ABSTRACT
This paper presents an investigation of the feasibility of intercalating lignocellulose/xanthan gum (XG) and organic polymers into bentonite to obtain an efficient fire extinguishing gel material. The bentonite-based hybrid gel was prepared by adding polyacrylates, Al(OH)3, lignocellulose, and XG into a bentonite suspension, and the resulting gel was characterized. The results showed that no cracking and powdering were found on the surface of the hybrid gel due to the formation of the cross-linked network in the bentonite, and a wide mesopore size distribution and good thermal stability were observed. The hybrid gel also exhibits a wide range of water adsorption ratios, excellent water retention, adjustable gelation times, shear thinning characteristics, and improved compressive strength (the yield stress reaches up to 13 MPa). Based on these characterizations, the mechanism of hybrid gel formation is proposed. The inhibition performance of the hybrid gel on coal spontaneous combustion indicates that the addition of the gel slows down the oxygen chemisorption and thus increases the ignition temperature. Due to the presence of the hybrid gel in the coal, the crossing point temperatures were increased and the lowest CO concentration was produced.
ABSTRACT
Mine fires are one of the primary natural disasters in coal production. The majority of mine fires are caused by the spontaneous combustion of coal. To reduce the risk of spontaneous combustion of coal, a new fire prevention and extinguishing hydrogel has been developed. Poly(acrylic acid-co-methacrylamide) (P(AA-co-MAA)) and chitosan-grafted poly(acrylic acid-co-methacrylamide) (CTS-g-P(AA-co-MAA)) were prepared by aqueous solution polymerization, and their characteristics have been studied by scanning electron microscopy and Fourier transform infrared spectroscopy. The swelling ability and water retention of the hydrogels were also tested and compared. The experimental results showed that the grafting of chitosan can improve the water-absorbing ability of the hydrogel in acidic solution and deionized water and enhance the water retention of the hydrogel. The thermogravimetric experiments of the mixture of the hydrogel and coal showed that the thermal stability of the mixture was the best when the ratio of hydrogel to coal was 1:10, and the grafting of chitosan did not weaken the thermal stability of the hydrogel. In addition, the thermogravimetry and differential scanning calorimetry measurement of coal with the hydrogel in air proved that the CTS-g-P(AA-co-MAA) hydrogel effectively prevented the initial oxidation of coal. Thus, CTS-g-P(AA-co-MAA) is recommended as an inhibitor in preventing coal oxidation.
ABSTRACT
Some chemical substances could improve the sorption capacity of biochars. In this paper, sodium humate was introduced to the pyrolysis of two biomass samples at 600 °C, and sodium humate-biochars have been successfully synthesized. The surface area and surface morphologies of all of the biochars were characterized, and the results indicated that sodium humate-biochars have higher surface areas, and sodium humate particles were grown on the surfaces of the biochars. Adsorption isotherm and kinetics of methylene blue (MB) onto the biochars were carried out by batch adsorption experiments. The results suggested that incorporation of sodium humate could increase the adsorption capacity of MB onto the biochars (from 10.79 to 16.21, 8.62 to 11.03 mg/g for peanut shells and white clover residues, respectively). The adsorption experimental results also suggest that the adsorption process of MB onto sodium humate-biochars is controlled by both intraparticle diffusion and film diffusion. As a whole, this work probes the possibility of sodium humate to modify the surface of biochar and improve its adsorption ability with contaminants.
ABSTRACT
A series of 5-arylisoxazole derivatives were synthesized via the reaction of 3-(dimethyl-amino)-1-arylprop-2-en-1-ones with hydroxylamine hydrochloride in aqueous media without using any catalyst. This method has the advantages of easier work-up, mild reaction conditions, high yields, and an environmentally benign procedure.
Subject(s)
Isoxazoles/chemistry , Hydroxylamine/chemistry , Molecular Structure , WaterABSTRACT
A mild and efficient synthesis of pyrazolo[3,4-b]pyridine-6(7H)-one derivatives via a three-component reaction of an aldehyde, Meldrum's acid and 3-methyl-1H-pyrazol-5-amine using recyclable polyethylene glycol (PEG)-400 as a reaction medium is described. This method has the advantages of accessible starting materials, good yields, mild reaction conditions and begin environmentally friendly.
Subject(s)
Polyethylene Glycols/chemistry , Pyridines/chemistry , Aldehydes/chemistry , Dioxanes/chemistry , Pyrazoles/chemistryABSTRACT
The treatment of 2-amino-N'-arylbenzohydrazide and o-halogenated benzaldehyde in the presence of CuBr and Cs2CO3 gave 5-arylindazolo[3,2-b]quinazolin-7(5H)-one in high yields. This procedure contains an Ullmann-type reaction and provides an efficient method to construct fused tetracyclic heterocycles.
Subject(s)
Bromides/chemistry , Copper/chemistry , Quinazolinones/chemical synthesis , Catalysis , Molecular Structure , Quinazolinones/chemistryABSTRACT
A concise and efficient route to new and interesting heterohelicene-like molecules has been developed through the one-pot, cascade reductive coupling reaction of o-hydroxydiimines or o-nitrodiimines and triphosgene in the presence of TiCl4/Sm. Purification of the final products only required a single recrystallization leading to high purity. High diastereoselectivity was also achieved, and two structures of the final products were confirmed by X-ray diffraction analysis.
ABSTRACT
A highly efficient, catalyst-free synthesis of polysubstituted pyrroles by means of a novel four-component domino reaction of an arylglyoxal monohydrate, an aniline, a dialkyl but-2-ynedioate, and malononitrile is reported. This transformation proceeded via a 6,6a-dihydrofuro[2,3-b]pyrrole as the key intermediate.
Subject(s)
Pyrroles/chemical synthesis , Aniline Compounds/chemistry , Catalysis , Molecular Structure , Nitriles/chemistry , Pyrroles/chemistryABSTRACT
An efficient and convenient method for the preparation of cis-bispyrimidodiazepinone derivatives has been described. A variety of substrates can participate in the process with good yields, making this methodology suitable for library synthesis in drug discovery efforts. The mechanistic course of the reaction suggests the involvement of reduction, coupling which determine the products' configuration and cyclization by one-pot.
Subject(s)
Azepines/chemical synthesis , Pyrimidinones/chemical synthesis , Samarium/chemistry , Titanium/chemistry , Models, Molecular , Molecular StructureABSTRACT
A series of novel spiropyrrolidines and spirothiapyrrolizidines were synthesized via a three-component 1,3-dipolar cycloaddition reaction of isatin or acenaphthenequinone, sarcosine or thiaproline and 4-hydroxy-6-methyl-3-((E)-3-phenylacryloyl)-2H-pyran-2-ones in refluxing ethanol. Advantages of this method include the availability of starting materials, mild reaction conditions, high yields, and the complete regioselectivity observed.
Subject(s)
Azo Compounds/chemistry , Pyrrolidines/chemical synthesis , Spiro Compounds/chemical synthesis , Thiazolidines/chemical synthesis , Thiosemicarbazones/chemistry , Combinatorial Chemistry Techniques , Crystallography, X-Ray , Cyclization , Models, Molecular , Molecular Structure , Pyrrolidines/chemistry , Spiro Compounds/chemistry , Stereoisomerism , Thiazolidines/chemistryABSTRACT
An efficient, convenient, one-pot synthesis of 2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazolin-5(1H)-one and 2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazoline-1,5-dione was accomplished in good yields via the novel reductive cyclization of 2-nitrobenzamides with haloketones or keto acids mediated by SnCl(2).2H(2)O system. A variety of substrates can participate in the process with good yields, making this methodology suitable for library synthesis in drug discovery efforts.
Subject(s)
Pyrroles/chemical synthesis , Quinazolinones/chemical synthesis , Tin Compounds/chemistry , Combinatorial Chemistry Techniques , Crystallography, X-Ray , Models, Molecular , Molecular Structure , Pyrroles/chemistry , Quinazolinones/chemistry , Small Molecule Libraries , StereoisomerismABSTRACT
A convenient and efficient method for the synthesis of novel dispiropyrrolidine bisoxindole derivatives by 1,3-dipolar cycloaddition reaction of azomethine ylides has been developed. The synthesis was achieved by using a one-pot multicomponent procedure. The features of this procedure were characterized by the following: mild reaction conditions, high yields, high regio- and stereoselectivity, one-pot procedure, and operational simplicity.
Subject(s)
Indoles/chemical synthesis , Pyrrolidines/chemistry , Magnetic Resonance Spectroscopy , Mass Spectrometry , Models, Molecular , Spectrophotometry, Infrared , StereoisomerismABSTRACT
A series of new naphtho[1,2-e][1,3]oxazine derivatives such as trans-1,3-diaryl-1H-naphtho[1,2-e][1,3]oxazine-2(3H)-carbonyl chloride, 1-aryl-2-benzyl-1,2- dihydronaphtho[1,2-e][1,3]oxazine-3-one, and trans-1,3-diaryl-1H-naphtho[1,2-e] [1,3]oxazine-2(3H)-carbaldehyde were selectively synthesized via a chemoselective reaction of 1,3-diaryl-2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazines and triphosgene or triethyl orthoformate, respectively, induced by different low-valent titanium systems. This method has the advantages of short reaction time (15 min), convenient manipulation, and high chemoselectivity.
Subject(s)
Combinatorial Chemistry Techniques/methods , Naphthols/chemical synthesis , Oxazines/chemical synthesis , Titanium/chemistry , Magnetic Resonance Spectroscopy , Molecular Structure , Substrate Specificity , Time FactorsABSTRACT
The synthesis of a series of biquinazoline-2,2'-diones starting from o-nitrobenzaldehydes, anilines, and triphosgene is presented. This general approach features a novel and easy way for access to the target products. The mechanistic course of the reaction suggests the involvement of reduction, coupling, and cyclization by one-pot. These compounds were also investigated in vitro for anticancer activity, and some were found to have good anticancer activity.
Subject(s)
Antineoplastic Agents/chemical synthesis , Quinazolines/chemical synthesis , Aniline Compounds/chemistry , Antineoplastic Agents/chemistry , Antineoplastic Agents/therapeutic use , Benzaldehydes/chemistry , Cell Line, Tumor , Humans , Inhibitory Concentration 50 , Liver Neoplasms/drug therapy , Molecular Structure , Phosgene/analogs & derivatives , Phosgene/chemistry , Quinazolines/chemistry , Quinazolines/therapeutic useABSTRACT
A mild, efficient, one-pot protocol for the synthesis of indazole-3(2H)-ones via cyclization of nitro-aryl substrates through low-valent titanium reagent has been described. The method used Triethylamine (TEA) to control pH. Particularly, 2-aminobenzonitriles were synthesized by one step easily. The mechanistic course of the reaction suggests the involvement of an anion leading to an intramolecular cyclization via N-N bond formation.
Subject(s)
Indazoles/chemical synthesis , Nitriles/chemical synthesis , Combinatorial Chemistry Techniques/methods , Crystallography, X-Ray , Cyclization , Indazoles/chemistry , Models, Molecular , Molecular Structure , Nitriles/chemistry , StereoisomerismABSTRACT
The synthesis of a series of quinazolinone derivatives such as 2-thioxoquinazolinones, imidazo[1,2-c]quinazolin-5-amines, and benzimidazo[1,2-c]quinazolin-5-amines, starting from nitro-compounds has been described. This general approach features a easy way for access to the target quinazolinone derivatives. The key cyclization step embraces the formation of a thiourea intermediate, mediated by low-valent titanium, and the other important intermediate was also obtained. A variety of substrates can participate in the process with good yields, making this methodology suitable for library synthesis in drug discovery efforts.
Subject(s)
Nitro Compounds/chemistry , Quinazolinones/chemical synthesis , Titanium/chemistry , Combinatorial Chemistry Techniques , CyclizationABSTRACT
1,2,3,5-Tetrasubstituted and 1,2,3,4,5-pentasubstituted pyrroles may be synthesized through three-component reaction of 1,3-diketones, aldehydes, and amines induced by low-valent titanium reagent. High regioselectivity was achieved. Compared with the classical synthetic method, this new method has the advantages of short reaction time (15 min), high yields, convenient manipulation, and high regioselectivity.