Surface Energy and Wetting Behavior of Dolomite in the Presence of Carboxylic Acid-Based Deep Eutectic Solvents.

This study endeavors to apply experimental and theoretical analyses to assess the viability of wettability alteration for two carboxylic acid-based deep eutectic solvents (DESs). To prepare these chemicals, oxalic acid and citric acid were used as hydrogen bond donors mixed with choline chloride as the hydrogen bond acceptor in an equimolar ratio. In the theoretical part, dolomite and crude oil were characterized using a three-phase setup. Then, the adhesion propensity of brines/crude oil toward dolomite was evaluated by calculating the work of adhesion. Contact angle and interfacial tension measurements were conducted in the experimental part to investigate the impact of chemicals on brine-crude oil and brine-rock interactions. Results revealed that the oxalic acid-based DES outperformed the citric acid-based DES in terms of interfacial tension reduction. In addition, choline chloride/oxalic acid (1:1) could effectively restore the wettability of the dolomite sample to its original state with a wettability alteration index of 82%. Theoretical calculations also confirmed the wettability alteration potential of DESs. Finally, a correlation was proposed to predict the contact angle of brine on the dolomite surface in the presence of crude oil using surface-energy components of brine, crude oil, and dolomite.

Donor-acceptor interactions in tri(phosphonio)methanide dications [(Ph3P)2CP(X)Ph2]2+ (X = H, Me, CN, NCS, OH, Cl, OTf, F).

The impact of the strongly electron donating carbodiphosphorane moiety in the series of tri(phosphonio)methanide dications as triflate salts [(Ph3P)2CP(X)Ph2][OTf]2 (X = H, Me, CN, NCS, OH, Cl, OTf, F) deriving from [(Ph3P)2CPPh2][OTf] (19[OTf]) is presented. The influence of the introduced substituents X on the electronic structures of these dications is investigated by means of detailed NBO analysis, NMR spectroscopy and X-ray analysis.

Carbodiphosphorane mediated synthesis of a triflyloxyphosphonium dication and its reactivity towards nucleophiles.

A carbodiphosphorane ((Ph3P)2C) mediated synthesis of the first triflyloxyphosphonium dication (12+) bearing two electrophilic sites is presented. Depending on the nucleophile, 12+ reacts selectively either at the sulfur atom of the triflyloxy moiety or at the directly attached phosphorus atom. In substitution reactions at the phosphorus atom the triflyloxy moiety serves as a leaving group and enables the synthesis of rare examples of pseudo-halophosphonium dications.

Formation of the spirocyclic, Si-centered cage cations [ClP(NSiMe3)2Si(NSiMe3)2P5](+) and [P5(NSiMe3)2Si(NSiMe3)2P5](2).

On account of our interest in P4 activation by phosphenium ion insertion into P-P bonds we have developed synthetic routes to bicyclic N-P-Si-heterocycle 7 and probed its reactivity towards GaCl3 and P4. A GaCl3-induced rearrangement of 7 leads to the in situ formation of spirocyclic, Si-centered phosphenium ions. Their insertion into P-P bonds of one or two P4 tetrahedra yields polyphosphorus cages [ClP(NSiMe3)2Si(NSiMe3)2P5](+) (19(+)) and [P5(NSiMe3)2Si(NSiMe3)2P5](2+) (13(2+)).

Synthesis of Selected Cationic Pnictanes [LnPnX3-n](n+) (L = Imidazolium-2-yl; Pn = P, As; n = 1-3) and Replacement Reactions with Pseudohalogens.

Herein we report on reactions of "imidazoliumyl-transfer" reagents [L((R/R'))SiMe3][OTf] (4((R/R'))[OTf]); L = imidazolium-2-yl, R/R': Me/Me, (i)Pr/Me, Dipp/H, Dipp/Cl) with pnictogen trichlorides PnCl3 (Pn = P, As, Sb) in various stoichiometries. In the case of the 1:1 reaction of [L((R/R'))SiMe3][OTf] with PCl3 the corresponding cationic imidazoliumyl-substituted dichlorophosphanes [L((R/R'))PCl2](+) (1P((R/R')))(+) are obtained as triflate salts on a multigram scale. We found that the reactions using various stoichiometries of [L((R/R'))SiMe3][OTf] and PnCl3 are less selective in the case of the heavier congeners or by decreasing steric demand of the R-group attached to the N atoms of the heterocycle. An equilibrium between the monocation [L((Me/Me))PCl2](+) (1P((Me/Me)+)), the dication [L((Me/Me))2PCl](2+) (2P((Me/Me)2+)), and the trication [L((Me/Me))3P](3+) (5P((Me/Me)3+)) is observed in solution. Reactions of the monocationic derivatives [L((R/R'))PnCl2][OTf] (Pn = P, As) with Me3SiX (X = CN, N3) resulted in the exchange of the chloro groups for the respective pseudohalogen and yielded the dicyano [L((R/R'))Pn(CN)2][OTf] (6Pn((R/R'))[OTf]) and diazido-substituted pnictanes [L((R/R'))Pn(N3)2][OTf] (7Pn((R/R'))[OTf]), respectively. All new compounds are thoroughly characterized by multinuclear NMR, IR, and Raman spectroscopy. For most cases the molecular structure was confirmed by X-ray crystal structure analysis.