Post-treatment involving organotin reagents _ alkyl

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Original Title: Reprocessing Involving Organotin Reagents Organotin reagents are common toxic substances in organic synthesis. Generally speaking, it can not be used, and the most commonly used ones can also be replaced. However, for some reactions that cannot be carried out, organotin reagents have to be used, and the results are usually good. In this case, the post-treatment of the organotin reagent is involved. Let's first understand what organotin reagents are. 【 J. Am. Chem. Soc . 2006, 128, 740-742】 Organotin compounds refer to organometallic compounds containing Sn-C bonds. The general formula is RnSnX4-n (n = 1-4, R is alkyl or aryl). There are two types of alkyl tin compounds and aromatic compounds. Its basic structure has one substitution, two substitution, three substitution and four substitution (referring to the number of R). Dialkyltin mainly damages the hepatobiliary system, while trialkyltin and tetraalkyltin mainly damage the nervous system. There are also hexa-substituted ditin organotin compounds. Organotin compounds can cause the following damages to organisms: white matter edema in the central nervous system, impairment of oxidative phosphorylation in cellular energy utilization, inhibition of thymus and lymphatic system, impairment of cellular immunity, and diabetes and hyperlipidemia caused by inhibition of hormone secretion. Toxicity to human, local irritation to skin, respiratory tract and cornea, and systemic poisoning or even death through skin or brain edema. General operation: wear protective glasses, mask, gloves, white coat, and operate in a fume hood. [When conditions permit, it is best to wear an isolated respirator, a one-piece rubberized gas suit, decarboxylation after extraction ,wiped film distillation, and rubber gloves.] Besides the most common, there are several other reactions involving organotin reagents, such as. Expand the full text Post-processing 1. After the Stille coupling reaction, most of the substrate organotin reagent is converted to R3SnX, in addition to a slight excess of R1SnR3, which is usually post-treated by adding saturated KF aqueous solution or Py-HF solution and stirring for at least one hour. Celite filtration [KF + R3SnCl KCl + R3SnF (precipitation)] followed by the usual workup and purification. R1SnR3 was added as little as possible, and KF did not know whether it could react with it in a shorter time. For the destruction of R1SnR 3, DBU and iodine treatment can be added to convert it into alkyl tin iodide [J. Org. Chem. 1989, 54, 13, 3140–3157 】。 2. There is a good method to remove alkyl tin halides when using R 3SnCl to prepare organotin reagents. The article [Chem. Commun. , 2010, 46, 6335。 DOI: 10.1039/c0cc01328e] reported that the alkyl tin halide, tin oxide, tin triflate, etc. Can be removed by separation using a silica gel column made of silica gel containing 10 wt% of anhydrous potassium carbonate, and the residue can be in the ppm level. However, this method has no effect on the removal of organotin hydrides, tetra-substituted organotin and hexa-substituted ditin. Therefore, for the Stille coupling reaction, if the excess of the organotin reagent substrate R1SnR3 is too much, it is not suitable for the post-treatment of this method. 3. Removal of medium trialkyltin hydride. Due to the removal of trialkyltin hydride or other small polar organotin reagents, you can refer to the article [] a few days ago. If the product has good solubility in methanol or DMF, while trialkyltin hydrides or other small polar organotin reagents have good solubility in small polar solvents such as petroleum ether and n-hexane, the principle of similarity and compatibility. Back-extraction is enough. First, concentrate the reaction solution, add methanol or DMF to dissolve it, and extract the small polar organotin reagent with petroleum ether. However,wiped film evaporator, this operation is risky and should be operated with caution. In addition, the liquid separation extraction of organotin compounds is often easy to emulsify. At this time, adding a little CaF can make the stratification more obvious. Responsible Editor:.


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