Classes Of Epoxides Research Articles

A novel class of bio-lubricants are synthesized by epoxidation of 10-undecylenic acid-based esters

Mineral-based lubricants are being supplanted by bio-based lubricants because of environmental concerns and the depletion of fossil resources. The derivatives of edible and non-edible oils are considered potential alternatives to existing natural mineral oil base stocks in certain lubricant applications, where immediate intraction with the environment is predicted. A new class of epoxides were synthesized from the undecylenic esters of 2-ethyl hexanol, neopentyl glycol (NPG), and trimethylolpropane (TMP). These unsaturated esters were epoxidized by using meta chloro perbenzoic acid. The synthesized epoxides were characterized by spectral studies (1HNMR, 13CNMR, IR) physio-chemical (density, specific gravity) and lubricant properties (kinematic viscosity, viscosity index, flash point, fire point, cloud point, pour point, copper strip corrosion). TMP epoxide has a high viscosity index, high flash point, and low pour point compared to 2-ethyl hexyl epoxide and NPG epoxide.

Facile Conversion of Epoxides to 1,2-Diacetates with NaOAc•3H2O/Ac2O System

This study represents a highly efficient and regioselective ring-opening of epoxides with acetic anhydride in the presence of NaOAc·3H2O at solvent-free conditions. The ring-opening of different classes of epoxides were carried in oil bath (70-80 °C) to afford 1,2-diacetates in high to excellent yields.

A Green Protocol for the Easy Synthesis of Thiiranes from Epoxides Using Thiourea/Silica Gel in the Absence of Solvent.

The use of thiourea/silica gel provides a green protocol for the easy and high-yielding preparation of thiiranes from different classes of epoxides in the absence of solvent at room temperature. The high stereospecific conversion of (R)(+)-styrene oxide to (S)(+)-styrene sulfide is also reported using this reagent system.

A Green Protocol for the Easy Synthesis of Thiiranes from Epoxides Using Thiourea/Silica Gel in the Absence of Solvent

The use of thiourea/silica gel provides a green protocol for the easy and high-yielding preparation of thiiranes from different classes of epoxides in the absence of solvent at room temperature. The high stereospecific conversion of (R)(+)-styrene oxide to (S)(+)-styrene sulfide is also reported using this reagent system.

Comparative Kinetic Studies of the Copolymerization of Cyclohexene Oxide and Propylene Oxide with Carbon Dioxide in the Presence of Chromium Salen Derivatives. In Situ FTIR Measurements of Copolymer vs Cyclic Carbonate Production

The catalysis of the reaction of carbon dioxide with epoxides (cyclohexene oxide or propylene oxide) using the (salen)Cr(III)Cl complex as catalyst, where H(2)salen = N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexenediimine (1), to provide copolymer and cyclic carbonate has been investigated by in situ infrared spectroscopy. As previously demonstrated for the cyclohexene oxide/CO(2) reaction in the presence of complex 1, coupling of propylene oxide and carbon dioxide was found to occur by way of a pathway first-order in catalyst concentration. Unlike the cyclohexene oxide/carbon dioxide reaction catalyzed by complex 1, which affords completely alternating copolymer and only small quantities of trans-cyclic cyclohexyl carbonate, under similar conditions propylene oxide/carbon dioxide produces mostly cyclic propylene carbonate. Comparative kinetic measurements were performed as a function of reaction temperature to assess the activation barrier for production of cyclic carbonates and polycarbonates for the two different classes of epoxides, i.e., alicyclic (cyclohexene oxide) and aliphatic (propylene oxide). As anticipated in both instances the unimolecular pathway for cyclic carbonate formation has a larger energy of activation than the bimolecular enchainment pathway. That is, the energies of activation determined for cyclic propylene carbonate and poly(propylene carbonate) formation were 100.5 and 67.6 kJ.mol(-1), respectively, compared to the corresponding values for cyclic cyclohexyl carbonate and poly(cyclohexylene carbonate) production of 133 and 46.9 kJ.mol(-1). The small energy difference in the two concurrent reactions for the propylene oxide/CO(2) process (33 kJ.mol(-1)) accounts for the large quantity of cyclic carbonate produced at elevated temperatures in this instance.

Characterization of model triacylglycerol (triolein, trilinolein and trilinolenin) autoxidation products via high-performance liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry

Oxidation products from the autoxidation of three triacylglycerol standards have been analyzed using reversed-phase high-performance liquid chromatography (RP-HPLC) coupled to mass spectrometry via an atmospheric pressure chemical ionization (APCI) source. Triolein, trilinolein and trilinolenin were autoxidized in the dark at 50–60°C until the oxidation products represented approximately 30% of the starting material. These oxidation product mixtures were then analyzed using RP-HPLC–APCI-MS. Several classes of oxidation products were directly detected and identified. Monohydroperoxides were present in the largest amounts in the oxidation products mixtures. The hydroperoxides were found to provide several structurally useful fragments: epoxide intermediates were formed which then underwent further fragmentation, and other fragments were formed from concerted loss of the hydroperoxide group to form a site of unsaturation. Fragments formed by intra-annular cleavage of epoxide intermediates allowed identification of several hydroperoxide isomers. Bishydroperoxides were observed which underwent similar fragmentation pathways. Mono- and diepoxides were also formed by the autoxidation reaction. Two classes of epoxides were observed: those in which an epoxide formed in place of an existing double bond, and those in which an epoxide formed away from a double bond. Two distinct fragmentation mechanisms were observed for epoxides which were not formed across a double bond. Other oxidation products which were observed included hydroxy trilinolenin, epidioxy trilinolenin and hydroperoxy, epidioxy trilinolenin.