Chapter 297: Don't offend medical students easily

After casting ICIN-2F/Cl in the last step of the reaction, Xu Qiu started to process the reaction product of the first step of IDTT, which is the TT-B-TT structure with two ester groups connected to the central benzene ring (B).
The dot plate developing agent used 1:1 volume ratio of dichloromethane and petroleum ether. The results showed that the main product dots were relatively deep and the yield should not be low. After all, the synthesis took more than 24 hours.
Xu Qiu judged that this kind of reaction that requires a longer reaction time might be more suitable for microwave reactors. It is estimated that the reaction time can be shortened a lot. You can try it later.
Wu Shengnan has also had column experience before, but he has never used this kind of advanced high pressure liquid chromatography machine. They have used the column manually. It may take a day to pass a column. Now she sees this kind of machine, naturally His eyes gleamed, exclaiming, "There is such an artifact."
Previously, the reaction product stayed in the previous step of the column, and the sample mixing has been completed, and now it can be directly loaded onto the column.
Xu Qiu picked out two of the disposable blank columns that were used before, which were still relatively clean, and completed the sample loading with Wu Shengnan.
Speaking of this, Xu Qiu contacted the manufacturer before and wanted to buy a batch of this kind of disposable blank silica gel column. After all, it is very convenient to use, but if you ask for the price, the big one is several hundred soft coins, and the small one is better. After thinking about it for a few dozens of soft sister coins, I still didn't buy it. It would take up to 10 minutes to fill the column by myself, and it would save hundreds of dollars. Let's save some money for Teacher Wei.
After installing the column, Xu Qiu explained to Wu Shengnan while operating the instrument: "Our high-pressure liquid chromatograph can achieve a flow rate of 30-60 ml per minute..."
The solvent used refers to the developing agent when the plate is applied. Dichloromethane and petroleum ether are selected as the A/B solvents.
It took more than three hours for Xu Qiu and Wu Shengnan to go through the columns. The products were separated and purified. The final yield of the two materials obtained was about 80%.
During this period, Xu Qiu re-distilled the tetrahydrofuran (THF) solvent in advance and prepared for the next reaction. Han Jiaying returned from the cryogenic physics laboratory with liquid nitrogen.
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Xu Qiu also got the device efficiency of Xuemei H21 and H22 system, and the H22 donor material with sulfur atom and thiophene side chain introduced at the same time has better performance. It combines with Xuemei’s IDT-T (EH)-ICIN acceptor unit, The highest efficiency reached 7.62%.
Although the improvement in efficiency is not large compared to H1x and the original FTAZ materials, it is more important to enrich the choice of donor libraries. After new receptor materials come out, they can be combined with a large number of donor materials at once. Combination makes it easier to achieve breakthroughs in efficiency. This kind of material optimization is difficult to accomplish overnight, and requires long-term accumulation and trial and error.
With liquid nitrogen, Xu Qiu continued the second step of the IDTT unit synthesis, low temperature reaction, using n-butyllithium to introduce side chains and hydroxyl groups.
In the field of organic synthesis, there are different ways to achieve the same one-step reaction. For example, in this step, some people in the literature also use format reagents, that is, use organometallic compounds containing magnesium halide instead of n-butyl lithium. , The conditions are relatively mild, and it is carried out at the reflux temperature of THF.
However, their yield using the Grignard reagent reaction is relatively low, only about 30%. In addition, Xu Qiu is more experienced in low-temperature reactions involving n-butyllithium, so he did not rashly change the reaction conditions.
It is the first time for Wu Shengnan to use n-butyl lithium, and Xu Qiu first demonstrated it.
First, stir in a bowl-shaped Dewar flask with liquid nitrogen and absolute ethanol to obtain a low temperature device that can maintain about minus 78 degrees Celsius.
Then, 10 millimoles of 1-bromo-4hexylbenzene was dissolved in 30 milliliters of re-distilled THF solvent, and the reaction flask was placed in a cryogenic device at minus 78 degrees Celsius under stirring conditions.
Next, 4.2 ml, that is, 10 millimoles of n-butyl lithium n-hexane solution (concentration 2.4M), was slowly injected drop by drop into the reaction flask through a syringe.
After maintaining the low temperature and stirring for one hour, dissolve about 1 millimole of the product synthesized in the first step of the IDTT unit in 80 ml of THF solvent, and slowly pour it into the reaction flask drop by drop.
Finally, the temperature of the reaction vessel was slowly returned to room temperature and stirred overnight.
Compared with the previous malononitrile reaction involving cyanide, the low-temperature reaction of n-butyl lithium is much easier for Xu Qiu. Just be careful not to let it in the air when extracting the n-butyl lithium solution. Spontaneous combustion is fine.
The reaction was successfully completed, and Wu Shengnan next to Xu Qiuchao said: "This reaction is done, let's continue to deal with the reaction of ICIN derivatives."
"Okay." Wu Shengnan nodded and thought silently in his heart: "Following Xu Qiuqian, there is really no time to rest for a moment. I feel like I have been experimenting all day. No wonder only an undergraduate can publish so many articles. Although it is very hard, But as long as there are results, everything is worth it."
Xu Qiu did not know what the postdoctoral sister was thinking. He focused on the several reaction devices in the fume hood, and calculated the reaction time of the previous ICIN-2F/Cl last step reaction. It should have exceeded the expected reaction time by more than one hour. , The problem should not be big, and even the reaction yield may be higher.
However, in order to allow this reaction to proceed more fully, malononitrile is 2 times excessive relative to IN-2F/Cl, which means that even if the yield is 100%, a portion of malononitrile will still remain. Dispose of malononitrile.
As for why IN-2F/Cl should not be doubled in excess, it is because IN-2F/Cl is synthesized through a three-step reaction, and malononitrile is a very cheap chemical raw material, and industrial grades are sold by ton. Yes, tens of thousands of dollars a ton...
High toxicity does not mean that it is cheap. In fact, many highly toxic and dangerous substances are cheap and easy to buy from the laboratory.
I won't talk about the more elementary things like splashing concentrated sulfuric acid, and there will be similar reports every once in a while.
The poisoning case of the Magic City University that made a lot of noise before was a medical graduate student who was dissatisfied with his roommate because of trivial matters in life, and eventually poisoned his roommate, using the highly toxic reagent N-dimethylnitrosamine.
There is another news that a female medical student stabbed her boyfriend with dozens of knives, avoiding the key with the knife, and finally identified as a minor injury.
In conclusion, don't offend medical students (dog heads) easily.
Xu Qiu has checked the processing method of malononitrile. For organic cyanide (nitrile), it will hydrolyze under acidic conditions to form ammonium salt and carboxylic acid, and malononitrile reacts with hydrogen chloride and water to form malonic acid. And ammonium chloride.
Xu Qiu poured the reactants into 30 ml of water, then added hydrochloric acid to keep the pH of the mixed liquid between 1-2, and stirred for fifteen minutes. At this time, the product ICIN-2F/Cl had precipitated, and then used Brinell Filter through a funnel, then wash the product with water and petroleum ether, and place it in a vacuum oven for drying to obtain a crude product. Among them, ICIN-2F is a pale yellow solid.
In the evening, Xu Qiu again chose to stay in Zhangjiang overnight to purify the three products through the column, and finally obtain about gram of product each with a yield of 70-80%.
This busy work, it was more than 12 o'clock in the evening.
On Friday, Han Jiaying left her two materials H21 and H22 at the Handan campus, and asked her senior sister Chen Wanqing to help prepare the devices, and then came to Zhangjiang with Wu Shengnan. The senior sister came to accompany Xu Qiu, after all, she wrote You can write articles anywhere.
It is worth mentioning that because Han Jiaying’s H22 donor material and Chen Wanqing’s IDT-T (EH)-ICIN acceptor material are both new materials, even if the performance of the devices based on these two materials is not low, it can reach 7.6%. It will not report directly.
On the one hand, the acceptor materials are all new materials, so it is not clear whether the improvement of device performance is caused by the donor material or the acceptor material; on the other hand, the most important point is the two new materials. Two articles can be published, it is too wasteful to put together.
After preparing for the experiment, Xu Qiu and Wu Shengnan continued their reaction yesterday, the synthesis of IDTT and other D units.
Today's experiment pressure is not great, because the three A units have been synthesized, and only D units are left.
In the fume hood, the liquid nitrogen in the Dewar has completely evaporated, leaving only a small amount of residual ethanol.
In a fume hood with good air circulation, a solvent with a low boiling point such as ethanol will evaporate relatively quickly.
Just like a damp quilt, even if the sun is blocked in a cloudy weather, it is faster to "dry" the quilt outside than at home because of the effect of wind.
Xu Qiu poured the reaction liquid in the reaction flask into water for washing, and then extracted with dichloromethane, dried over anhydrous magnesium sulfate, and then rotatory-evaporated the solvent to obtain a crude product.
Immediately afterwards, Xu Qiu put the crude product directly into the reaction flask, poured 50 ml of acetic acid and 1 ml of concentrated sulfuric acid, heated to 130 degrees Celsius, and refluxed for two hours.
This step of the reaction is the dehydration reaction involving sulfuric acid to convert the TT-B-TT structure to the TTTBTTT structure. The target product is the IDTT unit. Compared with the TTBTT structure of the IDT unit, there is one more T on each side of the IDTT. , The linear conjugate length has also changed from 5 to 7.
As for the reaction of the male sister Wu Sheng, it is to convert the TT-BDT-TT unit into TTTBDTTTT, and BDT is actually the structure of TBT, and the target product is the structure of TTTTBTTTT, which has one more T unit on both sides of the IDTT unit, linear The conjugate length is 9.
Of course, the side chain positions of the structures synthesized by Xu Qiu and Wu Shengnan are not the same, so the changing trend of specific properties is still unclear. Only after obtaining specific products can they be known after performance testing.
Two hours later, Xu Qiu shut down the reaction and started the post-reaction treatment, which was also washed with a large amount of water, and then extracted with n-hexane, dried, and mixed with silica gel.
When referring to the literature, Xu Qiu found that unlike the usual petroleum ether/dichloromethane system, the other party used a mixed solvent of n-hexane/dichloromethane to pass the column.
Then, when I took a closer look at the author's unit, it was from a beautiful country, and Xu Qiu suddenly came across.
Although petroleum ether has an "ether" in its name, it is not an ether compound at all. It is a metaphor to describe its light weight and volatile characteristics. It is a common name used in the petrochemical industry. The main components are pentane and hexane. , Octane, these saturated aliphatic alkane mixtures with 5-7 carbon atoms.
Petroleum ether and n-hexane have similar polarities, and both are very low-polarity solvents. In theory, they can replace each other when passing through the column.
Domestic petroleum ether is more expensive than n-hexane. It is said that the opposite is true abroad. N-hexane is cheaper than petroleum ether. Therefore, domestic documents mostly use petroleum ether, while foreign documents mostly use n-hexane.
Anyway, Xu Qiu didn't understand why pure n-hexane is more expensive than the mixture of petroleum ether in foreign countries, but it doesn't matter.
In the afternoon, Xu Qiu chose a system familiar with petroleum ether/dichloromethane, and processed the product with a column.
In the end, the IDTT material was successfully separated and purified, and Wu Shengnan also obtained the BDT-based D unit with a conjugate length of 9, which she named FN.
Returning to the A501 office, Xu Qiu washed his hands while calculating the next experiment. He had two steps left to react:
The aldehyde reaction of IDTT unit, UU read www.uukanshu.com to get IDTT-CHO;
The reaction of IDTT-CHO with several ICIN derivatives resulted in the final ADA-type non-fullerene acceptor material.
In these two steps, the senior sister already has a lot of synthesis experience, and Xu Qiu has the system, so the senior sister's experience is his experience, and it is not difficult for him.
However, no matter how simple the reaction is, it takes time to synthesize.
If you force the synthesis, work overtime one day on Saturday and another day on Sunday, you can almost synthesize two or three final products, but the time is too rush.
Xu Qiu glanced at Han Jiaying, who was working at the desk, and the other person raised her head as if consciously and blinked her big cute eyes.
The two looked at each other for a while, and Xu Qiu felt that somewhere in his heart was melted.
What the sentence said, it was like suddenly having weakness and suddenly having armor.
Experiment or something, let's talk next week...