecting the estimated area so far. Carbon / proton = a / c, a / j, which leads to the planar structure by g / i. Also, b / i, a quaternary carbon by b d / j, which can be attributed the d.

Then fill all the HMBC correlations led to the structure, there is no place to check whether the correlation is not connected. Also, make a table similar to the above table, entering the number of protons and carbon within three bonds if it was this structure. To check for inconsistencies in comparison with the above table. Here is some correlation with the circle. HMBC measurements to set the delay time 1/2J. J values ​​deviate significantly from having a carbon value - can hardly be the correlation between the protons. Coupling constant values ​​refer to the remote data collection. Protons through the coupling of two or three - and even out the carbon is not always correlated. More than four out of the correlation, however, are accustomed to explain why such should be able to shape W.

NOESY, NOE difference spectra

A method to detect the spatial proximity between protons. Relative configuration, perform the attribution of methylene inequality. NOESY spectrum diagonal peak is negative (red), normally a positive NOE peak (black) was obtained at a peak negative exchange unwanted peak sometimes appear in the form of a COSY peak dispersion. Also used one-dimensional NOE difference spectra performed by irradiating a particular proton. Irradiation position is negative, becomes positive NOE, would like spectrum and cross section of the NOESY diagonal peak position and the irradiation position exactly.

When considering the stereochemistry molecular model formed a let.

E in the NOESY spectra, focusing on the methylene protons e ', e' is on the ring protons, e is this inequality can be attributed from the fact that the methylene gives NOE correlations of methyl protons of i. h, h ', f, the attribution of methylene inequality f' (or the same side or opposite protons g) the molecular model is used. axial substituents on carbon and g is less likely because, equatorial substituents, axial proton next g, and this time, close to the adjacent methylene protons g and those of cis protons and g, the trans What can be seen farther. is rotatable between an e gb free, while the e 'is on the ring proton h, h', g, f, and f ', and can approach the other methyl protons of i.

 Since h was observed in NOE difference spectrum upon irradiation of g in NOE, and cis protons of g can be attributed with this.

f, for f 'is a clear NOE correlation has not been obtained, can be reserved for the J coupling between the proton. From molecular models, f, g and those of the cis methylene protons f ', g and small values ​​of J closer to 90 ° dihedral angle g, and those of trans dihedral angles near 180 ° The higher the expected value of g and J since. The largest division of the division of the methylene protons splitting pattern of protons and these show that it is aware geminal coupling, shows that large values ​​of g and J f '. As shown below, can be estimated from these relative stereochemistry. one proton geminal f is one reason that despite being split into pieces ddd one vicinal proton can be estimated from molecular models will be W-shaped coupling h and the proton.

In addition, the asymmetric carbon and carbon-g, this compound is present in two optical isomers, by NMR to determine the absolute configuration is not to be derivatized.

HETCOR

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THANKS AND REGARD'S
DR ANTHONY MELVIN CRASTO Ph.D
amcrasto@gmail.com

MOBILE-+91 9323115463

GLENMARK SCIENTIST ,  INDIA
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