Oximes spectroscopic data

Spectroscopic Data. Freshly prepd nitrosomethane has an IR absorption band at 6.3—6.4 p which slowly decays and is replaced by a band at 11 y characteristic of formaldehyde oxime (Ref 8). The visible absorption Amax is 287my in eth and at 266—7m p in w (Ref 4)... 

Our opinion is that the actual configuration of oximes 37 should be inverted. Nitrosation of 36 in the presence of an alcoholate should result in the two E and Z oximes the Z isomer will suffer a spontaneous base-induced rearrangement into the furazan 39 and will not be isolated. Furthermore, the reported spectroscopic data agree with the inverted configuration. The intermediacy of open-chain species in the rearrangement... 

Recently a series of condensation products of the oximes (7 R = H, Me R = Me, CH2Ph, Ph, p-MeC6H4) and (8) with amines have been prepared by reactions (2) and (3) respectively, and the species formed investigated by X-ray, NMR and IR studies.55 IR spectroscopic data obtained from the product of reaction (2) suggest structure (9) instead of (9 ) for the oxime (7), while lH NMR spectral data from the product of reaction (3) are in agreement with an equilibrium between (10) and (10 ). A crystal structure analysis indicates that the tautomers (9 R = Me, R = p-MeC6H4) and (10) are those preferred in the solid state.56 Furthermore, compound (9) is the sj n-Me.s n-Me isomer, while (10) is the anri-Me,an -acetyl isomer. 

Structures (316) with an oxetan ring, recently proposed250 for two iodo-compounds obtained during the hypoiodite reaction of cholesterol, have now been revised.251 Spectroscopic and X-ray data show the compounds to be iodo-acetals (317), converted by de-iodination and reaction with BF3-acetic anhydride into the dihydropyran (318). Photolysis of the oxime of a l,5-dien-3-one gave mainly rearranged ketonic products, isomers of type (319), which are also obtained by photo-rearrangement of the l,5-dien-3-one.252... 

The blocking agents most widely used commercially are phenols, oximes, alcohols, e-caprolactam (hexahydro-2i7-azepin-2-one) [105-60-2], 3,5-dimethylpyrazole, 1,2,4-triazole, and diethyl malonate (propanedioic acid diethyl ester) [105-53-3]. It is common to see tables of unblocking temperatures. The implication is that there is some magic temperature above which the various blocked isocyanates abruptly unblock however, no such temperature exists. Published unblocking temperature data are based on some measurement of extent of reaction under a specific set of conditions. Examples of such criteria are the lowest temperature at which free isocyanate can be detected spectroscopically or the temperature required to achieve a specified degree of solvent... 

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