Thermal degradation of poly(alkyl acrylates). III. A secondary ester: Isopropyl acrylate

A quantitative analysis of the products of the thermal degradation of poly(isopropyl acrylate) has been made principally by the application of GLC and mass and infrared spectrometry. The major products are carbon dioxide and propylene. The carbon dioxide/propylene ratio is very low in the initial stages but converges to approximately 0.6 late in the reaction. There is some tendency to autocatalysis in the production of propylene. Carbon monoxide and isopropanol are very minor products, and there is no chain fragment fraction as in the degradation products of the poly(primary acrylates). Changes in the infrared spectrum of the polymer during degradation are in accordance with the formation of these products and the reaction characteristics are accounted for mechanistically.     

Thermal and photo-decomposition of 1,4-disubstituted alkylaminoanthraquinone dyes in polymers and solution: A chromatographic and spectroscopic study

The photo-decomposition products of five 1,4-disubstituted anthraquinones produced in polyester and nylon 6,6 fabrics and related solvents have been compared with those produced in the thermal oxidation of the dyes on silica gel plates at 150°C. Using TLC, ultraviolet-visible absorption spectroscopy and mass spectrometry, the decomposition products were found to be generally very similar. The number and complexity of the products formed were found to be very dependent on the duration of exposure. These results indicated that the thermal and light stability of the dye is considerably less than that predicted by normal visual colour assessments. From an analysis of the products of decomposition early theories on N-dealkylation are confirmed and their arguments on N-formylation are partially resolved.     

A theoretical study of the OH-initiated gas-phase oxidation mechanism of β-pinene (C10H16): first generation products

An extensive mechanism for the OH-initiated oxidation of β-pinene up to the first-generation products was derived based on quantum chemical calculations, theoretical kinetics, and structure-activity relationships. The resulting mechanism deviates from earlier explicit mechanisms in several key areas, leading to a different product yield prediction. Under oxidative conditions, the inclusion of ring closure reactions of unsaturated alkoxy radicals brings the predicted nopinone and acetone yields to an agreement with the experimental data. Routes to the formation of other observed products, either speciated or observed as peaks in mass spectrometric studies, are also discussed. In pristine conditions, we predict significant acetone formation following ring closure reactions in alkylperoxy radicals; in addition, we predict some direct OH recycling in subsequent H-migration reactions in alkylperoxy radicals. The uncertainties on the key reactions are discussed. Overall, the OH-initiated oxidation of β-pinene is characterized by the formation of a few main products, and a very large number of products in minor to very small yields.     

Synthesis of functionalized thiazoles via attack of heterocyclic nucleophiles on allenyl isothiocyanates

New examples of substituted thiazole derivatives carrying different heterocyclic ring systems at C-2 position were prepared via the reaction of several allenyl isothiocyanates with nucleophiles such as imidazoles, pyrazoles, benzimidazoles, indazole, 1,2,3-triazole, 1,2,4-triazole, and 1H-benzotriazole. Although these allenyl isothiocyanates are very reactive electrophiles and tend to polymerize, the yield of the thiazole products ranked between modest and very good. The regiochemistry of the reactions was proved by NMR and X-ray studies indicating that the attack of ambident nucleophiles proceeded very selectively. In some cases, however, the products were formed as mixtures of aromatic heterocycles and non-aromatic isomers. The latter could be rearranged to yield the uniform aromatic thiazoles.     

Niobium (V) chloride catalyzed Knoevenagel condensation: An efficient protocol for the preparation of electrophilic alkenes

The condensation reaction has been carryout very conveniently to obtain the corresponding substituted olefins in excellent yields and showing all the products in excellent E-geometry. The reaction conditions are very mild and applicable to various aldehydes as well as active methylene compounds.     

Reaction of Amidrazones with Phthaloyl Chloride—Synthesis of 1,2,4‐Triazolium Salts (Part I)

Phthaloyl chloride reacts with N‐arylbenzamidrazones to give 1,2,4‐triazolium salts in very good yields. The mechanism described the products formation was discussed. The structure of the obtained products was proved by IR, mass, NMR spectra, and elemental analyses.     

Facile O-arylation of phenols and carboxylic acids

[reaction: see text] A facile, transition-metal-free O-arylation procedure for phenols and aromatic carboxylic acids has been developed that affords good to excellent yields of arylated products under very mild reaction conditions. A methoxy-substituted aryl triflate affords O-arylated products in high yields with excellent regioselectivity. This chemistry tolerates a variety of functional groups.     

Catalytic degradation of polyethylene and polypropylene to fuel oil

Thermal and catalytic degradation of plastic polymers, polyethylene and polypropylene to fuel oil were carried out in batch operations. The catalysts employed were acid silica-alumina (SA-1, SA-2) and zeolite ZSM-5, and non-acidic mesoporous silica FSM (folded sheet material). The yields of product gas, liquid and residues, recovery rate of liquid products, and boiling point ranges of liquid products due to degradation were compared with those of non-catalytic thermal degradation. Both the effect of catalytic contact mode and of catalyst type on the degradation were studied. In liquid-phase degradation of PP over SA-1, liquid hydrocarbon products were obtained in a yield of 69 wt.-% with a boiling point range 36-270°C, equivalent to the boiling point of normal paraffins C6 - C15. The liquid products from catalytic degradation have a carbon-number distribution very similar to commercial motor gasoline. In vapor-phase contact, the yield of liquid products was much lower (54%) and the rate of liquid recovery was much slower. With FSM, the initial rate of degradation of PP and PE to liquid products was as fast as that over acid catalyst SA-1, but the yield of liquid products was higher. The liquid products from catalytic degradation over FSM have a carbon-number distribution similar to kerosene and diesel oil. In repeated use, SA-1 deactivated very rapidly due to coke deposition on the catalyst, whereas FSM deactivated much more slowly. These findings suggest that mesopores surrounded by the silica sheet may act as reservoir for radical species, which accelerate the degradation of plastic melt.     

Facile N-arylation of amines and sulfonamides

[reaction: see text] A facile, transition-metal-free N-arylation procedure for amines and sulfonamides has been developed, which affords good to excellent yields of arylated products under very mild reaction conditions. A methoxy-substituted aryl triflate affords N-arylated products in high yields with excellent regioselectivity. This chemistry tolerates a variety of functional groups.     

Thermal decomposition of cyclo-linear methylsiloxane polymers

The pyrolysis products from two cyclo-linear methylsiloxane polymers have been analysed, and formation of the important products interpreted in terms of a simple decomposition mechanism. This mechanism is very similar to that of the polydimethylsiloxane degradation; thus cyclic oligomers are formed from the linear segments, and polycyclic compounds from the cyclic segments of the cyclolinear methylsiloxane polymers.     

Synthesis of fused polycyclic aromatics by palladium-catalyzed annulation of arynes using 2-halobiaryls

The Pd-catalyzed annulation of arynes by 2-halobiaryls and related vinylic halides provides a very efficient, high yielding synthesis of polycyclic aromatic and heteroaromatic hydrocarbons. This process appears to involve the catalytic, stepwise coupling of two very reactive substrates, an aryne and an organopalladium species, to generate excellent yields of cross-coupled products.     

Bromodimethylsulfonium bromide mediated Michael addition of amines to electron deficient alkenes

Bromodimethylsulfonium bromide has been found to be an efficient catalyst for the Michael addition of a wide variety of amines to electron deficient alkenes at room temperature. The protocol is very simple and chemoselective. Aliphatic and benzylic amines undergo conjugate addition within a very short period under solvent-free conditions and provide excellent yields of products.     

1,1-Carboboration

The use of very electrophilic boranes RB(C(6)F(5))(2) widens the scope of the 1,1-carboboration reaction substantially. Simple terminal alkynes HC≡CR undergo this reaction with the RB(C(6)F(5))(2) reagents rapidly under mild conditions to give high yields of very useful new alkenylborane products. Even internal alkynes RC≡CR undergo 1,1-carboboration with the RB(C(6)F(5))(2) reagents to provide a novel way of carbon-carbon σ-bond activation. Variants of these reactions involving phosphorus substituted alkynes and more complex bisalkynyl main group and transition metal substrates give rise to the formation of very interesting functionalized metallacyclic products upon treatment with RB(C(6)F(5))(2) reagents by means of reaction sequences involving selective 1,1-carboboration steps.     

Intramolecular endo-dig hydrosilylation catalyzed by ruthenium: evidence for a new mechanistic pathway

The ruthenium catalyst [Cp*Ru(MeCN)3]PF6 effects a novel intramolecular hydrosilylation of homo- and bis-homopropargylic alcohols, producing products of unique regioselectivity under very mild conditions with excellent selectivity. The reaction is compatible with a wide range of functional groups and tolerates substantial steric bulk. In addition to producing valuable synthetic intermediates thus far obtainable only in circuitous fashion, the results imply the necessity for a reexamination of the mechanism surrounding trans-hydrosilylation reactions, at least for ruthenium catalysts. At the very least, a simple cis addition/isomerization mechanism almost certainly cannot be active in this case. A silicon-ruthenium transposition could potentially provide a rationalization. However, the evidence for any products of syn addition with nonhydrido ruthenium catalysts is very scarce. Alternatively, a direct trans addition to orthogonal p-systems is also a possibility.     

Reduction of β-hydroxysulfoxides: Application to the synthesis of optically active epoxides

β-hydroxysulfoxides of opposite stereochemistry can be prepared in very high diastereoisomeric excesses (90 to 95%) by reduction of β-ketosulfoxides with DIBAL or DIBAL/ZnCl₂. A very efficient method to transform these reduction products into optically active epoxides is also described.     

Palladium-catalyzed cross-coupling reaction: Direct allylation of aryl bromides with allyl acetate

Various aryl bromides underwent a palladium-catalyzed cross-coupling reaction with allyl acetate in the presence of hexa-n-butylditin to give the allylated products in very high yields.     

X射线荧光光谱法测定洗衣粉中硅、铝、磷、硫的初步研究

用X射线荧光光谱法测定了洗衣粉中硅，铝，磷，硫的含量，并与化学法进行了比较。结果表明，本法样品处理简单，分析速度快，可用于快速确定洗衣粉的化学成分。     

Determination of short-lived activation products in neutron-irradiated sodium through application of hydrated antimony pentoxide

A method for the determination of short-lived activation products in neutron-irradiated sodium is described. It is based on hydrolysis of sodium with methanol, separation of Na⁺ with specially prepared antimony pentoxide (HAP) possessing very high selectivity and capacity, and subsequent gamma-spectroscopic measurement of the activation products.     

CNS‐Agent Precursor: A Simple and Efficient Synthesis of an Antipsychotic Drug Fluanisone

An efficient synthesis of antipsychotic drug fluanisone has been carried out in seven steps with an overall yield of 32.2%. The synthesis was started from 4‐fluorobenzaldehyde. All the reactions were very clean and the isolation of products was very easy.     

Transfer of surface polymerase reaction products to a secondary platform with conservation of spatial registration

Here, we describe a method for directly transferring very small amounts of reaction products from one surface to another. The approach is illustrated using a T4 DNA polymerase reaction to extend primers hybridized to a surface-confined DNA template. Following the extension reaction, the resulting oligonucleotide is transferred to a product surface. The important results are that (1) the spatial registration of the product is preserved after transfer; (2) the same reactant surface can be used to generate and transfer multiple iterations of products; and (3) the reaction products are biologically active after transfer.