How can I monitor the reaction process with TLC?

It's very simple, I am doing organic synthesis, first you need to understand the polarity of the reactants and the expected synthetics, choose the right agent, or more simply, directly from tetrahydrofuran.

Ethanol, chloroform.

and other simple and ordinary organic solvents to pick some as agents to point the plate (generally mix the above several kinds in a certain proportion to adjust the appropriate polarity), so that the point of the reactant is between rf = (how to point the plate does not need to be taught). Then the reaction on the shelf, during the period with a capillary to suck out a little reaction solution, point the plate, to see if there are any more points in addition to the reactant point, of course, you still have ready-made products in your hands, you can point 4 points side by side on the plate, which are the reactant point, the product point, the reaction solution point (the amount of the point should be the same), and the three mixing points, and then observe whether there are points on the same level as the reaction solution and the product point, a little bit of the reaction to a large extent indicates that the reaction you want has happened smoothly, and then change to another polar agentIf you still get the previous results, you will be more sure. Then there's how to monitor the reaction process

According to the size and depth of the product point in the reaction solution, if you have a ready-made product, prepare a product solution of known concentration, and then compare with the size and depth of the product point in the reaction solution, you will know the approximate amount generated (provided that the amount of the point plate should be consistent), if you combine the chemical formula and the volume and yield of the reaction liquid, calculate the concentration of the theoretical product, you can know how far the reaction has progressed! Generally, the yield of mature reaction is more than 95%, and if it is made raw, it is between 70-90%. Hope.

Looking for a master to bring, one or two sentences are not clear.

First of all, it is necessary to choose a good agent, the main point of the choice of agent is the choice of polarity, petroleum ether has the smallest polarity, the water polarity is the largest, generally little water, and the large polarity is used with methanol. The order of the polarity of the solvent can be found on the Internet.

The reason why you have to choose the agent is because sometimes with a small polarity agent, your reaction hydraulic root will not be able to move, and it will stay at the origin.

Of course, as long as the TLC chooses a drug that can be seen to move around. If it is through the column, it is necessary to ensure that the agent can make the point of the reaction solution reach the RF value.

The polarity of the agent should be selected according to the polarity of the product molecule. For molecules with large polarity, such as salts, it is necessary to choose agents with large polarity, and small polarity should be selected for small polarity.

Next, take a sample with a capillary, then point it on a plate and dry the solvent with a hair dryer. Generally, when spotting, there are three points, some more, one is the point of raw materials, one is the point of reaction solution, and one is the point of mixing.

After blow-drying, you can put it in the tank and run. The bar cylinder needs to be activated is not the word I don't remember. The column line can be put directly into it, and it does not need to be activated.

The agent can be taken out without passing the leading edge, and it can be directly placed under the ultraviolet lamp to see, and this should pay attention to radiation. Alternatively, it can be seen directly under visible light with a chromogenic agent.

TLC tracking refers to the thin layer plate tracking reaction, when the reaction is carried out, the interval is fixed at a fixed time (for example, ten minutes, half an hour or an hour) to point the thin layer plate, point the plate and then climb the plate, and then bake the plate, observe the situation of the baking plate to know the amount of starting product and product or other impurities to understand how the reaction is going.

If the point of the starting substance slowly fades, and the trend of the point of the product is slowly thickening and there are no impurity spots, it indicates that the reaction only obtains the product without impurities, and can continue until the point of the starting substance completely disappears or stops the reflection when it no longer fades.

If the point of the starting substance is lightened, the point of the product and the impurities are becoming concentrated, and the value of the impurity and the product is not much different, then the reaction should generally be stopped immediately.

I'm not a master, and our lab is also tracking with TLC when doing experiments now, and what I say is just the feeling of doing experiments from Zihong. If there is a mistake or question, please feel free to correct or consult!