Process and apparatus for continuous synthesis of trialkyl phosphite from triethylamine

Abstract

The present application relates to the technical fields of trialkyl phosphite synthesis, and a continuous process and equipment for synthesizing trialkyl phosphite by using triethylamine, which comprises a stirring blade, a flow guide cylinder and a reaction kettle, the reaction kettle is provided with a jacket and an embedded coil, the top of the reaction kettle is communicated with an external condenser through a steam rising pipeline, a nozzle group embedded through a water inlet pipeline is arranged on the steam rising pipeline and the tube of the external condenser, the condensate outlet of the external condenser is connected with the reaction kettle and has a reflux extension pipe, the other end of the condensate outlet penetrates into a water washing kettle, and a reflux sight glass is arranged on the pipeline leading to the water washing kettle, by changing the structure of the phosphorus trichloride nozzle of the reaction kettle and additionally arranging a phosphorus trichloride nozzle ball valve, the mass transfer effect of the reaction can be improved, the concentration of the reactant can be improved, the concentration of triethylamine is increased from 12%-15% to 20%-30%, the steam used during the distillation of the product is reduced, and more than 5 tons of steam per ton of product trimethyl phosphite can be saved.

Description

Technical Field

[0001] This invention relates to the field of trialkyl phosphite synthesis technology, specifically to a continuous process and equipment for the synthesis of trialkyl phosphite from triethylamine. Background Technology

[0002] Trimethyl phosphite is an important chemical intermediate that can be used to prepare a series of vinyl phosphate insecticides such as dichlorvos and phosphatidylcholine, as well as in pharmaceuticals, the production of flame retardant DMMP, and cyclic phosphates.

[0003] Trimethyl phosphite was patented by Ciba Geigy of Switzerland in 1974. It is synthesized using a continuous triethylamine process with a capacity of 6,000 tons per year. The cryogenic synthesis process consumes 1.3 million kcal per ton, resulting in high energy consumption, 60 kg of triethylamine, and 1 kg of tar per ton of product, causing significant environmental pollution. The product purity is ≥98%.

[0004] Patent application number 200610086054X describes a process for producing trimethyl phosphite using methanol, phosphorus trichloride, xylene (N·N-dimethylaniline), and ammonia as raw materials. The process involves synthesis, washing, layering, drying, and distillation to obtain the product. However, the quality of this patented product is not high enough, the cost is 2000 yuan per ton higher than that produced using the triethylamine method, and it causes significant pollution.

[0005] Triethyl phosphite is an important chemical intermediate that can be used to produce the herbicide glufosinate, insecticides such as fumarate and fenitrothion, the pharmaceutical analgesic benzothiazide, and whitening agents.

[0006] Patent application number 202010941312.8 discloses a method for preparing triethyl phosphite. This application relates to the field of organic chemical intermediates production and specifically discloses a method for preparing triethyl phosphite. The preparation method involves: uniformly mixing anhydrous ethanol, an organic solvent, the catalyst trioctylamine, and an acid-binding agent to obtain a mixed solution; cooling the mixed solution to maintain the system temperature at 1-10°C, and adding phosphorus trichloride solution dropwise to the mixed solution, with a molar ratio of phosphorus trichloride to anhydrous ethanol of 1:(3-6); continuing to maintain the temperature for 1-4 hours after the addition is complete to obtain a reaction solution; separating and purifying to obtain triethyl phosphite, wherein the molar ratio of trioctylamine to the acid-binding agent is 2:(3-5). The preparation method of this application has the advantages of reducing the ammonium chloride content in the reaction waste liquid and reducing waste liquid treatment costs while ensuring a product yield of not less than 90% and a purity of not less than 95%. The patented method suffers from low yield, poor quality, difficulty in recovering trioctylamine, and high cost.

[0007] Patent Application No. 96220646.6. Patentee: Jingzhou Oriental Organic Chemical Research Institute, Hubei Province. Designers: Luo Fangming and Luo Chaolin. Utility Model Title: Continuous Synthesis Reactor for Manufacturing Trimethyl Phosphite. A continuous synthesis reactor for manufacturing trimethyl phosphite comprises a vertical cylindrical jacketed reaction vessel with a suspended guide tube inside. A vertical shaft is located in the center of the guide tube, with turbine agitators installed at the upper and lower ends. A paddle agitator is installed between the two turbine agitators. The feed of the mixture of phosphorus trichloride and methanol enters radially into the guide tube near the paddle agitator and converges at the end. Because the feed channel enters radially into the guide tube, and because the outlet of the channel is located on the vertical shaft where the paddle agitator is added, the generated trimethyl phosphite is protected, greatly improving the product reaction yield. This utility model patent is suitable for using low-temperature water or low-temperature brine as a heat transfer medium. The reaction temperature cannot be too high, and the concentration of triethylamine in the two-in-one mixture cannot be too high, which limits the yield and results in a low output. Summary of the Invention

[0008] The purpose of this invention is to provide a continuous process and equipment for the synthesis of trialkyl phosphite from triethylamine, in order to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a continuous process and equipment for the synthesis of trialkyl phosphite from triethylamine, comprising a stirring impeller, a guide tube, and a reaction vessel. The reaction vessel is equipped with a jacket and an internal coil, and the top of the reaction vessel is connected to an external condenser via a steam riser pipe. The steam riser pipe and the external condenser tubes are equipped with nozzle groups embedded in a water inlet network. One end of the condensate outlet of the external condenser is connected to the reaction vessel and has a reflux extension pipe, while the other end passes through a water washing vessel. A reflux sight glass is provided on the pipe returning to the water washing vessel.

[0010] Preferably, a butterfly valve and an expansion joint are installed sequentially on the steam riser pipe of the external condenser. The butterfly valve is used to isolate the gas phase during maintenance, and the expansion joint is used to reduce equipment vibration during operation.

[0011] Preferably, the phosphorus trichloride discharge direction of the nozzle group is the same as or opposite to the rotation direction of the stirring blade, the radial angle between phosphorus trichloride and the two-in-one nozzle is 3° to 60°, the longitudinal direction of the phosphorus trichloride feed pipe is consistent with that of the two-in-one feed pipe, and the angle with the horizontal direction is maintained at 3-60 degrees; a ball valve is installed on the feed pipe of the phosphorus trichloride nozzle group.

[0012] Preferably, the built-in coil of the reactor is divided into multiple layers, and each layer of the coil is independently equipped with an inlet valve and an outlet valve for adjusting production capacity, cleaning and maintenance.

[0013] Preferably, the external condenser is a plate condenser, a rotary plate condenser, or a vertical tube condenser, with a vertical tube condenser being the most preferred; and both the gas riser pipe and the condenser body of the external condenser are equipped with cleaning nozzles for introducing water or alkaline water to remove triethylamine hydrochloride crystals.

[0014] Preferably, a continuous process for synthesizing trialkyl phosphite from triethylamine includes the following steps: S1: Material preparation and equipment pretreatment.

[0015] Prefill the reactor with the combined solution, turn on the circulating water system of the jacket, built-in coil and external condenser, and turn on the stirring device.

[0016] S2: Continuous feeding and reaction with the guide tube

[0017] After the metered alcohol and the two-in-one solution are mixed, they are fed into the guide tube through a nozzle;

[0018] Phosphorus trichloride is metered and enters the guide tube non-radially through a phosphorus trichloride nozzle, forming an angle of 3° to 60° with the stirring direction, and rapidly mixes and reacts within the guide tube;

[0019] S3: Reaction Temperature Control and Heat Removal

[0020] The exothermic reaction is removed by the jacket, built-in coil, and external condenser, controlling the reaction temperature to be between room temperature and 73°C.

[0021] An external condenser condenses and recovers benzene, triethylamine, and alcohol from the gas phase, while the alcohol in the reflux liquid is returned to the reactor via the reflux extension tube to continue the reaction.

[0022] S4: Condensate diversion and anti-clogging treatment

[0023] Initially, the aqueous condensate is directly discharged into the water washing tank to prevent water from entering the reaction tank and reducing the yield;

[0024] The transparent condensate is returned to the reactor; the steam riser and condenser are cleaned regularly with alkaline water to prevent triethylamine hydrochloride crystallization and blockage;

[0025] S5: Continuous discharge and triethylamine regeneration

[0026] The reaction solution automatically overflows from the reaction vessel into the water washing vessel;

[0027] The triethylamine hydrochloride was reduced to triethylamine by washing with alkaline water. The triethylamine was recovered and recycled. The crude trialkyl phosphite was obtained by separation.

[0028] S6: Refining and Obtaining Finished Products

[0029] After drying and dehydration, the crude product is purified by distillation to obtain a high-purity trialkyl phosphite product.

[0030] Preferably, the condensate from the external condenser is delivered in two ways: the initial water-containing condensate is directly sent to the washing vessel, and the transparent condensate is returned to the reaction vessel via the reflux extension tube; the reflux extension tube is immersed in the reaction vessel to a depth greater than 300 mm below the liquid surface.

[0031] Preferably, the non-condensable gas from the reactor is connected to a water washing vessel after passing through an external condenser for cooling and recovery. The mass concentration of triethylamine in the two-in-one solution is 20% to 30%, the controlled temperature of the synthesis reaction is room temperature to 73°C, and circulating water is used as the heat transfer medium.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] (1) By changing the structure of the reactor nozzle and adding a ball valve for the phosphorus trichloride nozzle pipeline, the mass transfer effect of the reaction can be improved, the concentration of reactants can be increased, the concentration of triethylamine can be increased from 12%-15% to 20%-30%, and the steam used during product distillation can be reduced. More than 5 tons of steam can be saved per ton of product trimethyl phosphite.

[0034] (2) This invention increases the reaction temperature from 40℃±5℃ to 73℃ by using an external condenser, and changes the heat transfer medium from frozen brine to circulating water, saving 900,000 kcal of frozen brine per ton of product. The reactor capacity increases several times, and equipment investment is greatly reduced.

[0035] (3) By relatively reducing the consumption of raw materials, the consumption of methanol is reduced from 960 kg / t to about 860 kg / t, the consumption of other raw materials such as phosphorus trichloride is reduced by 20 kg / t, and the consumption of caustic soda is reduced by 30 kg / t; the consumption of triethyl phosphite can reduce the consumption of phosphorus trichloride, ethanol and caustic soda by about 20 kg / t per ton of product. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the process in this invention;

[0037] Figure 2 This is a schematic diagram of the rotation of the stirring blade in this invention;

[0038] In the diagram: 1. Stirring blade; 2. Flow guide tube; 3. Jacket; 4. Coil; 5. Reactor; 6. External condenser; 7. Washing vessel; 8. Butterfly valve; 9. Expansion joint; 10. Nozzle assembly; 11. Reflux extension tube; 12. Reflux sight glass. Detailed Implementation

[0039] To further illustrate the technical means and effects of the present invention in order to achieve the intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0040] Please see Figure 1-2 As shown, the equipment for the continuous synthesis of triethylamine to trialkyl phosphite includes a stirring impeller 1, a guide tube 2, and a reaction vessel 5. The reaction vessel 5 is equipped with a jacket 3 and an internal coil 4. The top of the reaction vessel 5 is connected to an external condenser 6 through a steam riser pipe. A phosphorus trichloride and a two-in-one nozzle group 10 are provided on one side of the guide tube 2. A reflux extension pipe 11 extends out of the reaction vessel 5 and is connected to the condensate outlet of the external condenser 6. The reflux extension pipe 11 extends into the reaction vessel 5 to a depth of >300mm. The other end of the condensate pipe extends into a water washing vessel 7. A reflux sight glass 12 is provided on the reflux pipe.

[0041] It should be noted that before the reaction, the reaction vessel 5 is filled with the two-in-one solution. Under stirring, the metered alcohol is mixed with the two-in-one solution and then fed into the guide tube 2 through the two-in-one nozzle. At the same time, the metered phosphorus trichloride is fed into the guide tube 2 through the nozzle non-radially for the synthesis reaction. The heat generated by the reaction is removed by the jacket 3, the built-in coil 4 and the external condenser 6 of the reaction vessel 5. The reaction liquid overflows from the reaction vessel 5 to the water washing vessel 7, where the triethylamine hydrochloride is reduced to triethylamine by alkaline washing. The triethylamine is recycled. The crude trialkyl phosphite obtained is dried and distilled to obtain the finished product.

[0042] A butterfly valve 8 and an expansion joint 9 are installed sequentially on the steam riser pipe of the external condenser 6. The butterfly valve 8 is used to isolate the gas phase during maintenance, and the expansion joint 9 is used to reduce the vibration of the equipment during operation.

[0043] It is important to note that the gas phase disc valve 8 is installed on the steam riser pipe of the external condenser 6, which can quickly cut off the gas phase passage between the reactor 5 and the external condenser 6. During shutdown maintenance, it effectively blocks high-temperature and harmful process gases inside the reactor, ensuring operational safety. It also facilitates separate cleaning and maintenance of the condenser without affecting the overall system status of reactor 5. The expansion joint 9 is installed in the steam riser pipe, which absorbs the mechanical vibration and thermal expansion and contraction generated during equipment operation, reducing pipeline stress, minimizing fatigue wear on pipes, valves, and welds, preventing vibration-induced seal failure, pipeline loosening, or excessive noise, thus improving the overall operational stability and service life of the unit and ensuring stable and reliable continuous production.

[0044] The discharge direction of phosphorus trichloride from nozzle assembly 10 is the same as or opposite to the rotation direction of stirring blade 1, and the radial angle between phosphorus trichloride and the two-in-one is 3° to 60°; a ball valve is installed on the feed pipe of nozzle assembly 10.

[0045] It is important to note that maintaining the consistent direction of the phosphorus trichloride feed and the combined solution, forming an angle of 3°–60° with the horizontal, is a key design feature for achieving efficient reactions. An angle less than 3° results in near-radial feeding, where the material tends to directly impact the stirring shaft, leading to short residence times and insufficient mixing. An angle greater than 60° results in near-tangential feeding, easily forming wall flow and preventing the material from entering the core reaction zone of the guide tube 2. An angle of 3°–60° creates stable shear turbulence, allowing for rapid and uniform mixing of phosphorus trichloride with the alcohol and the combined solution, significantly improving mass transfer efficiency, reducing side reactions and tar formation, while simultaneously supporting higher triethylamine concentrations and reaction temperatures, ensuring high yields, high capacity, and stable operation in continuous production.

[0046] The built-in coil 4 of the reactor 5 is divided into multiple layers. Each layer of coil 4 is independently equipped with an inlet valve and an outlet valve for adjusting production capacity, cleaning and maintenance.

[0047] It should be noted that the multi-layer built-in coil 4 is equipped with independent inlet and outlet water valves, which can switch the number of coils 4 as needed, accurately control the temperature and flexibly adjust the production capacity; the independent valves facilitate segmented water flow for cleaning, leak detection and maintenance, without affecting the operation of the whole machine, ensuring continuous and stable production and convenient maintenance.

[0048] The external condenser 6 can be a plate condenser, a rotary plate condenser, or a vertical shell-and-tube condenser, with a vertical shell-and-tube condenser being preferred. The steam riser pipe and the condenser body of the external condenser 6 are equipped with cleaning nozzles for introducing water or alkaline water to remove triethylamine hydrochloride crystals.

[0049] It is important to note that the external condenser 6 can be a plate, rotary plate, or vertical shell-and-tube condenser to adapt to different production conditions and heat exchange requirements. A vertical shell-and-tube condenser is preferred, as it allows for periodic purging with water or alkaline solution to effectively dissolve and remove triethylamine hydrochloride crystals, preventing crystal buildup that could cause pipe blockage, poor condensation reflux, abnormal system pressure, and decreased alcohol recovery efficiency. This design ensures unobstructed gas phase flow, reduces equipment downtime for cleaning, and improves production continuity and stability.

[0050] Continuous synthesis process of triethylamine to trialkyl phosphite:

[0051] S1: Material preparation and equipment pretreatment

[0052] Prefill the reactor 5 with the combined solution, turn on the circulating water system of the jacket 3, the built-in coil 4, and the external condenser 6, and turn on the stirring device.

[0053] S2: Continuous feeding reacts within guide tube 2

[0054] After the metered methanol / ethanol and the two-in-one solution are mixed, they are fed into the guide tube 2 through the nozzle;

[0055] Phosphorus trichloride is metered and enters the guide tube 2 non-radially through the phosphorus trichloride nozzle. The phosphorus trichloride and the two-in-one form an angle of 3° to 60° with the stirring direction, and react rapidly in the guide tube 2.

[0056] S3: Reaction Temperature Control and Heat Removal

[0057] The exothermic reaction is removed by the jacket 3, the built-in coil 4, and the external condenser 6, controlling the reaction temperature to be between room temperature and 73°C.

[0058] External condenser 6 condenses and recovers benzene, triethylamine and alcohol in the gas phase, and alcohol in the reflux liquid is returned to reactor 5 via reflux extension tube 11 to continue the reaction;

[0059] S4: Condensate diversion and anti-clogging treatment

[0060] Initially, the aqueous condensate is directly discharged into the water washing tank 7 to prevent water from entering the reaction tank 5 and reducing the yield;

[0061] The transparent condensate is returned to reactor 5; the steam riser and condenser are cleaned regularly with alkaline water to prevent triethylamine hydrochloride crystallization and blockage;

[0062] S5: Continuous discharge and triethylamine regeneration

[0063] The reaction solution automatically overflows from reaction vessel 5 to water washing vessel 7;

[0064] The triethylamine hydrochloride was reduced to triethylamine by washing with alkaline water. The triethylamine was recovered and recycled. The crude trialkyl phosphite was obtained by separation.

[0065] S6: Refining and Obtaining Finished Products

[0066] After drying and dehydration, the crude product is purified by distillation to obtain high-purity trimethyl / triethyl phosphite.

[0067] Working Principle: This invention utilizes triethylamine as an acid-binding agent for the continuous synthesis of trialkyl phosphite. The core principles are enhanced mass transfer, efficient heat exchange, and material circulation. Before the reaction, the two-in-one solution is filled into reaction vessel 5, and the stirring impeller 1 and circulating water system are turned on. Metered amounts of alcohol, the two-in-one mixture, and phosphorus trichloride are fed non-radially into the guide tube 2 through nozzles. The feed direction forms an angle of 3°–60° with the stirring direction, creating strong shear turbulence, significantly improving mass transfer efficiency, and increasing the triethylamine concentration to 20%–30%.

[0068] The exothermic reaction is rapidly removed by the jacket 3, the built-in coil 4, and the external condenser 6, controlling the reaction temperature at ambient temperature -73℃. Circulating water replaces traditional chilled brine, significantly reducing energy consumption. The external condenser 6 condenses excess benzene, triethylamine, and alcohol in the gas phase. The alcohol in the transparent condensate returns to the reactor 5 via the reflux extension tube 11 for further reaction. The initial water-containing condensate directly enters the water washing reactor 7, avoiding moisture reduction in product yield. The steam riser pipeline is equipped with a gas phase butterfly valve 8 and an expansion joint 9 for easy maintenance and reduced equipment vibration. Cleaning nozzles are installed in the condenser and pipelines to remove triethylamine hydrochloride crystals with water or alkaline solution, preventing blockage.

[0069] The reaction solution continuously overflows into a water washing vessel 7, where alkaline water is added to reduce triethylamine hydrochloride to triethylamine, which is then recycled. The byproduct sodium chloride is separated from water. The crude product is dried and purified by distillation to finally obtain high-purity trialkyl phosphite. This method achieves continuous production and has advantages such as good mass transfer, high temperature, low energy consumption, high yield, and triethylamine recycling.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any indirect modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A continuous synthesis apparatus for triethylamine to trialkyl phosphite, comprising a stirring impeller, a guide tube, and a reaction vessel, characterized in that: The reactor is equipped with a jacket and an internal coil, and the top of the reactor is connected to an external condenser through a steam riser pipe. The steam riser pipe and the external condenser tubes are equipped with nozzle groups embedded in the water inlet network. One end of the condensate outlet of the external condenser is connected to the reactor and has a reflux extension pipe, and the other end passes through a water washing tank. A reflux sight glass is provided on the pipe that returns to the water washing tank.

2. The continuous triethylamine to trialkyl phosphite synthesis apparatus according to claim 1, characterized in that: A disc valve and an expansion joint are installed sequentially on the steam riser pipe of the external condenser. The disc valve is used to isolate the gas phase during maintenance, and the expansion joint is used to reduce equipment vibration during operation.

3. The continuous triethylamine to trialkyl phosphite synthesis apparatus according to claim 1, characterized in that: Phosphorus trichloride enters the guide tube non-radially, with a radial angle greater than 3 degrees. The direction of entry into the guide tube may be the same as or different from the stirring direction. The two-in-one feed pipe is in the stirring direction and forms an angle of 0-80 degrees with the tangent of the guide tube. The longitudinal direction of the phosphorus trichloride feed pipe is consistent with that of the two-in-one feed pipe, and the angle with the horizontal direction is maintained at 3-60 degrees. A ball valve is installed on the phosphorus trichloride nozzle pipe.

4. The continuous triethylamine to trialkyl phosphite synthesis apparatus according to claim 1, characterized in that: The reactor's built-in coils are divided into multiple layers, with each layer having its own independent inlet and outlet valves for adjusting production capacity, cleaning, and maintenance.

5. The continuous triethylamine to trialkyl phosphite synthesis apparatus according to claim 1, characterized in that: The external condenser can be a plate condenser, a rotary plate condenser, or a vertical tube condenser, with a vertical tube condenser being preferred; and the steam riser pipe and the condenser body of the external condenser are both equipped with cleaning nozzles for introducing water or alkaline water to remove triethylamine hydrochloride crystals.

6. A continuous process for synthesizing trialkyl phosphite from triethylamine, characterized in that: S1: Material preparation and equipment pretreatment Prefill the reactor with the two-in-one solution, turn on the circulating water system of the jacket, built-in coil and external condenser, and start stirring; S2: Continuous feeding and reaction with the guide tube After the metered alcohol and the two-in-one solution are mixed, they are fed into the guide tube through a nozzle; Phosphorus trichloride is metered and enters the guide tube non-radially through a phosphorus trichloride nozzle, forming an angle of 3° to 60° with the stirring direction, and rapidly mixes and reacts within the guide tube; S3: Reaction Temperature Control and Heat Removal The exothermic reaction is removed by the jacket, built-in coil, and external condenser to control the reaction temperature from room temperature to 78°C. An external condenser condenses and recovers benzene, triethylamine, and alcohol from the gas phase, while the alcohol in the reflux liquid is returned to the reactor via the reflux extension tube to continue the reaction. S4: Condensate diversion and anti-clogging treatment Initially, the aqueous condensate is directly discharged into the water washing tank to prevent water from entering the reaction tank and reducing the yield; The transparent condensate is returned to the reactor; the steam riser and condenser are cleaned regularly with alkaline water to prevent triethylamine hydrochloride crystallization and blockage; S5: Continuous discharge and triethylamine regeneration The reaction solution automatically overflows from the reaction vessel into the water washing vessel; The triethylamine hydrochloride was reduced to triethylamine by washing with alkaline water. The triethylamine was recovered and recycled. The crude trialkyl phosphite was obtained by separation. S6: Refining and Obtaining Finished Products After drying and dehydration, the crude product is purified by distillation to obtain a high-purity trialkyl phosphite product.

7. The continuous synthesis process for triethylamine to trialkyl phosphite according to claim 6, characterized in that: The condensate from the external condenser is delivered in two ways: the initial water-containing condensate is directly sent to the washing vessel, and the transparent condensate is returned to the reaction vessel via the reflux extension tube; the reflux extension tube is immersed in the reaction vessel to a depth greater than 300 mm below the liquid surface.

8. The continuous synthesis process for triethylamine to trialkyl phosphite according to claim 7, characterized in that: The non-condensable gas from the reactor is connected to a water washing vessel via an external condenser for cooling and recovery. In this reaction, the mass concentration of triethylamine in the two-in-one solution is 20% to 30%, the controlled temperature of the synthesis reaction is room temperature to 73°C, and circulating water is used as the heat transfer medium.

Images