Optical spectra carbonyls

Examination of the optical spectrum of the filtered purple solution gave a structured absorption band with maxima at 514 and 543 nm. This position is remarkably close (566 nm) to the n-n electronic transition predicted by Davis and Goddard for the parent system H2N=N. As expected for an n-n transition, the position of the absorption maximum is solvent dependent. In dichloromethane solution, A,i ax is 541 nm, in 2-propanol it is 526 nm. The blue shift of 15 nm is completely consistent with the n-n absorptions of isoelectronic carbonyl compounds. 

Simple aziridines are optically transparent in the UV region of the electromagnetic spectrum (B-69MI50401). In more highly substituted aziridines, such as the 2-aroyl-3-arylaziridines (9), there is an interaction between the carbonyl and aryl ring substituents... 

A systematic investigation of the free amino acids of the Leguminosae led to the isolation of a novel ninhydrin-positive compound from the leaves of Derris elliptica Benth. (Papilionidae) (93). This substance was analyzed as C6H,3N04 (microanalysis and high resolution mass spectrometry) and was shown to be an amino alcohol. The absence of a carbonyl in the 1R, the loss of 31 mass units in the mass spectrum, and a positive periodate cleavage reaction were best embodied into a dihydroxydihydroxymethylpyrrolidine structure. The relative simplicity of the NMR spectra (three peaks in the 13C spectrum four spin-system in the H spectrum) pointed out a symmetrical structure. Inasmuch as the material was optically active ([a]D 56.4, c = 7, H20), meso structures were ruled out, and the 2R, 3R, 4R, 5R relative configuration was retained (93). This structure (53) was further confirmed by an X-ray determination (94). 

Compound 58 was isolated as a yellow crystalline, optically active compound. HREIMS data for 58 gave a molecular formula of C15H16O4 with an inherent eight degrees of unsaturation. The IR spectrum was consistent with the presence of conjugated carbonyl functionalities including a y-lactone (1779 cm ) and a conjugated ketone (1665 cm ). The... 

Albertidine, isolated from Leontice Albertii Rgl. (196,197), is a crystalline, optically active tribase. There are IR absorption bands for a trani-quinolizidine system at 2750 and 2793 cm and a six-membered lactam carbonyl at 1640 cm The absorption in the fingerprint region is similar to that of matrine. The mass spectrum of albertidine is characterized by ion peaks at miz 247 (M -1), 219, 205, 192, 177, 150, 137, 98, and 96 which are typical for matrine alkaloids (209). On the basis of spectroscopic data and taking into account the tranj-quinolizidine band in the IR spectrum, the probable structure 182, with rings A/B-trans, was proposed. 

Albertine, isolated from Leontice Albertii Rgl. (216,226,227), is an optically active monoacidic tribase. There are the absorption bands at 1655 (lactam carbonyl), 1675 (double bond), 2795-2760 (tra i-quinolizidine), and 3300 cm (hydroxyl group) in the IR spectrum. The UV spectrum shows an absorption maximum at 224 nm (log e = 4.2) for a —C=C——C=0 group. Albertine... 

As an example, both monofunctional and multifunctional polymeric mercapto-esters were deposited onto optically smooth silicon wafers coated with vapor-deposited copper. The copper had been oxidized to Cu20, as verified by XPS. Infrared reflectance (RAIRS) at 81° (4 cm-1 resolution, 2000 scans) using an MCT detector yielded information on both the nature and the durability of the mercaptoester bond to the metal oxide film. A 16 cm l shift (1740— 1724 cm-1) was observed in the carbonyl absorption of stearyl thioglycolate (STG) deposited onto the Cu20 mirror. The absorption spectrum of the carbonyl region is illustrated in Fig. 11, both for the pure STG and the reacted monolayer. 

When the extract is passed over an anion-exchange resin, approximately 40-45 percent of the solids are retained on the resin and the remainder passes through. Infrared absorption spectra of the two fractions are presented in Figure 3. The neutral fraction shows absorption of infrared at 3 microns (hydroxyl), 5.9 microns (aldehydic carbonyl), and at 9-10 microns (C-O-C and C-O-H), with little absorption at 3.4 microns (C-H stretch). This spectrum resembles that of the common simple sugars when scanned as a melt between NaCl optics. 

Quinine is an optically pure derivatizing reagent that forms a diastereomeric mixture of salts whose 13c NMR spectrum would be expected to show individual peaks for the diastereomers present. A 13c NMR of the salt formed from 1 equivalent of quinine and 1 equivalent of racemic acid (V) revealed two peaks for the carbon atom 3 to the carbonyl group. The NMR (25.2 MHz) of the salt of the partially resolved acid (Figure 1) indicates that the ratio of diastereomers is approximately three to one (optical purity 75%). As is seen in the expansion, overlap of peaks precludes precise determination of enantiomeric composition, but a more powerful instrument should completely resolve the two peaks. We are currently investigating the generality of this procedure. 

Electronic Spectrum. Propynal exhibits a sharp, clearly structured absorption band with 382.1 nm as the 0-0 transition. This band has been studied extensively in absorption (38,39) and emission, and has been shown to be that of the iA" +- - -A transition. It is only recently, however, that optically excited emission has been observed. At longer wavelengths starting about 420 nm, a weak absorption band was observed. This is probably due to the A" - A transition (111). Analysis of the 382.1-nm band has shown that the A" (n,ir ) state differs from that of many other carbonyl compounds in that it is planar there is no evidence that a planar excited state is at a potential maximum. 

Structurally symmetric achiral compounds may show optical activity in the presence of chiral solvent molecules owing to asymmetry induced by the chiral solvent. For example, the achiral carbonyl compounds benzil and benzophenone surprisingly show optical activity in the region of the n absorption in the CD spectrum when dis-... 

Fig. 20. Electronic spectrum of a rhenium(I) carbonyl complex (23) featuring an optical charge transfer transition at Xj =lW nm involving a coordinated quinone acceptor ligand (181).

Free 4-acetamido-4,5-dideoxy-D (or L)-xylose is a syrup, and its infrared spectrum shows negligibly small bands for the imino and carbonyl groups. The syrup consists of two components, present in about equal amounts, - that are chromatographically separable. They yield the same (2-benzyl-2-phenyl)hydrazone, and are interconvertible by acid catalysis. Their optical rotations and their nuclear magnetic resonance spectra show that they are anomeric forms - of 195. Their nuclear magnetic resonance spectra are differentiated by the positions of the signals for their H-1 protons (t 4.72 and 4.84). The spectrum of each anomer shows, on acidification, a rapid attainment of anomeric equilibrium. A... 

Infra-red spectra of the products, volatile at ordinary temperatures, of the thermal degradations represented in figure 9 are a superlmposltlon of the spectrum of methyl methacrylate monomer on that of the volatile products of the thermal degradation of polypropylene. However, the amount of methyl methacrylate, as measured by the optical density of the carbonyl peak at 1740 cm , is strongly suppressed by pre-irradiation, as shown in figure 10. 

This alkaloid (LXVII) is isomeric with kurchiline and shows close similarity to it in spectral data except for those pertaining to the ketone group. The position of the carbonyl band in the IR-spectrum (1748 cm i) demonstrated the keto group to be a part of a five-membered ring. This fact, in conjunction with strong negative optical rotation shown by the base, led to location of the ketone group in position 16. Both kurchi-... 

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