Simultaneous comparison of δ31P and 1JPN for the assignment of E/Z-stereochemistry of the phosphorus-nitrogen double bond in iminophosphines R-P=N-R′

 The analysis of ³¹P and ¹⁵N NMR data of a series of 40 iminophosphines R-P=N-R′ reveals that the E/Z-stereochemistry of the PN double bond can be predicted on the basis of a simultaneous comparison of the values of δ³¹P and ¹J_PN. Received: 31 May 1996/Revised: 2 July 1996/Accepted: 5 July 1996     

Meldrum's acid and its analogs

2-Substituted or 2,2-disubstituted 4,6-dioxo-1,3-dioxanes, which are analogs of Meldrum's acid and were obtained by reaction of malonic acid with acetic anhydride and the appropriate carbonyl compound in the presence of sulfuric acid, exist in solution preferably in a single form according to the PMR and ¹³C NMR spectral data. Fluctuation of the CH₂ group is not observed. The mass spectra are characteristic and are distinguished by splitting out of the carbonyl compound from the molecular ion or successive splitting out of CO₂ and ketene molecules. The Meldrum acid analogs do not affect plant growth but have a depressive effect on the central nervous system of animals and low toxicity.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1482–1486, November, 1975.     

Hydrolysis study of organic acid anhydrides by differential thermal analysis-I Pyromellitic dianhydride

A technique for following the hydrolysis of pyromellitic acid dianhydride (PMDA) by differential thermal analysis (DTA) is described. On exposure of PMDA to moisture, an endothennic peak is initiated between 190 and 200 degrees . As the degree of hydrolysis increases, this peak becomes more intense and shifts to higher temperatures. The formation of pyromellitic acid (PMA) during the hydrolysis of PMDA can be determined qualitatively by DTA.     

Pyrans,their analogs,and related compounds

Reaction of 4, 4-dichloroflavine (I) with sulfurylchloride affords 2, 3, 3, 4, 4-pentachloroflavan (II). Hydrolysis of II gives 2-hydroxy-3, 3-dichloro-4-flavanone (III), while alcoholysis with aqueous alcohols yields 2-alkoxy-3,3-dichloro-4-flavanones (IVa, b). Treatment of III with SOCl₂ gives 2,3,3-trlchloro-4-flavanone (V), which with caustic alkali or sodium ethoxide is converted into o-(1-phenyl-2, 2-dichlorovinyloxy)benzoic acid (VIc) or its ethyl ester (VIb), respectively.For Part XLII, see [7].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1167–1170, September, 1970.     

Calculation of Siegert eigenvalues for molecular systems: results for He(21,3S)+ H

The variational calculation of Siegert eigenvalues has previously been shown to provide reliable positions and widths for atomic resonances. This approach is herein extended to molecular problems, and the first such calculations for a molecular autoionizing system, He(2^1,3S)+H→ He+H⁺+e^?, are reported.