Guanidine Carbonate Research Articles

Hydrogen bonded complexes of cyanuric acid with pyridine and guanidinium carbonate

Hydrogen bonded complexes of cyanuric acid (CA) with pyridine, [C3N3H3O3:C5H5N], 1, and guanidinium carbonate [C3H2N3][C(NH2)3],2, have been prepared at room temperature and characterized by single-crystal X-ray diffraction. Structure of 1 shows pyridine molecules substituting the inter-tape hydrogen bond in CA by N-H… N and C-H…O hydrogen bonds. The structure reveals CA-pyridine hydrogen-bonded single helices held together by dimeric N-H…O hydrogen bonding between CA molecules. In2, the CA tapes, resembling a sine wave interact with the guanidinium cations through N-H…O and N-H…N hydrogen bonds forming guanidinium cyanurate sheets.

Fast advancement and hardening acceleration of low condensation alkaline phenol-formaldehyde resins by esters and copolymerized urea. II. Esters during resin reaction and effect of guanidine salts

Guanidine carbonate is shown to be an accelerator of phenol-formaldehyde (PF) resins that while yielding slightly slower gel times than triacetin when added to a PF resin glue mix, is also capable of giving glue-mix pot lives on the order of several days. Hence, this is long enough to be premixed with the resin long before use. Both triacetin and guanidine carbonate used as simple glue-mix additives are shown to increase the ultimate strength of the resin bond, whatever the length of the curing time used for the purpose. This is shown by thermomechanical analysis and the application to wood particleboard. Triacetin is shown to be usable during PF resin preparation rather than just being added to the glue mix, yielding better resins capable of giving higher bond values without a great acceleration of the geling of the resin itself. The mechanisms involved in the acceleration of PF resins introduced by both compounds appears to be based on facilitating reactions of crosslinking involving carbonic acid ions present in the resin solution. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 249–259, 2000

An Approach toC-Branched and Heterocyclic Anellated Pyranosides by Reaction ofα-D-erythro-Hexopyranosid-2-ulose with Orthoformic Acid Derivatives

The push-pull functionalization of the ulose 1 to give the (E)-configurated dimethylaminomethylene pyranosidulose 2 was achieved with bis(dimethylamino)tert-butoxymethane. Substitution of the dimethylamino group by different amines provided the corresponding sugar enamines 3 as (Z) isomers. 2 reacted with hydrazine hydrate to furnish the pyrano[3,4-c]pyrazole 4. Treatment of 2 with acetamidine hydrochloride, benzamidine hydrochloride, S-methylisothiouronium methylsulfate and guanidine carbonate, respectively, in the presence of bases yielded the pyrimidoanellated pyranosides 5. Reaction of 2, ethyl 2-cyano-acetimidate hydrochloride 7 and sodium hydride afforded a mixture of a pyrido- and pyranoanellated pyranoside 9 and 10, respectively.

Synthesis and crystal structure of [Tb4(H2O)2](C2O4)2(C5H6O4)4

A terbium complex associating two ligands, oxalate and glutarate, was prepared under hydrothermal conditions at 200°C by treating an aqueous suspension of terbium oxalate decahydrate with glutaric acid and guanidinium carbonate. Its structure was solved by X-ray diffraction on a single crystal. It crystallizes in the monoclinic space group P21 with lattice constants, a = 9.514(1) A, b = 9.0681(8) A, c = 19.702(2) A, and β = 97.90(1)°. The terbium atoms and the oxalate ligands build dense chains which are connected by one side of the carboxylic group of some glutarate ligands, thus forming a sheet at the c level ≅ 0 and 1/2. These sheets are bridged by glutarate groups. The terbium atoms are ninefold coordinate with nine oxygen atoms of the ligands or with one water molecule and eight oxygen atoms of the ligands. Each polyhedron of the terbium atoms share one edge and one face of oxygen atoms with the two neighboring ones. The oxalate ligands are bischelating and bismonodentate. The coordination scheme of glutarate differs: either they are bismonodentate from one side and chelating and monodentate from the other side or they are chelating and monodentate from both sides.

Mineralization of guanidine derivatives in soils

Mineralization of eleven guanidine derivatives was studied in three soils of varying levels of microbial biomass C to evaluate their potential as fertilizer N sources. The guanidines mineralized slowly. Their mineralization generally started after a lag phase which increased with concentration. Mineralization of dimethylguanidine sulphate was the fastest (7–63 days) and tetramethyl guanidine slowest (>98 days) in all soils and at concentrations equivalent to 100 and 500 μg N g-1 soil. The mineralization rates increased with concentration except for guanidine hydrochloride, guanidine thiocyanate, nitroguanidine, and tetramethyl guanidine. They mineralized faster in soils with higher microbial biomass C. The mineralization of guanidines may be classified into four groups: rapidly mineralized (dimethyl guanidine sulphate); mineralized after a lag phase (guanidine sulphate, guanidine carbonate, guanidine acetate, guanidine hydrochloride and guanidine thiocyanate); a fraction of applied N rapidly mineralized with the gradual mineralization of the remaining N (guanidine nitrate, aminoguanidine nitrate, aminoguanidine carbonate); and very slowly mineralized (nitroguanidine, tetramethyl guanidine). None of the guanidines inhibited germination of wheat and excepting guanidine hydrochloride which reduced growth or guanidine thiocyanate that killed seedling, other guanidines increased the dry matter production.

Investigation into the Hydrothermal Assembly of Molybdenum Polyoxoanion Solids in the Presence of 4-Aminobenzoic Acid, Guanidinium Carbonate, and Aminoacetic Acid

The hydrothermal synthesis of three novel molybdenum polyoxoanion solids in the presence of 4-aminobenzoic acid, guanidinium carbonate, and aminoacetic acid and their crystal structures are reporte...

Cloud points and Θ temperatures of aqueous poly( N-vinyl-2-pyrrolidone) solutions in the presence of denaturing agents

Cloud point curves have been determined for various concentrations of aqueous solutions of poly( N-vinyl-2-pyrrolidone) in the presence of a variety of denaturing agents (e.g. thiourea, guanidinium chloride and guanidinium carbonate). From these θ temperatures have been found. The resulting dependences of the critical temperature theta (between 320 and 350 K) on the molar concentration can be expressed as a sequence showing the increasing effect of denaturants in salting out the polymer. The increasing order of effectiveness of denaturing agents increasing the θ temperature is guanidinium carbonate > guanidinium chloride > thiourea. The change of θ temperature by denaturing agents was found to be the result of the changes taking place in the hydrophobic/ hydrophilic interactions among the polymer, solvent and additive denaturing agents, and of the influence of denaturing agent—polymer interactions.

Spectrophotometric behavior of polyvinylpyrrolidone in aqueous solutions. II. The effects of denaturing agents

Electronic spectral behavior of aqueous polyvinylpyrrolidone solutions have been investigated by UV-vis spectrophotometry. n → * electronic excitations of the polymer were observed to shift longer wavelengths with a variety of denaturing agents. The shifting effect of denaturing agents on the λmax increased in the order guanidinium carbonate ≡ guanidinium sulfate > guanidinium chloride > urea. Intrinsic viscosities of different concentrations of aqueous solutions of polyvinylpyrrolidone with the same denaturing agents have also been determined. Intrinsic viscosity number, [η], of polymer solutions decreased with the addition of denaturing agents. The slope, kH[η]2, of the polymer was also observed to decrease in the presence of denaturing agents. Shift to the longer wavelengths and decrease in the viscosity characteristics can be explained by the break of the molecular association between the polymer and the water molecules. © 1997 John Wiley & Sons, Inc. J Appl Polm Sci 65:1307–1311, 1997

Synthesis of 2‐aminoquinazolines from ortho‐fluorobenzaldehydes

AbstractThe reaction of guanidine carbonate with various ortho‐fluorobenzaldehydes in N,N‐diinethylacetamide was investigated as a potential route for preparing 2‐aminoquinazolines. Eleven new 2‐aminoquinazolines were elaborated in this manner in low to moderate yields. In general the best results were obtained with ortho‐fluorobenzaldehydes possessing an electron withdrawing substituent at the other ortho position. Complex mixtures were obtained using 2‐fluorobenzaldehyde, 2,5‐difluorobenzaldehyde and 2‐fluoro‐5‐methoxybenzaldehyde which were not resolved.

Enhancing Biodegradation of Petroleum Hydrocarbons with Guanidinium Fatty Acids

Bioremediation of hydrocarbon-contaminated soils is an attractive process for treating contaminated soils because it converts contaminants into harmless byproducts at low cost. However, the process is slow and typically requires months to years to reach regulated end points. In laboratory studies, we have been able to improve the process by adding selected guanidinium fatty acids to the contaminated soils. One of these materials, guanidinium cocoate, was synthesized from coconut acid and guanidine carbonate in a facile one-step process. Rates of biodegradation enhancement of nonvolatile hydrocarbons were evaluated using either oxygen and carbon dioxide respirometry in soil slurries or periodic measurements of extractable hydrocarbon residues in unsaturated soil microcosms. Results show rate enhancements in both soil slurries and unsaturated soil microcosms when these systems were treated with 500−1500 ppm of the surfactant. Adding small amounts of CGS to a silty clay soil containing aged lubricant-type hydrocarbons increased rates of hydrocarbon disappearance, mineralization, and oxygen utilization in unsaturated soil and soil slurry systems. Based on these initial investigations, doses of approximately 2 lb of CGS/t of soil appear effective at increasing rates of biodegradation.

Synthesis of 5‐(4‐substituted benzyl)‐2,4‐diaminoquinazolines as inhibitors of candida albicans dihydrofolate reductase

AbstractSeveral 5‐(4‐substituted benzyl)‐2,4‐diaminoquinazolines were prepared as potentially selective inhibitors of Candida albicans dihydrofolate reductase. These compounds were synthesized by a novel route, which included as a key step the displacement of a fluoro group in 2,6‐difluorobenzonitrile by the anions of ethyl or methyl 4‐substituted phenylacetates. The resultant diarylacetates were saponified and decarboxylated to the 2‐fluoro‐6‐(4‐substituted phenyl)benzonitriles. Ring closure of these benzonitriles with guanidine carbonate gave the 5‐(4‐substituted benzyl)‐2,4‐diaminoquinazolines.

Synthesis of 2‐aminoquinazolines from ortho‐fluoroketones

AbstractThe reactions of ten ortho‐fluoroketones with guanidine carbonate in N,N‐dimethylacetamide were investigated as a new synthetic approach to 2‐amino‐4‐alkyl‐ and 2‐amino‐4‐arylquinazolines. The yields obtained ranged from low to moderate and were highly dependent upon the nature of the substituents on the reactant. Eight new quinazolines were elaborated in this study.

Effects of denaturing agents on the molecular association of dextran. I. Aqueous solutions

AbstractMolecular association of aqueous dextran solutions have been investigated by viscosimetric measurements. Intrinsic viscosities of different concentrations of aqueous solutions of dextran with a variety of denaturing agents have been determined. Intrinsic viscosity numbers and Huggins constants of dextran solutions decreased with the addition of denaturing agents. The reducing effect of denaturing agents on the intrinsic viscosities and Huggins constants decreased in the order guanidinium sulfate > guanidinium carbonate > guanidinium chloride > thiourea > urea. The effect of temperature on the intrinsic viscosities of dextran and dextran denaturing agent solutions have also been investigated. A small change in the intrinsic viscosity values was observed for dextran in 1M of guanidinium carbonate and sulfate solutions with the increase of the temperature from 25 to 40 °C. Aqueous dextran solutions, however, showed a significant decrease in the intrinsic viscosities in the same temperature range. © 1995 John Wiley & Sons, Inc.

Studies in fluorinated 1,3-diketones and related compounds. Part XVII. Synthesis and spectroscopic studies of some new 5-alkyl-3-fluoroaryl-1-pentafluoroaryl-pyrazoles and 2-amino-6-alkyl(perfluoroalkyl)-4-aryl pyrimidines

Six new 3-(4′-fluorophenyl)-1,5-trisubstituted pyrazoles have been synthesized from the appropriate fluorinated 1,3-diketones and pentafluorophenylhydrazine in the presence of absolute ethanol and hydrochloric acid, viz., 1-pentafluorophenyl-3-(4′-fluorophenyl)-5- methylpyrazole, 1-pentafluorophenyl-3-(4′-fluorophenyl)-5-trifluoromethylpyrazole, 5- ethyl-1-pentafluorophenyl-3-(4′-fluorophenyl) pyrazole, 5-(pentafluoroethyl)-1-pentafluorophenyl-3-(4′-fluorophenyl) pyrazole, 1-pentafluorophenyl-3-(4′-fluorophenyl) 5-n-propylpyrazole and 5-(heptafluoropropyl)-1-pentafluorophenyl-3-(4′-fluorophenyl) pyrazole. In addition, six new 2-amino-4-(4′-fluorophenyl)-6-alkyl(perfluoroalkyl)-trisubstituted pyrimidines have been prepared from the same diketones and guanidine carbonate in the presence of hydrochloric acid using absolute ethanol as a solvent, viz., 2-amino- 4(4′-fluorophenyl)-6-methylpyrimidine, 2-amino-4(4′-fluorophenyl)-6-trifluoromethylpyrimidine, 2-amino-6-ethyl-4(4′-fluorophenyl)pyrimidine, 2-amino-6-pentafluoroethyl-4-(4′-fluorophenyl)pyrimidine, 2-amino-4-(4′-fluorophenyl)-6-n-propylpyrimidine and 2- amino-6-(heptafluoropropyl)-4-(4′-fluorophenyl)pyrimidine. All new fluorinated pyrazoles as well as pyrimidines have been characterized by elemental analyses as well as spectral studies.

Crystal Structures and 35Cl NQR Spectra of the Metastable and the Stable Phase of Guanidinium bis-Monochloroacetate, [C(NH2)3 ]⊕[(ClH2C)COOH ••• OOC(CH2Cl)l⊖

Abstract From acid aqueous solutions of guanidinium carbonate and monochloroacetic acid, (ClH2C)COOH :H2 NC( = NH)NH2 ≧ 2.5, the compound [C(NH2)3]⊕ [(ClH2C)COOH • • • OOC(CH2Cl)]⊖ crystallizes with the space group Ci 1P1̄,Z = 4, a = 1147.4 (5) pm, b= 1113.2 (5) pm, c = 876.5 (4) pm, α = 88.66 (2)°, β = 80.31 (2)°, γ = 84.41 (2)° (metastable phase I). Cooled to 77 K once, phase I transforms at room temperature slowly into the stable phase II, orthorhombic, D2h 15 - Pbca, Z = 8, a= 1299.2 (4) pm, b= 1533.7 (4) pm, c= 1073.9 (3) pm. The crystal structure determinations show for both phases an ionic lattice with guanidinium cations [C(NH2)3]⊕ and acid bis-(monochloroacetate) anions [(ClH2C)COOH • • • OOC(CH2Cl)]⊖ in which a monochloroacetic acid molecule and a monochloroacetate ion are bound to the dimer anion by an asymmetric hydrogen bond O-H • • • O. A strong crystal field effect, much dependent on temperature, is observed in the 35Cl NQR quadruplet spectrum of phase I, with a frequency spread of ≈4 MHz at 300 K, whereas in phase II the frequency splitting of the observed 35Cl NQR doublet is almost constant between 77 K and 310 K, about 700 kHz. The phase transition I → II is very sluggish and unidirectional. The transition II → I needs the recrystallization of II from water. Structure and dynamics of the two solid phases are discussed.

Synthesis of some novel halogenated 2,4‐diaminoquinazolines

AbstractThree new 2,4‐diaminoquinazolines, the 5,6‐difluoro, 6,7‐difluoro and 7,8‐difluoro isomers were prepared by the reaction of the requisite trifluorobenzonitrile and guanidine carbonate. Surprisingly, 2,3,6‐trifluorobenzonitriles gave 2,4‐diamino‐5,6‐difluoroquinazoline exclusively as determined by high resolution nuclear magnetic resonance spectroscopy. On the other hand, 3‐amino‐2,6‐difluorobenzonitrile on reaction with guanidine carbonate yielded only 5‐fluoro‐2,4,8‐triaminoquinazoline. This compound was subsequently converted to 8‐chloro‐2,4‐diamino‐5‐fluoroquinazoline using the Sandmeyer procedure. The nitration of 2,4‐diamino‐8‐fluoroquinazoline occurred exclusively at position six yielding 2,4‐diamino‐8‐fluoro‐6‐nitroquinazoline, which upon reduction with stannous chloride afforded 8‐fluoro‐2,4,6‐triaminoquinazoline. In a similar fashion 7‐fluoro‐2,4‐diaminoquinazoline underwent nitration at position six and was then reduced to give 7‐fluoro‐2,4,6‐triaminoquinazoline. Finally, both of these triaminoquinazolines were converted to the 6‐chloro derivatives under Sandmeyer conditions to yield 6‐chloro‐2,4‐diamino‐8‐fluoroquinazoline and 6‐chloro‐2,4‐diamino‐7‐fluoroquinazoline, respectively.

Further studies on the synthesis of quinazolines from 2‐fluorobenzonitriles

AbstractRecently, we reported that appropriately substituted 2‐fluorobenzonitriles undergo cyclization with guanidine carbonate to afford 2,4‐diaminoquinazolines usually in good to excellent yield. This paper describes the preparation of a variety of new 2,4‐diaminoquinazolines substituted at positions five or seven. In addition, the reactions of selected 2‐fluorobenzonitriles with formamidine acetate or acetamidine acetate were examined. The results obtained demonstrate that the analogous 4‐amino‐ and 2‐methyl‐4‐aminoquinazolines can be prepared by this approach but that the yields are considerably lower than when guanidine carbonate is employed as the cyclization reagent.

Measurement of (C13)arginine incorporation into apolipoprotein B-100 in very low density lipoproteins and low density lipoproteins in normal subjects using (13C)sodium bicarbonate infusion and isotope ratio mass spectrometry

We describe a new stable isotope technique for the in vivo study of hepatic plasma protein synthesis in humans. The method involves the infusion of (13C)sodium bicarbonate for 1 h and the measurement of the isotopic enrichment of (13C)arginine in newly synthesized apolipoprotein B of very low density lipoproteins (VLDL-apoB) and low density lipoproteins (LDL-apoB) in blood samples taken over a 5-6 h period from the commencement of the infusion. Isotope ratio mass spectrometry was utilized to measure 13CO2 enrichment following hydrolysis of these proteins and conversion of the guanidinium carbon of arginine in the hydrolysate to carbon dioxide by sequential incubation with arginase and urease. The method is capable of measuring isotopic enrichment as low as 0.001 at.% excess (APE) with a precision of 1.2%. In both subjects studied, the (13C)arginine of VLDL-apoB reached enrichments of 0.2 APE and that of the arginine of LDL-apoB, 0.03 APE. Incorporation of labeled arginine into LDL-apoB was demonstrable at 60-90 min. The new technique is safe and is applicable to the study of the hepatic biosynthesis of a wide range of plasma proteins.

ChemInform Abstract: Special Reactions of α,β‐Unsaturated Ketones. Part 1. Dimerization of 2‐Benzylidene‐1‐indanone in the Presence of Strong Bases.

AbstractHeating of the indanone (II) with guanidine carbonate or thiourea yields not the expected indenopyrimidines, but ‐ without consumption of guanidine or thiourea ‐ the dimer (I).

Direct synthesis of 2,4‐diaminoquinazolines from 2‐fluorobenzonitriles

AbstractIn a search for new methods for preparing 2,4‐diaminoquinazolines having a diversity of substituents in the benzenoid ring, it was found that the reaction of 2,6‐difluorobenzonitrile with guanidine carbonate gave 2,4‐diamino‐5‐fluoroquinazoline in excellent yield. Extension of this approach to other 2‐fluorobenzonitriles, some of which were elaborated for the first time, showed that this reaction possesses considerable generality. The cyclization was successful even when electron donating groups were present at position six. Only in two cases where a primary or secondary amino group was also present ortho to the cyano group was this transformation unsuccessful.