H NMR Measurements

The H NMR spectra were recorded on a Bruker WM-500 spectrometer operating at a field strength of 11.74 Tesla. Preliminary and comparative experiments were performed on a Bruker WP-60 spectrometer. Dioxane was used as internal standard. All chemical shifts reported are in d (ppm) downfield from TMS tms = dioxane — 3.52 ppm. 

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The microstmctures of several synthetic i7j -l,4-polyisoprenes and natural mbber as determined by C-nmr (8,13) are shown ia Table 1. H-nmr measurements may also be used for microstmcture characterization (8,13—15). 

However, other studies on the nitration of a series of 3-methyl- and 3-ethyl-1,2-benzisoxazoles have shown that a mixture of the 5-nitro and 5,7-dinitro derivatives is formed (77IJC(B)1058, 77IJC(B)1061). The effect of substituents in the benzene ring is also of interest. If the 5-position is blocked, e.g. by a chloro group or by alkyl groups, nitration then occurs at the 4-position. 3-Alkyl-7-chloro and 3,7-dialkyl derivatives result in the formation of the appropriate 5-nitro derivative. The isomeric 3-alkyl-6-chloro- and 3,6-dialkyl-1,2-benzisoxazoles yield a mixture of the 5-nitro and 5,7-dinitro compounds. Both H NMR measurements and alternate syntheses were used in establishing the structures of these substitution products. 

The diastereomeric purity (d.r. >99 1) is evaluated by saponification (refluxing for 15 h with potassium hydroxide in mcthanol/water) to (R)-3-hydroxy-3-phcnylpi opanoic acid and H NMR measurement of the diazomethanc derived methyl esler in Ihe presence of hu(hfc)3. 

Note This hyperbranched polyester was also prepared by the bulk polymerization of 3,5-bis(trimethylsilyloxy)benzoyl chloride.202 DSC Tg = 190°C. DB = 0.55-0.60 ( H NMR measurements). 

The FT-IR spectroscopic measurements shown that in most cases the -COO or -0 groups formed a bridge between two Sn central atom, and polymerization occurred. The pqs approximations proved the formation of complexes with Oh, Tbp, and structures. H NMR measurements performed in DMSO solution have shown that the polymeric structure of the complexes does not persist in solution, and depolymerization occurs.. ... 

The author is grateful to Mr. H. Horiuchi for the preparation of photoelectrochemical cells. Professor S. Yamada for discussion, and Professor Y. Tanimoto and Associate Professor Y. Fujiwara for using the superconducting magnets. The author also thanks The Center of Advanced Instrumental Analysis, Kyushu University, for H-NMR measurements. This study was financially supported by the Grant-in-Aids for Scientific Research Priority Areas (Area 767, No. 15085203) and (Area 432, No. 17034051), Scientific Research (C) (No. 17550131), and twenty first century COE Program Function Innovation of Molecular Informatics from M EXTof the Japan. 

Fig. 21. lst-Generation dendrimer 57 with nitro groups at the periphery and 2nd-generation dendrimers 58-60 used for optical and H-NMR measurements [1,89]... 

The above mentioned second moment values of the three samples and their linewidths indicate that the molecules of ODA in the sample CT ODA 5 are more tightly bound in this sample than in the sample CT ODA 2 and that they are placed closer to each other. As for the kind of bond of the ODA within the samples, there is no direct proof about it in the H NMR measurements... 

Solvent destabilization of the molecular structure of organic materials can be quantified by simple proton nuclear magnetic resonance ( H NMR) measurements at ambient temperatures. Such measurements have shown that up to 60% of a coal s molecular structure can be destabilized by pyridine and, by the same token, that at least 40% Is Impervious to this solvent (15-18). 

Metalated vinyl ethers are configurational stable up to —20°C in tetrahydrofuran. H-NMR measurements of 1-ethoxy-1-lithioethene TMEDA did not show any coalescence of the signals for the vinyl protons until the onset of decomposition. Thus, there is no evidence of inversion in this case . Similar configurational stability is displayed by a-lithiated thioethers in tetrahydrofuran no inversion occurs up to 0°C. On the contrary, deprotonated vinyl sulfoxides and sulfones are configurationally less stable . ... 

Similarly to their 2-aryl-substituted analogs <1996CHEG-II(6)301>, 2-methyl- and 2-benzyl-5-phenyl-l,3-oxazine-4,6(57T)-diones 26B proved to be less favored tautomers than the corresponding 4-hydroxy-l,3-oxazin-6-ones 26A in (003)280. H NMR measurements showed the ratio of the tautomers 26A and 26B to be 55 45 for the 2-methyl- and 60 40 for the 2-benzyl-substituted derivative <2005ARK(xv)88>. 

In the case of alkylated SAMP-hydrazones derived from aldehydes, only two stereoisomers are observed, i.e., the (S,R)-(E)- and the (S,S)-( )-isomers. During H-NMR measurements of alkylated SAMP-hydrazones derived from ketones, a slow isomerization of the (S,R)-(Z)- and (5,S)-(Z)-isomers, generated during metalation, to the thermodynamically more stable (SJi)-(E)- and (S,5)-( )-isomers occurs3. 

Site-specific natural isotope fractionation (SNIP) NMR (SNIF-NMR) quantitative H-NMR measurements... 

Although the final products of the amination of 5-bromo-4-R-pyrimidines are the 6-amino-4-R-pyrimidines,106 107 two mechanisms, by which these same products are formed, have been recognized. The substrate is converted in part to the product via C-6 adduct 41, whereas the remaining part follows an ANRORC mechanism requiring attack of the reagent at C-2.105 Evidence for the existence of C-2 adducts as intermediates in nucleophilic substitutions is hard to obtain. However, the formation of an adduct of this kind (34) from 4,6-diphenyIpyrimidine was definitely proved by H-NMR measurements (Table XI).98 C-6 adducts such as 42-44 have also been described (see also Table XI) and shown to be the sole intermediates in the amination of 5-chIoro-4-te/T-butyIpyrimidine and 5-X-2,4-di-tert-butyIpyrimidines (X = Cl, Br), the ANRORC mechanism remaining excluded with the latter substrates.98... 

As mentioned above, H NMR measurements indicated a higher association constant for the monoamide-macrocycle complex than for the diacid dichloride-macrocycle complex. Further hints of a route to monoamide intermediates like 54 were supplied when diisocyanates 69 and 70 were subjected to rotaxane synthesis (Figure 28) [45]. 

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