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    Home > In − ex tube: a new design for gas organic reaction

    In − ex tube: a new design for gas organic reaction

    • Last Update: 2017-10-31
    • Source: Internet
    • Author: User
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    In the field of modern organic synthesis, a large part of synthesis methods involve gases For reactions involving non-toxic and non flammable gases, such as CO2, the operation is relatively simple and the safety requirements are relatively low However, special attention should be paid to the reactions of CO, so 2 and H 2 For example, CO is highly toxic, so attention should be paid to the use process and tail gas treatment As a result, chemists have developed many in situ and ex situ reaction systems The in-situ system has defects in cost and waste generation, while the non in-situ system has problems such as air leakage and flask cleaning and maintenance Xiao Feng Wu research group from Leibniz Institute Fu ̈ R katalyse in Germany has been devoted to the research of CO chemistry in the past few years Part of their work focuses on the development of CO replacement reagents in carbonylation process Recently, they tried to use formic acid and its derivatives as CO source of carbonylation cross coupling reaction Using anhydrides or DCC as initiators, formic acid can be excited to release a molecule of Co When anhydrides are used as the initiator, when one molecule of CO is generated, two amount of acid by-products will be generated at the same time, so alkali needs to be added into the reaction system to neutralize the acid; when DCC is used as the initiator, 1,3-dicyclohexylurea by-products will be generated, resulting in the decrease of the purity of the target product (Figure 1) All these problems need to be solved Fig 1 Reaction source of formic acid as CO source: org Process res dev in view of the advantages of formic acid, such as non-toxic, easy storage, cheap, easy separation of by-products, the author tends to use formic acid as CO source, and hopes to solve the problem of by-product removal by designing a new reactor The new reactor needs to contain an independent co generating tube and a reaction generating tube, that is, two reaction tubes are in the same environment In consideration of the above requirements, the author has drawn a drawing of the new reactor: the small tube with hole in the middle is used as the ex situ co generation reaction tube, and the generated co directly enters the reaction tube below and participates in the carbonylation reaction (Figure 2) The author named the new reactor "in - ex tube" When in - ex tube is used, by-products are excluded from the reaction tube, which successfully avoids the problem of product separation and additional waste Figure 2 Source of design concept of new reactor: org Process res dev next, verify whether in - ex tube is practical through experiment Firstly, the author carbonyls amines with iodobenzene and aniline as reaction substrate and triethylamine as base The yield of amides is 55% (Fig 3, EQ 1) The carbonylation Suzuki reaction of iodobenzene and phenylboronic acid and the carbonylation Sonogashira reaction of iodobenzene and phenylacetylene can also be carried out smoothly (Fig 3, EQ 2 & 3) Figure 3 Source of palladium catalyzed carbonylation using in ex tube operation: org Process res dev in addition, the new reactor can also operate the reaction of SO 2 and H 2 (Figure 4) In this paper, Na 2SO 3 and Zn were used to produce so 2 and H 2 under the action of H 2SO 4 The relative yields were 58% and 82%, respectively Figure 4 Source of SO 2 and H 2 participating in the reaction with in ex tube operation: org Process res dev conclusion: Wu designed a new reactor for gas related organic reaction, named in ex tube, and tested the reaction with CO, so 2 and H 2 Without any optimization, the corresponding products can be obtained in medium to good yields The author believes that the new reaction tube can make the gas reaction in a more efficient and simple way Original link: http://pubs.acs.org/doi/abs/10.1021/acs.oprd.7b00332 author profile: https://www.catalysis.de/en/people/wu-xiao-feng/dr.xiao-feng Wu source: leibniz-institutfu ̈ R katalyse
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