Chapter 208: A man like liquid nitrogen

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"Senior sister, how about the experiment?" Xu Qiu promptly mentioned the reaction on the way to the cafeteria at noon.
"Failed." Chen Wanqing sighed.
"Is there any stock from the previous step?" Although Xu Qiu had guessed the result, he still asked.
"No..." Chen Wanqing said in a low tone, "The reaction in the first few steps was too smooth, so I just used up all the products from the previous step."
"What should we do, do we make another batch?" Han Jiaying interjected.
"I haven't figured it out yet," Chen Wanqing shook her head, "but I analyzed it, but I probably know the reason for the failure of the reaction. It should be that the by-products in the previous step were not removed."
Then, she paused and said: "The two reactions in the previous step only had two and three sample points respectively. I originally thought that after the reaction was over, I would purify them uniformly. As a result, I got the result of this point. It's inseparable," she sighed again, "or I have too little experience in synthesis.
Xu Qiu silently, the senior sister’s reaction failed. On the one hand, she was a little anxious and used up all the products directly. On the other hand, it was also related to the liquid chromatography equipment occupied by him and the senior sister. After the reaction is passed through the column once, it is best to obtain the pure product, which can avoid the by-products from the previous step to produce by-products again.
‘This is a bit embarrassing. After the bromine substitution reaction is over, they will have to occupy the liquid chromatography for a while. ’
‘Furthermore, the subsequent PDI dimerization or the synthesis of 3D-PDI molecules will also frequently use liquid chromatography. ’
‘How can I be able to experiment with peak shifting? ’
‘Senior Sister’s experimental idea of ​​synthesizing A-D-A small molecules is divided into three steps, first synthesize the A and D units separately, and then connect the A and D units together. ’
‘What she is currently doing is the synthesis of unit A. If you switch to the synthesis of unit D, the number of reaction steps will be fewer, and the by-products will be fewer. Even if you use liquid chromatography, it will not be so frequent. ’
Xu Qiu had a clever move and suggested: "Or, Sister, try another route and synthesize Unit D first?"
"I have also considered, but this route is more dangerous. The introduction of aldehyde groups in the central D unit involves liquid nitrogen and butyl lithium reagents." Chen Wanqing said.
"This is indeed a problem, but if we are all in the laboratory, even if it is a dangerous reagent, there is a care for it." Xu Qiu said, he is no stranger to the two reagents, liquid nitrogen and butyl lithium, they are both dangerous reagents. It was more troublesome than the liquid bromine he used today.
Liquid nitrogen can provide a low temperature reaction environment of minus 78 degrees Celsius, and there is a risk of frostbite; butyl lithium will react exothermic when it meets water and oxygen, and high-concentration butyl lithium solution will burn quickly when exposed to moist air, which may cause spontaneous combustion or even explosion.
The elder sister seemed to guess Xu Qiu’s thoughts, and gave him a blank glance, "Even if I put the synthesis reaction of Unit A, I can continue until the reaction stopped yesterday, and then wait until your liquid chromatograph is idle. It's not too late to purify."
Xu Qiu smiled awkwardly, and said nothing.
After a while, Chen Wanqing spoke suddenly and made a decision: "Listen to you, let's synthesize Unit D today."
"Okay," Xu Qiu nodded, and then asked curiously: "Liquid nitrogen will be used to synthesize the D unit. Is there a place for liquid nitrogen in Zhang Jiang?"
He had only used liquid nitrogen for electron microscopy experiments before, and he had not personally conducted low-temperature experiments. Of course, he had contacted them in the simulation laboratory, but that is not reality after all.
"There are some from the School of Pharmacy, I have already done my homework in advance." Chen Wanqing replied.
"I have a question," Han Jiaying interjected, "There seems to be no container for liquid nitrogen in Zhang Jiang's laboratory. I have seen one in Handan."
"You can use a thermos instead. Wait for two 8-pound thermos bottles in the medicine warehouse." Chen Wanqing added: "I also need a pot-shaped Dewar to keep it warm."
"Pot-shaped Dewar? What does it look like?" Han Jiaying tilted her head.
"It's probably a food bowl similar to cat food? It's like this..." Chen Wanqing tried to make gestures with her hands, but failed. "You can see it later anyway."
...
After the meal, the three of them went to the medicine warehouse and took two 8-pound bottles. Xu Qiu picked up one in one hand. The empty bottles were not heavy.
After confirming that the pot-shaped Dewar is in stock, there is no rush to receive it. This is a fragile product. It is not too late to receive it after the liquid nitrogen is returned.
As expected, the school girl saw the shape of a pot-shaped Dewar, a short cylindrical shape with a hollowed out hemispherical inner tank, which was plated with silver.
It's a bit like a food bowl for cat food.
To get liquid nitrogen, you need to go to the School of Pharmacy. Zhangjiang School is divided into two areas, separated by a big road. The School of Pharmacy is on the other side of the road, far away from the laboratory of Xu Qiu and his microelectronics building.
They had sent waste liquid once before, and walked back and forth for nearly an hour. Of course, this was related to the slow moving speed in the process of transporting waste liquid.
This time, it took them less than a quarter of an hour to follow the navigation to find the location of the liquid nitrogen, and the door sign next to it said Cryogenic Physics Laboratory.
This is a bungalow connected back and forth, with a huge liquid nitrogen tank outside the room, which is continuously spraying white mist outside.
The three people entered the bungalow, and the environment was a bit cold. In the inner room, there were two uncles lying on the bed and watching TV. They should be responsible for looking after it.
The two uncles glanced at each other, one of them got up, walked to Xu Qiu and the others, and pointed to the ground.
Xu Qiu understood, put the 8-pound bottle on the ground, removed the two corks, and held the cork in his hand.
"Ticket." Uncle Jia stretched out his hand.
"What ticket... do you have to pay? How do you pay?" Xu Qiu suddenly thought that the liquid nitrogen should be charged, just like the test.
"Look here, bring it here next time." Grandpa A pointed to the notice posted on the door next to him.
Then he ignored Xu Qiu and put on his thick protective gloves, and then took a metal tube about 40 cm long from the side. The back of the metal tube was connected to the pipe on the wall.
While watching the notice, Xu Qiu was distracted to observe the actions of Uncle Jia.
The notice read: "From now on... use the intra-campus transfer method to transfer funds to the'Madu Comprehensive University Cryogenic Physics Laboratory'. You can purchase liquid nitrogen tickets at the cryogenic laboratory with the intra-campus transfer slip. There are two specifications for liquid nitrogen tickets. The pound bottle is 17 yuan each, and the 10-liter liquid nitrogen container is 40 yuan each."
‘Sure enough, you have to pay, and it doesn’t seem to be very expensive. ’
"Senior Sister, how do I get transfers on campus?" Xu Qiu turned around.
"I sent a message to Feifei Wu," Chen Wanqing explained: "This kind of small intra-school transfer is usually her responsibility, including the tests we go to the school and the department, which are ultimately completed through the intra-school fund transfer. of."
At the same time, the uncle put the metal tube in his hand into the 8-pound bottle, and with the other hand he unscrewed a valve on the wall.
Soon, there was the sound of liquid nitrogen hitting the inner wall of the bottle, and a trace of white mist floated from the mouth of the bottle.
"Teacher, I will bring the transfer slip from school next time. Do I need to leave a student number or contact information?" Xu Qiu said.
"No." Uncle Jia stared at the TV without turning his head back.
After dozens of seconds, Uncle Jia approached the 8-pound bottle, tentatively moved the metal tube, and looked at the mouth of the bottle again. After confirming that the liquid nitrogen was about to be full, he closed the valve and took out the metal tube.
"Cover it." He ordered.
"Oh, okay." Xu Qiu hurriedly plugged the bottle cork, and the white mist swept across from his hand, feeling a little cool.
Uncle A followed the same procedure and started adding liquid nitrogen to another bottle. After dozens of seconds, he closed the valve, retracted the metal tube, and put it back in place, saying:
"All right."
"Thank you teacher." Xu Qiu plugged the cork and picked up two 8-pound bottles.
The three of them walked out of the door of the cryogenic laboratory. Xu Qiu was waiting to complain, but was rushed by Han Jiaying: "What a cold man."
"Well," Xu Qiu nodded, "Looks like an uncle like liquid nitrogen? There seems to be something weird...but the uncle is not bad, we didn't have a ticket and didn't send us back."
"Yes, the school really trusts the students~EbookFREE.me~Chen Wanqing also feels the same way. "We also get the medicine at the drug warehouse. You only need to report a student number, sign and you can get it directly. "
...
Even if the two 8-pound bottles were filled with liquid nitrogen, Xu Qiu didn't feel very heavy to lift it.
It's just walking with a bit of trepidation, as if holding two pots of bombs in his hands.
The three slowly walked back to the medicine warehouse and received a pot-shaped Dewar.
Afterwards, they exchanged the division of labor. Xu Qiu held the Dewar flask, and the senior sister and senior sister each carried a pot of liquid nitrogen and returned to the microelectronics building.
Wu Feifei is very efficient. When they returned to A501, she had already completed the transfer. Small transfers within the school did not need to be reviewed by the Finance Department and could be transferred directly.
She transferred 170 yuan to the cryogenic physics laboratory, which happened to be enough to buy 10 8-pound bottles of liquid nitrogen tickets.
However, another trip to the School of Pharmacy would be too much trouble.
The three discussed it and decided to talk about it next time.
Certainly next time.
When he walked into the laboratory, Xu Qiu suddenly remembered that his reaction was still in progress, because there was a small episode of liquid nitrogen in the middle, which wasted a lot of time.
Will it time out?
He hurried to the fume hood to check the stopwatch.
Two hours, six minutes and twelve seconds.
Really timed out.
Fortunately, Xu Qiu had experienced many battles, he quickly calmed down and began to think about countermeasures.
This bromine substitution reaction is different from the past. It is not possible to stop the reaction by stopping the reaction.
Because the condition is normal temperature, as long as the liquid bromine is still in the reaction flask, the reaction will continue.
To stop the reaction, excess liquid bromine must be removed.
However, if the bromine is directly removed, if the reaction is not complete, the reaction must be repeated.
Xu Qiu quickly made a decision, first click the board to see the product.