Method for measuring water in complex compounds

FIELD: chemistry.

SUBSTANCE: invention refers to the quantitative and qualitative measurement of water as shown by an inner sphere of complex compounds (CCs) and can find application in coordination chemistry and pharmacy. What is presented is a method for measuring water in the solid CC, wherein water molecules in the inner sphere of the solid CC are identified by a sample dehydration temperature of 150-165°C on thermal curves - thermograms drawn within the temperature range of 20-1,000°C at a sample heating rate of 10 degrees/min, as well as by hydroxocomplex formation as a result of the alkalimetric titration of the CC solutions pre-dehydrated at a temperature of 120°C for 8 hours by detecting an endpoint respective to pH within the range of 4.87-4.95 on the differential titration curve; further, the quantitative content of water in the inner sphere of the solid CC is determined for the solid CC samples dehydrated by drying up at a temperature of 120°C for 8 hours as shown by specific areas of the thermogravigrams in the graphic system "Quantity of Removed Water, mmole - Dehydratation Temperature, °C".

EFFECT: achieving the higher information value and reliability, as well as simplifying the analysis.

5 tbl, 11 dwg

 

The invention relates to methods for qualitative and quantitative determination of water in the inner sphere of coordination compounds (COP) and may find application in coordination chemistry and pharmacy.

The most effective natural means of detoxification of the human body from the harmful effects of radionuclides, heavy metals and toxic elements pectins are capable of various functional groups and oxygen atoms to form with metal ions KC - pectinate metals (Komissarenko S. N., Spiridonov V. N. Pectin - their properties and applications. Raising. resources, 1998, vol. 34, ISS.1, pp. 111-119). Along with metal ions and pectin, a very important role in building the COP played by water molecules that significantly affect the structure and composition of the COP. This is because the appearance of pectin in the reaction medium containing hydrated metal cations leads to the complete or partial replacement of water molecules: water may remain in coordinating the ion, i.e., along with pectin, a ligand in the COP can move in the outer sphere of the COP or be a capillary bound (adsorbed). The determination of the position of water molecules in the COP needed to establish the structure and composition of the COP, and justification of therapeutic dosages of medicines.

Of the few ways of finding water in the COP may be noted the following�following.

Described polarographic method of studying the structure of the COP based on the electrolysis of substances under restoration at the cathode or oxidized at the anode, including water (Zeligowska N. N., Chernyaev, I. I. Chemistry of complex compounds, Wiley, HS, 1966, pp. 291-298). However, this method does not allow to determine the position of water molecules: are they in the Board or are associated capillary. In addition, the electrodes redox properties, in addition to water, exhibit other structural components of the COP.

More informative is the study of the structure of the COP on the infrared absorption spectra, in which case the nature and position of characteristic frequencies suggest a link type of "metal - ligand". The described method of determining the structural components of solid pectin, pectinates metals in the form of films by recording the IR spectra in the current vapor D2O at a fixed temperature and the area of absorption within 700-3800 cm-1(Filippov M. P. Infrared spectra of pectin and its derivatives. Izv. An MSSR, 1976, No. 4, pp. 80-87). In this way identify water molecules, including associated by intermolecular hydrogen bonds, three types of oscillations: two types (stretching vibrations) are accompanied by a periodic variation of bond lengths (shown in the form of absorption bands 3652 cm-1and 3756 cm-1), Tr�rd type (deformation vibrations) - periodic changing of the angle of contact (in the form of a strip 1515 cm-1). As a result of coordination of ligands to metal ions symmetry properties of molecules and the nature of the fluctuations in General be preserved, although the molecules that became the ligands in the COP, undergo some changes, which affects the types and frequencies of oscillations (Zeligowska N. N., 1966, ... pp. 319-320). However, these changes do not allow to differentiate the molecules of water in certain areas (internal or external) of the COP and, in addition, can be due to a different ligand (pectin), complexing agent (metal ion). Thus, the main disadvantage of this method is orientirovannosti definition of water molecules in the COP on the relative changes in the types and frequencies of oscillations and the relative bond strength, so the Board can be judged only presumably.

The described method of determining the structure of pectinate sodium obtained in the form of a film length of 5 microns and a weight of 10 mg, IR spectrum, registered in the current vapor D2O in vacuum in the field 700-3800 cm-1(O. D. Kurilenko, Fabulas J. G., Klimovich V. M. C spectroscopy at iï the water yablochnym pectin (i Yogo natrio Slu. Reports iï Sciences ïï PCP, series B: Geology, geofizika, chemistry, the biology, Kiev, Naukova Dumka, 1975, No. 4, pp. 332-334). By comparison Apple pectin establish different� structural features of pectinate sodium: relation between sodium ions and the oxygen atoms of hydroxyl groups (the appearance of absorption bands 3200 cm -1and 3500 cm-1); the ionization of hydroxyl groups and hydrolysis of the ether groups (a decrease in the intensity of bands in the region 1000-1100 cm-1); the disappearance of free carboxyl groups (no stripes 1740 cm-1and the appearance of ionized carboxyl groups (detection strips 1615 cm-1and 1420 cm-1; change the conformation of the pyranose cycle of "chair" in "the tub" (disappearance of the band at 925 cm-1and the appearance of a band at 820 cm-1). Due to the impossibility of determining the water molecules in the COP on these data, further carry out dehydration of the samples (in vacuum P=10-5mm Hg.PT. and temperature 185°C) with subsequent quantitative treatment of films of water to determine its involvement in the education of pectinate sodium. In the IR spectrum of the prepared in the same way pectinata sodium presumably establish the presence of the three forms of water: filling of the internal cavity formed pyranose cycles (band 2190 cm-1); associated ionized carboxyl groups (band 2750 cm-1) and associated hydroxyl groups (band 3440 cm-1), unlike pectin, where the second form of water is water, bound carboxyl groups (strip 2650 cm-1). The higher the intensity of all of these absorption bands in the spectrum of pectinate sodium compared with pectin svidetelstvo� about his increased capacity for water adsorption. Step separating water from both samples by treatment of the chloride tiomila, establish the existence of common, rapidly excreted, and water (lane 3440 cm-1) and more strongly bound water (band 2190 cm-1).

This method of determining water content in the structure of the COP closest to the claimed and selected as a prototype.

The disadvantages of this method are:

1) drying the samples at a temperature of 185°C, even in vacuum, removes molecules, such as adsorption and coordination of water that does not allow them to detect in the infrared spectrum;

2) subsequent processing of dehydrated samples of specific quantities of water may not lead to the inclusion of water molecules in the COP and then the conclusion about the lack of coordination water in the COP to dehydration would be unlawful;

3) differentiation of water on the principle of "common, rapidly excreted and more firmly connected" is relative and does not identify belonging to the COP, the more elaborate the position of water molecules in the COP;

4) the ambiguity of the identification of water molecules in the IR spectra: classification as of different absorption bands (3440 cm-1, 2650 cm-1, 2190 cm-1, 3500-3000 cm-1, 1800-1600 cm-1) and "overlay", for example, ionized carboxyl groups (1800-1600 cm-1);

5) in connection with vasastaden�m, the impossibility to establish both qualitative and quantitative composition of the COP;

6) the complexity of obtaining films of samples, the need to create a vacuum for dehydration.

The purpose of the invention is identification and quantification of the water in the inner sphere of the COP to establish a composition (formula) of the COP.

The goal is achieved by three stages of the analysis of the COP in comparison with the original substances.

I. First, determine the presence of "high temperature" water, which samples in the solid state analyze in embodiments, differential thermal (DTA), differential thermogravimetric (TGA), thermogravimetric (TGA) analysis in the temperature range 20÷1000°C at a heating rate of substances 10 deg/min.

II. Then determine the possibility of formation gidroksosoedineniya at alkalimetric titration of samples (i.e., the manifestation of their acid properties) with potentiometric fixing the pH at the equivalence point. For this purpose, 0.1 to 0.3% aqueous solutions prepared from the dried at 120°C for 8 h samples, titrated 0,1 mol/l solution of sodium hydroxide and determine the equivalence point on the titration curve of the differential method in a graphics system "(Δ/ΔV)-VTITRANT".

III. Further, in establishing the presence of "high temperature� water (temperature dehydration > 150°C) thermal curves and the identification of education gidroksosoedineniya curve alkalimetric titration (pH at the equivalence point <5), indicating the presence of "vnutrivennoi" water, determine its contents and the formula of the COP: for dried at 120°C for 8 h samples thermogravimetry the graphics system, "the Number of remote water, mmol - Temperature dehydration, °C, determine the content vnutrikorporativnoj water and calculate the molar composition (formula) of the COP.

At low speed heating substances (2 deg/min) during thermal curves can occur restructuring the COP associated with the transition of water molecules in the coordination sphere of the complex ion (Coordination chemistry of rare earth elements. Edited by Spitsyn, V. I., Martynenko, L. I., Moscow, 1979, 254 S.), therefore, in the disclosed method, the removal of thermal curves carried out at a high heating rate of substances (10 ° C/min).

The proposed method of analysis can be described on the example of the COP - pectinate metals (II) obtained in the solid state (precipitation) in a known manner by mixing 0.1 mol/l solution of metal acetate (II) and 0.25% solution of pectin in a ratio of 1:10 (Lakatos B., J. Maisel, M. Varia Method for producing complex metal ion with oligo - or polygalacturonic acids. Pat. THE USSR 886750, MKI �N 23/00, publ. 30.11.81).

To obtain pectinata of copper (II) used beet pectin and acetate of copper (II), their derivatory shown in figures 1, 2, 3, feature derivatograph in table 1. Comparative analysis of thermal curves of the starting materials and pectinata shows that the first endothermic effect on the curve of TGA observed at temperatures: 80-105°C for pectin, 110-115°C for acetate of copper (II), 90-115°C for pectinata of copper (II). Given the moisture content in the samples (17,2%, to 9.0%, 7.4%, respectively), this effect relates to the loss of capillary bound (adsorbed) water. The same effect on the curve corresponds to the DTA endothermic peak: at 100-115°C for pectin, 115-120°C for acetate of copper (II), 115-120°C for pectinata of copper (II). A significant difference between the analyzed samples observed at a temperature of 150-165°C and 155-160°C for the curves TGA and DTA respectively: pectinata of copper (II) endothermic effect is observed, is not detected for the original substances. We can assume that this effect also applies to the loss of water by pectinatum of copper (II), i.e. pectin and acetate of copper (II), the process of dehydration is single-stage: tiny water molecules in a single stage at a temperature of 80-115°C and 110-120°C, and for pectinata of copper (II) - two-stage: at 90-120°C and 150-165°C. Other observed effects (endothermic) due �straccia organic part of the pectin and pectinate of copper (II): by carboxyl groups (190-230°C), glycosidic linkages (230 to 270°C). The subsequent increase in temperature leads to complete degradation of all substances.

Thus, thermal analysis curves shows that all the investigated substances contain water, useplease at a lower temperature (which is typical for the adsorption of water), and only paktinat of copper (II) includes "high-temperature" (150-165°C) component, presumably the molecules of coordination water.

To confirm or refute this assumption, first of investigated substances removed water adsorption. According to derivatograph, the upper limit of the temperature range corresponding to the dehydration adsorption of water from various samples was 120°C, so the effect of the duration of drying in the loss of adsorption of water set at the same temperature (table 2). As follows from table 2 that for all the investigated substances the optimal duration of drying, which achieved almost complete removal of adsorption of water is 8 hours.

Further dehydrated from adsorption of water at a temperature of 120°C for 8 h samples were subjected to alkalimetric titration with 0.1 mol/l sodium hydroxide solution with potentiometric fixing the equivalence point on a pH-meter mark "pH-340" when used as an electrode �compared to silver chloride electrode, as flat - glass electrode. For a reliable determination of the equivalence point use differential method (Ponomarev, V. D. Analytical chemistry. M., VS, 1982, part 2. pp. 219-228) by constructing graphical dependencies "(Δ/ΔV)-VTITRANT". Curves alkalimetric titration are shown in figures 4, 5, 6. From the presented data it follows that the pH at the equivalence point in the titration of pectinate of copper (II) is 4.87, while during the titration of pectin - 9,14, acetate of copper (II) - is 6.42. These results indicate that neither during the titration of pectin, or when titration of the acetate of copper (II) is not coming to the equivalence point in an acid environment, unlike pectinata of copper (II), which proves the formation of pectinatum of copper (II) gidroksosoedineniya. Set the pH at the equivalence point (4,87) is significantly lower pH for pectin and acetate of copper (II), and cannot be considered even as an intermediate. Consequently, hydroxocomplexes in pectinate of copper (II) form only water molecules, increased acidic properties which (according Zeligowski N. N., 1966, pp. 139, 142) is the result of coordination with the complexing agent (metal ion).

Thus, the identification of two facts in pectinate of copper (II): the presence of "high temperature" component (150-165°C) and the manifestation of the acidic properties of preseentation with alkali with the formation of gidroksosoedineniya (pH at the equivalence point 4,87), prove the presence of water molecules in the inner coordination sphere of pectinate of copper (II).

Two temperature range of dehydration in pectinata of copper (II) can be explained by the different length and, consequently, the strength of bonds formed by copper ions (II) (exhibiting strong polarizing action) with water molecules inside the coordination sphere and outside of it.

Selecting dried at a temperature of 120°C for 8 hours pectinate of copper (II) presence of molecules "vnutrivennoi" water, determine its quantity thermogravimetry built in graphics system "the Number of remote water, mmol - Temperature dehydration, °C, in comparison with precursors (figures 7, 8, 9). Unlike pectin (figure 7) and copper acetate (II) (figure 8), thermogravimetry of pectinate of copper (II) (figure 9) revealed "Playground", the corresponding coordinating the water. Defining at thermogravimetry her number (at a temperature of 150-165°C) taken during the suspension pectinata of copper (II) and taking into account the molar ratio of the other components of the COP - copper ion (II) and monomer of pectin residues of galacturonic acid (L)) equal to 1:2 (mass ratio to 15.46%:84,54%) (Kaisheva N. W. Scientific basis for the use of polyuronides in pharmacy. Pyatigorsk, Pathf, 2003, 194 p.), and calculate the quantitative composition of the inner sphere, which is expressed by the formula [u(H 2O)2L2]. These results suggest that the interaction of pectin with ion copper (II) there is a partial substitution of water molecules in the hydration shell of an ion of copper (II) monomer of pectin.

Similarly, the definition of water in pectinate of copper (II), the claimed method identify water and other COP.

The proposed method of determining vnutrikorporativnoj water in the COP is illustrated by the following examples of specific performance.

Example 1. To obtain pectinata of copper (II) mix 100 ml of 0.1 mol/l solution of copper acetate (II) and 1000 ml of 0.25% solution of sugar beet pectin, the residue is green after 2 hours, filtered through a paper filter red ribbon, washed on the filter with water until neutral reaction of the wash water, dried at a temperature of 70±5°C for 3 hours.

The analysis is carried out in 3 stages.

I. Identification of "high temperature" component

Samples weighing about 0.5 g (exact linkage): the sugar beet pectin - 0,60802 g, acetate of copper (II) - 0,52315 g, pectinate of copper (II) - 0,58683 g is subjected to thermal analysis in derivatograph brand "Q-1500" firm MOM (Hungary) using various options: DTA, TGA, TGA. Derivatory recorded in the temperature range 20÷1000°C in dynamic air atmosphere with heating rate of substances 10 deg/min, the speed of movement of paper 5 mm/min, using� as a reference alumina. Received derivatograph (figures 1, 2, 3) are compared with each other, especially noting thermal effects in the temperature range 80-180°C on the curves TGA, DTA. The first effect (endothermic) is similar for all three substances, it is observed in the temperature range 80-115°C on the curves TGA and 100-120°C in DTA curves. This effect on TGA curves corresponds to a loss in weight: 17.2 per cent of pectin (figure 1), 9.0 percent for copper acetate (II) (figure 2), with 7.4% for pectinata of copper (II) (figure 3), which refers to the loss of water adsorption. This conclusion is based on results of the determination of moisture in the samples: after drying at 120°C for 8 h samples were: beet pectin 0,50344 g (loss of moisture 17.2 per cent), copper acetate (II) - 0,47607 g (loss of moisture 9,0%), pectinate of copper (II) - 0,54340 g (water loss of 7.4%). Unlike pectin (figure 1) and cupric acetate (II) (figure 2), for pectinata of copper (II) (figure 3) discovered endothermic effect at a temperature of 150-165°C (curve DTGA), 155-160°C (DTA curve) ("high temperature" component).

II. Identification of education gidroksosoedineniya From samples released from the adsorption of water by drying at a temperature of 120°C for 8 hours, to prepare aqueous solutions with a volume of 50 ml with a concentration of 0.2% solution of beet pectin, 0.1% solution of cupric acetate (II), 0.3% solution (suspension) of pectinate of copper (II). Get�record the solutions were titrated with 0.1 mol/l sodium hydroxide solution at pH-meter mark "pH-340"; as the indicator electrode using a glass electrode as reference electrode - silver chloride. The results of titrations of solutions of the substances under study are shown in table 3. Differential method (Ponomarev, V. D., 1982) in a graphics system "(Δ/ΔV)-VNaOHml" establish the equivalence point (figures 4, 5, 6). From the presented data it follows that in the titration of pectin the equivalence point occurs at pH 9,14 (corresponds to the volume of titrant 3,4 ml at (Δ/ΔV)=28,70), during the titration of the acetate of copper (II) - pH to 6.42 (corresponds to a volume of 2.5 ml titrant at (Δ/ΔV)=2,78), and during the titration of pectinate of copper (II) - pH 4,87 (corresponds to a volume of 4.0 ml titrant at (Δ/ΔV)=1,62). Therefore, only paktinat of copper (II) if the alkalimetric titration has the equivalence point in an acid environment, which demonstrates the manifestation of them acidic properties with the formation of gidroksosoedineniya. For copper acetate (II), the equivalence point is observed practically in a neutral environment, for pectin - in an alkaline environment.

Thus, detection by thermal curves "high temperature" component (150-165°C) in pectinate of copper (II) and the manifestation of them acidic properties with the formation of gidroksosoedineniya in an acidic environment (pH 4,87) proves the existence of water molecules in the inner sphere of the COP, which is not observed for the starting materials.

III. Op�adelene content vnutrikorporativnoj water and quantitative composition of pectinate of copper (II)

For dried at a temperature of 120°C for 8 h samples recalculate the content of water from remote % (source: TGA) in mmol (table 4), and then build the graphical dependence of the Number of remote water, mmol - dehydration, °C (figures 7, 8, 9). As before (I and II stage of the analysis), the presence of vnutrikorporativnoj water neither for pectin (figure 7), or acetate of copper (II) (figure 8). Pectinata of copper (II) on thermogravimetry (figure 9) clearly there has been a "Playground", the corresponding vnutrikorporativnoj water (temperature dehydration 150-165°C). According to figure 9, the amount of this water is equal 2,42 mmol (or 0,04356 g). Subtracting from the mass is dried at a temperature of 120°C for 8 hours of pectinate of copper (II) (0,54340 g) mass vnutrikorporativnoj water (0,04356 g), find the mass of a fragment of copper (II) with pectin, i.e. 0,49984 G. Given molar ratio in pectinate of copper (II) ion copper (II) and residues of galacturonic acid (monomer of pectin) 1:2, or the weight ratio of 15.4 b%:84,54% (Kaisheva N. W., 2003), and calculate the content of copper ion (II) - 0,07728 g or 1,217 mmol and residues of galacturonic acid (molar mass of 175 g/mol) - 0,42256 g or 2,415 mmol.

Thus, the composition of pectinate of copper (II) exempt from the adsorption of water, is expressed by the following relations ion copper (II): galacturonic acid (L): CCW�focal point water:

mass (in g) - 0,07728:0,42256:0,04356;

the amount (mmol) - 1,217:2,415:2,420 or 1:2:2,

ie pectinate of copper (II) has the formula: [CuL2(H2O)2].

Example 2. Obtaining pectinata lead (II) is carried out analogously to obtaining pectinata of copper (II), as described in example 1, using instead of the acetate of copper (II) acetate lead (II). Pectinate lead (II) has a light brown color.

I. Identification of "high temperature" component Samples weighing about 0.5 g (exact linkage): the sugar beet pectin - 0,57942 g, acetate of lead (II) - 0,53274 g, pectinate lead (II) - 0,56358 g is subjected to thermal analysis under conditions similar to example 1. Feature derivatograph the investigated samples are shown in table 5. For all the investigated samples shows an endothermic effect in the temperature range 80-115°C on the curves TGA and 100-120°C in DTA curves. This effect on TGA curves corresponds to a loss in weight: 17,2% for pectin, 13,5% for lead acetate (II), and 9.4% for pectinata lead (II), which refers to the loss of water adsorption. This conclusion is confirmed by the results of the determination of moisture in the samples: after drying at 120°C for 8 h samples were: beet pectin 0,47976 g (loss of moisture 17.2 per cent), lead acetate (II) - 0,46082 g (loss of moisture 13,5%), pectinate lead (II) - 0,51060 g (water loss of 9.4%). Unlike pectin and acetate pig�and (II), for pectinata lead (II) found "high temperature" component, which corresponds to the endothermic effect at a temperature of 150-160°C (curve DTGA), 150-158°C (DTA curve).

II. Identification of education gidroksosoedineniya Field drying at a temperature of 120°C for 8 h samples, prepare their aqueous solutions with a volume of 50 ml with a concentration of 0.2% solution of beet pectin, 0.2% solution of lead acetate (II), 0.3% solution (suspension) of pectinate lead (II). The resulting solutions titrated 0,1 mol/l sodium hydroxide solution under conditions similar to example 1. Curves alkalimetric titration of lead acetate (II) and pectinate lead (II) is presented in figure 10. If during the titration of pectin (figure 4), the equivalence point occurs at pH 9,14, and during the titration of lead acetate (II) (figure 10, curve 1) - pH 7,84 (volume of titrant 4,9 ml at (Δ/ΔV)=2,84) during the titration of pectinate lead (II) (figure 10, curve 2) has a pH of 4.95 (the volume of 4.2 ml (ΔpH/ΔV)=1,83). Therefore, only pectinate lead (II) when the alkalimetric titration has the equivalence point in an acid environment that testifies about them acidic properties with the formation of gidroksosoedineniya. Unlike pectinata lead (II), the original substances are of the equivalence point in an alkaline environment.

Thus, detection by thermal curves "height�totemperatures" component (150-160°C) in pectinate lead (II) and the manifestation of them acidic properties with the formation of gidroksosoedineniya in an acidic environment (pH of 4.95) proves the existence of water molecules in the inner sphere, the COP what is not observed for the starting materials.

III. The definition of the content vnutrikorporativnoj water and quantitative composition of pectinate lead (II)

For dried at a temperature of 120°C for 8 h samples according to the TGA determine the content of water in remote and build mmol thermogravimetry in the "Number of remote water, mmol - TDEHYDRATION, °C (figure 11). As in the previous phases of analysis, nor for pectin (figure 7) or lead acetate (II) (figure 11, curve 1) is not observed the presence vnutrikorporativnoj water. In contrast, pectinata lead (II) on thermogravimetry (figure 11, curve 2) found ' Playground, which is associated with vnutrikorporativnoj water (temperature dehydration 150-160°C). According to figure 11 (curve 2), the amount of this water is equal to 3.25 mmol (or 0,05850 g).

Subtracting from the mass is dried at a temperature of 120°C for 8 hours of pectinate lead (II) (0,51060 g) mass vnutrikorporativnoj water (0,05850 g), find the mass of a fragment of lead (II) with pectin, i.e. 0,45210 G. Given molar ratio in pectinate lead (II) ion lead (II) and residues of galacturonic acid (monomer of pectin) 1:2 or their mass ratio 37,19%:62,81% (Kaisheva N. W., 2003), and calculate the content of the ion lead (II) -0,16814 0,811 g or mmol and residues of galacturonic acid (molar mass of 175 g/�ol) - 0,28396 g or 1,623 mmol.

Thus, the composition of pectinate lead (II) exempt from the adsorption of water, is expressed by the following relations ion lead (II): galacturonic acid (L): coordinating water:

mass (in g)- 0,16814:0,28396:0,05850;

the amount (in mmol) is 0,811:1,623:3,25 or 1:2:4,

ie pectinate lead (II) has the formula: [PbL2(H2O)4].

Thus, the proposed method provides the following benefits:

1) reliable identification of water molecules in the inner sphere, the COP

This ensures that the determined first temperature characteristic of adsorptive removal of water (the nature of water, such as adsorption, confirm moisture content in the sample) and remove vnutrikorporativnoj water (with a characteristic temperature of dehydration ≥150°C), then at the proper temperature adsorption water is removed, leaving the COP vnutrikorporativnye water. Confirmation of the presence of water as a ligand in the COP is the education at alkalimetric titration gidroksosoedineniya in an acidic environment, due to the increased acidic properties of molecules vnutrikorporativnoj water due to the strong polarizing influence of metal cations. If water molecules were not associated with metal ion in the inner sphere, and would be outside of her polarizing effect on n�x metal ion would be weak and would be observed by their acidic properties when interacting with alkali, leading to the formation of hydroxocomplexes. Thus, in the proposed method, the identification of water molecules, as vnutrivennoi, is carried out in two ways: the temperature of dehydration of ≥150°C (thermal curves) and pH<5.0 in the equivalence point when the alkalimetric titration. These symptoms are not typical of other structural components of the COP.

2) quantification vnutrikorporativnoj water in COP

This ensures that the characteristic "sites" typical vnutrikorporativnoj water, thermogravimetric determine the quantity of water taken during the suspension of the COP;

3) deducing the formula of the COP

Set amount vnutrikorporativnoj water at a specific linkage of the COP with regard to the content of other components allows to derive the formula (molar composition) of the COP. Knowledge of the formula of the COP is of great theoretical importance in coordination chemistry in the study of the structure of the COP and practical significance in pharmacy in the determination of therapeutic doses of drugs.

4) the proposed method has good reproducibility and comparability of results of the determination, and the simplicity, both from the point of view of preparation of samples for analysis (not required for the production of films), and from the point of view of conditions of the analysis (not required vacuum creation).

Table 1Thermal characteristics of pectinate of copper (II) and of the starting materials to obtainThe effect of DTA (T1-T2), °CThe nature of the effectThe effect of DTGA (T1-T2), °CThe total loss in weight, %The sugar beet pectin100-115 (max 113)↓ removal of the solvent80-105 (max 105)98,0190-210 (max 200)↓ destruction by carboxyl groups210-230 (max 230)230-260 (max 240)↓ destruction by 1,4-glycosidic links255-270 (max 265)420-450↓ destruction410-415 (max 415)Acetate of copper (II)115-120 (max 118)↓ removal of the solvent110-115 (max 115)68,0300-430 (max 400)td align="center"> ↓ destruction by melting320-450 (max 390)Pectinate of copper (II)115-120 (max 120)↓ removal of the solvent90-115 (max 110)75,0155-160 (max 160)↓ removal of the solvent150-165 (max 165)200-220 (max 215)↓ destruction by carboxyl groups215-230 (max 225)240-260 (max 255)↓ destruction by 1,4-glycosidic links250-265 (max 260)470-500↓ destruction460-480 (max 475)Note: ↓ - endothermic effect;
max - the maximum point of thermal effect;
(T1-T2- the range of temperatures of the beginning and end of the effect.

Table 2
The effect of the duration of drying samples at a temperature of 120±5°With loss of water adsorption
SamplesLoss of moisture (%) duration of drying:
4 h6 hour8 hour10 h
The sugar beet pectin8,7±0,2614,5±0,4417,2±0,5217,0±±0,52
Acetate of copper (II)6,1±0,197,5±0,239,0±0,289,1±0,28
Pectinate of copper (II)4,9±0,156,2±0,197,4±0,247,4±0,23
Acetate of lead (II)7,4±0,22P,1±0,3313,5±0,4113,3±0,42
Pectinate lead (II)6,4±0,198,3±0,259,4±0,299,4±0,30

Table 3
These alkalinities�th titrations of solutions of sugar beet pectin acetate of copper (II), pectinate of copper (II)
PectinAcetate of copper (II)Pectinate of copper (II)
VNaOHvkpHVNaOHmlpHVNaOHmlpH
-3,24--4,12--3,25-
0,23,320,400,54,150,060,53,340,18
0,43,400,401,04,210,12 1,03,440,20
0,63,490,451,5To 4.410,401,5It was 3.540,20
0,83,580,452,05,031,242,03,650,22
1,03,700,602,5Is 6.422,782,53,760,22
1,23,820,603,06,830,823,03,890,26
1,43,950,653,57,13 0,603,54,060,34
1,64,080,654,07,350,444,04,871,62
1,8The 4.250,854,57,530,364,5The 5.451,16
2,04,420,855,0To 7.680,305,05,850,80
2,24,651,155,56,070,44
2,44,971,60 6,06,220,30
2,65,532,806,5System 6.340,24
2,86,303,857,06,430,18
3,07,67Of 6.857,5-6,490,12
3,28.66 roubles27,308,06,540,10
3,49,1428,70 8,56,590,10
3,69,501,809,0To 6.620,06
3,8Case 9.83The 1.659,5Of 6.650,06
4,010,151,6010,06,680,06
4,210,401,25
4,4At 10.641,20
4,610,861,10
4,8Of 11.050,95
5,011,140,45

Pectinate of copper (II)
Table 4
Data for building thermographers beet pectin, acetate of copper (II), pectinate of copper(II)
Temperature, °CPectinAcetate of copper (II)
The number of remote waterThe number of remote waterThe number of remote water
mgmmolmgmmolmgmmol
70To 8.140,45226,681,48222,471,248
809,400,52228,281,57123,901,328
9011,590,64430,281,68225,331,407
10014,780,82131,721,76228,731,596
110 17,510,97333,231,84631,341,741
120And 20.591,14434,961,94233,461,859
13023,811,32337,152,06435,851,992
14026,661,48138,932,16338,542,141
15029,201,62241,492,30540,322,240
16030,961,72044,142,45241,042,280
170 33,161,84246,462,58147,802,656
18033,891,88348,312,68452,272,904

Table 5
Thermal characteristics of pectinate lead (II) and of the starting materials to obtain
The effect of DTA (T1-T2), °CThe nature of the effectThe effect of DTGA (T1-T2), °CThe total loss in weight, %
The sugar beet pectin
100-115 (max 113)↓ removal of the solvent80-105 (max 105)98,0
190-210 (max 200)↓ destruction by carboxyl groups210-230 (max 230)
230-260 (max 240)↓ destruction by 1,4-glycosidic St�of Sam 255-270 (max 265)
420-450↓ destruction410-415 (max 415)
Acetate of lead (II)
100-110 (max 105)↓ removal of the solvent100-115 (max 110)70,4
275-320 (max 280)↓ destruction by melting300-350 (max 310)
Pectinate lead (II)
110-120 (max 110)↓ removal of the solvent80-110 (max 110)73,0
150-158 (max 155)↓ removal of the solvent150-160 (max 157)
190-220 (max 220)↓ destruction by carboxyl groups215-235 (max 235)
245-250 (max 250)↓ destruction by 1,4-glycosidic links250-255 (max 250)
340-530↓ destruction350-500 (max 380)
Note: the same notation as in table 1.

Method of determination of water in CA in the solid state, in which the water molecules in the inner sphere of the COP, in solid state, identify the temperature of dehydration of the samples in the field 150-165°C thermal curves - derivatograph obtained in the temperature range 20-1000 °C at a heating rate of samples 10 deg/min, and the formation of hydroxocomplexes as a result of alkalimetric titrations of aqueous solutions of the COP, pre-dehydrated at a temperature of 120°C for 8 hours, by identifying differential titration curve equivalence point, corresponding to the pH value in the field 4,87-4,95, further, for dehydrated by drying at 120°C for 8 hours solid samples, the COP on the typical sites on thermographical the graphics system, "the Number of remote water, mmol - Temperature dehydration, °C" are the quantitative content of water in the domestic sphere, the COP solid sample.



 

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FIELD: chemistry.

SUBSTANCE: invention relates to analytical chemistry and can be used in a system for monitoring content of sodium thiosulphate in solutions. The method of determining sodium thiosulphate in solutions is characterised by adding an analysed sample into a reaction vessel containing a corresponding amount of photogenerated iodine, obtained by blowing with air for 1-2 minutes and irradiating the reaction mixture with a stabilised light source, the mixture consisting of 0.5 M potassium iodide solution, an acetate buffer solution with pH 5.6 and a sodium eosinate sensitising agent, by detecting change in current in a cell and upon achieving constant current, re-blowing the reaction mixture with air for 2-3 minutes and re-irradiating with the stabilised light source until achieving the initial amount of iodine in the vessel, measuring the iodine generation time spent on achieving the decrease thereof, determining the amount of sodium thiosulphate from a calibration curve from the change in current and generation time.

EFFECT: invention provides a simple method of determining sodium thiosulphate in solutions and avoids use of expensive equipment.

10 tbl, 5 dwg

FIELD: chemistry.

SUBSTANCE: in order to extract iron (III) from water solutions diphenylguanidine (DPG) is applied as the first organic reagent. As the second organic reagent, salicylic acid (SA) is applied, and as solvent of organic phase chloroform is applied. In organic phase complex with molar component ratio DPG: Fe3+:SA, equal 1:1:1, is extracted. Process of iron (III) extraction is carried out at medium acidity pH=1.5-2.5 with the following detection of iron (III) by trimetric method.

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SUBSTANCE: method of determining concentration of grafted amino groups on the surface of mineral filling agents includes preparation of acetylating solution by mixing initial components, its addition to weighed portion of modified mineral filler sample, exposure for quantitative realisation of reaction, titration with alkali solution in presence of indicator, calculation of concentration of amino groups by difference of results of idle titration and sample titration. As acetylating solution used is 0.5-0.6 M solution of acetic anhydride in mixed solvent dichloroethane-pyridine in ratio from 0.5:1-2:1, which contains 0.025-0.15 mol/l of chloric acid as catalyst. 0.5-0.6 M of acetylating solution in mixed solvent, containing chloric acid, is added to weighed portion of modified mineral filler, ratio of weighed portion of sample weight to volume of acetylating solution constitutes 1:4-1:5, after which it is exposed and hydrolysing mixture, consisting of dimethylformamide, pyridine, water, taken in ratio 6:3:1 respectively, is added. After that, obtained mixture is centrifuged to separate residue.

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13 ex, 1 tbl

FIELD: chemistry.

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2 tbl, 1 dwg, 1 ex

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15 cl, 1 tbl, 5 dwg

FIELD: chemistry.

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EFFECT: improved method.

4 cl, 1 tbl, 1 ex

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FIELD: chemistry.

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FIELD: agriculture.

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EFFECT: reduced operating costs and higher safety of measurements.

FIELD: instrumentation.

SUBSTANCE: proposed method consists in filling measuring vessel of known volume with dry air and weighing it. Then, measuring vessel is filled with air and weighed to record air temperature and pressure using measured magnitudes. Then, air moisture content d is defined by the formula: g/kg dry, where m1 is the weight of measuring vessel with dry air, g; m2 is the weight of measuring vessel with analysed air, g; V is measuring vessel volume, liter; Pap is analysed air barometric pressure, mm Hg; Tat is analysed air temperature, °C; gn is specific weight of steam, g/l (gn = 0.803 g/l); gc is specific weight of dry air, g/l (gc= 1.2928 g/l); P0 is normal pressure, mm Hg (P0=760 mm Hg); T0 is normal temperature °C(T0=273°C).

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EFFECT: automation of correction of the graduated characteristic of the hygrometre during measurement and providing long-term stability of measurement errors.

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FIELD: measurement technology.

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EFFECT: prolonged service life; higher stability of operation; increased moisture resistance.

5 cl, 1 dwg

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