Deuterated compounds Chloroform

Hanstein and Traylor544 used a 4.3 M solution of trifluoroacetic acid in chloroform to measure the rates of deuteration of (PhCH2)2Hg at 35 °C, for which kx = 2,100 x 10"7. Comparison with other deuteration rates (which, however, were neither quoted nor referred to) was said to give a (CH2HgCH2Ph) = — 1.14 and the ortho para ratio was 0.84. For the compound PhCH2B(OH)j, the rate of deuteration by 3 M tartaric acid at 100 °C was found to be 5 x 10 7 (ortho para ratio = 1.1) and from this a value of ff4 (CH2B(OH)J) of —1.11 was claimed, but without the relevant data used to obtain these c+ values cautious use of them seems appropriate. 

The divalent Co(salen) complex (69a) is one of the most versatile and well-studied Co coordination compounds. It has a long and well-documented history and we shall not restate this here. Recent applications of (69a) as both a synthetic oxygen carrier and as a catalyst for organic transformations are described in Sections 6.1.3.1.2 and 6.1.4.1 respectively. Isotropic shifts in the HNMR spectrum of low-spin Co(salphn) (69b) were investigated in deuterated chloroform, DMF, DMSO, and pyridine.319 Solvent-dependent isotropic shifts indicate that the single unpaired electron, delocalized over the tetradentate 7r-electron system in CHCI3, is an intrinsic property of the planar four-coordinate complex. The high-spin/low-spin equilibrium of the... 

If your compound does not happen to dissolve in CC14, you still have a shot because deuterium atoms do not give PMR signals. This is logical, since they re not protons. The problem is that deuterated solvents are expensive, so do NOT ask for, say, D20 or CDC13, the deuterated analogs of water and chloroform, unless you re absolutely sure your compound will dissolve in them. Always use the protonic solvents — H20 or CHC13 here — for the solubility test. There are other deuterated solvents, and they may or may not be available for use. Check with your instructor. 

The absence of an EPR signal in solution or in the solid state is indicative of a singlet ground state for the diradical ( BuBP Pr2)2- An indication of the radical character of this derivative is provided by a variety of facile oxidative addition reactions (Scheme 9.12). " For example, the treatment of ( BuBP Pr2)2 with diphenyl diselenide (or elemental selenium) produces a bicyclic compound in which a selenium atom bridges the two boron atoms. Trimethyl tin hydride reacts rapidly with ( BuBP Pr2)2 to give the trans adduct. Finally, ( BuBP Pr2)2 is slowly oxidised by deuterated chloroform to produce a R,R -dichloro adduct as a mixture of cis and trans isomers. 

The H NMR spectra of organic compounds are usually obtained in an aprotic solvent at concentration levels of a few percent. The most widely used solvent is deuterated chloroform (CDC13), sufficiently polar to dissolve most organic compounds. Acetone-r/6 (C3D60), methanol-e 4 (CD3OD), pyridinc-r/5 (C5D5N) and heavy water (D20) are also used. 

The most widely used solvent is deuterated chloroform (CDCI3) which is sufficiently polar to dissolve the majority of organic compounds. Also used are acetone-d5(C3DgO), methanol-d4(CD30D, pyridine-d5(C5D5N) or heavy water (D2O). 

Most NMR experiments with resveratrol oligomers are performed in deuterated acetone. This solvent has proven itself ideal for this class of compounds due to the high degree of solubility of the resveratrol oligomers and the lack of overlap between the solvent and analyte peaks. The second most commonly employed solvent is deuterated methanol, with deuterated dimethyl sulfoxide and pyridine used only occasionally. In some cases the NMR spectra of some O-methyl and O-acetyl resveratrol oligomer derivatives have been collected in deuterated chloroform [51,57,93,103]. 

In synthetic organic and organometaUic chemistry, solution-state NMR means a 300—500 MHz NMR spectrometer, high-precision glass sample tubes, 2 ml of deuterated solvent (typicaUy fully deuterated chloroform, acetone, benzene, or dichlorobenzene), several milligrams of pure sample, and a basic suite of H and NMR experiments [3 7]. With several hours of spectrometer time and data interpretation, the stuctures of new compounds with molecular weights up to 2000 Da can be determined, espedaUy when analyzed along with results from NMR databases and mass spectroscopy. 

To prepare the solution, you must first choose the appropriate solvent. The solvent should not have NMR absorption peaks of its own that is, it should contain no protons. Carbon tetrachloride (CCl ) fits this requirement and can be used in some instruments. However, because FT-NMR spectrometers require deuterium to stabilize (lock) the field, organic chemists usually use deuterated chloroform (CEKIlg) as a solvent. This solvent dissolves most organic compounds and is relatively inexpensive. You can use this solvent with any NMR instrument. You should not use normal chloroform CHClg because the solvent contains a proton. Deuterium does not absorb in the proton region and is thus "invisible," or not seen, in the proton NMR spectrum. Use deuterated chloroform to dissolve your sample, unless you are instructed to use another solvent, such as deuterated derivatives of water, acetone, or dimethylsulfoxide. 

Look up the solubilities for the following compounds and decide whether you would select deuterated chloroform or deuterated water to dissolve the substances for NMR spectroscopy. 

Purification was performed by preparative TLC. The compounds obtained were analyzed by Ultraviolet, Infrared and Nuclear Magnetic Resonance spectroscopy and by Gas Chromatography-Mass Spectrometry (GC-MS). The GLC analysis was carried out with a Perkin Elmer mod.990 equipped with a flame ionization detector, on a glass column OV 17 3%. NMR spectra were measured with a Varian 100 MHz for solutions in deuterated chloroform with tetramethyl-silane as internal standard. IR spectra were performed on a Perkin Elmer mod. 157 G in chloroform solution. GLC-MS spectra were carried out with an LKB 9000 at 70 eV. and a glass column OV 17 at 235 C. 

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