Syntheses and bioactivities of mixed butyl/cyclohexyl tin carboxylates

Eight novel compounds have been synthesized and they are two series of mixed tri(butyl/cyclohexyl) tin carboxylates:Bu_nCy_(3-n) SnO_2CR (n=1,2;R=n-C_3H_7,C_6H_5,4-ClC_6H_4,4-NO_2C_6H_4).Inaddition to the studies of their structures with IR,~(119)Sn and ~(13)C NMR,we tested their fungicidal,insec-ticidal and acaricidal activities.The percentage of inhibition to the aforementioned phytopathogen isabout 80—100% at 50 ppm in glasshouse and 100% for T.Uriticae at 500 ppm.Those findingsindicate that this kindof compounds have both fungicidal and acaricidal activities and mayhave a goodprospect for applications.     

Temperature-dependent relaxation study of tertiary butyl alcohol–water mixtures using TDR technique

Using time-domain reflectometry (TDR) technique, we have measured the complex permittivity of tertiary butyl alcohol (TBA)–water mixtures in the frequency range of 10 MHz–30GHz, at temperatures 15°C, 20°C and 25°C. The complex permittivity of TBA–water mixture shows Debye-type behaviour. The dielectric parameters such as dielectric constant and relaxation time were obtained from the complex permittivity spectra. The Kirkwood correlation factor and Bruggeman factor have also been determined to investigate inter- and intramolecular interaction among associating liquids.     

Influence of temperature on excess molar volumes for butyl acetate + aromatic hydrocarbons

Excess molar volumes dependence with temperature for the mixtures butyl acetate?+?aromatic hydrocarbons (toluene, ethylbenzene, p-xylene, mesitylene, isopropylbenzene, butylbenzene, isobutylbenzene, and t-butylbenzene) were determined from density measurements by a vibrating-tube densimeter. The excess molar volumes are positive or slightly negative in the studied mixtures over the whole composition range, attending to the solvent molecular weight, only the isobutylbenzene showing a sigmoid trend. Steric hindrance in these mixtures was analyzed in the light of partial excess molar volumes behavior. The experimental data were used to test semiempirical procedures of density prediction, and compute the binary interaction parameters of the Soave–Redlich–Kwong (SRK) and Peng–Robinson (PR) equations of state, which are of general interest in multicomponent thermodynamic functions estimation. The obtained results point out the interest of the equations of state to study complex mixtures and as a tool for predicting other magnitudes of general application for theoretical studies or processes calculations.     

Vapour–liquid equilibria of butyl acetate with aromatic hydrocarbons at 298.15 K

Vapour pressures of butyl acetate?+?benzene or toluene or o- or m- or p-xylene were measured by static method at 298.15?±?0.01?K over the entire composition range. The activity coefficients and excess molar Gibb's free energies of mixing (G ^E) for these binary mixtures were calculated by fitting vapour pressure data to the Redlich–Kister equation using Barker's method of minimizing the residual pressure. The G ^E values for the binary mixtures containing benzene are positive; while these are negative for toluene, ortho, meta and para xylene system over the whole composition range. The G ^E values of an equimolar mixture for these systems vary in the order: benzene?>?m-xylene?>?o-xylene?>?p-xylene?>?toluene     

Irradiation Initiated Grafting of Poly（butyl acrylate） onto Nano-sized Calcium Carbonate Particles

The present work reports the irradiation induced grafting polymerization onto nano-sized CaCO3 particles, mainly focusing on the effects of pretreatment with silane coupling agent. It is proved that poly(butyl acrylate) can be grafted onto the nanoparticles using the technical route suggested by the authors, and the silane treatment of the nanoparticles promotes the grafting polymerization.     

Intermolecular effects in macromolecular reactions—2. Decomposition of tert.butyl acrylate-styrene copolymers

Decomposition of tert.butyl acrylate (TBA) units in copolymers of TBA and styrene (STY) at 453 K has been studied. The rate diminishes with increase of STY content in the copolymer; pronounced autoacceleration is observed for all samples. Calculations revealed inadequacy of the intrachain mechanism of acceleration. Experimental data have been interpreted quantitatively in terms of both intra and intermolecular interactions of ester and carboxylic groups. Rate constants of the thermal and autocatalytic stages of the reaction appear to be independent of copolymer composition. The results confirm previous conclusion about determining contribution of intermolecular effects in the kinetics of the decomposition of poly TBA.     

Preparation and characterization of 2,4–D butyl ester capsule suspension for mitigation of its drift risk

A novel capsule suspension (CS) formulation was prepared by in situ polymerization of melamine formaldehyde (MF) resin which was the first time to be used to encapsulate 2,4–D butyl ester. The prepared 2,4–D butyl ester capsule suspensions were studied by ultraviolet spectrophotometer (UV), laser particle size analyzer, Optical microscopy (OM), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Results showed that the encapsulation efficiency reached 93.23%, and the mean particle size (D₅₀) could be reduced to 13.80 µm by adding 4% Tween80. OM and SEM images illustrated that the core-shell structure related largely to the stability of emulsion. The spherical microcapsules possessed with rougher outer surface and the shell was about 1.5-2.0 µm thick with good methanol tolerance. Then, the formation of pre-polymer, shell material and microcapsules were revealed by FT-IR. Finally, experiments showed that the 2,4–D butyl ester CS exhibited a sustained releasing behavior in water, which could reach to 14 days.     

Morphology and film formation of poly(butyl methacrylate)–polypyrrole core–shell latex particles

 Core–shell latex particles made of a poly(butyl methacrylate) (PBMA) core and a thin polypyrrole (PPy) shell were synthesized by two-stage polymerization. In the first stage, PBMA latex particles were synthesized in a semicontinuous process by free-radical polymerization. PBMA latex particles were labeled either with an energy donor or with an energy acceptor, in two different syntheses. These particles were used in a second stage as seeds for the synthesis of the core–shell particles. The PPy shell was polymerized around the PBMA core latex in an oxidative chemical in situ polymerization. Proofs for the success of the core–shell synthesis were obtained using nonradiative energy transfer (NRET) and atomic force microscopy (AFM). NRET gives access to the rate of polymer chain migration between adjacent particles in a film annealed at a temperature above the glass-transition temperature T _g of the particles. Slower chain migration of the PBMA polymer chains was obtained with the PBMA–PPy core–shell particles compared to rate of the PBMA polymer chain migration found with the pure, uncoated PBMA particles. This result is due to the coating of PBMA by PPy, which hinders the migration of the PBMA polymer chains between adjacent particles in the film. This observation has been confirmed by AFM measurements showing that the flattening of the latex film surface is much slower for the core–shell particles than for the pure PBMA particles. This result can again be explained by the presence of a rigid PPy shell around the PBMA core. Thus, these two complementary methods have given evidence that real core–shell particles were synthesized and that the shell seriously hinders film formation of the particles in spite of the fact that it is very thin (thickness close to 1 nm) compared to the size (750 and 780 nm in diameter) of the PBMA core. Transparency measurements confirm the results obtained by NRET and AFM. When the films are placed at a temperature higher than the T _g of PBMA, the increase in transparency is faster for films made with the uncoated PBMA particles than for films made with the coated PBMA particles. This result indicates again that the presence of the rigid PPy layer around the PBMA core reduces considerably the speed at which the structure of the film is modified when heated above the T _g of PBMA. Received: 02 September 1999 Accepted: 21 December 1999     

Liquid–liquid equilibria for butyl tert-butyl ether + (methanol or ethanol) + water at several temperatures

Liquid–liquid equilibrium (LLE) data for butyl tert-butyl ether + (methanol or ethanol) + water were measured experimentally at 298.15, 308.15 and 318.15 K. The experimental data were correlated with the NRTL and UNIQUAC equations. The equations were used to perform the correlation of each temperature data set and for the three temperatures data set simultaneously. The best results were found with UNIQUAC and NRTL (α = 0.1), respectively. Data prediction was carried out using the UNIFAC method, however the results found were not quantitative.     

A facile method to prepare polypropylene/poly(butyl acrylate)alloy via water–solid phase suspension grafting polymerization

Polypropylene/poly(butyl acrylate) alloy is produced by water–solid phase suspension grafting polymerization with a submicrometer microdomain where graft polymerization occurs within micropores of polypropylene particles prepared by reactor granule technology(RGT). The results show that the grafting percentage(GP) of butyl acrylate(BA) increases with the increase of the monomer concentration, which could reach 32.6% while the grafting efficiency(GE) is up to 98%. The addition of the crosslinking agent, triethylene glycol diacrylate(TEGDA), could improve GP up to 36.3%. Transmission electron microscopic(TEM) micrographs demonstrate that PBA microdomains distributed in PP matrix increase in size less than 500 nm. Moreover, TEM images show that the grafting phase exhibits a singlephase behavior with the addition of TEGDA, which implies that the ratio of graft copolymer increased.     

Use of Di‐tert‐butyl‐dicarbonate Both as a Protecting and Activating Group in the Synthesis of Dipeptides

Amide formation from amino acids was achieved in an easy and convenient one‐pot procedure using di‐tert‐butyl dicarbonate both as a protecting and an activating agent. A number of dipeptides have been synthesized in good yields.     

Preparation of a butyl–silica hybrid monolithic column with a “one-pot” process for bioseparation by capillary liquid chromatography

A butyl–silica hybrid monolithic column for bioseparation by capillary liquid chromatography (cLC) was prepared with butyl methacrylate and alkoxysilanes through a “one-pot” process. The effects of polycondensation temperature, volume percentage of N,N′-dimethylformamide, and content of cetyltrimethylammonium bromide and butyl methacrylate on the morphologies of the hybrid monolithic columns prepared were investigated in detail. Baseline separations of proteins and small peptides on the hybrid monolithic column were achieved by cLC with gradient elution. In addition, the resulting hybrid column was also applied for analysis of tryptic digests of bovine serum albumin by cLC coupled with tandem mass spectrometry. The results demonstrate its potential application in separation of complex biological samples.     

Two-dimensional correlation analysis of continuous online in situ ATR-FTIR on the adsorption of butyl xanthate at the surface of α-PbO

The adsorption behavior of butyl xanthate on the surface of lead oxide was investigated using continuous online in situ attenuated total reflectance Fourier transform infrared(ATR-FTIR) spectroscopy technique and two dimensional(2D) correlation analysis.The adsorbed layer studied was prepared by coating α-PbO particles onto the surfaces of the ZnSe crystal.The appearance of spectral peaks at 1203 cm~(-1),1033 cm~(-1) and their red shift indicated the formation and aggregation of xanthate at the surface of α-PbO.According to 1R intensity changes after rinsing with deionized water and a NaOH solution,the adsorption was proved to be a chemisorption type.The competition between xanthate and OH for the surfaces leads to desorption of xanthate at higher pH.The technique of 2D correlation ATR-FTIR spectroscopy was used to evaluate the changing order of spectral intensities in the adsorption process,and the results indicated that xanthate micelles were formed at the surfaces.The adsorption kinetics of butyl xanthate was found to be a pseudo-second-order reaction model and the adsorption capacity of butyl xanthate at α-PbO was as high as 281 mg g~(-1) after 150 min.     

ChromiumVI oxide −70% tert.butyl hydroperoxide,a simple catalytic system for oxidation of alcohols to carbonyl compounds

Oxidation of alcohols to carbonyl compounds was carried out by using catalytic amounts of CrO₃ and excess of aqueous t.BuOOH. This system is highly efficient in the case of secondary benzylic alcohols. A catalytic cycle which retains the initial oxidation state of chromium is proposed.     

Ring-opened Crystal Structure and Photochromism of 2,2-Bis（4-tertiary butyl phenyl）-3H-naphtho[2,1-b]pyran

The title compound, 2,2-bis（4-tertial butyl phenyl） naphthopyran, has been prepared and characterized by means of IR, ^1H NMR and elemental analysis, and its crystal structure was determined with X-ray diffraction in the ring-opened form after hydrolyzation. It belongs to monoclinic, space group P21/c, with a = 14.358（3）, b = 7.6725（15）, c = 24.470（5） А, β= 97.147（4）°, C_33H_36O2, Mr=464.62, V= 2674.8（9）А^3, Z = 4, Dc = 1.154 g/cm^3,μ= 0.070 mm^-1, F（000） = 1000, the final R = 0.0514 and wR = 0.1272 for 5444 observed reflections （I 〉 2σ（I））. X-ray analysis revealed that the C（13）-O（1） bond of the title compound cracks after UV irradiation, the six-membered heterocycles are destroyed, and zwitterionic intermediates come into being. The molecular structure in the ring-opened form is obtained after hydrolyzation. It is infrequent that the single-crystal structure is determined in a ring-opened form. A two-dimensional framework is formed by O-H…O and CAr-H…O hydrogen bonds. The UV-vis spectra show that the title compound exhibits excellent photochromic properties in solutions and polymers.