Chapter 81: Synthesis experiment (on)

　　 Resting on the sofa for a while, Xu Qiu went to the medicine warehouse to return the cart.
　　 He took away Chen Wanqing's pass, because his pass has not yet been opened.
　　 once again returned to the microelectronics building, he copied A501-503 into the simulation laboratory.
　　 The current level 2 simulation laboratory has 1,000 cubic meters of space, which now takes up more than half.
　　 No way, Zhang Jiang’s synthesis laboratory is really too big, covering an area of ​​nearly two hundred square meters.
　　 In the laboratory, Chen Wanqing had already put on her lab coat, fiddling with the supplies she had just received.
　　 She saw Xu Qiu coming in and said:
　　" The chemical laboratory here is more dangerous, so the protective measures must be more stringent.
　　 I usually wear four layers of gloves, the innermost layer of PE gloves, a small rubber glove on the outside, and a large rubber glove.
　　Because there may be powdery particles such as talcum powder on rubber gloves, it is necessary to put a layer of PE gloves on the outermost to prevent contamination of reagents or reaction vessels.
　　 If you use a lot of solvents or very toxic reagents, you must wear a gas mask.
　　 If you don’t need a gas mask for now, just use a disposable activated carbon mask.
　　Because wearing a gas mask will be very boring, and the voice will be reduced, making it difficult to communicate.
　　 Also, gloves should cover the cuffs of the lab coat to prevent drugs from entering the clothes from the cuffs. For this reason, I also specially used lab coats with elastic cuffs. "
　　 Xu Qiu nodded, and then imitated the appearance of the senior sister, taking protective measures.
　　 "Yes," Chen Wanqing looked at Xu Qiu up and down, then pointed to a few unopened cartons and said:
　　 "There are the reagents I ordered before, mainly solvents. Duan Yun helped to sign for them last week. Go and take them apart and put them in the reagent cabinet."
　　 "Okay." Xu Qiu found a pair of scissors, cut the packing tape outside the carton, and opened the box.
　　There are brown glass bottles and plastic barrels of solvents, all of which are from Sinopharm.
　　 Among them, toluene and n-octane are in 500 ml bottles, and anhydrous methanol, acetone, and absolute ethanol are all in 4 liter barrels.
　　 In addition, there are two boxes of 500 grams of sodium hydroxide, and two barrels of one-liter simethicone.
　　 In addition to the cardboard box, there is also a foam box with an ice box and empty dry ice bags, which seem to be transported under refrigeration.
　　 There are several small reagent bottles in the foam box, and their outer packaging is sealed with black plastic, with Chinese and English labels on the sides.
　　 "Tetra(triphenylphosphine) palladium," Xu Qiu read it out, thinking for a moment and then said:
　　 "It seems to be a catalyst, I have seen it in the literature."
　　 "Yes, we need zero-valent palladium as a catalyst for the coupling reaction, and triphenylphosphine is the ligand." Chen Wanqing said:
　　 "This needs to be refrigerated at minus 20 to 4 degrees Celsius, but when you want to use it, put it outside first, and put it in the refrigerator when it's used up."
　　 After Xu Qiu sorted out the medicines, Chen Wanqing began experimental teaching:
　　"The solvent used in the Stille coupling reaction is toluene. You cannot use the purchased toluene directly. It needs to be re-steamed before it can be used.
　　Because the purchased toluene contains trace amounts of water and other impurities.
　　The water molecules will react with the trimethyltin-bearing monomer to make it lose tin, and the material ratio of the two raw materials for the polymerization reaction is no longer 1:1, thereby reducing the molecular weight of the polymer obtained.
　　 And the polymer materials we need, under the condition of ensuring solubility, their molecular weight is as high as possible.
　　 The success of a synthesis reaction is judged mainly by the molecular weight of the product. Generally, the number average molecular weight is between 20,000 and 70,000. "
After 　　 was introduced, she began to set up experimental equipment in the fume hood.
　　 Because the toluene solvent re-vaporized by this device is enough for two people to use, there is no need to set up twice.
　　 After Xu Qiu copied her skills, he stood by and watched the elder sister while studying with system images.
At the bottom of 　　 is a magnetic constant temperature heating stirrer, which can control the reaction temperature and the speed of the magnetic stirrer.
　　 There is an oil bath on the stirrer, which is filled with dimethyl silicone oil, which can be used below 200 degrees Celsius to ensure constant temperature and uniform heating.
　　 Above the oil bath, the senior sister fixed a round-bottomed flask with a clamp so that two-thirds of the volume was submerged in the simethicone.
　　 Then, insert a solvent distillation head into the mouth of the round bottom flask.
　　 Insert a spherical condenser on the solvent distillation head.
　　Put a three-way valve with a balloon on the spherical condenser.
　　The mouth of each glassware is fixed with iron clamps.
　　 Then, she installed the condensate tube on the spherical condenser tube, connected it with a rubber hose and fixed it with a cable tie according to the method of "into the lower mouth and out the upper mouth".
The form of 　　 is roughly: faucet-hose-lower mouth of condenser pipe-upper mouth of condenser pipe-hose-sewer.
　　 After the installation is set up, including the height of the fume hood table, it is taller than a person.
　　 "Finally finished." Chen Wanqing said.
　　 "Sister, wait, I have a question," Xu Qiu asked:
　　 "Aren't we going to re-evaporate toluene? What about toluene?"
　　 "Oh, I forgot to add it." Chen Wanqing said in embarrassment.
　　 She took the toluene reagent bottle, opened the connection between the round bottom flask and the solvent distillation head, then pulled the fume hood door down, and poured about 250 ml of toluene.
　　 "Next, we will use sodium wire to remove water and use benzophenone indicator."
　　 "Sodium wire?" Xu Qiu wondered: "Is it metallic sodium?"
　　 "Right~EbookFREE.me~ Benzophenone reacts with sodium metal to form a blue intermediate." Chen Wanqing said:
　　 "If there is water in the solvent, the reaction will continue to form a colorless compound, and if there is no water, it will stay in the blue state of the intermediate."
　　 She took out the box of metallic sodium from the reagent cabinet.
　　 Metal sodium is very active and needs to be stored in kerosene.
　　 She spread several layers of toilet paper on the lab bench, then used a long tweezers to grab a piece of sodium, then cut a small piece with a knife, and put the remaining sodium piece back into the kerosene.
　　 Next, she used a knife to cut the sodium block into filaments, dried the kerosene on the surface with paper, and put the sodium filaments into the round bottom flask.
　　 Finally, in the round bottom flask, use a stainless steel spatula to add benzophenone twice, and then add a spindle-shaped magnetic stirrer.
　　 "There should be no problem now," Chen Wanqing said.
　　 "Sister, wait, I have one more question," Xu Qiu asked:
　　 "What is the purpose of the blue balloon we are wearing?"
　　 "This can be made into a nitrogen ball to ensure that the entire closed distillation system is in a nitrogen atmosphere." Chen Wanqing said:
　　" If toluene is simply redistilled, it is not necessary to add nitrogen balloon.
　　 But let's come one, after all, safety comes first.
　　First of all, it is necessary to ensure that the air content in the nitrogen ball is extremely low, so it is necessary to repeatedly charge and discharge nitrogen. "
　　 Chen Wanqing took off the balloon connected to the three-way valve and connected one end of the three-way valve to a nitrogen hose.
　　 Then, she slowly opened the nitrogen valve.
　　 "Wait, why is it not venting?" Chen Wanqing wondered.
　　 Xu Qiu shook his head, thinking:
　　 Sure enough, the laboratory with the senpai is always full of surprises.