[Calculation of a single and of subsequent extraction-reextraction cycles]. / K raschetu odnogo i posledovatel'nykh tsiklov éktrakstiia-reéktraktsiia.

Estimation of the equilibrium distribution in the organic solvent-water system provided analysis of efficiency and optimal arrangement of subsequent extraction-reextraction cycles in isolation of various compounds. The analysis was performed with respect to optimization of the total yield and required volumes of the intermediate phases. It was shown that the best arrangement of the subsequent extraction-reextraction cycles depended on the compound distribution coefficients at various stages.

[Benzylpenicillin interaction with amines in the organic phase]. / Vzaimodeistvie benzilpenitsllina s aminami v organizheskoi faze.

Benzylpenicillin interaction with amines in the nonaqueous phase was studied by pH dependence of the coefficient of the antibiotic distribution in the system of amine butyl acetate solution--water. A distribution scheme involving interaction of the amine molecular and cationic forms with benzylpenicillin and amine dissociation equilibrium in organic solution is described. On the basis of the experimental data the interaction and dissociation constants were determined for a number of aromatic and aliphatic amines.

[Separation of emulsions during extraction of antibiotics from native solutions]. / Issledovanie protsessa separirovaniia émul'sii pri ékstraktsii antibiotikov iz nativnykh rastvorov.

The separating capacity of a laboratory cup centrifuge and industrial centrifugal separator was compared. It was shown that the process of emulsion centrifugal separation could be modeled under laboratory conditions: antibiotic fermentation broth filtrate--organic solvent in industrial apparatus under similar conditions of preliminary mixing aqueous and organic phases.

[Mathematical model of removal of impurities from antibiotic pastes]. / Matematicheskaia model' protsessa osvobozhdeniia past antibiotikov ot primesnykh veshchestv.

The process of antibiotic paste washing by repulpation in a solvent, as well as the process of replacing washing of antibiotic filter cakes was studied. This enabled to develop a mathematical model of the process of admixture removing from antibiotic pastes by successive repulpation and replacing washing. The model connects the initial admixture levels in pastes, the filter cake characteristics, the specification requirements to the drug quality and the technological parameters of the process. The results of the studies confirmed the model adequacy.

[Hydrodynamic study of a centrifugal differential-contact extractor]. / Issledovanie gidrodinamiki tsentrobezhnogo differentsial'no- kontaktnogo ékstraktora.

Centrifugal extractors of the differential-contact type are widely used all over the world in production of antibiotics. Lately, new extractors were developed by Hitachi (Japan). Model E is of a special interest. In the present study the values of the working zone of the Hitachi extractor, EP-02 Ultrex were determined by the pressure levels and the effect of the main parameters characterizing the apparatus hydrodynamic conditions on the minimum and maximum critical pressure was estimated. The results of the study provide wide variation of the hydrodynamic parameters in determination of the most rational extraction conditions.

[Calculated rates of the filtration of antibiotic suspensions in leaf filters with horizontal filtering elements]. / Raschetnye sootnosheniia dlia protsessa fil'tratsii suspenzii antibiotikov na listovykh fil'trakh s gorizontal'nymi fil'truiushchimi elementami.

A procedure for calculating sediment distribution on horizontal filtering elements of multileaf filters used for separation of antibiotic suspensions, as well as for calculation of the filtration time in such apparatus is described. The correlations derived on the basis of this procedure may be used for preliminary technological evaluation of the stage of suspension filtration in production of antibiotic powders for injection with the use of closed air-tight apparatus schemes including multileaf filters.

[Elimination of admixtures from antibiotic sediments during their treatment with solvents]. / Udalenie primesei iz osadkov antibiotikov pri obrabotke ikh rastvoriteliami.

A model for determination of the admixture concentration in the secondary mother solution was developed. The concentration was determined depending on the solvent volume used for repulping the precipitate and on the impurity level of the initial antibiotic paste. When the values of X1 and X2 are known it is possible to estimate the amount of the admixtures remaining in the paste layer after separation of the secondary mother solution with regard to the volume of the latter in the precipitate pores. Optimization of paste repulping should be considered in combination with displacement washing and the apparatus used for separation of the phases, as well as the requirements for the purity level of the finished product.

[Stability of rifamycin B in aqueous solutions]. / Ustoichivost' rifamitsina B v vodnykh rastvorakh.

Stability of rifamycin B in aqueous solutions at various values of pH and temperature was studied. It was shown that inactivation of the antibiotic in neutral and alkaline solutions proceeded according to the first order equation. In acid solutions rifamycin B was oxidized with air oxygen to form rifamycin O.

[Effect of the quality of regenerated butanol on the process of producing the potassium salt of benzylpenicillin]. / Issledovanie vliianiia kachestva regenerirovannogo butanola na protsess polucheniia kalievoi soli benzilpenitsillina.

The effect of water and butylacetate contained in butanol used in production of potassium benzylpenicillin on the yield and quality of the latter was studied. It was found that normal butyl alcohol with the moisture level not more than 0.2 per cent provided the optimal conditions for the antibiotic production. Butyl acetate contained in butanol in an amount of 25 per cent was shown also to have practically no effect on the yield and quality of benzylpenicillin.

[Flocculant interaction with native antibiotic solutions. The effect of flocculants on the quality indices of native solutions as dependent on a number of factors]. / Izuchenie vzaimodeistviia flokkuliantov s nativnymi rastvorami antibiotikov. Vliianie flokkuliantov na pokazateli kachestva nativnykh rastvorov v zavisimosti ot riada faktorov.

Flocculants had a significant effect on the characteristics of the fermentation broth filtrates of some antibiotics. They decreased the filtrate turbidity, concentration of the organic ballast, etc. The size of the floccules depended on a number of factors, including the fluocculant concentration, agitation rate, concentration of the dispersing phase in the initial filtrate. The optimal concentration of the flocculant was defined not only by the type of the antibiotic-producing organism but also by composition of the nutrient medium used for the biosynthesis. Floccculant treatment provided a significant increase in the quality of the fermentation broth filtrates with respect to the main parameters: levels of proteins, pigments, emulgation capacity.

[Rifamycin in B distribution between aqueous and organic phases]. / K voprosu o raspredelenii rifamitsina B mezhdu vodnoi i organicheskoi fazoi.

Dependence of the coefficient of rifamycin B distribution in the system of butyl acetate-buffer solution on pH of the equilibrium acqueous phase, antibiotic concentration in the solution and temperature was studied. It was shown that the coefficient value did not depend on the antibiotic concentration within 1000-2000 gamma/ml and temperature.

[Flocculant interaction with native antibiotic solutions. An examination of the mechanism of the process]. / Izuchenie vzaimodeistviia flokkuliantov s nativymi rastvorami antibiotikov. Rassmotrenie mekhanizma protsessa.

Some characteristics of the fermentation broth filtrates, i.e. concentration of the disperse particles and some of their parameters (projected length, area, distribution of the particles along the maximum chord) were determined and estimated after flocculation. It was shown that the floccules were mainly formed as fine colloid admixtures present not only in "turbid", but also in visually transparant solutions. It was found that the mechanism of flocculation was rather complicated and not always similar for different batches of the fermentation broth filtrate: it was, in particular, affected by the electrostatic interactions, the flocculant interaction with inorganic reagents, bridge-forming processes.

[Effect of the crystallization conditions of tetracycline base on the properties of the powders and drug forms obtained. The dependence of the degree of dispersion of tetracycline base on the crystallization conditions]. / Vliianie uslovi kristallizatsii tetratsiklina osnovaniia na svoistva poluchaemykh poroshkov i lekarstvennykh form. Zavisimost' dispersnosti poroshkov tetratsiklina osnovaniia ot uslovii kristallizatsii.

Characteristics of the powder dispersity of tetracycline base samples prepared by directed crystallization with variation of the process conditions were determined by the sedimentation method. It was found that the speed of the solution agitation had the maximum effect on the level and nature of the dispersity. The rate of the solution temperature and pH changing during the crystallization process had also a significant effect at low agitation speed.

[Effect of tetracycline base crystallization on the conditions properties of the powders and drug forms obtained. The development of directed crystallization procedures for tetracycline base]. / Vliianie uslovii kristallizatsii tetratsiklina osnovaniia na svoistva poluchaemykh poroshkov i lekarstvennykh form. Razrabotka priemov napravlennoi kristallizatsii tetratsiklina osnovaniia.

The study of the process of tetracycline base crystallization showed that with an increase in the rate of pH, temperature and mixed rotation changes, the specific surface of the crystalline precipitate increased with a simultaneous decrease in the bulk weight, looseness and volume density of the powder. The residual content of tetracycline in the mother solution decreased. The level of the effect of various parameters on the final results was different.

[Effect of different factors on the rate of benzylpenicillin conversion in an aqueous system-butylacetate system]. / Vliianie razlichnykh faktorov na skorost' perekhoda benzilpenitsillina v sisteme vodnaia sreda-butilatsetat

It was shown that the mass-transfer coefficient of non-dissociated benzylpenicillin during extraction was more than 1000 times higher than that during reextraction. For the latter it was found that the aqueous phase exerted limiting resistance during mass-transfer of benzylpenicillin. The effect of a number of factors on the kinetics was shown. These factors were the following: hydrodynamic conditions, temperature, pH of the aqueous phase.

[Purification of antibiotic solutions of finely dispersed admixtures]. / Ochistka rastvorov antibiotikov ot tonkodispersnykh primesei

A possibility of complete separation of fine disperse admixtures from antibiotic fermentation broth filtrates by filtration with the use of special additives was shown. The purity of the filtrates and filtration rate depended on the procedure of addition, amount and average size of the particles of the filtration material.

[Use of a rotation chart for studying the flocculation of admixtures in native solutions]. / Primenenie rotatabil'nogo planirovaniia éksperimenta dlia izucheniia flokkuliatsii primesei v nativnykh rastvorakh

The process of admixture flocculation in fermentation broth filtrates of penicillin was studied experimentally according to the schemes of rotatabel planning of the 2nd order. Equations describing the effect of the main factors on the process were worked out and the main effects of the pair interactions were found.