Chapter 210: Laboratory safety... we guard it!

"I have a scientific research support system ( to find the latest chapter!
Chen Wanqing started the experiment, Xu Qiu and Han Jiaying stood on the left and right like two guards.
In the fume hood, there is a solvent re-steaming device on the left side. Now the re-steaming has been completed, and a lot of solvents remain in the distillation head.
"This is tetrahydrofuran THF, the solvent to be used in the reaction later." The senior sister actively explained:
"N-butyllithium is a very strong base, many solvents with hydrogen atoms can react with it, such as water, ethanol, dichloromethane, etc., and a lot of heat is released during the reaction, which is also it Causes of spontaneous combustion in humid air.
THF will not react with n-butyllithium under normal temperature and low temperature conditions, so it is chosen as the reaction solvent. "
An iron stand is placed in the center of the fume hood. On the iron stand is a Dewar flask. Next to it are a 500ml bottle of Sinopharm anhydrous ethanol reagent bottle and an 8-pound bottle of liquid nitrogen.
"Liquid nitrogen and absolute ethanol, after mixing in a Dewar flask, can maintain a temperature of minus 78 degrees Celsius."
While introducing Chen Wanqing, she poured absolute ethanol into the Dewar flask, the volume roughly less than half of the hemispherical liner.
‘Ethanol, which is alcohol, is a colorless and transparent liquid. Its freezing point is more than minus 110 degrees Celsius. When it drops below this temperature, it will freeze like water. ’
‘The temperature of liquid nitrogen is around minus 200 degrees Celsius, so how do you use liquid nitrogen and absolute ethanol to control the temperature at around minus 78 degrees Celsius? ’
Xu Qiu was puzzled because his synthesis did not involve low-temperature reactions, so he had not done relevant research before.
He and the school sister were curiously watching her operation.
"I'm going to pour liquid nitrogen." Chen Wanqing focused on the experiment at this time and did not look at the two people around him.
She removed the stopper of the 8-pound bottle and set it aside. The white mist escaped from the bottle. Because the liquid nitrogen bottle has been in the laboratory for a while, some of the liquid nitrogen has evaporated, so it now looks Not very full.
The elder sister tilted the bottle directly and poured liquid nitrogen into the Dewar.
It was a bit like pouring boiling water. The liquid nitrogen hit the surface of the ethanol liquid, beeping loudly, and some small droplets splashed out, and then disappeared in midair.
"Then stir." The senior sister put down the 8-pound bottle, capped the bottle, took a glass rod, and stirred the mixture of ethanol and liquid nitrogen in the Dewar.
Xu Qiu stared at the Dewar for a while. The ethanol in it was still a colorless and transparent liquid. He did not make a sound to disturb the senior sister, but thought to himself: ‘It seems that there is no change. ’
"I will add some more liquid nitrogen." Chen Wanqing explained to herself, adding some liquid nitrogen to the Dewar flask and continuing to stir with the glass rod.
After that, adding liquid nitrogen and stirring repeatedly for more than a minute, the ethanol in the Dewar finally changed.
"You're done, it's in this viscous state." Chen Wanqing turned around and said, "Do you want to try it."
"I'm coming." Xu Qiu took the glass rod directly. He had been watching just now, feeling that the liquid nitrogen cryogenic experiment was not as dangerous as he thought.
Xu Qiu tried to stir it with a glass rod, like stirring glue. ‘Perhaps a critical state between solid and liquid? ’
Han Jiaying also tried it out and exclaimed: "It's amazing."
Chen Wanqing smiled: "In this state, it can be considered that the temperature is around minus 78 degrees Celsius. After that, just keep adding liquid nitrogen and keep the temperature."
...
With the help of Xu Qiu and Han Jiaying, Chen Wanqing built a complete set of reaction devices.
Dewar flasks are placed on the iron stand.
Above the Dewar flask is an iron clamp, which holds a reaction flask.
The reaction flask contains the tetrahydrofuran solution of the D unit raw materials and a magnetic stirrer.
A nitrogen ball is inserted on it, which has been pumped three times for three rows, and the entire reaction system is under nitrogen protection.
"The last step, n-butyl lithium." Chen Wanqing went to the refrigerator and took out the reagent bottle containing the n-butyl lithium tetrahydrofuran solution.
When she returned to the fume hood, she suddenly saw Xu Qiu and Han Jiaying holding a fire blanket and a nitrogen ball in the other.
"What are you doing... Do you want this, it's scary."
"Laboratory safety..."
"Guarded by us!"
"You two, husband and wife are only n-butyllithium, not tert-butyllithium." Chen Wan gave them a clean glance and continued to operate.
In theory, dangerous reagents like n-butyl lithium are best used in a nitrogen glove box, but Zhang Jiang’s laboratory does not have this condition and can only be forced to use it.
She fetched a newly opened syringe and a needle with a nitrogen ball, and put the syringe needle and the needle of the nitrogen ball into the rubber stopper of the reagent bottle containing the n-butyl lithium solution.
Then, pull the plunger of the syringe to up the n-butyl lithium solution. After a sufficient amount, lift the needle out of the liquid surface, in nitrogen gas for a while, then slowly push it out, it in again, and push it out to ensure that the liquid in the needle mouth is drained.
Next, take out the syringe needle, keep the needle downward, and the syringe upward, the needle and the upper part of the syringe are filled with nitrogen, move to the rubber stopper at the mouth of the reaction flask, and inject the n-butyl lithium solution into the reaction flask.
Finally, unplug the nitrogen ball needle on the n-butyl lithium reagent bottle, seal the rubber stopper of the reagent bottle with tape, and put it back in the refrigerator.
"Finish!" Chen Wanqing exhaled for a long time.
"Congratulations, senior sister." Xu Qiu and Han Jiaying congratulated each other.
Chen Wanqing's entire operation process went smoothly.
Sure enough, I never had to worry that my senior sister would be in danger when doing experiments, Xu Qiu muttered to himself:
The elder sister handled it very delicately. She used two needles to the n-butyl lithium solution to ensure that the n-butyl lithium would not come into direct contact with the air.
Otherwise, if the solution is directly absorbed, even if spontaneous combustion does not occur, a spark from the needle tip is possible.
If she can maintain this state when doing experiments, it is estimated that her scientific research achievements will be much better than now.
Could it be that the senior sister is destined to make some high-risk experiments?
...
After the onlookers voted for the reaction, Xu Qiu and Han Jiaying also began to work on their own business, purifying today's four reaction products.
"How do we divide the work?" The school girl ran to the liquid chromatograph and turned on the machine.
"I've been to the pillar first, you can spin steam, and then rotate." Xu Qiu thought for a while.
"Yeah." Han Jiaying nodded.
This time, I used a disposable blank silica gel column. There were fewer samples and the column size was much smaller than last time.
Knowing in advance that this separation will be difficult, Xu Qiu has a twelve-point spirit, which is why he chose to take the lead.
However, he was cautious. He was very confident in his experimental ability, so he did not adjust the flow rate of the solution, which was still 30 mg/ml.
Xu Qiu controlled the computer program to slowly increase the content of the B component in the AB solvent, while always paying attention to the state of the blank silica gel column next to it.
When the B% reached 26%, a red color appeared on the upper end of the blank silica gel column, and he was busy fixing the B component content at the ratio one minute ago, which is 24%.
The touch of red slowly moved downwards, but not as exaggerated as yesterday, forming a red band, this time only a small ball.
After a while, the red group moved to the bottom of the silica gel column, and the UV detector simultaneously produced sample signals, Xu Qiu immediately switched the mode to working mode.
The upper needle began to spray a stream of light red liquid, and soon the first test tube was filled.
Point board, climb board, check.
There is only one sample point, which is one of the deeper product points in the previous spotting results.
Seeing this result, Xu Qiu breathed a sigh of relief.
Continue to collect, click the plate every 3 test tubes, and the results are consistent with the results of the first plate.
Of course, this consistency refers to the same height of the climbing board.
In fact, the concentration of the solution in each test tube is different, and the dots on the dot plate are also different in depth. Usually, the concentration of the solution will rise first and then decrease, so the sample dots when the plate is dotted will also be darker and lighter.
Collecting the products this time is not as time-consuming and laborious as yesterday, because the flow rate is small and there is no need to use PE cups to receive them directly.
After all, there is only 0.5 grams of raw materials, which is one-tenth of yesterday's ~EbookFREE.me~ The first wave of products ended soon, and only more than 20 test tubes were used.
After the end, Xu Qiu handed the collected solution to the school girl for rotary steaming.
Then switch the mode to waste liquid mode and continue to slowly increase the volume fraction of B solvent to increase the polarity of the mobile phase.
The second wave of samples is the shallower raw material point.
In fact, it does not matter if it is not collected, but it must be cleaned, or it will contaminate the next third product.
Soon the second wave of samples was also collected. He continued to increase the solvent polarity and collected the third wave of samples.
Finally, in the third wave of samples, the solution of more than 20 test tubes was also collected and transferred to the school girl for rotary evaporation.
And the second wave of samples in the middle, that is, the raw material only collected the solution of 5 test tubes.
Xu Qiu thought about it and treated them directly as waste liquids. For recycling, up to 50 mg of raw materials would not make much sense.
After completing the separation and purification, he rinsed the column with pure dichloromethane, and finally left it empty, and then replaced the sample column for the second sample.
This time I have experience, and I am not as cautious as last time. The rate of increasing B% has increased a bit.
It went very smoothly and there were no problems.
After passing the two pillars, Xu Qiu was also aware of the difficulty of purification, "School girl, change you?"
"Okay," Han Jiaying was confident, "Brother, wait to see me show my power."
"Come on," Xu Qiu didn't say anything to attack, and smiled and said: "Today's progress is so fast, so far it has passed three pillars."
"Yes, I will definitely get two more before leaving at night, so I can count five in one day," Han Jiaying suddenly muttered:
"It's just a little tired, ohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh.
"Then let's take a day off tomorrow."
"Good~"