Researches on 2,1,3-thia-and selenadiazoles

Chloromethylation of 4- and 5-chlorobenzo-2,1,3-thiadiazoles with dichlorodimethyl ether in the presence of anhydrous aluminum chloride gives 4-chloro-7-chloromethyl- and 5-chloro-4-chloromethylbenzo-2, 1,3-thiadiazoles respectively. Reductive scission followed by treatment with thionyl chloride converts them to 4-chloro-7-methyl- and 5-chloro-4-methylbenzo-2,1,3-thiadiazoles; Chlorination of the latter gives 4-methyl-5,7-dichlorobenzo-2,1,3-thiadiazole. Replacement of the chlorine in the chloromethyl groups gives 4-chloro-7-hydrosymethyl-,5-chloro-4-hydroxymethyl-, 4-chloro-7-cyanomethyl-,4-chloro-7-carboxymethyl-,5-chloro-4-carboxymethylbenzo-2,1,3-thiadiazoles. Reductive scission of 4-chlorobenzo-2,1,3-thidiazole followed by treatment with sodium selenite gives 4-chlorobenzo-2,1,3-selenadiazole.Part XLIII see [1].     

Researches on 2,1,3-thia- and selenadiazole XLV. Nitration of 4-hydroxy- and 4-ethoxybenzo-2,1,3-thiadiazoIe

Nitration of 4-hydroxybenzo-2,1,3-thiadiazole under conditions generally used for phenols, gave a high yield of 4-hydroxy-5-nitrobenzo-2,1,3-thiadiazole. The latter is readily reduced to 4-hydroxy-S-aminobenzo-2,1,3-thiadiazole which on treatment with orthoformic ester gives oxazolo [5,4-e]benzo-2,1,3-thiadiazole. 4-Ethoxybenzo-2,1,3-thiadiazole is nitrated under similar conditions, giving a high yield of a mixture of equal quantities of 4-ethoxy-S-nitro- and 4-ethoxy-7-nitrobenzo-2,1,3-thiadiazole.     

Researches on 2,1,3-thia- and selenadiazole XLV. Nitration of 4-hydroxy- and 4-ethoxybenzo-2,1,3-thiadiazoIe

Nitration of 4-hydroxybenzo-2,1,3-thiadiazole under conditions generally used for phenols, gave a high yield of 4-hydroxy-5-nitrobenzo-2,1,3-thiadiazole. The latter is readily reduced to 4-hydroxy-S-aminobenzo-2,1,3-thiadiazole which on treatment with orthoformic ester gives oxazolo [5,4-e]benzo-2,1,3-thiadiazole. 4-Ethoxybenzo-2,1,3-thiadiazole is nitrated under similar conditions, giving a high yield of a mixture of equal quantities of 4-ethoxy-S-nitro- and 4-ethoxy-7-nitrobenzo-2,1,3-thiadiazole.For Part XLIV see [1].     

Research on 2, 1, 3-thia-and selenadiazole

Reductive decomposition followed by hydrolysis of 5-(,-dicarethoxy--acetylamino) ethylbenz-2, 1, 3-selenadiazole gives -(3, 4-diaminophenyl)alanine.For Part XLVII see [1].     

Investigations of 2,1,3-thia- and selenadiazole s

All of the possible isomeric monoaminobenzo-2,1,3-selenadiazoles are formed in the reaction of benzo-2,1,3-selenadizaole 4- or 5-irethyl-, or 5,6-dimethylbenzo 2,1,3-selenadiazoles with hydroxylaminesulfate in concentrated sulfuric acid.See [1] for communication LXV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 328–330, March, 1972.     

Researches on 2, 1, 3-thia- and selenadiazole

Depending on the reaction conditions, benzo-2, 1, 3-selenadiazole (I), dichlorodimethyl ether and aluminum chloride react to give a complex IV, or else 4-chloromethyl-(V) or 4, 7-di(chloromethyl) benzo-2, 1, 3-selenadiazole (VI). 5-(II) and 4-methylbenzo-2,l,3-selenadiazole(III) are chloromethylated by dichlorodimethyl ether in the presence of chlorosulfonic acid. Compound II is converted mainly into 5-methyl-4-chloromethylbenzo-2, 1, 3-selenadiazole(VII) or a mixture of three possible isomers VII, VIII, and IX, depending on the amount of base or pseudo-base in the reaction mixture. Ill gives mainly 4-methyl-7-chlorornethylbenzo-2, 1, 3-selenadiazole(X), independent of the presence of base. The structures of the chloromethylation products are shown by reductive splitting to o-diamides, and chromatography of the latter in the presence of reference spots. The high reactivity of the chlorine in the chloromethyl group made it possible to obtain new derivatives by replacing it with a hydroxyl, cyano, or thiocyano group.For Part XL see [1].     

Researches on 2, 1, 3-thia- and selenadiazole

4-Hydroxy-, 4-hydroxy-5-methyl-, 4-hydroxy-7-methylbenzo-2,1,3-thiadiazoles are polymorphous.4-Hydroxybenzo-2,1,3-thiadiazole (I), 4-hydroxy-5-methyl- and 4-hydroxy-7-methylbenzo-2, 1, 3-thiadiazoles (II and III) melt at 114–115°, 110–112°, 100–102° C, respectively, after recrystallization from water [2–4], but after recrystallization from petrol ether [5] they melt at 128–129°, 124–125°, and 119–120° C [5]. In this connection we recrystallized these phenols repeatedly from petrol ether after recrystallizing them from water, and their melting points rose as expected [5]. On the other hand, the compounds with melting points 128–129°, 124–125°, 119–120° C (ex petrol ether), after repeated crystallization from water melted at 114–115°, 110–112°, 100–102° C, respectively.For Part XXXVIII see [1].     

Researches on 2, l, 3-thia- and selenadiazole

4-(,-Dicarboethoxy--acetylamino) ethyl-7-aminobenzo-2,1, 3-thiadiazole (IV) and ethylene oxide form mainly the 7-(-hydroxyethyl) amino derivative (V); the 7- di (-hydroxyethyl) amino derivative VII was isolated in low yield. Action of POCl₃ on compound VII gave the 7-di (-chloroethyl) amino derivative VIII, which was converted into 4-(-amino--carboxy)-ethyl-7 -di (-chloroethyl) aminobenzo-2, 1, 3-thiadiazole (IX). 5-(, -dicarboethoxy--acetylamino) ethyl-4-nitrobenzo-2, 1, 3-thiadiazole (XI) was converted to 5-(-carboxy--amino) ethyl-4-nitrobenzo-2, 1, 3-thiadiazole hydrochloride (XII), from which was prepared, by known routes, and in satisfactory yield, 5-(-carboxy--amino) ethyl-4-di (-chloroethyl)-aminobenzo-2, l, 3-thiadiazole hydrochloride (XVII).For Part XXXIX see [8].     

Oxidationsreaktionen methyl-substituierter 2,1,3-Benzothiadiazole und 2,1,3-Benzoselenadiazole mit Selen-dioxid

Oxidation Reactions of Methyl Substituted 2,1,3-Benzothiadiazoles and 2,1,3-Benzoselenadiazoles with Selenium Dioxide The synthesis 5–8 by oxidation of 4-methyl-( 1 ),5-methyl( 2 ), 5,6-dimethyl-2,1,3-benzoselenadiazole ( 3 ), and 5,6-dimethyl-2,1,3-benzothiadiazole ( 4 ), respectively, with selenium dioxide as well as their spectroscopic properties are described.     

Research on 2, 1, 3-thia- and selenadiazole

The stability of the thiadiazole ring in chloro-substituted benzo-2, 1, 3-thiadiazoles to reductive fission increases with increasing chlorine substitution.For part LIII, see [1].     

Investigations in the field of 2,1,3-thiadiazole and 2,1,3-selenadiazole

The action of sodiomalonic ester on 4-bromomethylbenzo-2,1,3-thiadiazole forms a malonate which is converted by acid hydrolysis into 4-(-carboxyethyl)benzo-2,1,3-thiadiazole. When this reaction is carried out with 5-bromomethylbenzo-2,1,3-thiadiazole, mono- and disubstituted malonic esters are formed the acid hydrolysis of which gives the corresponding acids. The nitration of 4-and 5-(-carboxyethyl)benzo-2,1,3-thiadiazoles forms, respectively, 4-(-carboxyethyl)-5,7-dinitrobenzo-2,1,3-thiadiazole and 5-(-carboxyethyl)4-nitrobenzo-2,1, 3-thiadiazole. The reaction of 4-bromomethylbenzo-2,1, 3-thiadiazole with potassium cyanide forms two products: 4-cyanomethylbenzo-2,1, 3-thiadiazole and 1,2-di(benzo-2,1, 3-thiadiazole-4-yl)-2-cyanoethane.For part LVIII, see [1].     

Synthesis of 2,1,3-benzothiadiazolecarbonitriles

2,1,3-Benzothiadiazolecarbonitriles, 2 , have been prepared by two different methods. Reaction of bromo-2,1,3-benzothiadiazoles, 1 , with cuprous cyanide occurs advantageously in refluxing dimethylformamide to give 2 , complexed with curpous bromide. Hydrogen peroxide in hydrochloric acid at 30–40° is shown to be an effective reagent for efficient decomposition of these reactions complexes, 2 CuBr, and subsequent isolation of 2. Yields in the Sandmeyer method for preparing nitriles 2 were improved by diazotizing amino-2,1,3-benzothiadiazoles, 3 , with nitrosyl-sulfuric acid prior to reaction with the cuprous-sodium cyanide complex.     

The mass spectra of some 2,1,3-benzothiadiazoline and 2,1,3-benzothiadiazine 2,2-dioxides

Although the behaviour of 1H, 2H-2,1,3-benzothiadiazoline 2,2-dioxide is similar to that of sulphoxides in the mass spectrometer in losing a molecule of SO₂, the 1,3-dimethyl derivative loses the radical SO₂H. In addition the radical CH₃SO₂ is lost in a one step process that must involve a methyl migration. The radical SO₂H is also lost from 2,1,3-benzothiadiazine 2,2-dioxides methylated in the 3-position and the hydrogen involved is shown to originate from this methyl group by deuterium labelling. The mass spectra of other 2,1,3-benzothiadiazine 2,2-dioxides are also discussed.     

New many fold 1,2,3‐selenadiazole aromatic derivatives

The many fold aromatic ketones 2a‐d are versatile compounds for the synthesis of the many fold 1,2,3‐selenadiazole aromatic derivatives 5a‐d . The preparation starts with the reaction between the many fold bromomethylene benzene derivatives 1a‐d and 4‐hydroxyacetophenone, which are transformed through the reaction with semicarbazide hydrochloride or ethylhydrazine carboxylate into the corresponding semicarbazones derivatives 3a‐d or hydrazones 4a‐d . The reaction with selenium dioxide leads to regiospecific ring closure of semicarbazones or hydrazones to give the many fold 1,2,3‐selenadiazole aromatic derivatives in high yield.     

Benzo[1,2,5]selenadiazole bridged amines: electro-optical properties

New diamines and tetramines bridged by a low band gap rendering chromophore benzo[1,2,5]selenadiazole were synthesized by following palladium-catalyzed methodologies developed by Hartwig, Stille, or Suzuki. These donor-acceptor compounds display unique absorption and emission characteristics, which are dependent on the strength of the donors.     

Theoretical study on photophysical properties of 2,1,3-benzothiadiazole-based star-shaped molecules

Star-shaped molecules with tailoring functional groups in the core and the arms have great potential application in organic light-emitting devices, because it can be designed to realize low band gap, broad absorption, and excellent solubility for low-cost solution process. To gain an insight into the structure?Cproperty relationships, a set of four-arm star-shaped molecules with 2,1,3-benzothiadiazole as the core, different ??-conjugated groups as the arm, and triphenylamine or 2-(pyridin-2-yl) pyridine as the end-group were designed. In this study, a systematic investigation into them was carried out using the density functional theory and time-dependent density functional theory methods. The calculated ionization potentials, electron affinities, and reorganization energies (??) show that the properties of the ??-conjugated bridge and the end-group significantly affect the carrier injection and transport characteristics of these molecules, especially for S-BTDP and S-EBTD. Among these molecules, S-BTDP exhibits better electron injection ability due to the introduction of 2-(pyridin-2-yl) pyridine as the end-group. However, S-EBTD, with ethylene as ??-conjugated bridge, has excellent hole injection and carrier transport behaviors. We also calculated the singlet-to-triplet exciton-formation cross-section ratio (??_S/??_T), the exciton-formation fractions (??_S), and the absorption and emission spectra of these molecules. We calculated that ??_S/??_T ranges from 1.78 to 2.76 and that ??_S is ca. 0.37?C0.48. These molecules have two absorption bands in the range of 340?C410?nm and 500?C613?nm, respectively. The calculated emission spectra range from 619 to 706?nm. It can be deduced that the studied 2,1,3-benzothiadiazole-based star-shaped molecules can serve as efficient red light-emitting electroluminescent materials.     

Investigations of 2,1,3-thia- and selenadiazoles

All three possible isomeric amines are obtained by the reaction of 4- or 5-methylbenzo-2,1,3-thiadiazoles with hydroxylamine sulfate in concentrated sulfuric acid. Under similar conditions, 5,6-dimethyl-4-aminobenzo-2,1,3-thiadiazole is obtained from 5,6-dimethylbenzo-2,1,3-thiadiazole.See [1] for communication LXIV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 601–602, May, 1971.