Excess density in oilfield water-crude oil dispersions

Extensive density measurements were performed with mixtures of 12 degassed (dead) crude oils with respective oilfield brines (formation waters). All unprocessed samples were collected directly from wellheads and contained only indigenous surfactants, such as asphaltenes and fine solids. Nonzero excess densities and excess thermal expansions (evaluated on the assumption of quasi-binary water-oil mixtures) were observed for water cuts in the range from X=0.4 to 0.6 at all studied temperatures T=5-50 degrees C. We suggest that these results are due to the formation of a dense asphaltene-mediated "middle phase" in the studied w/o dispersions. This suggestion is substantiated by plotting T-X phase diagrams which topologically strongly resemble those conventionally observed in some standard Winsor III-type systems. The formation of a complexly structured "middle phase" has been directly verified by preliminary visual/microscopic studies of a phase separation in a crude oil-water mixture.     

Acid-catalyzed acetylation of N-methallyl lactam and imide derivatives

The reactions of N-methallyl derivatives of cyclic amides and imides with acetic and propionic anhydride have been studied in the presence of perchloric acid. The reaction products have been found to be pyrylium and oxazolinium salts. The relationship between the reaction pathway and the structure of the imide or amide starting material has also been determined. Pyrylium salts have been converted to their corresponding pyridine bases.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1414–1419, October, 1988.     

Synthesis of 3-amino derivatives of benzo[b]furo[2,3-c]pyridines

The reaction of 1,7-dimethyl-3(2H)-benzo[b]furo[2,3-c]pyridone with phosphoric acid amides gave 1,7-dimethyl-3-dimethylamino (morpholino)benzo[b]furo[2,3-c]pyridines. A method for the synthesis of 3-amino derivatives of 4-nitrobenzo[b]furo[2,3-c]pyridines, which consists in heating 1,7-dimethyl-4-nitro-3(2H)-benzo[b]furo[2,3-c]pyridone with hexamethyldisilazane and secondary or primary amines in pyridine, was developed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1552–1555, November, 1991.     

Photoelectron spectra and orbital structures of silatranes: Organic derivatives of pentacoordinate silicon

The photoelectron (PE) spectra of silatranes (1), 2,8,9-trioxa-5-aza-1-silabicyclo [3.3.3] undecanes, have been analyzed and partially reinvestigated. In the PE spectra of 1 the bands in the 8.2–8.9 eV region, which were previously ascribed to the lone electron pair (LEP) orbital of the nitrogen atom or the SiN bond, are due to the presence of impurities, the products of incomplete hydrolysis. Interpretation of the bands in the PE spectra of pure compounds was carried out by analysis of orbital-correlation diagrams and results of MNDO and AM1 calculations. The first ionization potential of1 is associated with a MO localized to a great extent on the axial X-Si-N fragment. The increase with shortening of the Si-N distance is related to the corresponding increase in the degree of noncoplanarity of the nitrogen atom when its LEP is involved in the hypervalent X-Si-N bond.     

Electrophilic substitution in benzo[b]furo[2,3-c]pyridines: nitration,acylation

It has been shown that the nitration and acylation of substituted benzo[b]furo[2,3-c]pyridines proceeds exclusively at position 6 of the benzene ring. If position 6 is blocked by a substitutnt, the product of monosubstitution at the C₍₈₎ atom is formed. The molecules that were investigated have been calculated in the MNDO approximation.L. M. Litvinenko Institute of Physical Organic Chemistry and Coal Tar Chemistry, National Academy of Sciences of Ukraine, Donetsk 340114. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 694–699, May, 1995. Original article submitted March 22, 1995.     

1-Substituted 5,10-Dihydro[1,2]diazepino[4,5-b]indol-4(3H)-ones. Synthesis and Functionalization

Russian Journal of Organic Chemistry - A number of new 1-substituted 5,10-dihydro[1,2]diazepino[4,5-b]indole-4(3H)-ones were synthesized, and their structural modification was performed to obtain...     

The effect of impermeable boundaries of arbitrary geometry on the apparent diffusion coefficient

The apparent diffusion coefficient (ADC) obtained from NMR measurements is modelled for diffusion in a compartment restricted by an impermeable boundary. For a given pulse sequence, the ADC can be determined from the connected velocity autocorrelation function (the second-order velocity cumulant), which we show can be expressed as a double surface integral over the boundary, involving the probability for molecules to diffuse from one boundary point to another. There is no restriction on the geometry of the boundary. This result allows a fast calculation of the ADC for an arbitrary time course of the diffusion-sensitizing gradient. Explicit examples are given for diffusion within three basic geometries for different pulse sequences. The ADCs measured with the Stejskal-Tanner pulse sequence and a more realistic pulse sequence with slice selection gradient and eddy current compensation are found to yield almost identical results. The application of the results are discussed in relation to determination of the microscopic structure of brain white matter.     

Simple and efficient preparation of 3-substituted 6-(4-chlorophenyl)-9-methyl-12H-[1]benzofuro[3,2-e][1,2,4]triazolo[4,3-b][1,2]diazepines via a silylation–amination reaction

Abstract  

A series of new 3-substituted 6-(4-chlorophenyl)-9-methyl-12H-[1]benzofuro[3,2-e][1,2,4]triazolo[4,3-b][1,2]diazepines was synthesized from the corresponding bicyclic 1-(4-chlorophenyl)-3,5-dihydro-8-methyl-4H-[1]benzofuro[2,3-d][1,2]diazepin-4-one. The synthesis strategy makes use of silylation–amination as the key step, allowing a wide range of derivatives to be prepared.     

Condensed diazepines. synthesis of 1-aryl-3,5-dihydro-4H-1-benzofuro-[2,3-<Emphasis Type=Italic>d</Emphasis>][1,2]diazepin-4-ones

The cyclocondensation of (2-aroyl-1-benzofuran-3-yl)acetic acids and their methyl esters with hydrazine hydrate under various experimental conditions has been studied. Optimal conditions have been found for obtaining 1-aryl-3,5-dihydro-4H-1-benzofuro[2,3-d][1,2]diazepin-4-ones.