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1990 Volume 7 Issue 1
1990, 7(1): 1-9
Abstract:
A U-shaped induced-fitting model of sweet-bitter receptor with multiple point attach-ment was proposed by the author in 1980. In this paper it is employed to illustrate the structure-activity relationships of di- and tripeptide sweeteners analogous to Aspartame.The glucophore is taken to be G=-O2C(CH2)0-1 CHNH2+R when R=H, the auxogluc on the N-end to be AN=R when R=any acyl group and that on the C-end to be Ac=CONH-CR1R2R3 where R3 > R2 > R1 in size. The main chains of both AN and Ac will attain a maximal sweetness, if either or both can reach the C-9 position of the top layer of the receptor membrane. However, the depth where the main chain of AN or Ac can reach de-pends on the orientation and position where G is ancholed on the sulface. Nevertheless, itwill cause the highest perturbation shuold it reach this C-9 position. Thus the optimal chainlength of an auxogluc is often equivalent to no more or less than that of a C8 to C10 acyl group. If one supposes that the size instead of the atomic number of substituents R1 > R2 > R3 on the dissymmetric α-carbon atom be adopted as the standard for what we call "topo" configuration, then the three amino acids in paralle connection AN-G-Ac must allbe of a "topo"-D-configuration to have a high sweetness intensity whiie only an A2c of them in series connection G-A1c-A2c must be of a "topo"-L enantiomer. For a dipeptide G-Ac, the width R1-C-R2 of Ac must be≤(CH2)4;for a tripeptide G-A1c-A2c, that of A2c must be≤(CH2)5. The polar, steric and hydrophobic effects of substituents on R, R2 and R3 have understandable influences, inter alia, on the stability as well as sweetness intensity of these concerned sweetencrs.
A U-shaped induced-fitting model of sweet-bitter receptor with multiple point attach-ment was proposed by the author in 1980. In this paper it is employed to illustrate the structure-activity relationships of di- and tripeptide sweeteners analogous to Aspartame.The glucophore is taken to be G=-O2C(CH2)0-1 CHNH2+R when R=H, the auxogluc on the N-end to be AN=R when R=any acyl group and that on the C-end to be Ac=CONH-CR1R2R3 where R3 > R2 > R1 in size. The main chains of both AN and Ac will attain a maximal sweetness, if either or both can reach the C-9 position of the top layer of the receptor membrane. However, the depth where the main chain of AN or Ac can reach de-pends on the orientation and position where G is ancholed on the sulface. Nevertheless, itwill cause the highest perturbation shuold it reach this C-9 position. Thus the optimal chainlength of an auxogluc is often equivalent to no more or less than that of a C8 to C10 acyl group. If one supposes that the size instead of the atomic number of substituents R1 > R2 > R3 on the dissymmetric α-carbon atom be adopted as the standard for what we call "topo" configuration, then the three amino acids in paralle connection AN-G-Ac must allbe of a "topo"-D-configuration to have a high sweetness intensity whiie only an A2c of them in series connection G-A1c-A2c must be of a "topo"-L enantiomer. For a dipeptide G-Ac, the width R1-C-R2 of Ac must be≤(CH2)4;for a tripeptide G-A1c-A2c, that of A2c must be≤(CH2)5. The polar, steric and hydrophobic effects of substituents on R, R2 and R3 have understandable influences, inter alia, on the stability as well as sweetness intensity of these concerned sweetencrs.
1990, 7(1): 10-18
Abstract:
The, recent developments of ligand-exchange chromato graphy in the resolution of a-amino acid enantiomers by asymmetric resins are reviewed briefly.
The, recent developments of ligand-exchange chromato graphy in the resolution of a-amino acid enantiomers by asymmetric resins are reviewed briefly.
1990, 7(1): 19-22
Abstract:
Co2+ ion has the adsorption rate smaller than that of molybdate ion on γ-Al2O3 but with larger apparent diffution coefficient (Dco=1.2×10-5, DMo=4.4×10-6cm2/s at 25℃).The adsorption curves of Co and Mo consist with Langmuir and Freundlich isotherm,respectively. Adsorption of Mo decreased by increasing the pH of impregnating solution and adsorptions of Co and Mo were mutually enhanced due to coadsorption in a mixed solution of cobalt nitrate and ammonium heptamolybdate at pH=5.3.Most of Mo was distributed in the outter shell of Al2O3 in the catalyst prepared by pore volume imrpeg-nating with Co-Mo mixed solution at low pH value owing to its large adsorytivity, but a more uniform distribution could be obtained at high pH solution. Adsorption of K2CO3 on Co-Mo catalyst can be described by Langmuir isotberm. An even distribution of K on Co-Mo/Al2O3 was obtained by pore volume impregnating with enough quantity of K2CO3 in the impregnating solution. An even distributed catalyst is more active than an uneven distributed one with the same composition for water gas shift reaction.
Co2+ ion has the adsorption rate smaller than that of molybdate ion on γ-Al2O3 but with larger apparent diffution coefficient (Dco=1.2×10-5, DMo=4.4×10-6cm2/s at 25℃).The adsorption curves of Co and Mo consist with Langmuir and Freundlich isotherm,respectively. Adsorption of Mo decreased by increasing the pH of impregnating solution and adsorptions of Co and Mo were mutually enhanced due to coadsorption in a mixed solution of cobalt nitrate and ammonium heptamolybdate at pH=5.3.Most of Mo was distributed in the outter shell of Al2O3 in the catalyst prepared by pore volume imrpeg-nating with Co-Mo mixed solution at low pH value owing to its large adsorytivity, but a more uniform distribution could be obtained at high pH solution. Adsorption of K2CO3 on Co-Mo catalyst can be described by Langmuir isotberm. An even distribution of K on Co-Mo/Al2O3 was obtained by pore volume impregnating with enough quantity of K2CO3 in the impregnating solution. An even distributed catalyst is more active than an uneven distributed one with the same composition for water gas shift reaction.
1990, 7(1): 23-27
Abstract:
Cyclo(L-Phe-L-His) prepared by a modified procedure showed high activity. and enan-tioselectivity in the asymmetric synthesis of aromatic Cyanohydrins from benzaldehyde and m-phenoxybenzaldehyde. The influence of the reaction conditions on the activity and sele-ctivity of the dipeptide has been investigated. The cyclodipeptide can be easily recovered and reused without any loss of the catalytic activity. The optical and chemical stability as well as the relationship between the aggregation and properties of the catalyst have been discussed.
Cyclo(L-Phe-L-His) prepared by a modified procedure showed high activity. and enan-tioselectivity in the asymmetric synthesis of aromatic Cyanohydrins from benzaldehyde and m-phenoxybenzaldehyde. The influence of the reaction conditions on the activity and sele-ctivity of the dipeptide has been investigated. The cyclodipeptide can be easily recovered and reused without any loss of the catalytic activity. The optical and chemical stability as well as the relationship between the aggregation and properties of the catalyst have been discussed.
1990, 7(1): 28-32
Abstract:
The negative ion electron impact mass spectra (NIEJ-MS) and their cleavage in some phosphonothionates were discussed on the basis of low resolution mass spctral and meta-stable ion analysis. It is found that the property and the position of the substituents have a marked influence on the isomeric rearrangement of the phosphonothionate.
The negative ion electron impact mass spectra (NIEJ-MS) and their cleavage in some phosphonothionates were discussed on the basis of low resolution mass spctral and meta-stable ion analysis. It is found that the property and the position of the substituents have a marked influence on the isomeric rearrangement of the phosphonothionate.
1990, 7(1): 33-37
Abstract:
The extraction mechanism of palladium in chloride system by di(1-methyl heptyl) acetamide (N503) has been studied. The compsition of the extracted complex is (CH3CONR2H)2PdCl4 as determined by the equimolar series method and the slope method. The extraction mechanism of palladium with N503 based on UV-vis spectra is proved to be an anion exchange reaction:2CH3CONR2HCl(o)+PdCl42-(a)⇌(CH3CONR2H)2PdCl4(o)+2Cl-(a)
The extraction mechanism of palladium in chloride system by di(1-methyl heptyl) acetamide (N503) has been studied. The compsition of the extracted complex is (CH3CONR2H)2PdCl4 as determined by the equimolar series method and the slope method. The extraction mechanism of palladium with N503 based on UV-vis spectra is proved to be an anion exchange reaction:2CH3CONR2HCl(o)+PdCl42-(a)⇌(CH3CONR2H)2PdCl4(o)+2Cl-(a)
1990, 7(1): 38-42
Abstract:
The mechanical properties, dynamic mechanical and thermal behavior, crystalline stru-cture and morphology of PB/LDPE blends were investigated. Comparison of the properties of uncured and dynamically cured blends of various compositions showed that the PB/LDPE blend system is incompatible.
The mechanical properties, dynamic mechanical and thermal behavior, crystalline stru-cture and morphology of PB/LDPE blends were investigated. Comparison of the properties of uncured and dynamically cured blends of various compositions showed that the PB/LDPE blend system is incompatible.
1990, 7(1): 43-48
Abstract:
The morphology of highly oriented melt-drawn films of iPP/HDPE blends has been investigated by TEM and DSC. Both the HDPE and the iPP in the films consist of hig-hly oriented crystalline lamellae. Blending iPP with HDPE results in decrease of crystal-line width and melting point of HDPE, as well as the change of HDPE texture from a single crystal texture to fibre symmetric structure. No marked phases of iPP were found in the films at low iPP contents(<20%). Individual phases of iPP were observed at iPP contents>30% .There is no sharp boundary between the two phases. The lamellae of HDPE and iPP in the boundary region are higher interpenetrating or connecting each other. When the preparation temperature of the film is higher(135-140℃) and the content of HDPE in the blends is below 30%, epitaxial growth of HDPE lamellae on highly oriented iPP lamellae has been observed. The intercrossing angle of the two kinds of epitaxial la-mellae is about 45°-50°, while the contact planes are (010) of iPP and(100) of HDPE.
The morphology of highly oriented melt-drawn films of iPP/HDPE blends has been investigated by TEM and DSC. Both the HDPE and the iPP in the films consist of hig-hly oriented crystalline lamellae. Blending iPP with HDPE results in decrease of crystal-line width and melting point of HDPE, as well as the change of HDPE texture from a single crystal texture to fibre symmetric structure. No marked phases of iPP were found in the films at low iPP contents(<20%). Individual phases of iPP were observed at iPP contents>30% .There is no sharp boundary between the two phases. The lamellae of HDPE and iPP in the boundary region are higher interpenetrating or connecting each other. When the preparation temperature of the film is higher(135-140℃) and the content of HDPE in the blends is below 30%, epitaxial growth of HDPE lamellae on highly oriented iPP lamellae has been observed. The intercrossing angle of the two kinds of epitaxial la-mellae is about 45°-50°, while the contact planes are (010) of iPP and(100) of HDPE.
1990, 7(1): 49-52
Abstract:
Heavy rare earths can form a stable ternary complex with cetyltrimethylammonium bro-mide (CTMAB) and Ferron (7-iodo-8-hydroxyquinoline-5-sulfonic acid) in molar ratio of Y: Ferron:CTMAB=1:6: 9 for yttrium. The maximum absorption wavelength of the Y ternary complex was at 385nm at pH 3.2-3.8 of acetic acid-sodium acetate buffer.The ap-parent molar absorption coefficient was 1.5×104 L·mol.cm-1. The absorbance was linear to the concentration of yttrium below 44μg/10mL. A method has been developed for the rapid and selective microdetermination of yttrium subgroup in mixed rare earths, using NaF as a masking agent.
Heavy rare earths can form a stable ternary complex with cetyltrimethylammonium bro-mide (CTMAB) and Ferron (7-iodo-8-hydroxyquinoline-5-sulfonic acid) in molar ratio of Y: Ferron:CTMAB=1:6: 9 for yttrium. The maximum absorption wavelength of the Y ternary complex was at 385nm at pH 3.2-3.8 of acetic acid-sodium acetate buffer.The ap-parent molar absorption coefficient was 1.5×104 L·mol.cm-1. The absorbance was linear to the concentration of yttrium below 44μg/10mL. A method has been developed for the rapid and selective microdetermination of yttrium subgroup in mixed rare earths, using NaF as a masking agent.
1990, 7(1): 53-57
Abstract:
The electropolishing behavior of tive organopolyphosphonic acids has been studied. The results showed that 1-hydroxyethylidene-1,1-diphosphonic acid(HEDP), 1-ethylphosphono-ethylidene-1, 1-diphosphonic acid(EEDP) and N, N'-dimethylidene-phosphonoglycine(DMPG) can be used for electropolishing copper and its allcy,and among them the HEDP gave the best result.Viscous liquid film was observed in all conditions used, such as HEDP concen-trations,pH of solutions and kind of electropolishing solution (H3PO4,HEDP, and H3PO4+HEDP). Detection of phosphorus in electropolished copper surface was made by XPS and Auger line.No phosphorus was found. The viscous liquid film obtained from H3PO4+HEDP solution possesses very good film-forming characteristics., The composition of the viscous film can be established from the constant composition region of the depth profile curve and may be considered to be a polynuclear coordination polymeric compound [Cu4(PO4)(HEDP)n]
The electropolishing behavior of tive organopolyphosphonic acids has been studied. The results showed that 1-hydroxyethylidene-1,1-diphosphonic acid(HEDP), 1-ethylphosphono-ethylidene-1, 1-diphosphonic acid(EEDP) and N, N'-dimethylidene-phosphonoglycine(DMPG) can be used for electropolishing copper and its allcy,and among them the HEDP gave the best result.Viscous liquid film was observed in all conditions used, such as HEDP concen-trations,pH of solutions and kind of electropolishing solution (H3PO4,HEDP, and H3PO4+HEDP). Detection of phosphorus in electropolished copper surface was made by XPS and Auger line.No phosphorus was found. The viscous liquid film obtained from H3PO4+HEDP solution possesses very good film-forming characteristics., The composition of the viscous film can be established from the constant composition region of the depth profile curve and may be considered to be a polynuclear coordination polymeric compound [Cu4(PO4)(HEDP)n]
1990, 7(1): 58-61
Abstract:
A direct determination method of cerium,praseodymium and neodymium in the light rare earth-aluminium alloy by using higher-derivative spectrophotometry in perchloric acid solution is proposed. The content of lanthanum is determined by substraction. The results were in good agreement with those determined by x-ray fluorescence method. The method is rapid, simple and accurate.
A direct determination method of cerium,praseodymium and neodymium in the light rare earth-aluminium alloy by using higher-derivative spectrophotometry in perchloric acid solution is proposed. The content of lanthanum is determined by substraction. The results were in good agreement with those determined by x-ray fluorescence method. The method is rapid, simple and accurate.
1990, 7(1): 62-65
Abstract:
The structure of the crosslinked copolymers(and/or blends) of epoxy resin/polyethylene oxide (ER/PEO) and their complexes with sodium thiocyanate after extraction has been studied by using WAXD, SAXS, DSC and SEM methods. The results showed that the samples after extraction have an amorbhous structures of the crosslinked copolymers (ER-PEO). The crystallinity of the complexes ER/PEO-NaSCN was decreased as compared with corresponding blends ER/PEO, due to the presence of Na ion.
The structure of the crosslinked copolymers(and/or blends) of epoxy resin/polyethylene oxide (ER/PEO) and their complexes with sodium thiocyanate after extraction has been studied by using WAXD, SAXS, DSC and SEM methods. The results showed that the samples after extraction have an amorbhous structures of the crosslinked copolymers (ER-PEO). The crystallinity of the complexes ER/PEO-NaSCN was decreased as compared with corresponding blends ER/PEO, due to the presence of Na ion.
1990, 7(1): 66-69
Abstract:
In a supporting electrolyte containing potassium hydrogen phthalate (KHP) at pH 3.3,a sensitive derivative peak of Cu(I)-allylthiourea(ATU) complex was found by single-sweep oscillopolarography. The peak shows a potential of-0.32V(vs.SCE) and its height is linearly proportional to the concentration of Cu in the range of 0.002 to 0.12μg/mL.The mechanism of the wave formation has been discussed. It is confirmed that the peak wave is the adsorptive-complex wave of Cu(I)-ATU.
In a supporting electrolyte containing potassium hydrogen phthalate (KHP) at pH 3.3,a sensitive derivative peak of Cu(I)-allylthiourea(ATU) complex was found by single-sweep oscillopolarography. The peak shows a potential of-0.32V(vs.SCE) and its height is linearly proportional to the concentration of Cu in the range of 0.002 to 0.12μg/mL.The mechanism of the wave formation has been discussed. It is confirmed that the peak wave is the adsorptive-complex wave of Cu(I)-ATU.
1990, 7(1): 70-71
Abstract:
The synthesis of title compound (TATB) via 3,5-dinitroaniline is described.
The synthesis of title compound (TATB) via 3,5-dinitroaniline is described.
1990, 7(1): 72-73
Abstract:
1, 5-Diferrocenyl-4-hexene-1, 3-dione has been firstly synthesized by condensation rea-ction of acetylferrocene with 3-ferrocenyl-crotonic ester and characterized by elemental analysis, 1H NMR and IR spectrophotometry.
1, 5-Diferrocenyl-4-hexene-1, 3-dione has been firstly synthesized by condensation rea-ction of acetylferrocene with 3-ferrocenyl-crotonic ester and characterized by elemental analysis, 1H NMR and IR spectrophotometry.
1990, 7(1): 74-75
Abstract:
Incorporating Sb to BiPbSrCaCuO system led to the appearance of a second phase.Besides this impure phase the XRD pattern of the main phase of Bi1.6Pb0.4Sb01Sr1.5-2.0Ca2Cu2Oy could be indexed with a tetragonal structure with cell parameters a=0.54 and c=3.06nm, i.e. it corresponds to the low-Tc phase of BiSrCaCuO system,the so called 2212 phase.It is of interest to indicate that this phase (with Sb and Pb incorporation) showed a Tc at ~110K and Tonset at ~120K favorably close to that of the high-Tc phase of Bi(Pb)SrCaCuO system the so called 2223 phase.It is also observed that the c-axis was increased from 3.06nm to 3.08nm and Tc was increased as the ignition time was lengthened.
Incorporating Sb to BiPbSrCaCuO system led to the appearance of a second phase.Besides this impure phase the XRD pattern of the main phase of Bi1.6Pb0.4Sb01Sr1.5-2.0Ca2Cu2Oy could be indexed with a tetragonal structure with cell parameters a=0.54 and c=3.06nm, i.e. it corresponds to the low-Tc phase of BiSrCaCuO system,the so called 2212 phase.It is of interest to indicate that this phase (with Sb and Pb incorporation) showed a Tc at ~110K and Tonset at ~120K favorably close to that of the high-Tc phase of Bi(Pb)SrCaCuO system the so called 2223 phase.It is also observed that the c-axis was increased from 3.06nm to 3.08nm and Tc was increased as the ignition time was lengthened.
1990, 7(1): 76-79
Abstract:
In this paper, 1-14SrO-0.5Al2O3-4.5SiO2:0.05Eu3+, 0.005Bi3+ was prepared at 850℃ by the sol-gel method. Optimum conditions wcre judged by the relative intensity of lumi-nescence.Transition of gel to luminophor was investigated by TG-DTA, XRD and IR spe-ctroscopy.The luminescent properties of Eu3+ and the energy transfer from Bi3+ to Eu3+ were discussed according to the emission and excitation spectra of the luminophor.
In this paper, 1-14SrO-0.5Al2O3-4.5SiO2:0.05Eu3+, 0.005Bi3+ was prepared at 850℃ by the sol-gel method. Optimum conditions wcre judged by the relative intensity of lumi-nescence.Transition of gel to luminophor was investigated by TG-DTA, XRD and IR spe-ctroscopy.The luminescent properties of Eu3+ and the energy transfer from Bi3+ to Eu3+ were discussed according to the emission and excitation spectra of the luminophor.
1990, 7(1): 80-82
Abstract:
The kinetics of butadiene polymerization with NdCl3·2Phen-HAl(i-Bu)2 system (Phen=1, 10-phenanthroline) has been studied. The results show that the rate of polymerization is first order to both concentrations of monomer and neodymium complex, but 1/3 order with respect to the concentration of HAl(i-Bu)2.The number of active center and the apparent activation energy of butadiene polymerization with this system were derermined.
The kinetics of butadiene polymerization with NdCl3·2Phen-HAl(i-Bu)2 system (Phen=1, 10-phenanthroline) has been studied. The results show that the rate of polymerization is first order to both concentrations of monomer and neodymium complex, but 1/3 order with respect to the concentration of HAl(i-Bu)2.The number of active center and the apparent activation energy of butadiene polymerization with this system were derermined.
1990, 7(1): 83-85
Abstract:
Polymer-bound 3-benzyloxypropane-1,2-diol 2 was used for the protection of 2,6-haptanedion 3. 3,7-Dimethyl-2,7-octadien-1-yl propanoate la, lb,the main component of San Jose scale's sex pheromone was obtained in 34.8% yield by Wittig reaction. The product has a Z:E isomer ratio of 18.8% to 81.2%
Polymer-bound 3-benzyloxypropane-1,2-diol 2 was used for the protection of 2,6-haptanedion 3. 3,7-Dimethyl-2,7-octadien-1-yl propanoate la, lb,the main component of San Jose scale's sex pheromone was obtained in 34.8% yield by Wittig reaction. The product has a Z:E isomer ratio of 18.8% to 81.2%
1990, 7(1): 86-87
Abstract:
Cd-rich polycrystalline Hg1-xCdxTe was electrodeposited on a Ti substrate from an acidic solution(pH=1.o) of mixture of 0.2mol/L CdSO4, 5×10-4mol/L TeO2 and 1.13×10-5 mol/L HgCl2. The film has a cubic structure with preferential orientation in (111) .Thevalue of 1-x in Hg1-xCdxTe was determined by EDAX to be 0.09. The photoelectro-chemical cell has a solar energy conversion efficiency of about 0.43% under AM1.5 illu-mination in a polysulfide redox solution (1.0mol/L Na2S+0.2mol/L S+1.0mol/L NaOH).The bandgap of Hg0.09Cd0.91 Te was about 1.26eV.
Cd-rich polycrystalline Hg1-xCdxTe was electrodeposited on a Ti substrate from an acidic solution(pH=1.o) of mixture of 0.2mol/L CdSO4, 5×10-4mol/L TeO2 and 1.13×10-5 mol/L HgCl2. The film has a cubic structure with preferential orientation in (111) .Thevalue of 1-x in Hg1-xCdxTe was determined by EDAX to be 0.09. The photoelectro-chemical cell has a solar energy conversion efficiency of about 0.43% under AM1.5 illu-mination in a polysulfide redox solution (1.0mol/L Na2S+0.2mol/L S+1.0mol/L NaOH).The bandgap of Hg0.09Cd0.91 Te was about 1.26eV.
1990, 7(1): 88-90
Abstract:
The heat capacity of the solid solution of trimethylolpropane and pentaerythritol (60:40 mol%) was measured by means of an automated adiabatic calorimeter. A solid-solidt ransition and a melting transition of the solid solution were found at 330.51 K and433.0 K with the transition enthalpies of 9.72 and 5.76 kJmol-1, respectively.
The heat capacity of the solid solution of trimethylolpropane and pentaerythritol (60:40 mol%) was measured by means of an automated adiabatic calorimeter. A solid-solidt ransition and a melting transition of the solid solution were found at 330.51 K and433.0 K with the transition enthalpies of 9.72 and 5.76 kJmol-1, respectively.
1990, 7(1): 91-93
Abstract:
Using polyaniline modified electrode as an indicator electrode and calomel electrode as a reference electrode, the oscillographic potentiometric acid-base titrations were per-formed successfully in aqueous solutions containing strong acids or bases, weak acids orbases, polyprotontic acids or mixtures of bases. In comparison with biplatinum acid-base oscillo-potentiometric titration this method gives more distinct potential breaks and the stoichiometric point can be observed easily with good roproducibility.
Using polyaniline modified electrode as an indicator electrode and calomel electrode as a reference electrode, the oscillographic potentiometric acid-base titrations were per-formed successfully in aqueous solutions containing strong acids or bases, weak acids orbases, polyprotontic acids or mixtures of bases. In comparison with biplatinum acid-base oscillo-potentiometric titration this method gives more distinct potential breaks and the stoichiometric point can be observed easily with good roproducibility.
1990, 7(1): 94-97
Abstract:
The inhibition effects of five 1-isonicotinoyl-4-arylthiosemicarbazides and some 1,2,4-triazoline-5-thione derivatives on the polymerization of VAc, initiated by AIBN, have been investigated by dilatometric method. The results showed that being added in the amount of 1000-3000ppm, the thiosemicarbazides have a more prominent inhibiting effect than trizoline-5-thiones. When the compounds studied were incorporated with 1,4-benzoquinone or hydroquinone the inhibiting effect increased strikingly.
The inhibition effects of five 1-isonicotinoyl-4-arylthiosemicarbazides and some 1,2,4-triazoline-5-thione derivatives on the polymerization of VAc, initiated by AIBN, have been investigated by dilatometric method. The results showed that being added in the amount of 1000-3000ppm, the thiosemicarbazides have a more prominent inhibiting effect than trizoline-5-thiones. When the compounds studied were incorporated with 1,4-benzoquinone or hydroquinone the inhibiting effect increased strikingly.
1990, 7(1): 98-100
Abstract:
The aqueous solution of salicylic acid can be recovered by liquid membrane process.The influence of rate of stirring (n), molar ratio of NaOH in internal phase and salicylic acid in external phase (r), volume ratio of oil phase to internal solution phase (Roi) and volume ratio of emulsion phase to external solution phase (Rew) on the kinetics of mass transfer process were studied. It was shown that when r=1.2-1.5 the diffusion of salicy-lic acid was nonstationary and there was a linear relationship between concentration C and √t(t-time). When r≥3.52 the diffusion of salicilic acid was stationary and therewas a linear relationship between Ln (Co/C) and t.
The aqueous solution of salicylic acid can be recovered by liquid membrane process.The influence of rate of stirring (n), molar ratio of NaOH in internal phase and salicylic acid in external phase (r), volume ratio of oil phase to internal solution phase (Roi) and volume ratio of emulsion phase to external solution phase (Rew) on the kinetics of mass transfer process were studied. It was shown that when r=1.2-1.5 the diffusion of salicy-lic acid was nonstationary and there was a linear relationship between concentration C and √t(t-time). When r≥3.52 the diffusion of salicilic acid was stationary and therewas a linear relationship between Ln (Co/C) and t.
