Alcohols spectroscopic analysis

Careful chromatographic and detailed HNMR spectroscopic analysis of the products from the thermolyses of ethyl azidoformate in o-, m- and p-xylene revealed in all cases a mixture of 1 //-azepines.80 In o-xylene, only two of the four possible isomers were separated and characterized, namely, ethyl 4,5-dimethy 1-1 //-azepine-1 -carboxylate (9 %) and ethyl 3,4-dimethyl-l H-azepine-1-carboxylate (7 %). w-Xylene yielded a 2 3 mixture of ethyl 3,5-dimethyl-l//-azepine-1-carboxylate and ethyl 2,4-dimethyl-l//-azepine-l-carboxylate. The 2,4-dimethyl isomer (20 %) can be isolated from the mixture by removal of the 3,5-dimethyl isomer as its Diels-Alder cycloadduct with ethenetetracarbonitrile. p-Xylene gave a mixture of the two possible isomeric azepines which were partially separated by column chromatography. A pure sample of ethyl 2,5-dimethyl-1//-azepine-1-carboxylate (26%) was obtained from the mixture by selective decomposition of the 3,6-dimethyl isomer with refluxing alcoholic potassium hydroxide. 

Imidates 60 were prepared in two steps by first reacting nitrile derivatives with various alcohols. The condensation of the obtained iminoester with appropriate acetyl chloride resulted in the formation of the title compounds 60a-c (Scheme 12). The structures of the products 60 were elucidated by means of spectroscopic analysis. 

Since koumine has been reductively cleaved by nascent hydrogen (sodium-EtOH) to afford a C20 primary alcohol (39), the above deduction based on spectroscopic analysis is supported chemically (Scheme 6). 

These achiral poly(A -propargylamides) form helices with an equivalent amount of right- and left-handed screw senses. Addition of chiral alcohols induces predominantly one-handed screw sense in polyl7a and polyl7d. NMR spectroscopic analysis has revealed that the amide side chains interact with optically active alcohols by hydrogen bonding. Terpenes also induce a one-handed helix. In this case, hydrophobic interaction plays an important role for helix induction. 

Neohydnocarpin (80), C24H20O9, showed a UV absorption spectrum typical of a flavone. Detailed NMR spectroscopic analysis led to the proposal of the presence of a luteolin (118) and a coniferyl alcohol moiety (45). Careful examination of the C NMR spectrum showed the absence of oxygen functions at C-7" and C-8", which resonated at 35.2 and 40.9 ppm, compared to those in silybin A (89) at Sc... 

In contrast, Matsukawa and Hinakubo proposed Sm(II)-mediated pinacol coupling in water (Scheme 8.11).11 In all cases, the corresponding reduced product benzyl alcohols were formed in low yields. Unexpected disproportionation in water was also observed via UV-visible spectroscopic analysis. This indicated that low-valent samarium species can exist in water. Furthermore, the SmCl3-Sm and SmCl3-Mg systems were found to act as good one-electron reducing agents in water (Scheme 8.11). 

In an alternative mechanism, the substrate molecule is again coordinated to tetrahedral Zn, with the coordinated water molecule now serving as a site for transient proton transfer, thereby generating a penta-coordin ated zinc intermediate. Formation of this intermediate during substrate turnover was supported by time-resolved freeze-quenched X-ray absorption fine spectroscopic analysis of the thermophilic bacterium Thermoanaerobaaer brockii alcohol dehydrogenase (TbADH). These results thus provided further evidence for the dynamic alteration of the Zn from a tetrahedral to a penta-coordinated form with detection of two new penta-coordinated intermediate states these included the water molecule in the zinc coordination sphere during a single catalytic cycle. 

The cis- and trans-1,4-polybutadienes used in this work were obtained from The B. F. Goodrich Research and Development Center, Brecksville, OH, and had initial cis/trans ratios of 98/2 and 2/98, respectively. The procedures for the photosensitized oxidation of purified samples of the 1,4-polybutadienes, using visible light and methylene blue, chlorophyll and Rose Bengal as sensitizers, the procedures for the reduction of the hydroperoxidized polymers to the corresponding alcohols, as well as the procedures for the spectroscopic analysis of the reaction products, were similar to those described previously (8). 

Kalvin and Woodard (116) synthesized samples of homoserine labeled in all of the diastereotopic hydrogens. In their first synthesis, they used R)- and (S)-alpine boranes to reduee the deuterated aldehyde 109. (/ )-Alpine borane gave the (S)-[ HJ alcohol 110, Hg = H, (S)-alpine borane gave the corresponding (/ )-alcohol 110, NMR spectroscopic analysis of... 

The most characteristic feature in the spectroscopic analysis of ethers is the strong band of C-0 stretching. It occurs in the 1060-1300 cm range. In this region, many bands are present, but this alone does not establish the presence of an ether. For note, alcohols, carboxylic acids, and esters also show C-0 stretching. They can be eliminated as possibilities, however, by the fact alcohols would also show the strong and broad 0-H stretch in the 3200-3600 cm , car-... 

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