Spectral Study

The PMR spectra of several reduced proaporphines have been recorded both in deuteriochloroform and in pyridine-dg. PMR chemical shifts for 8,9-dihydroglaziovine in deuteriochloroform are shown below. The CMR spectra of fifteen reduced proaporphines have been recorded. 

The UV and IR spectra of alkaloids with a cyclohexadienone or cyclohex-enone ring, including proaporphines, homoproaporphines, and morphinandi-enones have been discussed and compared. Some of the available UV data are given below.  

The fragmentation process in the mass spectra of proaporphines is strongly dependent on the character of the spiranoid ring D, as well as on the substitution pattern in the aromatic ring A and the relative stereochemistry. Cleavage patterns should, therefore, be compared only among structurally close analogs. 

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Walrafen G E 1967 Raman spectral studies of the effects of temperature on water structure J. Chem. Phys. 47 114-26... 

Peteanu L A, Schoenlein R W, Wang Q, Mathles R A and Shank C V 1993 The first step In vision occurs In femtoseconds complete blue and red spectral studies Proc. Natl Acad. Sc/. USA 90 11 762-6... 

Nuclear magnetic resonance B spectral studies of BF have given a value of 9.4 1.0 ppm for the chemical shift relative to BF3 0(02113)3 as the... 

The melting points, optical rotations, and uv spectral data for selected prostanoids are provided in Table 1. Additional physical properties for the primary PGs have been summarized in the Hterature and the physical methods have been reviewed (47). The molecular conformations of PGE2 and PGA have been determined in the soHd state by x-ray diffraction, and special H and nuclear magnetic resonance (nmr) spectral studies of several PGs have been reported (11,48—53). Mass spectral data have also been compiled (54) (see Mass spectrometry Spectroscopy). 

Hydrogen sulfide reacts with molten sulfur and depresses the viscosity of the latter, particularly at 130—180°C iafrared spectral studies show that polysulfanes, H2S, form. The average chain length of these polysulfanes is shorter than the equiUbrium chain length of molten sulfur alone at the same temperature consequendy, the viscosity of the molten sulfur is markedly reduced (99,100). 

Preliminary IR spectral studies were said to suggest that pyrimidinones existed as pyrimidinols <50JCS3062) but this conclusion was promptly reversed <52JCS168) on better experimental evidence subsequent comparison with their N- and O-methyl derivatives showed that the pyrimidinones (39a R = H) and (40a R = H) along with their A-methyl derivatives (39a R = Me), (40a R = Me) and (40b R = Me) all exhibited vqo in the range 1600-1700 cm, whereas the methoxypyrimidines (39b R = Me) and (40c R = Me) showed no such absorptions <53JCS33l, 55JCS211). Closer analysis of the spectra for pyrimidin-4-one (40a R= H) showed that the ort/jo-quinonoid form (40a R = H) is the predominant tautomer (see Section 2.13.1.4). 

The major component of the oil extracted from bell peppers has been shown, initially on the basis of mass spectral studies but subsequently by total synthesis, to be 2-methoxy-3-... 

Echinomycin (131) has been shown to be an antitumor agent and to have antiviral and antibacterial properties. Its structure elucidation represents a triumph for and mass spectral studies (75JA2497). It has been demonstrated that echinomycin functions by inhibiting RNA synthesis in organisms such as Staphylococcus aureus. Echinomycin, levomycin and actinoleutin are members of the quinoxaline-peptide antibiotic family and all contain one or more quinoxaline rings (67MI21402). 

The review by Takeuchi and Ferusaki is quite encompassing and, in addition to synthesis and reactivity, the physical and spectroscopic properties of isoxazolidines are discussed in detail. Additional spectral studies on the parent and derivatives include H NMR (68MI41600, 77H(7)201, 78IZV850). 

Spectral studies at low temperatures enable us to broaden the number of test molecules for surface acidic sites and besides ammonia pyridine and nitriles, to use CO, NO and that do not adsorb at 300 K. 

Azauracil and its alkyl derivatives are readily reducible by polarography, in contrast with uracil. This makes it possible to exploit the method analytically. More detailed studies of the polaro-graphic behavior of these substances are in good agreement with the results of spectral studies about the tautomeric form and type of dissociation. ... 

Although cytosine was assigned structure 109 on the basis of early infrared spectral studies,and other infrared and ultraviolet spectral... 

In solution, benzotriazole also exists almost exclusively as the IH tautomer 25a,c. This conclusion was drawn on the basis of early NMR [69T4667 76AHC(Sl),p. 295] and NNMR (82JOC5132 97MRC35) spectral studies and confirmed by measurements of enthalpies of solution, vaporization, sublimation, and solvation in water, methanol, and DMSO (89JA7348). 

Spectral studies reported about this time were even less conclusive. " In 1953, an oxo structure was assigned to 4-monosubstituted 1,3-diphenylpyrazol-5-ones on the basis of ultraviolet and infrared spectral data. ... 

The first assumption springs from the similarities noticed in Table 15-11 and is well substantiated by a wealth of spectral study of these atoms. The second assumption is stimulated by the factor of two needed in the last column of Table 15-11. 

Subsequently, dimethyl 3,6-diphenyl-l-tosyl-l//-azepine-4,5-dicarboxylate was shown by HNMR spectral studies to be a 97 3 azepine/benzene imine 6/7 mixture at room temperature.71... 

Another example is dimethyl 3,6-dichloro-l-tosyl-l//-azepine-4,5-dicarboxylate which, on the basis of ]H and 13C NMR spectral studies, is a 9 1 equilibrium mixture of azepine and benzene imine tautomers at —70 C(AG = 50.16 kJ mol-1) 22 however. X-ray analysis indicates that the mixture crystallizes as the 1//-azepine isomer. 

O Kane, D. J., Fuhrer, B., and Lingle, W. I. (1994). Spectral studies of fungal bioluminescence. In Campbell, A. K., et al. (eds.), Bioluminescence and Chemiluminescence Fundamentals and Applied Aspects, pp. 552-555. John Wiley Sons, Chichester. 

V.V. Kleimenov et al, GorenieVzryv, MaterVsesSimp, 3rd, 426-28 (1971) CA 78,161666 (1973) Motion-picture and spectral studies of the combustion products from a model rocket engine were conducted to determine the progressive temps, to identify the combustion products, and to establish equilibrium coirKli-... 

Bromine and Chlorine.—Accurate values of the internuclear distances in the molecules Bra and Cl2 are known from band spectral studies, namely, Br-Br = 2.281 A. and Cl-Cl = 1.988 A. The visual method led to results (2.289 A. and 2.009 A., respectively) in satisfactory agreement with these.8 Radial distribution curves for these substances are shown in Fig. 3, the data used being given in Tables II and III. For bromine, with seven rings, three different estimates of intensities lead to the same Br-Br distance, 2.270 A., less... 

An interesting mass spectral study of 17 mono- and dflialogenoquinoxahnes, some bearing methyl groups, has been reported the X-ray crystallographic structure of hexachloroquinoxaline has been measured. ... 

Dithiocarbamate complexes of copper have been sythesized at a high rate. Reports of new complexes include the morpholine-4- (44), thio-morpholine, AT-methylpiperazine-4-, and piperidine- (291) dithiocarba-mates. Novel, polymeric complexes of the type Cu(pipdtc)2 (CuBr) in = 4, or 6) and Cu(pipdtc)2 (CuCl)4 have been prepared by reactions of[Cu(pipdtc)2] with the respective copper halide in CHCla-EtOH (418). The crystal structures of the polymers are known to consist of sheets of individual [Cu(pipdtc)2] molecules linked to polymeric CuBr chains via Cu-S bonds. A series of copper(I) dtc complexes have been the subject of a Cu and Cu NQR-spectral study (440). 

Infrared spectral studies of polymeric sulfur are scarce and mainly the overtone region was studied [142, 180]. In the range of the stretching vibrations, two bands at ca. 460 cm (strong) and ca. 423 cm (medium) were reported for Crystex after extraction of the soluble ring fraction by CS2 [180]. The results of the literature are summarized in Table 12. 

Several ESR studies of various cobalt(II) isocyanide complexes have been carried out (77,81,88). A Raman and infrared spectral study on [Co(CNR)5]-... 

Chemical-ionization mass-spectral studies for typical per-O-acetylglyco-pyranosyl and -furanosyl fluorides have been reported. 

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