Method of inhibiting hydrolysis of dimethylformamide or dimethylacetamide in the processes of isolation of diene hydrocarbons by extractive distillation
(57) Abstract:Method of inhibiting hydrolysis of dimethylformamide or dimethylacetamide in the process of selection of diene hydrocarbons from C4-C5hydrocarbon mixtures by extractive distillation derivatives research with unsaturated carbonyl compounds or a mixture of them with morpholine. The mass ratio of morpholine: the product of its interaction with the carbonyl compound is changed in a wide range: from 0.1 to 99.9% to 99.9-0.1 wt.%. The optimal dosage of the inhibitor of 0.1-5, 0 wt. % extractant. Introduction in the extractant of the research and/or products of interaction of research with unsaturated carbonyl compounds increases the effectiveness of the inhibition of the hydrolysis of extragenic. 1 tab. The invention relates to methods of inhibiting hydrolysis of dimethylformamide (DMF) or dimethylacetamide (DMAA) in the processes of isolation of diene hydrocarbons from C4-C5hydrocarbon mixtures by extractive distillation (ER) and may find application in the petrochemical industry for the production of diene hydrocarbons.In the process of extractive distillation for solvent use various organic is aetsa hydrolytic instability.To prevent hydrolysis of the extractants used inhibitors. Usually the role of the latter perform aliphatic and aromatic carbonyl compounds (ed. N 307996, class C 07 C 7/10, 1969). In the domestic industry, in particular in the processes of isolation of diene hydrocarbons have been used cyclohexanone and furfural (liokumovich A., and others, the Inhibition of hydrolysis of dimethylformamide.-Chem. industry, No. 3, 1970, S. 22-24).The main shortcomings in the industry inhibiting compositions are insufficient efficiency of inhibition, loss of extractant and inhibitors with heavy resins.The purpose of the invention is improving the efficiency of inhibition of the hydrolysis of extractants.This goal is achieved by introducing into the extractive agent as an inhibitor of the research and/or products of interaction of research with unsaturated carbonyl compounds of General formula
R1= H, C1-C12; R3-CO-R4(R3and R4= C1-C10;
R2= C1-C12; R3-CO-R4(R3and R4= C1-C10)
Components inhibitor soluble in DMF, DMAA, are the inhibitor is nil economic expediency.The advantages of this method are the ease of preparation and dosage of the inhibitor.In addition, the physical properties of the research (TKip.= 128oC) reduce the loss of inhibitor heavy resins.Example 1 (control experiment).In a glass three-neck flask with a capacity of 500 ml equipped with a thermometer and reflux condenser, download dimethylformamide containing 10 wt.% water and 0.1 wt. % formic acid (HCOOH - catalyst in the hydrolysis of DMF). Refrigerator connected to a system of flasks Drexel filled titrated with an aqueous solution of acid or water to absorb the product hydrolyse DMF-dimethylamine, which is then subjected to analysis. Studies of the hydrolysis of DMF is carried out at a temperature of 150oC and atmospheric pressure. The duration of the experiment 135 hours On the degree of hydrolysis of DMF is judged by the amount of released dimethylamine and formic acid, followed by conversion to DMF. The results are presented in the table.Example 2 (the prototype). In the conditions of example 1 determine the degree of hydrolysis of DMF containing 10 wt.% water; 0.1 wt.% HCOOH and 1.0 wt.% furfural. The results are presented in the table.Example 3.
Example 4.In the conditions of example 3 instead of the research as an inhibitor of the hydrolysis of DMF using 1-morpholinomethyl-1,3 in the amount of 1.0 wt.%. The results are presented in the table.Examples 5-9.In the conditions of example 3 instead of the research as an inhibitor of the hydrolysis of DMF using 1.0 wt.% a mixture of morpholine + 1-morpholinomethyl-1,3 in the following mass ratios: 99,9+0,1; 90 + 10; 50 + 50; 10 + 90; 0,1 + 99,9. The results are presented in the table.Example 10.In the conditions of example 3 instead of the research as an inhibitor of the hydrolysis of DMF using 4-morpholinomethyl-2 in the amount of 1.0 wt.%. The results are presented in the table.Examples 11-15.In the conditions of example 3 instead of the research as an inhibitor of the hydrolysis of DMF using 1.0 wt.% a mixture of morpholine + 4-morpholinomethyl-2 in the following mass ratios: 99,9 + 0,1; 90 + 10; 50 + 50; 10 + 90; 0,1 + 99,9. The results are presented in the table.Example 16.In the conditions of example 3 instead of the research as an inhibitor of the hydrolysis of DMF using 1,3-dimorpholino in the amount of 1.0 wt.%. The results are presented in the table.Examples 17-21.In the conditions of example 3 instead of the research as in eniah: 99,9 + 0,1; 90+10; 50 + 50; 10 + 90; 0,1 + 99,9. The results are presented in the table.Examples 22-23.In the conditions of example 3 instead of the research as an inhibitor of the hydrolysis of DMF using 5.0 wt.% a mixture of morpholine + 1,3-dimorpholino in the following mass proportions: 90 + 10; 50 + 50. The results are presented in the table.Example 24.In the conditions of example 3 instead of the research as an inhibitor of the hydrolysis of DMF used to 0.10 wt.% a mixture of morpholine + 1,3-dimorpholino in a mass ratio of 10+90. The results are presented in the table.Examples 25-27.In the conditions of example 1 determine the degree of hydrolysis DMAA containing 10 wt. % water; 0.1 wt.% CH3COOH and 1.0 wt.% a mixture of morpholine + 1,3-dimorpholino in the following mass ratios: 90 + 10; 50 + 50; 10 + 90. The results are presented in the table.From the table it is seen that the interaction products of the research with unsaturated carbonyl compounds such as 1-morpholinopropan -1,3, 4-morpholinomethyl-2, 1,3-dimorpholino, etc. are more effective inhibitors of the hydrolysis of DMF or DMAA than furfural, and the use of mixtures of the research and its derivatives is observed synergistic effect.
hydrocarbons from C4- C5-hydrocarbon mixtures by extractive distillation in the presence of these extractants by the introduction of a hydrolysis inhibitor, characterized in that as an inhibitor use morpholine or its derivative selected from a range that contains 1-morpholinopropan-1,3,4-morpholinomethyl and 1,3-dimorpholino, or a mixture of the research with the specified derivatives of the research in their mass ratio of from 0.1: to 99.9 to 99.9: 0.1, respectively in an amount to provide its concentration in the extractant is 0.1 to 5.0 wt.%.
FIELD: organic chemistry.
SUBSTANCE: invention relates to method for production of H-type nateglinide crystals. Claimed method includes addition of nateglinide-containing reaction mixture to inorganic acid(s) to produce acidic medium, wherein said reaction mixture in produced by interaction of trans-4-isopropylcyclohexylcarbonyl chloride with D-phenyl alanine in mixed solvent comprising of ketone solvent and water in water/ketone solvent ratio from 10:1 to 0.5:1 in presence of alkali followed by adjusting of mixture temperature to 58-72°C and ketone solvent concentration to 8-22 mass % to precipitate nateglinide crystals.
EFFECT: industrially advantageous methods for production of nateglinide crystals.
10 cl, 13 ex, 1 tbl
SUBSTANCE: method involves crystallisation of iodixanol from a crude product containing approximately 75-90 wt % iodixanol, 3-10 wt % iohexol, 3-7 wt % 5-acetamido- N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodisophthalamide and trace amounts of other impurities in a solvent containing 1-methoxy-2-propanol. As a rule, the crystallisation process comprises a single step and lasts a total of 1-4 days, mainly approximately 2 days.
EFFECT: high output of desired product.
12 cl, 1 dwg, 4 ex
SUBSTANCE: invention can be used in reclamation of dimethylacetamide (DMAA). The method of reclaiming N,N-dimethylacetamide when producing high-strength aramid fibres includes neutralisation of starting solutions, fractionation of a stretch bath solution in two columns, vacuum evaporation of the mixture of the still residue of a vacuum evaporation apparatus, vacuum fractionation of the evaporated product of the vacuum evaporation apparatus and a third column to obtain the end product. The starting multi-component mixtures are first separated into mixtures containing lithium chloride and mixtures not containing lithium chloride. Mixtures which do not contain lithium chloride are then separated into mixtures containing DMAA and mixtures which do not contain DMAA. A stream which does not contain lithium chloride - a distillate of the vacuum evaporation apparatus and the third vacuum fractionation column - is fed into the last vacuum fractionation column operating at residual pressure of 0.04-0.15 kgf/cm2, where vapour of the dimethylacetamide end product is obtained.
EFFECT: high quality of dimethylacetamide as the end product.
SUBSTANCE: method of regenerating a complex lithium chloride - dimethylacetamide salt includes neutralising starting solutions, fractionating the stretch bath solution in two columns, vacuum evaporation of the mixture of the still residue of the second column and the settling bath, fractionating the still residue of the vacuum-evaporation apparatus, vacuum fractionation of stripped product of the vacuum-evaporation apparatus and a third column to obtain a solvent, crystallising the concentrated solution of lithium chloride in dimethylacetamide, separating crystals from the solution, separating the crystals on centrifuges and dissolving the crystals in the solvent to obtain the end product. Multi-component starting mixtures containing 0-60% dimethylacetamide (DMAA), 0-70% isobutyl alcohol (IBA), as well as lithium chloride (LiCl), hydrogen chloride, water and impurities - the balance up to 100%, are first separated into lithium chloride-containing mixtures and mixtures which do not contain lithium chloride. The mixtures which do not contain lithium chloride are then separated into mixtures containing DMAA and mixtures which do not contain DMAA. A liquid stream consisting of IBA and water is output from the system; a stream of concentrated lithium chloride is successively directed for heteroazeotropic fractionation, crystallisation and centrifuging, where the complex lithium chloride-dimethylacetamide salt is separated in a liquid phase and a pure complex salt is obtained.
EFFECT: obtaining an end product of high purity for return thereof into the production cycle.
SUBSTANCE: invention relates to an aqueous acrylamide solution for producing an acrylamide polymer, which contains acetaldehyde in concentration of 1.5 mg/kg acrylamide to 4 mg/kg acrylamide for stabilising the aqueous acrylamide solution. The invention also relates to a stabilised aqueous acrylamide solution and a method of stabilising an aqueous acrylamide solution.
EFFECT: obtaining a stable aqueous acrylamide solution owing to content of acetaldehyde in concentration of 1,5 mg/kg acrylamide to 4 mg/kg acrylamide.
5 cl, 2 tbl, 2 ex
FIELD: petroleum processing and petrochemistry.
SUBSTANCE: C5-hydrocarbons with different degrees of saturation are separated by extractive rectification in extractive rectification column using dimethylformamide as extractant followed by desorption of pentenes or pentadienes therefrom and passing desorbed extractant to extractive rectification column. Part of hot desorbed extractant is subjected to liquid-phase mixing with starting hydrocarbons at vigorous stirring, after which resulting mixture is introduced into column in liquid form.
EFFECT: reduced power consumption.
2 dwg, 1 tbl, 5 ex
FIELD: petrochemical processes.
SUBSTANCE: C4-hydrocarbon fractions obtained by cracking and/or pyrolysis of hydrocarbon feedstock in presence of amine-type extractant are subjected to rectification additionally involving butylene-isobutylene fraction resulting from butylene-to-isobutylene isomerization and containing 30-70% butylenes, 25-65% isobutylene, and 3-8% butanes. Weight ratio of C4-hydrocarbon fractions to added butylene-isobutylene fraction is 1:(3-7).
EFFECT: increased separation efficiency.
FIELD: petroleum industry.
SUBSTANCE: process in carried out in column having divider arranging in longitudinal direction to form the first section, the second one and the third bottom joint section, wherein extractive scrubber is includes before divider.
EFFECT: simplified technology.
16 cl, 3 dwg
FIELD: petroleum processing and petrochemistry.
SUBSTANCE: catalysate of reforming of long gasoline fractions containing more than 2% benzene is separated by rectification into three fractions: light-boiling fraction containing mainly nonaromatic C4-C6-hydrocarbons and no more than 1%, preferably no more than 0.5%, benzene; high-boiling fraction containing mainly aromatic and nonaromatic hydrocarbons C7 or higher and no more than 1%, preferably no more than 0.5%, benzene; and benzene fraction boiling within a range of 70-95°C and containing no more than 0.1%, preferably no more than 0.02%, toluene and no more than 0.02% nonaromatic hydrocarbons with boiling temperature above 110°C. Benzene fraction is routed into benzene isolation process involving extractive rectification with polar aprotic solvent having ratio of dipole moment to square root of molar volume above 0.3 db/(cm3/g-mole)1/2, preferably above 0.4 db/(cm3/g-mole)1/2, and boiling temperature 150 to 250°C.
EFFECT: improved quality of benzene.
4 dwg, 2 tbl, 5 ex
FIELD: petrochemical processes.
SUBSTANCE: process involves extractive rectification in presence of extractant mainly containing aliphatic N-alkylamide, while toluene is introduced into rectification column point disposed between extractant inlet and the top of column.
EFFECT: reduced loss of extractant with distillate.
6 cl, 3 dwg, 6 tbl, 6 ex
FIELD: petrochemical processes.
SUBSTANCE: invention provides a process flow rate comprising at least (i) zone of extractive rectification in presence of polar extractant to produce distillate mainly containing butanes and butane(s); (ii) desorption zone wherein desorption of extractant gives stream containing mainly 1,3-butadiene and. as impurities, at least 2-butene(s) and acetylene hydrocarbons; and (iii) optionally rectification zone for mainly 1,3-butadiene-containing stream. In the latter, α-acetylene hydrocarbons are subjected to liquid-phase selective hydrogenation with hydrogen or hydrogen-containing mixture in presence of solid catalyst containing metal(s) exhibiting high activity in hydrogenation process, preferably non-precious metal(s) on solid support. Temperature is maintained within a range 5 to 75°C at contact time ensuring hydrogenation of no more then 6%, preferably no more than 2% of butadiene present. After hydrogenation, 1,3-butadiene is optionally additionally separated from impurities via rectification.
EFFECT: simplified process.
13 cl, 3 dwg, 2 tbl, 10 ex