Block copolymerization. VI. Polymerization of pivalolactone with macromolecular initiators from polystyrene and polytetrahydrofuran

Polymerization of pivalolactone with polystyryl sodium or polystyryl ethoxysodium in tetrahydrofuran resulted in homopolymer mixtures. Block copolymers of pivalolactone and styrene were obtained by the polymerization of pivalolactone with sodium polystyrene carboxylate in tetrahydrofuran containing dimethyl sulfoxide. Block copolymers of pivalolactone and tetrahydrofuran were obtained by the polymerization of pivalolactone with polytetrahydrofuran containing carboxylate endgroups. The mechanism of the initiation reaction and various factors affecting block efficiency are discussed.     

Comment on: “Is linear group X–Y–Z in boron carbide the weakest link in the structure?” by S. V. Konovalikhin and V. I. Ponomarev (Russ. J. Phys. Chem. A 89 (10), 1850 (2015))

The characterization of the boron carbide investigated in the above-mentioned paper and some of the conclusions made on it by the authors are critically appraised with regard to reliable results obtained earlier by other scientists.     

Polymers with quinoxaline units. IV. Polymers with quinoxaline and oxazine units

Six ladder or partly ladder polymers have been prepared by the condensation of diaminodiphenols with tetrachloro- or terahydroxyquinoxaline derivatives with the use of poly (phosphoric acid), pyridine, and naphthalene as reaction media. The polymers thus obtained are highly colored powdery materials which are slightly soluble in concentrated sulfuric acid and methanesulfonic acid. These polymers show good thermal stability.     

Syntheses and Properties of Some New Polyamides. Part II

Interfacial condensation of decamethylenediamine and acid chlorides I, II, and III yielded polyamides the thermal stability of which decreased in the order III, I, II, a finding reasserted by calculating activation energy decomposition temperatures. Irradiation of these polyamides does not appreciably affect their properties, and thus they can be considered satisfactorily γ-irradiation resistant.

It appears that there are only few papers dealing with syntheses and properties of polyamidoarylates. Cleaver and Pratt [1] prepared polyamidoesters by the polymerization of bisoxazolones with glycols. Korshak and others [2], however, obtained a polyamidoester by the aminolysis of polyethylene-sebacate with hexamethylenediamine.

In a previous investigation [3] a few polyamidoarylates were obtained by the condensation of aminophenols with aromatic acid chlorides.

In this work we obtained some new polyamidoarylates by the inter-facial condensation of equimolar ratios of decamethylenediamine with     

Novel dialkylaminoalkyl- and dialkylaminoalcoxy-benzophenones as polymerization photoinitiators. II. Photocalorimetric study on photoinitiated polymerization of butyl and lauryl acrylates

A photocalorimetric study of butyl and lauryl acrylates (BA and LA) polymerization photoinitiated by several benzophenone derivatives is reported. Molecular weight measurements and end-chain group analysis of the samples are also described and the results are compared with those obtained by dilatometric technique. The role played by the long methylene chain in lauryl acrylate is discussed     

Flow-injection spectrophotometric determination of sulfadiazine and sulfamethoxazole in pharmaceuticals and urine.

A rapid and sensitive flow-injection spectrophotometric method is proposed for the determination of sulfadiazine and sulfamethoxazole. This method is based on the diazotization of sulfonamide with sodium nitrite, and a coupling reaction of the diazo-compound with alpha-naphthylamine. The optimum experimental conditions are obtained by using the controlled and weighted centroid simplex method. The linear ranges for the determination of sulfadiazine and sulfamethoxazole are 0.2-20 microg ml(-1) and 0.1-20 microg ml(-1), and their detection limits are 0.06 microg ml(-1) and 0.05 microg ml(-1), respectively, and the sampling frequency is 130 samples per hour. The method has been used to determine sulfadiazine and sulfamethoxazole in pharmaceuticals and urine without separation. The results are in agreement with those obtained by a high-performance liquid chromatograph technique at the 95% confidence level.     

Pyrimidines. 6. 6-trifluoromethyl chloropyrimidines and related compounds

A study of the chlorination of 6-trifluoromethylpyrimidines was made. On sequential treatment of 6-tri-fluoromethyluracil (6) with phosphorus oxychloride and phosphorus pentachloride, 2,4-dichloro-6-trifluoro-methylpyrimidine (7) (25%) and 4-chloro-6-trifluoromethylpyrimidin-2-yldichlorophosphate (8) (53%) were obtained. Compound 8 was converted to 7 by treatment with hydrogen chloride in phosphorus oxychloride in 72% yield. In a one-pot synthesis, 77% of 7 was obtained from 6. The preparation of 2,4,5-trichloro-6-tri-fluoromethyluracil (16) proceeded similarly. Although the pyrimidinyldichlorophosphate ester has been proposed as the intermediate in converting a pyrimidinol to a chloropyrimidine, these are the first examples of such compounds to be isolated, characterized, and made to yield the ring-chlorinated pyrimidines.     

Studies on phenothiazines. Part 16 . Synthesis and spectral studies of substituted 1,2-dichlorophenothiazines

Synthesis of the title compounds by the Smiles rearrangement has been reported. 1,2-Dichloro-7-substituted phenothiazines have been prepared by the Smiles rearrangement of 3,4-dichloro-2-formamido-2′-nitro-4′-substituted-diphenyl sulphides. The latter were obtained by the formylation of the diphenyl sulphides obtained by the condensation of 2-amino-3,4-dichlorobenzenethiol with o-halogenonitrobenzenes. 9-Nitrophenothiazines have been prepared by the reaction of 2-amino-3,4-dichlorobenzenethiol with substituted o-halonitrobenzenes containing a nitro group at both ortho positions to the halo atom in which Smiles rearrangement occurs in situ. The ir, nmr and mass spectral studies are also included.     

Polyhydrazides. IV. Preparation and properties of poly-N-ethyl- and isopropylhydrazide oxadiazoles

High molecular weight poly-N-alkylhydrazide-oxadiazoles have been prepared in poly-phosphoric acid by alkylation of poly-1,3,4-oxadiazole which was synthesized from terephthalic acid and hydrazine sulfate. Various kinds of reagents having an alkoxy group were used as alkylating agent, and N-ethylated and N-propylated polyhydrazides containing oxadiazole units were obtained. The thermal properties of the polymers obtained were investigated by using infrared spectroscopy, viscometry, differential thermometric and thermogravimetric techniques. Soluble poly-N-alkylhydrazide-oxadiazole are thermally cyclized to poly-1,3,4-oxadiazole with elimination of olefins and water at 226–330°C for propylated polydrazide and at 240–360°C for ethylated polyhydrazide. For both, weight loss in polyhydrazides occurs in two distinct stages corresponding, respectively, to cyclization and decomposition of the poly-1,3,4-oxadiazole formed in situ.     

Acetylene derivatives. Communication 177. Condensation of aromatic and aliphatic-aromatic ketones with acetylene under pressure. Part III.

Summary In presence of potassium hydroxide powder, aliphatic-aromatic and aromatic ketones of the aceto- and benzo-phenone types condense smoothly with acetylene at a pressure of 5–10 atm with formation of the corresponding tertiary acetylenic alcohols in yields of more than 90%. When the 2-aryl-3-butyn-2-ols so obtained are selectively hydrogenated over a palladium catalyst, 2-aryl-3-buten-2-ols are obtained in almost quantitative yield, and dehydration of these gives 2-aryl-1,3-butadienes, which are extremely reactive in polymerization (dimerization) reactions and in the diene condensation.     

Research of benzimidazole derivatives. XXXVI. Synthesis and transformations of N-propargyl-substituted 2-aminobenzimidazoles

1-(2′-Propynyl)-2-aminobenzimidazole and 1,3-di(2′-propynyl)-2-iminobenzimidazoline, which are cyclized by the action of bases to imidazo[1,2-a]benzimidazole derivatives, were obtained by alkylation of 2-aminobenzimidazole with propargyl bromide. The cyclization proceeds with the formation of intermediate N-propadienyl derivatives.     

Macroheterocycles. 5. Synthesis of macrocyclic amido esters and amido thioesters on the basis of derivatives of α-hydroxy and α-mercapto acids

3,6-Dioxa-4-keto-, 2-benzyl-3,6-dioxa-4-keto-, and 3-oxa-6-thio-5-ketooctanedioic acids were obtained by the reaction of diglycolic acid anhydride with glycolic, β-phenyllactic, and thioglycolic acids. 2,9-Dibenzyl-3,8-dioxa-4,7-diketodecanoic acid was obtained by the reaction of succinyl chloride with β-phenyllactic acid. Eight macrocyclic amido esters and amido thioesters that are new polydentate macrocyclic ligands were synthesized by the reaction of the chlorides of the acids obtained with 3-oxa-1,5-diaminopentane, 3,6-dioxa-1,8-diaminooctane, and 1,4-diaminobutane. See [1] for communication 4. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 306–309, March, 1980.     

Comparison of theoretical and experimental particle density distributions of traces in a d.c. arc

The spatial particle density distributions in a d.c. arc plasma are calculated according to various theoretical models and the obtained results are compared with experimental measurements. A comparative analysis of corresponding results by other authors is also given.     

New olefinic functionalized disilanes. Synthesis and NMR spectroscopical investigations

The new olefinic substituted aminodisilanes, which are obtained from the reaction of organometallic reagents with aminochlorodisilanes, are converted into the chlorodisilanes by equilibration reactions or treatment with HCI. The resulting olefinic functionalized disilanes are identified by means of ²⁹Si, ¹³C, ¹H NMR and GC MS measurements.     

Carrier mobility and long-range order in disordered systems. II

Recent comments by Fleming on a previous paper dealing with long-range order in disordered systems are answered. Discrepancies between the results given therein and those obtained by Fleming are discussed and ascribed to different normalization procedures. Experimental evidence for the existence of such order is adduced.     

Studies in the configuration interaction method. II. Generating functions and recurrence relations for the number of many-particle configurations

Generating functions are constructed and recurrence relations are derived for the number of configurations of any number of particles with an arbitrary elementary spin for both fermions and bosons. Similar results are obtained for the number of configurations specified by the total weight and by the degree of excitation.     

1,6- and 1,7-naphthyridines. II. Synthesis from acyclic precursors

A number of 8-hydroxy-6-methyl-1,6-naphthyridin-5(6H)-one-7-carboxylic acid alkyl esters 3 and the isomeric 5-hydroxy-7-methyl-1,7-naphthyridin-8(7H)-one-6-carboxylic acid alkyl esters 4 were synthesized from acyclic precursors obtained starting from quinolinic anhydride 5. Thus, methanolysis of 5 afforded the hemiester 6 which treated with oxalyl chloride and sarcosine ethyl ester gave 3-(N-ethoxycarbonylmethyl-N-methylcarbamoyl)pyridine-2-carboxylic acid methyl ester 8. Compound 8 was cyclized to naphthyridines 3a-e with sodium alkoxides. The isomeric naphthyridines 4a-c were obtained by cyclization of the open intermediary 2-(N-ethoxycarbonylmethyl-N-methylcarbamoyl)pyridine-3-carboxylic acid methyl ester 9 obtained by a route that involves treatment of 5 with sarcosine ethyl ester and esterification with diazomethane. Spectroscopic properties (¹H nmr, uv, ir) of compounds 3 and 4 are discussed and confirmed the proposed structures.     

PECVD of SiOxNyCzHw thin films from hexamethyldisilazane containing feed. Investigation on chemical characteristics and aging behavior

The chemical characteristics and aging behavior of thin films obtained by HMDSN/NH₃ or N₂ containing plasmas have been studied by means of FT-IR spectroscopy as a function of feed composition, substrate temperature and bias voltage. Deposits obtained with low energy ion bombardment are polyphasic and contain a consistent fraction of polysilazane. Reactive polymeric SiH₂ chains are formed when ammonia or nitrogen are added to the feed. Film aging is mainly due to the reactions of Si-H bonds and of linear polysilazane chains. Films with better stability are obtained by excluding ammonia or nitrogen from the feed and with bias superimposition.     

Human calcitonin. I. Isolation and characterization

Two highly active calcitonin peptides, M with 32 amino acids, and D a dimer of M, were isolated from a large human mediastinal C cell tumour. D can easily be transformed into M by the action of 1N ammonia; D and M afford two different sulphoxides, but all four peptides yield the same product upon oxidation with performic acid. Both D and M have a potency of about 120 MRC units/mg dry weight; their sulphoxides, by contrast, are almost inactive. Tryptic digestion of M produces an N-terminal octadecapeptide (Tr_I) and a C-terminal tetradecapeptide (Tr_II), the latter being also obtained from D. Amino acid analysis and other analytical data are presented. The structure of the human calcitonin peptides D and M is thus very different from that of porcine α-thyrocalcitonin.     

Spin-free quantum chemistry. XIX. Particle-hole and pairing symmetries

Particle–hole and pairing relationships are obtained within the framework of the unitary group formulation of the many-electron problem using the concept of particle–hole conjugation. Besides the familiar relationships for alternant hydrocarbons, relationships among various pericyclic reaction paths are obtained.