I Have a Research Support System

After returning to Handan Campus at night, Xu Qiu went directly to Room 218.

As soon as he entered the door, Teacher Wei pointed to the empty utility room next to him, "I have already vacated the place where the instruments are placed for you."

'I didn't expect Mr. Wei to be so proactive. He thought it would take a lot of talking. ’ Xu Qiu nodded repeatedly, walked to Mr. Wei’s desk, opened the WeChat chat records between him and Qiu Heming, and said, “This is the description and quotation of the TRPL instrument.”

Then he compared the files in the mobile phone, and relayed the results of the discussions with his seniors and juniors in the afternoon to Mr. Wei.

Teacher Wei is very satisfied with the general direction, but he only mentioned one point, that is, when designing the sample cabin, an additional interface should be reserved for connecting to the cryogenic device of the laboratory. This cryogenic device is from the beautiful country laboratory. The ones brought back have been left to Tian Qing to take care of. Xu Qiu has only seen the appearance of the instrument, which is long and cylindrical, but has never used it, so naturally he has not considered this point.

After the two exchanged, Wei Xingsi nodded: "Okay, then I will call Qiu Heming now and make a decision on this matter."

When Qiu Heming got on the phone, Wei Xingsi went straight to the point, saying that he wanted to buy an instrument and hoped to get it as soon as possible.

Then the two talked about other transaction matters. After all, it is about 200,000 instruments, and the procedures are still relatively cumbersome, such as preparing a formal purchase contract, filing with the department, follow-up fixed assets, reimbursement, etc. Yes, of course Xu Qiu doesn't need to worry about these things.

In addition, Mr. Wei also mentioned the modification of the sample cabin, and asked for supporting optical lenses, light reduction mirrors, filters and other things. Although they are all small gadgets, they can add up to thousands of dollars.

After hesitating for a while, Qiu Heming agreed, as if he just hit his bottom line.

Xu Qiu watched from the sidelines the whole time. His recent experience had deepened his understanding of Teacher Wei a lot, giving him the feeling of being shrewd and resolute.

Before that, he actually didn't have much direct contact with Mr. Wei, and in most cases, he would be separated by senior sister Chen Wanqing.

After the start of this semester, Teacher Wei paid more and more attention to him, often communicated with him directly, and handed over the purchasing rights of such a large-scale instrument to him, as if he had been treated as a doctoral student in advance.

...

The next morning, Zhang Jiang's laboratory.

Han Jiaying looked at the inexplicably stirring red viscous matter in several reaction bottles, and asked:

"Brother, the reaction time is not enough for 24 hours, should we shut down the reaction now, or write a summary for a while and talk about it in the afternoon?"

"Shut it down now, there are four reactions, maybe four pillars will be passed today, I'm afraid there will be too little time," Xu Qiu made a judgment after thinking for a moment, and then explained:

"Moreover, the reaction we are currently submitting is not as delicate as the polymerization reaction we did before. The reduction of this small molecule reaction by four or five hours is only equivalent to shortening the reaction time by about 20%, which may reduce the yield by a few percentage points." rate, no problem.

The two shut down the reaction, and while the reaction vessel was cooling down, Xu Qiu took the initiative to say, "To be on the safe side, light a plate first to check the purity of the product, and the result of the plate can also be used as a reference for the next column."

Han Jiaying nodded. She has attended "Organic Chemistry Experiments", so she is no stranger to the dot plate method.

The so-called dot plate method is a common name, and the written name is thin layer chromatography.

Its principle is similar to that of liquid chromatography. The support coated on the support plate is used as a stationary phase (such as silica gel on a silica gel plate), and a suitable solvent is used as a mobile phase (chromatographic fluid) to separate mixed samples. , a chromatographic separation technique for identification and quantification;

The difference between the two is that the chromatographic liquid moves from bottom to top in spot plate method, while liquid chromatography usually moves from top to bottom.

"Brother, let me prepare the chromatography bottle and the chromatography solution." Han Jiaying paused, "By the way, how to prepare the chromatography solution?"

"Petroleum ether: dichloromethane 1:1 volume ratio." Xu Qiu said casually, because it was the first time to explore, so he was not very clear.

After finishing speaking, he found a silica gel plate in the laboratory, that is, a glass plate coated with silica gel, and then cut it into a strip of 2 cm by 5 cm with a glass knife, and then used a pencil to trace the distance between the upper and lower edges of the silica gel plate. At a distance of about 1 cm, lightly draw a line with a ruler and a pencil.

Next, he took several disposable centrifuge tubes, each filled with about 1 ml of dichloromethane, and then used a clean capillary, that is, a thin tube with an inner diameter equal to or less than 1 mm, to take out an appropriate amount of product in the reaction bottle, and put Dissolve it into a centrifuge tube, and mark the sample name with a marker pen.

After completing these two steps, the school girl has also prepared two chromatography bottles and chromatography solution.

The cost of this plate method is very low. Compared with the 100,000 yuan instrument of liquid chromatography, it looks a little bit expensive, but the doorway inside is not small.

If the polarity of the chromatographic solvent is too high, the sample will climb too fast and it will be difficult to separate;

If the polarity of the solvent is too low, the sample will not climb and it will be difficult to separate;

If the sample concentration is too high, it will form a tail and affect the judgment;

If the sample concentration is too low, it may not be detected, which also affects the judgment.

In short, it is a handicraft.

Fortunately, Xu Qiu specially went to the aging building before, and found Associate Professor Qian Xingquan who taught him "Organic Chemistry Experiment", and copied 50% of the other party's fifth-level organic chemistry experiment skills. This is the highest skill proficiency he has seen so far. teacher.

Teacher Qian is in his fifties now, he is very nice, at least he is very responsible in teaching, maybe because he knows that his scientific research ability is not enough, he did not insist on doing scientific research in the front line, but switched to teaching experimental courses. That is more than ten years.

With the systematic teaching of level 5 50% proficiency, Xu Qiu didn't panic at all when faced with such a small experiment as making a board.

When everything was ready, he used a clean capillary to draw the sample solution in the centrifuge tube, then used the capillary to vertically spot samples at intervals on the previously drawn pencil line, and finally put the silica gel plate vertically into the chromatographic solution.

The chromatographic solution touches the silica gel plate and begins to climb from bottom to top. After the downward stroke, the solvent drives the sample in the upper sample point to climb.

"It's not bad, the chromatography solution is just right." Looking at the preliminary results, Xu Qiu nodded with satisfaction.

"Okay, I'll try it too." Following Xu Qiu's example, Han Jiaying picked out a silicone plate and began to make samples.

When the chromatographic solution reached the top, Xu Qiu immediately took out the silica gel plate, waited for the adsorbed solvent to volatilize, irradiated the surface of the silica gel plate with an ultraviolet lamp, and then marked the position of fluorescence with a pencil.

Aromatic compounds such as benzene rings, large conjugated systems, and nitro-containing substances will all develop color under ultraviolet light.

Although it can sometimes be judged with the naked eye, some colorless samples with a small content can also be detected with an ultraviolet lamp.

The final result, two sample points, one deep and one shallow, one in front and one behind.

It shows that there is a main product and a by-product, and the yield is not low, and the separation effect is not bad.

Soon, the spotting results of the four reaction products came out. Except for Xu Qiu, the other three were:

One deep and one shallow, one front and one back;

One deep and one shallow, but the two points rise very slowly and partially overlap;

Two deep, one in front and one in back.

Obviously, the results of the latter two point boards are problematic.

The one that rises very slowly is okay, you just need to increase the polarity of the chromatographic solution, Xu Qiu prepared a chromatographic solution with a volume ratio of petroleum ether:dichloromethane 1:2, re-pointed the plate, and chromatographically , the result becomes one deep and one shallow again, one in front and one in back.

The two-deep one is more difficult, which means that there are two main products of the reaction. Although it is not difficult to separate, the yield may be worrying, which may be less than 50%.

This is a system of the school girl, obviously she also knows what it means, and said with a bitter face: "Brother, what should I do?"

"Don't worry, there is still a chance." Xu Qiu reassured, and then analyzed: "The raw materials of perylenetetracarboxylic dianhydride and imidazole should not be a big problem, because the same raw materials are used in other reactions, but it is normal, so there is a problem. There is a high probability that the place is an amine molecule."

"Yeah, I guess it's because the amine molecules were added less." Han Jiaying nodded, and fell into thinking again: "But I didn't remember any mistakes in the experimental operation at the time."

"I have thought of two possibilities. One is that the materials you mentioned should be added less, and the other may be that different amines have different molecular structures and slightly different reactivity." Xu Qiu suggested:

"On the one hand, add some amine molecules, and on the other hand, increase the reaction temperature to 160 degrees Celsius. The two are carried out simultaneously. Before leaving tonight, I will check the board again. Anyway, small molecules can withstand tossing."

"Okay, brother is more thoughtful." Han Jiaying nodded happily.

"It's my fault too, I still lack experience," Xu Qiu blamed himself, "If I clicked the board before I left yesterday, I might be able to find out the problem in time and remedy it in advance."

"Brother, don't think so," Han Jiaying explained, "It's already good now, at least there is a possibility of remediation. I was planning to re-submit directly just now."

...

Han Jiaying fully referred to Xu Qiu's suggestion, and dealt with the reaction that the result of the order was two deep.

The pair then worked on three additional normal responses.

"Remember the post-processing method."

"Of course I remember, first add water, then extract with dichloromethane, finally separate the liquid, and spin evaporate... Well, it's written like this in the literature."

"That's right, adding water is mainly to remove imidazole, and dichloromethane can extract the product." Although Xu Qiu knew that the school girl should be familiar with these safety knowledge, she subconsciously reminded:

"If we want to use dichloromethane, let's operate it in a fume hood. Be careful to protect yourself and don't get the solvent in your hands. Gloves like dichloromethane can't prevent it."

"Okay." Han Jiaying nodded seriously.

The toxicity of dichloromethane is much lower than that of chloroform, so Xu Qiu didn't choose to wear a gas mask.

He would also prefer not to use these toxic solvents, most of which are potentially carcinogenic, if possible.

But their performance is too good, and there is no substitute.

This is also a risk that must be taken in the field of organic synthesis.

However, at least the physical and chemical properties of the reagents used in the experiment can be checked through MSDS, and various protective equipment have been developed, so that the safety of the experimenters can be guaranteed to a great extent.

However, in the early days of research, such as in the era of Marie Curie, radioactive elements were just discovered, and nothing was known about their properties.

Rich people even carry radioactive materials as "talismans" or display them as "luxury items" everywhere.

These behaviors are really the hanging of the birthday star--he thinks his life is too long.

Xu Qiu added about 150ml of water and 150ml of methylene chloride into the two reaction flasks, and then poured the mixed liquid into a 500ml separatory funnel.

Shake slightly a few times, then open the cork above the separatory funnel to deflate.

After all, the boiling point of dichloromethane is too low. If the liquid is shaken repeatedly without releasing the gas, the pressure inside the separatory funnel is too high, which may cause the liquid inside to push the plug directly and spray out.

After mixing thoroughly several times, he placed the separatory funnel on a shelf to rest.

After the solution was separated, the upper part was a yellowish transparent aqueous solution, and the lower part was a red dichloromethane solution.

The reaction product was mostly dissolved in methylene chloride, so he opened the valve below the separatory funnel to collect the solution.

After washing twice with water again, pour it into an eggplant-shaped bottle for later use.

Han Jiaying had only one reaction, so after finishing early, she ran to Xu Qiu's side to watch.

"Wait for me, my second reaction will be dealt with immediately." Xu Qiu took the initiative.

"Senior brother, your solution is so bright red, it looks a bit like..." Han Jiaying paused and said, "It looks like fresh duck blood in Wudu."

Xu Qiu was taken aback for a moment, she could even think of food.

"By the way, brother," Han Jiaying raised her hand and raised the sleeve of the lab coat, "I accidentally got a little PDI on the lab coat just now, so it shouldn't have any effect."

Xu Qiu glanced at it and said, "Fortunately, it's a lab coat. If it gets on the clothes, the clothes will basically be useless. This is an intermediate of a dye with strong adhesion, but the toxicity is very small."

"Well... that's it, that's good."

Not long after, Xu Qiu transferred the extracted and washed solution into an eggplant-shaped bottle, and said, "The second one is also done, let's prepare to mix the samples."

"Hey, what's a mixed sample?" Han Jiaying asked curiously, "Don't we just get the product by rotary steaming?"

Xu Qiu didn't know this operation before, but he knew it after seeing the video of the system. He patiently explained:

"After passing through the column, the sample needs to be evenly distributed, and the sample that is directly rotary evaporated may not be uniform. If a certain proportion of silica gel is mixed, then rotary evaporation can make the sample evenly distributed in the silica gel."

"So that's the case, how much should I add?" Han Jiaying nodded.

"We calculate based on 5 grams of product. The general sample mixing ratio is 1:1 to 1:2. Take the middle value, that is, add 7.5 grams of silica gel, and use 100-200 mesh silica gel." Xu Qiu took out the silica gel from the reagent cabinet, After weighing, add to the eggplant-shaped bottle.

Then rotary evaporation was carried out to obtain a red solid powder.

"Does it look like red fermented bean curd with rice?" Xu Qiu suddenly had an inspiration.

"As expected of a senior brother, what a good image!"

"You two, that's enough, we have to eat later."