NMR spectra of reaction products

Table I. 13C-NMR Spectra of Reaction Products Formed Between Methyl / -D-xylopyranoside and Saligenin...

Anthracene-derived tnsfaminophosphonate), l,3-bis[Af-methyl(diethoxyphosphynyl)-l-(9-anthryl)diaminobenzene was synthesized through the addition of diethyl H-phosphonate to the bis-imine, AA -di(9-anthrylidene)-l,3-phenylenediamine 1 [59]. The analysis of the NMR spectra of reaction products revealed that the addition of diethyl H-phosphonate to... 

By studying the NMR spectra of the products, Jensen and co-workers were able to establish that the alkylation of (the presumed) [Co (DMG)2py] in methanol by cyclohexene oxide and by various substituted cyclohexyl bromides and tosylates occurred primarily with inversion of configuration at carbon i.e., by an 8 2 mechanism. A small amount of a second isomer, which must have been formed by another minor pathway, was observed in one case (95). Both the alkylation of [Co (DMG)2py] by asymmetric epoxides 129, 142) and the reduction of epoxides to alcohols by cobalt cyanide complexes 105, 103) show preferential formation of one isomer. In addition, the ratio of ketone to alcohol obtained in the reaction of epoxides with [Co(CN)5H] increases with pH and this has been ascribed to differing reactions with the hydride (reduction to alcohol) and Co(I) (isomerization to ketone) 103) (see also Section VII,C). 

On the other hand, in accord with the free radical mechanism peroxynitrite is dissociated into free radicals, which are supposed to be genuine reactive species. Although free radical mechanism was proposed as early as in 1970 [111], for some time it was not considered to be a reliable one because a great confusion ensued during the next two decades because of misinterpretations of inconclusive experiments, sometimes stimulated by improper thermodynamic estimations [85]. The latest experimental data supported its reliability [107-109]. Among them, the formation of dityrosine in the reaction with tyrosine and 15N chemically induced dynamic nuclear polarization (CIDNP) in the NMR spectra of the products of peroxynitrite reactions are probably the most convincing evidences (see below). 

Figure 1.6 Catalytic cycle for a Stille reaction showing the vinylic regions of the and NMR spectra of the products detected in situ (in d -THF). 

The IR and H-NMR spectra of the product of this reaction follow. The formula of the product is C9Hg02. Show the structure of the product. 

The main thing to remember from this discussion is that CIDNP effects are seen in the NMR spectra of the products as they are being formed from reactions involving radical pairs. You do not observe the radicals themselves, as you do with EPR spectroscopy. So, the next time your NMR spec-... 

NMR Analyses of Reaction Products. Interpretation of mixtures of materials by 13C-NMR is complicated, and such interpretation was attempted only when the spectra were fairly simple or when known species could be picked out readily. 

The complexes [RuL3] (LH = tropolone, a-isopropenyltropolone) have been prepared by reaction of RuC13 with LH in the presence of NaHC03 the NMR spectra of these products show them to have predominantly the mer configuration.2095 Ketoenolate complexes incorporating phosphine, ammine and amine ligands are discussed in Sections 45.5, 45.4.1 and 45.4.2 respectively. 

Another burst of activity in free radical research occurred in the 1960s and 1970s, after several reports of anomalous intensities in the EPR spectra of photochemically or radiolytically produced radicals, and in the NMR spectra of the products from free radical reactions in solution." " These so-called chemically induced magnetic spin polarization (CIDNP and CIDEP) phenomena provided a wealth of mechanistic, kinetic, dynamic, and structural information and were a cornerstone of carbon-centered free radical research for the better part of three decades. The umbrella term for this area of research is spin chemistry, which is defined as the chemistry of spin-selective processes. 

Analysis of Si NMR spectra of HPC products in 26 days at molar ratios water/OTES = 0.32 and 0.4 demonstrated that the reaction mixture includes OTES with chemical shifts of silicon atoms... 

Figure 2 C NMR spectra of amination products, a. DEPT 135 spectra following an amination reaction using natural abundance, b. DEPT 45 spectra following an amination using [l- C]-ethanol.

The 13c and IH spectra of reaction products were obtained on a Brucker-WP 200SY NMR spectrometer (200 MHz) using CD3OD solutions with tetramethylsilan or aqueous solutions (D2O) with methanol as internal reference. 

In intermolecnlar heteropalladation of simple alkenes, clarification of the stereochan-istry is somewhat more difficult and involved. Thus, for example, the anft-stereochanistry of aminopalladation to alkenes was established by running a pair of reactions using both (E)- and (Z)-2-bntenes and comparing the NMR spectra of the products, as sununa-rized in Scheme 17. 

The products of these reactions were characterized through DSC and GPC (Table 4) and by 1H-NMR (Table 1) and i C-NMR (Table 2). In the m-NMR spectra of the products obtained from the VAc/linseed oil copolymerization, the same signals were present but the relative intensity of the linseed oil signals increased with the linseed oiWAc ratio. 

Our theoretical investigation suggests that the cyclic silyl cation 16 with a symmetrical Si-H-Si bridge is significantly more stable than its acyclic isomer 17, and that 16 should be stable in benzene solution at room temperature (see Table 1, entry 1). In agreement with this theoretical prediction, only one product is formed in the hydride transfer reaction between disilane 18 and trityl cation (Scheme 7). The NMR spectra of the product (see Fig. 3) are in accordance with the cyclic structure 16. 

This experiment provides an opportunity to verify experimentally that the hydration of a terminal alkyne occurs in accordance with Markovnikov s rule (see Historical Highlight in Chap. 10). For example, that the structure of the product of the hydration of 3 is 4 rather than 5 may be confirmed by comparing the IR, H, and NMR spectra of the product of the reaction with known standard samples of 4 and 5, the spectra of which are clearly distinct. When all of the spectral properties of a compound are superimposable with those of a standard sample, the two are identical. 

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