CN116283687A - A kind of synthetic technique of diisoamyl sulfide - Google Patents

Abstract

The invention discloses a synthesis process of diisoamyl sulfide, which comprises the steps of dissolving anhydrous sodium sulfide in hot water, adding absolute ethyl alcohol, heating and stirring, slowly dripping bromoisopentane when the mixture is subjected to reflux reaction, obtaining a reaction mixture upper layer which is crude diisoamyl sulfide, repeatedly washing the crude diisoamyl sulfide, and repeatedly carrying out reduced pressure distillation and purification to obtain the high-purity diisoamyl sulfide, wherein the whole production process has short flow, low labor intensity, less energy consumption, low production cost and short production period, the purity of the obtained diisoamyl sulfide can reach 99.5%, the yield is 80-85%, and the palladium extraction efficiency can be improved to more than 99.5%.

Description

A kind of synthetic technique of diisoamyl sulfide

technical field

The invention relates to the technical field of synthesis technology of novel palladium extractant, in particular to a synthesis technology of diisoamyl sulfide.

Background technique

Diisopentyl sulfide is a commonly used palladium extractant. The synthesis process of palladium extractant at home and abroad basically adopts bromoisopentane to add ethanol and sodium sulfide to reflux reaction. After it is cooled to room temperature, remove the precipitated Then pour the remaining liquid back into a certain concentration of sodium chloride aqueous solution, and also separate and remove the precipitated oil. The oil fractions were then combined, dried with anhydrous sodium sulfate, and distilled twice through a 36 cm Hempel fractionation column filled with glass beads to obtain the noble metal extractant diisoamyl sulfide.

There are problems in the original process: 1) The performance of the palladium extractant diisoamyl sulfide produced is unstable, the quality is not good, the odor is large, and divalent platinum will be co-extracted, and the selectivity of platinum-palladium extraction and separation is not high, which affects the palladium. Direct yield; 2) Diisoamyl sulfide needs to be used after adding copper chloride to deodorize before extraction, which is time-consuming and costly, and crystallization of the extract is prone to occur, which brings difficulty to subsequent separation and purification; 3) Two The palladium extraction capacity of isopentyl sulfide is small, the concentration of palladium stock solution cannot be effectively improved, and the production efficiency cannot be improved; 4) the purity of diisoamyl sulfide produced is not high, and the extraction rate only reaches 98%; 5) diisoamyl sulfide The direct recovery rate of sulfide is low, only 59%; 6) the original technological process is long, needs many chemical reagents, and the maintenance rate of special 36cm Hempel fractionating column equipment is high, resulting in high production cost.

Contents of the invention

The purpose of the present invention is to provide a kind of high yield, high purity, low-cost for the technical problems of the above-mentioned palladium extractant diisoamyl sulfide synthesis process with low direct yield, high cost, difficult purification and low purity. Diisoamyl sulfide synthesis process.

In order to achieve the above object, the technical scheme adopted in the present invention is:

Step 1. Dissolving: In the reactor, dissolve anhydrous sodium sulfide in hot water at 40°C to 50°C, then add absolute ethanol, heat the temperature in the reactor to a constant temperature of 74°C and turn on the stirring device; The mass ratio of anhydrous sodium sulfide, hot water and absolute ethanol is 1.1:1.25:1;

Step 2, reflux: under the constant temperature of 74 ° C under stirring conditions, when the absolute ethanol in the reactor starts to reflux, start to add bromoisopentane dropwise to the mixed solution prepared in step 1, and the dropping rate is controlled at 1.0-1.1 L/h, after the dropwise addition, continue to heat and reflux for 5-8 hours, cool to room temperature after the reaction to obtain the mixture; the mass ratio of the bromoisopentane solution addition to anhydrous sodium sulfide is 3:1; The mixture is two-phase, the upper layer is crude diisoamyl sulfide, accounting for 2/5 of the total volume, the lower layer is water-soluble sodium salt, mainly ethanol and sodium bromide solution, accounting for 3/5 of the total volume, and can be recovered reuse;

Step 3. Filtration and washing: The crude diisoamyl sulfide prepared in step 2 is continuously washed twice with a sodium hydroxide solution with a concentration of 30% by mass, and then washed with hot water at 40°C to 50°C until the pH value of the solution Equal to 7; The volume ratio of described thick diisoamyl sulfide, sodium hydroxide solution, hot water is 2:1:1;

Step 4. Purification by distillation under reduced pressure: add the crude diisoamyl sulfide prepared in step 3 into the reaction kettle, heat to 100°C, keep it warm for 0.5-1h, and distill the unreacted alcohol and water vapor; then connect it to a vacuum pump Vacuumize to 21.33-14.66KPa, heat to 118-122°C and distill under reduced pressure to remove unreacted isopentyl bromide until there is no effluent, return to normal pressure and replace the receiving bottle; then vacuumize to 80KPa (15mmHg) , heated to 185-207 ° C for a second vacuum distillation, collected the distilled product, and then followed the above process for 2 times of vacuum distillation to obtain diisoamyl sulfide;

The purity of the diisoamyl sulfide analyzed by gas chromatography can reach 99.5%, and the yield is 80-85%.

Preferably, the drop rate of isopentyl bromide in said step 2 is less than or equal to the reflux rate of absolute ethanol.

The working principle of the present invention is: normal pressure synthesis uses ethanol as a catalyst, and in the case of heating, bromoisopentane reacts with sodium sulfide to generate diisoamyl sulfide, according to the difference in density between the oil phase and the water phase , and immiscible for phase separation; the purpose of adding sodium hydroxide is to wash and remove impurities, remove a small amount of acetic acid in ethanol, and wash with water to dissolve water-soluble impurities and sodium salts in the oil phase. If a sufficient amount of quicklime is added, the reaction between acetic acid and calcium oxide will generate calcium acetate. The purpose of vacuum distillation is to distill water, ethanol, bromoisopentane, and diisoamyl sulfide according to different pressures and different boiling points. They are separated by distillation.

The chemical reaction equation in the above steps is:

X=Br

_CH3COOH +NaOH= _CH3COONa + _H2O .

Compared with the prior art, the present invention has the following advantages:

(1) In the diisoamyl sulfide synthesis process of the present invention, several major steps of dissolving, reflux, filtration and washing, and vacuum distillation purification are adopted, which shortens the preparation process of diisoamyl sulfide and adopts the best material-liquid ratio , Reasonable technical parameters reduce excessive waste of raw materials, so that raw materials can fully react.

(2) In the diisoamyl sulfide synthesis process of the present invention, a multi-stage negative pressure absorption process is adopted to replace the 36cm Hempel fractionation method full of glass beads, which avoids the drying link of anhydrous sodium sulfate, reduces the production cost, and reduces energy Consumption; returning the feed liquid in the multi-stage negative pressure absorption bottle to the negative pressure distillation kettle for circulation can improve the direct yield of the product diisoamyl sulfide.

(3) In the diisoamyl sulfide synthesis process of the present invention, pure water is used instead of ordinary water to prepare diisoamyl sulfide, so as to ensure the highest purity of the product and better performance.

Description of drawings

Fig. 1 is the synthetic process flowchart of diisoamyl sulfide of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with specific embodiments.

Example 1

A kind of synthetic technique of diisoamyl sulfide, comprises the following steps:

Step 1. Dissolving: In the reaction kettle, dissolve 1.1kg of anhydrous sodium sulfide in 1.25kg of 40°C hot water, then add 1kg of absolute ethanol, heat the temperature in the reaction kettle to a constant temperature of 74°C and turn on the stirring device;

Step 2, reflux: under the constant temperature of 74°C under stirring conditions, when the absolute ethanol in the reactor starts to reflux, start to dropwise add bromoisopentane solution with a mass percentage concentration of 99% to the mixed solution prepared in step 1 3.3kg, the drop rate is controlled at 1.0L/h, after the addition, continue to heat and reflux for 5h, cool to room temperature after the reaction to obtain a 2500ml mixture; the mixture is in two phases, and the upper layer is 1000ml of crude diisoamyl sulfide aqueous solution ;The lower layer is 1500ml of water-soluble sodium salt impurities, the main components are recyclable ethanol and sodium bromide solution;

Step 3, filtering and washing: 1000ml of crude diisoamyl sulfide aqueous solution prepared in step 2 was washed continuously for 2 times with 500ml of 30% sodium hydroxide solution by mass percentage, and then washed continuously for 3 times with 500mL of hot water at 40°C Wash until the pH value of the solution is equal to 7;

Step 4. Purification by distillation under reduced pressure: Add the crude diisoamyl sulfide prepared in step 3 into the reaction kettle, heat it to 100°C, keep it warm for 0.5h, distill the unreacted alcohol and water vapor; then connect it to a vacuum pump Vacuum to 14.33KPa, heat to 120°C to remove unreacted bromoisopentane under reduced pressure, return to normal pressure and replace the receiving bottle when there is no effluent; then vacuumize to 80KPa (15mmHg), heat to 205°C Carry out secondary vacuum distillation, collect the distilled product, then follow the above-mentioned process vacuum distillation 2 times, obtain 900ml diisoamyl sulfide;

The purity of the diisoamyl sulfide analyzed by gas chromatography is 99.5%, the yield is 80%, and the extraction rate of palladium is 99.5%.

Example 2

Step 1. Dissolution: In the reactor, dissolve 2.2kg of anhydrous sodium sulfide in 2.5kg of 50°C hot water, add 2kg of absolute ethanol, heat the temperature in the reactor to a constant temperature of 74°C and turn on the stirring device ;

Step 2, reflux: under the constant temperature of 74°C under stirring conditions, when the absolute ethanol in the reactor starts to reflux, start to dropwise add bromoisopentane solution with a mass percentage concentration of 99% to the mixed solution prepared in step 1 6.6kg, the rate of addition is controlled at 1.1L/h, after the addition, continue to heat and reflux for 8h, cool to room temperature after the reaction to obtain a 5000ml mixture; the mixture is two-phase, the upper layer is 2000ml thick diisoamyl sulfide, The lower layer is 3000ml water-soluble sodium salt, mainly ethanol and sodium bromide solution, which can be recycled and reused;

Step 3, filtering and washing: 2000ml of crude diisoamyl sulfide prepared in step 2 was washed continuously for 2 times with 1000ml of 30% sodium hydroxide solution by mass percentage, and then washed continuously for 3 times with 1000mL of hot water at 50°C Wash until the pH value of the solution is equal to 7;

Step 4. Purification by distillation under reduced pressure: Add 2000ml of crude diisoamyl sulfide prepared in step 3 into the reaction kettle, heat to 100°C, keep it warm for 1h, distill the unreacted alcohol and water vapor; then connect it to a vacuum pump Vacuum to 14.66KPa, heat to 122°C and distill unreacted isopentyl bromide under reduced pressure until there is no effluent, return to normal pressure and replace the receiving bottle; then vacuumize to 80KPa (15mmHg), heat to 207°C Carry out secondary vacuum distillation, collect the distilled product, then follow the above-mentioned process vacuum distillation 2 times, obtain 1800ml diisoamyl sulfide;

The purity of the diisoamyl sulfide analyzed by gas chromatography can reach 99.5%, the yield is 85%, and the extraction rate of palladium is 99.5%.

Example 3

A kind of synthetic technique of diisoamyl sulfide, comprises the following steps:

Step 1. Dissolving: In the reactor, dissolve 3.3kg of anhydrous sodium sulfide in 3.75kg of hot water at 45°C, add 3kg of absolute ethanol, heat the temperature in the reactor to a constant temperature of 74°C and turn on the stirring device ; The mass ratio of anhydrous sodium sulfide, hot water and absolute ethanol is 1.1:1.25:1;

Step 2, reflux: under the constant temperature of 74°C under stirring conditions, when the absolute ethanol in the reactor starts to reflux, start to dropwise add bromoisopentane solution with a mass percentage concentration of 99% to the mixed solution prepared in step 1 9.9kg, the rate of addition is controlled at 1.05L/h, after the addition, continue to heat and reflux for 6h, cool to room temperature after the reaction to obtain a 7500ml mixture; the mixture is two-phase, and the upper layer is 3000ml thick diisoamyl sulfide, The lower layer is 4500ml water-soluble sodium salt, mainly ethanol and sodium bromide solution, which can be recycled and reused;

Step 3, filtering and washing: 3000ml of crude diisoamyl sulfide prepared in step 2 was washed continuously for 2 times with 1500ml of 30% sodium hydroxide solution by mass percentage, and then washed continuously for 3 times with 1500mL of hot water at 45°C Wash until the pH value of the solution is equal to 7;

Step 4. Purification by distillation under reduced pressure: Add 3000ml of crude diisoamyl sulfide prepared in step 3 into the reaction kettle, heat to 100°C, keep it warm for 0.8h, distill the unreacted alcohol and water vapor; then connect to the vacuum pump Vacuumize to 14.5KPa, heat to 120°C and distill under reduced pressure to remove unreacted isopentyl bromide until there is no effluent, return to normal pressure and replace the receiving bottle; then vacuumize to 80KPa (15mmHg), heat to 206 ℃ for two times of vacuum distillation, collect the distilled product, and then follow the above process for 2 times of vacuum distillation to obtain 2250mL of diisoamyl sulfide;

The purity of the diisoamyl sulfide analyzed by gas chromatography can reach 99.5%, the yield is 83%, and the extraction rate of palladium is 99.6%.

The product yield and analysis results are shown in Table 1.

Table 1 Product yield and analysis result table

serial number Yield (%) purity(%) Palladium extraction rate (%) Example 1 80 99.5 99.5 Example 2 85 99.5 99.5 Example 3 83 99.5 99.6

Can draw a conclusion by the data of table 1, embodiment 1-3 adopts the synthetic technique of diisoamyl sulfide provided by the present invention, can obtain the diisoamyl sulfide of high yield, high purity, high palladium extraction rate ether. The method described in the present invention has been successfully applied to the precious metal palladium extraction production line of a certain company. Using this method, high-purity diisoamyl sulfide is self-sufficient, and 3 tons of high-purity diisoamyl sulfide are produced every year for use in Production, palladium extraction performance is good, the concentration of platinum and palladium in the original solution of palladium is increased from 16g/L to more than 28g/L, and the production efficiency is doubled; at the same time, the performance of co-extracting divalent platinum is reduced, effectively separating platinum and palladium, extracting The efficiency of palladium can be increased to more than 99.5%.

Claims (2)

1. A synthesis process of diisoamyl sulfide is characterized in that: the method comprises the following steps:

step one, dissolving: dissolving anhydrous sodium sulfide in hot water at 40-50 ℃ in a reaction kettle, adding absolute ethyl alcohol, heating the temperature in the reaction kettle to constant temperature of 74 ℃ and starting a stirring device; the mass ratio of the anhydrous sodium sulfide to the hot water to the anhydrous ethanol is 1.1:1.25:1;

step two, reflux: under the stirring condition of constant temperature of 74 ℃, when absolute ethyl alcohol in a reaction kettle starts to reflux, dropwise adding a brominated isopentane solution with the mass percent concentration of 99% into the mixed solution prepared in the step one, controlling the dropwise adding speed to be 1.0-1.1L/h, continuing to heat and reflux for 5-8 h after the dropwise adding, and cooling to room temperature after the reaction is finished to obtain a mixture; the mass ratio of the adding amount of the bromoisopentane solution to the anhydrous sodium sulfide is 3:1; the mixture is in two phases, the upper layer is coarse diisoamyl sulfide accounting for 2/5 of the total volume, the lower layer is water-soluble sodium salt, mainly ethanol and sodium bromide solution accounting for 3/5 of the total volume, and the mixture can be recycled;

step three, filtering and washing: continuously washing the crude diisoamyl sulfide prepared in the step two with a sodium hydroxide solution with the mass percent concentration of 30% for 2 times, and then washing with hot water at the temperature of 40-50 ℃ until the PH value of the solution is equal to 7; the volume ratio of the crude diisoamyl sulfide to the sodium hydroxide solution to the hot water is 2:1:1;

step four, vacuum distillation and purification: adding the crude diisoamyl sulfide prepared in the step three into a reaction kettle, heating to 100 ℃, preserving heat for 0.5-1 h, and distilling unreacted alcohol and water vapor; then pumping into a vacuum pump to be vacuumized to 21.33-14.66KPa, heating to 118-122 ℃ and distilling under reduced pressure to remove unreacted bromoisopentane until no effluent liquid is recovered to normal pressure and replacing a receiving bottle; vacuumizing to 80KPa (15 mmHg), heating to 185-207 ℃ for secondary reduced pressure distillation, collecting distilled products, and performing reduced pressure distillation for 2 times according to the process to obtain diisoamyl sulfide;

the purity of the diisoamyl sulfide can reach 99.5% by adopting a gas chromatography analysis method, and the yield is 80-85%.

2. The process according to claim 1, wherein the drop velocity of bromoisopentane in step two is less than or equal to the reflux velocity of absolute ethanol.

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