青霉素亚砜结晶生长与成核动力学

利用Mydlarz 和 Jones 模型（MJ2）,对乙酸丁酯中青霉素亚砜的成核与生长动力学进行研究。通过矩量法对MJ2模型进行处理后,利用晶体产品的粒度分布计算得到青霉素亚砜的生长速率与成核速率,然后利用最小二乘法拟合回归求解出成核与生长动力学方程参数。通过实验设计考察了过饱和度、温度与搅拌速度对青霉素亚砜晶体成核和生长过程的影响。研究表明青霉素亚砜晶体生长速率随过饱和度比的增加呈现指数型增长,确定青霉素亚砜晶体生长属于晶体表面生长控制过程。由于高速搅拌会增加青霉素亚砜晶体的破碎,促进了二次成核过程,随着搅拌速度的增加,晶体生长速率出现小幅下滑,而成核速率则明显升高。青霉素亚砜成核与生长动力学研究将有助于工业生产过程优化。     

Nucleation Kinetics and Growth Model of Penicillin Sulfoxide in Butyl Acetate

Nucleation kinetics and a growth model of penicillin sulfoxide in butyl acetate were studied. Nucleation parameters such as energy per unit volume, radius of critical nucleus, critical free energy barrier, and nucleation rate were evaluated. A laser method was selected to detect the first crystal in induction period studies. By means of scanning electron microscopy and surface entropy factor, the growth model of penicillin sulfoxide developed from butyl acetate could be determined.     

The effect of certain processing variables on the form ii to form i phase transformation in polybutene-1

Density and wide angle x-ray scattering techniques were used to study the form II to form I phase transformation in polybutene-1. The influence of deformation by cold rolling, orientation produced by melt processing (film blowing), and certain additives blended with the homopolymer on the phase transformation behavior were examined. A new technique based on a combination of wide angle X-ray diffraction and density measurements was devised to determine the relative fractions of form I, form II, and amorphous phases present. Small reductions in thickness by cold rolling cause a rapid partial transformation to form I followed by further transformation at enhanced rates. The enhancement of crystal transformation by cold rolling is primarily the result of the stresses or strains applied rather than the orientation produced. The introduction of molecular orientation by melt processing also enhances the rate of the form II to form I phase transformation, but it is rather less effective than small amounts of cold rolling which themselves produce comparatively little change in molecular orientation. The mechanical blending of polypropylene with polybutene-1 was found to accelerate the form II to form I phase transformation, while another additive (1-naphtylacetamide) known to be a good nucleating agent for crystallization of polybutene-1 did not increase the rate of phase transformation when added at concentration levels needed to nucleate crystallization from the melt.     

The II-I crystal transformation of poly(vinylidene fluoride) under tensile and compressional stresses

The mechanism for a crystal transformation in poly(vinylidene fluoride) by a tensile deformation at atmospheric pressure was investigated in the temperature range 25–150 °C. Simultaneous X-ray and stress-strain relationship measurements during the drawing process revealed that the crystal transformation from Form II to Form I occurred at the temperatures below 130°C where the sample deformed by cold-drawing, and always initiated at the deformation stage where necking was completed at the centre of the tensile sample. Above 140°C, on the other hand, the sample deformed uniformly without necking and did not perform the crystal transformation. Thus, it was suggested that a heterogeneous stress distribution in the sample played a critically important role in the crystal transformation phenomenon. A uniaxial compressional deformation also caused the crystal transformation from Form II to Form I in this sample. The crystal conversion ratio varied with the conditions of compressional pressure and temperature, and the molecular orientation in resultant samples depended on the shapes of the anvils employed in the compression experiment. By applying a high d.c. voltage during the compressional deformation, a highly uniaxially oriented Form I film with prominent piezoelectric properties was obtained.     

Molecularly imprinted polymer based on multiwalled carbon nanotubes for ribavirin recognition

The polymorphic transformations (from form II to form I) of three kinds of isotactic poly(1-butene) were characterized by FTIR and by changes in their macroscopic physical and mechanical properties, including density and tensile characteristics. The kinetics of the form II to form I transformation were followed by performing FTIR measurements in real time. At 25?°C, as the crystallization time increased, the characteristic FTIR peak of form I of the poly(1-butene) increased, while that of form II diminished and finally disappeared. The polymorphic transformation from form II to form I of the poly(1-butene) obtained by the solution method (S-PB) occurred the most rapidly, followed by the corresponding transformation for the poly(1-butene) obtained from Mitsui Chemicals (M-PB) and then that for the poly(1-butene) produced using the high-pressure bulk polymerization method (B-PB). This transformation behavior is due to the higher isotacticity of the S-PB, as also demonstrated by the results of the density and tensile tests. The density of S-PB is higher than the densities of M-PB and B-PB due to its greater crystallinity.     

青霉素G亚砜对-硝基苄酯的合成

青霉素G亚砜对—硝基苄酯是合成GCLE的重要中间体 ,可通过以青霉素G为原料 ,用低浓度过氧乙酸氧化 ,再以对—硝基苄氯进行羧基保护获得。本方法既能确保产品质量 ,又有利于安全生产 ,适合于工业化生产     

Improved extraction of penicillin G using hydrocarbon sulfoxides

Extraction of penicillin G with sulfoxide extractants, petroleum sulfoxide (PSO) and di‐isooctyl sulfoxide (DISO) was researched systematically. Based on research of the extraction equilibrium of penicillin G, the suitable extraction and re‐extraction conditions were determined, and then extraction cascade and bench‐scale experiments were carried out. The performance of extraction systems composed of PSO and DISO, with sulfonated kerosene as the diluent, is superior to that of n‐butyl acetate owing to the low solubility of these new extractants in water. Their consumption during the extraction process was lower, and the recovery step of extractants from aqueous raffinate was eliminated. Copyright © 2004 Society of Chemical Industry     

Pressure-Temperature Phase Diagram of Zirconia

The pressure-temperature phase diagram of zirconia was determined by optical microscopy and X-ray diffraction techniques using a diamond anvil pressure cell. At room temperature, monoclinic ZrO₂ transforms to a tetragonal phase ( t II) which is related to the high-temperature tetragonal structure ( t I). The transformation pressure exhibits hysteresis and is cycle dependent. At room temperature, the initial transformation pressure for the monoclinic- t II transition on a virgin monoclinic crystal can be as high as 4.4 GPa; on subsequent cycling the transition pressure ultimately lowers to 3.29 ± 0.06 GPa. The pressure for the reverse transition is essentially constant at 2.75 ± 0.06 GPa. At pressures > 16.6 GPa, the t II form transforms to the orthorhombic cotunnite (PbCl₂) structure. With increasing temperature, the t II form transforms to the high-temperature tetragonal phase. For increasing P and T , the monoclinic- t I- t II triple point is located at T = 596°± 18°C and P = 2.26 ± 0.28 GPa, whereas for decreasing P and T , the triple point is found at T = 535°± 25°C and P = 1.7 ± 0.28 GPa.     

青霉素G亚砜的合成

以青霉素G钾盐为原料,采用15%左右低浓度过氧乙酸为氧化剂合成青霉素G亚砜,反应时间2～2.5h,n(过氧乙酸):n(青霉素G钾盐)=(1.1～1.2):1.0,反应温度和结晶温度在0～5℃,总收率可达96%以上。所得青霉素G亚砜可直接从溶液中结晶析出,解决了产物与反应体系的分离。产品纯度较高。     

青霉素G亚砜二苯甲酯的合成研究

以青霉素G钾为原料制备青霉素G亚砜二苯甲酯。氧化反应优化条件为:n(过氧乙酸)∶n(青霉素G钾)=1.2∶1.0,氧化温度0～5℃,反应时间2h,青霉素G亚砜酸收率为97.3%;酯化反应优化条件为:二氯甲烷的用量为17mL/g青霉素G亚砜,投料比n(二苯甲醇)∶n(青霉素G亚砜)=1.8∶1.0,反应温度为-15℃,反应时间为60min,酯化收率为79.5%,反应总收率为77.4%。此工艺成本低廉,操作安全简便,对工业化生产具有积极意义。     

Structures of two crystal forms of poly(ethylene oxide)-sodium thiocyanate complex with molar ratios of 3:1 and 1:1

The poly(ethylene oxide) (PEO)-sodium thiocyanate system was found to exhibit polymorphism: there exist at least three crystal modifications. Among them, the crystal structures of two kinds of PEO-NaSCN complex with molar ratios (EO:NaSCN) of 3:1 (form I) and 1:1 (form II), respectively, were determined by X-ray diffraction. Crystal data are as follows: form I, monoclinic P2₁/a, a = 16.83, b = 10.64, c(chain axis)=7.19 Å^°

1 Å=10⁻¹ nm, γ=125.5° (c-unique), N=12 EO units (2 chains) and 4 NaSCN ions; form II, monoclinic P2₁/c, a=7.55, b=12.10, c(chain axis)=5.83 Å, β=97.5° (b-unique), N=4 EO units (2 chains) and 4 NaSCN ions. Form I has a crystal structure resembling that of the PEO-NaI complex. The polymer chains have a twofold helical structure of conformation, the chain repeat comprising six EO units. The helical polymer chain coils around an array of Na ions and each Na ion is coordinated by four polymer O atoms and two N of the SCN ions (the coordination number is six). In form II, which exists only under high tension, the polymer chains have a glide structure of conformation, the chain repeat comprising two EO units. Since the PEO chain in form II takes a rather stretched conformation, the Na ions are not wrapped by the polymer chain. The coordination number is again six, but each Na ion is coordinated by two polymer O atoms, two N and two S of the SCN ions. Form II is transformed into form I when the tension is released.     

青霉素发酵液直接氧化制备青霉素G亚砜反应条件优化

以过氧乙酸为氧化剂,研究了青霉素发酵液直接氧化制备青霉素G亚砜的过程,考察了不同影响因素对青霉素G亚砜转化率的影响,分析了氧化后菌丝中青霉素残留,建立并优化了青霉素发酵液直接氧化工艺。结果表明,搅拌转速、反应温度、过氧乙酸投料量、过氧乙酸浓度等因素是青霉素G亚砜转化率的关键影响因素,其他因素对青霉素发酵液直接氧化过程影响较小。过氧乙酸直接氧化青霉素发酵液可释放出残留在菌丝体内的青霉素,相比氧化青霉素G钾盐的转化率更高。最佳氧化工艺条件为反应温度5~10℃,搅拌转速100 r/min,30 min匀速加入青霉素摩尔量1.3倍的高浓度过氧乙酸,继续搅拌反应10 min。青霉素G亚砜的转化率可达98.6%,比青霉素G钾盐为原料的转化率提高1.2%。     

Effect of polymorphism of isotactic polybutene‐1 on peel behavior of polyethylene/polybutene‐1 peel systems

The effect of polymorphism of isotactic polybutene‐1 (iPB‐1) on the peel behavior of the specific peel system low‐density polyethylene/polybutene‐1 (LDPE/iPB‐1) was investigated using wide‐angle X‐ray scattering, calorimetry, and the T‐peel test. Melt‐crystallization of iPB‐1, initially, yields tetragonal form II crystals which transform as a function of time to trigonal form I crystals. The kinetics of transformation at ambient temperature follows an exponential function, and is completed after about 50–75 h. The presence of LDPE in the peel system does not affect the transformation kinetics. The structure of the crystalline phase of iPB‐1 controls the peel force which decreases by about 25% during the crystal–crystal transformation in a blend with 20m% iPB‐1. The reduction of the peel force depends linearly on the mass fraction of iPB‐1 crystals in the peel system which further evidences the correlation between the crystal–crystal transformation of iPB‐1 and the peel‐characteristics of LDPE/iPB‐1 blends. Isothermal reorganization of crystals of LDPE is excluded as reason for the change of the peel‐performance of LDPE/iPB‐1 blends, since it is 5 to 10 times faster than the decrease of the peel force, and crystal–crystal transformation of iPB‐1, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Rheology,polymorphic crystal transformation,thermal, and mechanical properties of long-chain branched isotactic poly(1-butene)

Effects of long-chain branches (LCBs) on the rheology, crystal polymorphism, polymorphic transformation, and corresponding thermal and mechanical properties at different crystallization conditions, of isotactic poly(1-butene) (iPB-1) are systematically studied. The complex viscosity decreases and tangent increases with the increase of LCB concentration, and they inversely correlate with gels. The low branched samples crystallize into pure Form II by compression molding and cooling the melt to room temperature at a low crystallization cooling rate, whereas the moderate-to-highly branched samples crystallize into mixtures of Forms II and III, with a 1–30% fraction of crystals of Form III. The transformation of Form II into Form I in low branched iPB-1 was not significantly decelerated at different crystallization cooling rates, which is important in thermoforming, foaming, and extrusion blowing processes. Upon heating, Form III in highly branched iPB-1 with gels does not cold-crystallize into Form II even at a low heating rate. The low-to-highly branched samples mainly in Form I exhibit high yield strength, high melting temperature, and lower ductility, while the highly branched iPB-1 containing gels and mixtures of Forms I, III, and I′ possess brittleness. Under stretching, Form III predominantly transforms into Form I via a solid–solid crystal transition. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48411.     

Antioxidants and stabilizers. L. Transformation of the 1,3,5-tris(4-hydroxy-3,5-di-tert-butylbenzyl)cyanuric acid into alkylperoxycyclohexadienones,their properties and effects on the oxidation of tetralin and polypropylene

The transformation of 1,3,5-tris(4-hydroxy-3,5-di-tert-butylbenzyl)cyanuric acid (I), designed as an antioxidant for polyolefins, during its reaction with tert-butylperoxyls was studied. In tert-butyl alcohol two oxidation products, II and III, are formed, while in benzene the reaction proceeds faster with formation of cyclohexadienone III. The structures of the oxidation products were confirmed, their thermal properties were measured (by DTA) and the effect on the oxidation of tetralin and isotactic polypropylene was determined. The oxidative transformation makes trisphenol I lose its antioxidative property. The different behaviour of trisphenol I and another important phenolic antioxidant, namely, 1,3,5-trimethyl-2,4,6-tris(4-hydroxy-3,5-di-tert-butylbenzyl)benzene (IV) under the conditions of inhibited oxidation of polyolefins is discussed.     

Effects of crystal phase transformation on tensile properties of polybutene‐1/cellulose composites

Morphologies and tensile properties of polybutene‐1 (PB), PB/fibrous cellulose (FC), and the PB/silanized FC with 3‐aminopropyltrimethoxysilane (APTMS) composites were studied. The scanning electron microscope micrographs exhibited the adherent PB parts on the FC and the silanized FC, suggesting that there was a certain affinity of PB to them. The spherulite observation suggested that there existed a secondary bonding between the PB and the FC or the silanized FC. These tensile properties were remarkably affected by the PB crystal phase transformation from the metastable tetragonal (II) to the stable hexagonal (I) phase. The transformation caused the ageing embrittlement even at r.t. In particular, the ageing embrittlement rate of the PB/silanized FC was much higher than other samples. Because the silanized FC became the excellent nucleating agent for the PB crystallization, the PB/silanized FC was found to easily form the thicker lamella having a higher probability of containing a crystal defect to serve as a starting point of the transformation. The higher transformation rate depended on the thicker lamella formation rate and its amount. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

青霉素钾,青霉素亚砜和青霉素砜的薄层色谱法分离和鉴别

用薄层色谱法分离和鉴别青霉素钾、青霉素亚砜、青霉素砜，斑点清晰，重现性好，可作为中间体的检测。     

Crystal structure and drawing‐induced polymorphism in poly(aryl ether ether ketone). IV

A new crystal modification induced by strain and denoted as form II exists alongside the dominant form I structure in the uniaxially oriented poly(ether ether ketone) (PEEK) and the related polymers. The crystal structure of form II for PEEK is also found to possess a two‐chain orthorhombic packing with unit cell parameters of a equal to 0.475 nm, b equal to 1.060 nm, and c equal to 1.086 nm. More extended and flattened chain conformation of form II relative to that of form I is expected to account for an 8% increase in c‐axis dimension, which is attributed to the extensional deformation fixed in situ through strain‐induced crystallization during uniaxial drawing. Annealing experiments suggest that form II is thermodynamically metastable and can be transformed into more stable form I by chain relaxation and reorganization at elevated temperature without external tension. This strain‐induced polymorphism exists universally in the poly(aryl ether ketone) family. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 237–243, 1999     

Study on the polymorphism of normal triglycerides of sal(Shorea robusta) fat by DSC. I. Effect of diglycerides

The effect of diglycerides (DG) on the phase transition of various polymorphic forms of normal triglycerides (TG) of sal fat was investigated by differential scanning calorimetry. Three levels of DG, 5, 10 and 15%, were used. DG delayed the phase transition of lower melting crystal forms to higher forms of TG when the samples were brought to a congealed state by rapid cooling (20 C/min) and heated at rates ranging from 1.25 to 10 C/min; the extent depended on the level of DG and the rate of heating. As the level of DG and the rate of heating increased, the delay in phase transition of crystal forms I → II → III was more pronounced. The phase transition of crystal forms I, II and III to form IV was delayed at 5 and 10% levels of DG, while at the 15% level the phase transition of form I to higher forms was completely stopped when the samples were tempered at 0 C for 18 hr and heated at 10 C/min. DG at 10 and 15% levels retarded the phase transition of form IV to the most stable (V) form of TG when the samples were tempered at 0 C for 1 hr followed by 3 hr at 26 C.     

Antioxidants and stabilizers. IL. 1,3,5-trimethyl-2,4,6-tris (1-tert-butylperoxy-3,5-ditert-butylcyclohexa-2,5-diene-4-onylmethyl)benzene: Formation,properties and effect on the oxidation of tetralin and isotactic polypropylene

The transformation of the antioxidant 1,3,5-trimethyl-2,4,6-tris(3,5-ditert-butyl-4-hydroxybenzyl)benzene (I) by the oxidation with tert-butyl hydroperoxide in the presence of Co(II)acetylacetonate was investigated. The reaction in tert-butyl alcohol gives rise to product II of partial oxidation, while in benzene cyclohexadienone III is formed. The oxidation products were defined, and their thermal properties and behaviour in light were determined. The oxidative transformation of trisphenol I leads to a loss of its antioxidative activity. The oxidation products II and III at the temperature of their formation do not exhibit an unfavourable effect on the process of thermal oxidation. However, after heating of the hydrocarbon substrate containing them to a temperature close to their decomposition point they act as initiators. They undergo photochemical transformation already at room temperature and give colour to the polymer.