Selenium Dichloride Research Articles

Selenium Dihalides Click Chemistry: Highly Efficient Stereoselective Addition to Alkynes and Evaluation of Glutathione Peroxidase-Like Activity of Bis(E-2-halovinyl) Selenides.

Highly efficient stereoselective syntheses of novel bis(E-2-chlorovinyl) selenides and bis(E-2-bromovinyl) selenides in quantitative yields by reactions of selenium dichloride and dibromide with alkynes were developed. The reactions proceeded at room temperature as anti-addition giving products exclusively with (E)-stereochemistry. The glutathione peroxidase-like activity of the obtained products was estimated and compounds with high activity were found. The influence of substituents in the products on their glutathione peroxidase-like activity was discussed.

Template-free synthesis of Se-nanorods-rGO nanocomposite for application in supercapacitors

AbstractBoth selenium and reduced graphene oxide have low specific capacitance due to their chemical nature. Nevertheless, their specific capacitance could be enhanced by hybridizing Se nanomaterials with reduced graphene oxide via formation of electrochemical double layer at their interfacial area. Therefore, novel Se-nanorods/rGO nanocomposite was successfully synthesized by template free hot reflux route starting with graphene oxide and selenium dichloride. The composite of rGO decorated by Se-nanorods is characterized using X-ray diffractometry (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption– desorption. The unique architecture of the composite exhibits high specific capacitance of 390 F/ g at 5 mV/s scan rate in 1.0 M KOH solution with ~ 90% cyclic stability after 5000 cycles making it very promising electrode material for supercapacitor applications.

Regio- and Stereoselective Addition of Selenium Dichloride to Alkyl Propiolates

The reaction of selenium dichloride with methyl and ethyl propiolates leads to formation of anti-Markovnikov adducts. The regio- and stereoselective synthesis of hitherto unknown bis[(E)-2-chloro-1-(alkoxycarbonyl)vinyl]selenides has been developed based on this reaction.

Synthesis of Fused Compounds on the Basis of Chalcogen Chlorides and 2-Allylphenols

Efficient methods have been developed for regioselective synthesis of new organochalcogen compounds containing 2,3-dihydro-1-benzofuran-2-ylmethyl and 7-methyl-2,3-dihydro-1-benzofuran-2-ylmethyl substituents by reactions of selenium and sulfur dichlorides and tellurium tetrachloride with 2-allylphenol and 2-allyl-6-methylphenol.

Regiospecific allyl chlorination of betulin and diacetylbetulin

For the first time it was established that in the reaction of selenium dichloride with betulin and diacetylbetulin it is realized regiospecific allylic substitution of hydrogen in these alkenes by chlorine atom with formation of a single product–an unsaturated chloride of allylic type. The structure of products was proved by 1Н NMR spectra.

Reaction of selenium dihalides with allyl benzyl ether

In recent time the chemistry of selenium dihalides has been extensively developed. Selenium dihalides have been shown to be efficient and selective reagents in the synthesis of organoselenium compounds. Although neither selenium dichloride nor selenium dibromide can be isolated in the pure state [1], these reagents can be generated in situ and involved in various transformations [2–14]. We perform systematic studies on reactions of selenium dichloride and dibromide with unsaturated compounds [5–14]. The reaction of selenium dihalides with vinyl ethers gave the corresponding Markovnikov adducts, bis(2-halo-2-organyloxyethyl) selenides, in high yield [8, 9]. The double C=C bond in vinyl chalcogenides is conjugated with the lone electron pair on the chalcogen atom, which largely determines chemical behavior of that bond. No such conjugation exists in the molecules of allyl chalcogenides. The reactions of selenium dichloride and dibromide with diallyl ether, diallyl sulfide, and diallyl selenide led to the formation of sixmembered heterocycles, 3,5-bis(halomethyl)-1,4-chalcogenaselenanes, whose structure corresponds to the anti-Markovnikov addition [10–12]. The reactions of selenium dihalides with divinyl and diallyl tellurides involved halogenation of the tellurium atom [13, 14]. In continuation of our studies on reactions of selenium dihalides with unsaturated chalcogenides [5–14], the present communication reports on the reaction of selenium dichloride and dibromide with allyl benzyl ether (I). The reactions were carried out in carbon tetrachloride or chloroform at room temperature, and the products were the corresponding antiMarkovnikov adducts, bis(3-benzyloxy-1-halopropan2-yl) selenides II and III, which underwent gradual rearrangement into thermodynamically more stable Markovnikov adducts IV and V. Conditions ensuring selective formation of compounds IV and V in high yield were found.

Chlorination of Phosphane Selenides

AbstractChlorination of the phosphane selenide iPrtBu2PSe with PhICl2 leads to the compound iPrtBu2PSe2Cl2, which contains a P–Se–SeCl2 moiety and is formally a phosphane selenide complex of selenium dichloride. Two polymorphs of the product were identified by X‐ray structure analysis. The analogous reaction with tBu3PSe gave an oil, presumably tBu3PSe2Cl2, from which small quantities of tBu3PSe3Cl2 were obtained and characterized by X‐ray structure analysis.

ChemInform Abstract: An Effective Method for the Synthesis of 3,5‐Bis(halomethyl)‐1,4‐oxaselenanes and Their Derivatives.

AbstractOxaselenane derivatives are obtained in reactions of diallyl ether with selenium dichloride and dibromide.

Quantum-chemical study of organic reaction mechanisms. Part 2. Addition of selenium dichloride to acetylene

The mechanism of the addition of selenium dichloride to acetylene has been studied theoretically at the DFT-B3LYP/6-311+G(d,p) level. The reaction proceeds as anti-anti-addition via the formation of the intermediate selenirenium compounds with the four-coordinated selenium atom. Both thermodynamically and kinetically, a favorable E-2-chloroselenenyl chloride is formed on the first stage of the reaction. The experimentally observed E,E-bis(2-chlorovinyl) selenide is kinetically more favorable as compared to E,Z-isomer. Possible alternative reaction mechanisms require much higher energy barriers. Stereoselectivity of the process is achieved through the kinetic control of the reaction. In the reaction profile of a preferable route leading to a kinetically favorable E,E-bis(2-chlorovinyl) selenide the entropy factor doesn't play a major role in the energetics of both stages.

Analysis of the Photoelectron Spectra of Selenium Difluoride and Selenium Dichloride Based on Franck-Condon Factors

ABSTRACT The vibrational structure of the photoelectron spectra of selenium difluoride and selenium dichloride have been simulated using the computed Franck-Condon factors in the harmonic oscillator approximation. Spectral simulations have been carried out employing the coupled-cluster singles, doubles, and triples (CCSD(T)) and the Becke three-parameter Lee, Yang, and Parr (B3LYP) values for the ground electronic states of the neutral molecules and the cations selenium difluoride and selenium dichloride, respectively. The Duschinsky rotations among the normal modes of two ground electronic states of species involved in the transition are fully taken into account. The ionization energies obtained for selenium difluoride and selenium dichloride are in reasonable agreement with the experimentally determined values. The spectral simulations of vibrational structures including frequency changes and Duschinsky rotation upon the electronic excitation are in agreement with the experimental results.

An Effective Method for the Synthesis of 3,5-bis(halomethyl)-1,4-Oxaselenanes and their Derivatives

We report the first study of selenium dichloride and dibromide reactions with diallyl ether, aimed at the preparation of selenium-containing heterocyclic compounds. It was established that selenium dichloride reacted regio- and stereoselectively, giving cis-3,5-bis(chloromethyl)-1,4-oxaselenane in 70% yield. Selenium dibromide gave 3,5-bis(bromomethyl)-1,4-oxaselenane in 76% yield, as a mixture of cis and trans diastereomers. The obtained compounds were used for the synthesis of previously unknown 1,4-oxaselenanes: 3,5-bis(methoxymethyl)-, 4,4-dibromo-3,5-bis(chloromethyl)-, and 3,5-bis-(bromomethyl)-4,4-dichloro-1,4-oxaselenane. The diastereomers of 3,5-bis(halomethyl)-1,4-oxa-selenanes were found to undergo unusually facile isomerization.

Synthesis of bis(2-haloethyl) selenides by reaction of selenium dihalides with ethylene

Introduction in the organic synthesis of new electrophilic reagents, selenium dichloride and dibromide, made it possible to develop effi cient methods of preparation of new organoselenium compounds [1–4]. Based on reactions of selenium dihalides with acetylene a new stereoselective method was developed for the synthesis of (Е,Е)-bis(2-halovinyl) selenides [2]. The reaction of selenium dihalides with alkenes proceeds stereoselectively leading to the formation of substituted bis-(2-haloethyl) selenides, products of addition by Markovnikoff rule or against it depending on the substituent at the double bond (electron-donor [3] or electron-acceptor [4]). Reactions of selenium dihalides with ethylene were not described in the literature. They would be applied to the direct atom economy synthesis of bis(2-haloethyl)selenides (I, II). Note that 2-haloethyl selenides are used in organic synthesis [5] and exhibit antitumor activity [6]. The published information exists on a reaction of selenium monochloride (Se2Cl2) with ethylene that results in bis(2-chloroethyl)selenium dichloride [7]. The reaction with ethylene of selenium tetrahalides afforded bis(2-haloethyl)selenium dihalides [8]. Therefore the preparation of selenides I, II in one stage from ethylene and selenium monohalides or tetrahalides failed [7, 8]. We investigated the reactions of selenium dihalides with ethylene and found the conditions ensuring the preparation of selenides I, II in up to 90–94% yield and minimum of side reaction products. SeX2 + 20_25°C X Se X

ChemInform Abstract: Synthesis of Bis(1,2,2‐trichloroethyl) and Bis(dichlorovinyl) Selenides by Electrophilic Reaction of Selenium Dichloride with 1,2‐Dichloroethylene.

AbstractThe reaction of 1,2‐dichloroethylene (I) with selenium dichloride is studied.

Stereoselective reaction of selenium dihalides with hex-3-yne

In recent time, the synthetic potential of new electrophilic reagents, selenium dichloride and selenium dibromide, has attracted much interest [1–6]. These reagents are more selective than selenium tetrahalides used previously [7]. For example, reactions of selenium dichloride and dibromide with acetylene follow stereoselective anti-addition pattern with formation of (E,E)-bis(2-halovinyl) selenides in nearly quantitative yield [2], whereas the addition of selenium tetrahalides to acetylene gives both (E,E)-bis(2-halovinyl) selenides and their halogenation products at one double bond [7]. The addition of selenium dihalides to acetylenic compounds is generally regioand stereoselective; however, the nature of substituents at the triple bond could considerably affect steric configuration of the product [1–5]. For instance, unexpected anti–syn-addition product, (Z,E)-bis(2-chloro-3-trimethylsilylprop1-en-1-yl) selenide was obtained in the reaction of selenium dichloride with 3-trimethylsilylprop-1-yne [3]. It was presumed that the first elementary step of this reaction occurs as anti-addition, but in the second step syn-addition of the primary adduct to the second 3-trimethylsilylprop-1-yne molecule appears to be energetically more favorable than the anti-addition due to strong steric effect of two trimethylsilyl groups [3]. Reactions of selenium dihalides with propargyl alcohols lead to the corresponding syn-addition products, (Z,Z)-bis(1-halo-3-hydroxyprop-1-en-2-yl) selenides [4]. Their steric structure is determined by the hydroxy group which acts as internal nucleophile [4].

ChemInform Abstract: Reaction of Selenium Dichloride with Acrylic Acid and Its Derivatives. Regioselective Synthesis of New Functionalized Selenides.

AbstractThe reaction of selenium dichloride, which can be prepared in situ from selenium and sulfuryl chloride, with acrylic acid (IIa), ethyl acrylate (IIb), or acrylonitrile at ‐20°C gives the corresponding selenides (II) in high yields.

Synthesis of bis(1,2,2-trichloroethyl) and bis(dichlorovinyl) selenides by electrophilic reaction of selenium dichloride with 1,2-dichloroethylene

Electrophilic reactions of sulfur dichloride with unsaturated systems underlie one of the most general methods for the synthesis of bis(2-chloroalkyl) sulfides [1]. Reactions of analogous unsaturated compounds with selenium tetrachloride yield the corresponding bis-adducts containing a four-coordinate selenium atom (>SeCl2) [2]. In recent years we performed systematic studies on reactions of SeCl2 with alkenes and their oxygenand sulfur-containing derivatives [3, 4]. Reactions with chlorinated ethylenes, such as chloroethene, 1,1and 1,2-dichloroethenes, and trichloroethene were reported only for SCl2, and they required the presence of Lewis acids as catalyst [5]. Garratt et al. [6] showed that SeCl4 failed to react with 1,2-dichloroethene in the presence of AlCl3 as catalyst. Nevertheless, we succeeded in adding SeCl2 to bis(2-chlorovinyl) selenide (a selenium-containing derivative of 1,2-dichloroethene) in the absence of a catalyst [7]. Sulfur and selenium dichlorides are known to act as chlorinating agents toward alkylsulfanyl derivatives of polychloroethenes, e.g., alkyl 2,2-dichlorovinyl sulfides [8].

ChemInform Abstract: Regioselective Reaction of Selenium Dichloride and Dibromide with Diallyl Sulfide.

AbstractThiaselenanes (II) are formed regioselectively as a result of anti‐Markovnikov addition of selenium dihalide at the allyl group.

Reaction of selenium dichloride with acrylic acid and its derivatives. Regioselective synthesis of new functionalized selenides

Selenium dichloride reacted with acrylic acid, ethyl acrylate, and acrylonitrile at −20°C in a regionselective fashion to give the corresponding anti-Markovnikov adducts. This reaction was used as a basis to develop an efficient procedure for the synthesis of new functionalized selenides in nearly quantitative yields. Raising the temperature to −10°C or ambient led to loss of regioselectivity and formation of mixtures of addition products at both α- and β-positions of the double bond.

Stereo- and regioselective reaction of selenium dichloride and dibromide with ethynyl(trimethyl)silane

We perform systematic studies on reactions of selenium halides with acetylene [1] and its derivatives [2–4]. Efficient procedures for the synthesis of previously unknown five-membered heterocycles, 1,4-selenasilafulvenes, were developed on the basis of reactions of selenium dichloride and dibromide with diorganyl(diethynyl)silanes [2]. Reactions of selenium dihalides with trimethyl(propargyl)silane lead to the corresponding Markovnikov adducts [3], whereas antiMarkovnikov adducts are formed in reactions of selenium dihalides with propargyl halides and phenyl propargyl ethers [4].

Regioselective reaction of selenium dichloride and dibromide with diallyl sulfide

Thiaselenanes (II) are formed regioselectively as a result of anti-Markovnikov addition of selenium dihalide at the allyl group.