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Wyszukujesz frazę "nucleophilic substitution" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
Synthesis and characterization of thiourea
Autorzy:
Dai, Chuanbo
Zhang, Hongyu
Li, Ruiduan
Zou, Haifeng
Powiązania:
https://bibliotekanauki.pl/articles/778378.pdf
Data publikacji:
2019
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
Urea
Lawesson’s reagent
thiourea
vulcanization reaction
Nucleophilic substitution
Opis:
Herein, a simple and effective method for the preparation of thiourea using a nucleophilic substitution reaction is reported. Urea and Lawesson’s reagent were used as the raw materials to prepare thiourea via a one-step method involving the sulfuration reaction, and the reaction mechanism was analyzed. The effect of the reaction time, reaction temperature, and mass ratio of the raw materials on the yield of thiourea were investigated.The most beneficial conditions used for the reaction were determined to be: Reaction time = 3.5 h, reaction temperature = 75°C, and mass ratio of urea to Lawesson’s reagent = 2:1. Under these optimal conditions, the average yield of thiourea over five replicate experiments was 62.37%. Characterization using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermogravimetric analysis (TGA) showed that the as-synthesized substance was thiourea. Our synthetic method has the advantages of high yield, mild reaction conditions and simplicity.
Źródło:
Polish Journal of Chemical Technology; 2019, 21, 3; 35-39
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nukleofilowe podstawienie wodoru w nitroarenach. Proces analogiczny i komplementarny do podstawienia elektrofilowego
Nucleophilic substitution of hydrogen in nitroarenes. An alogous and complementary process to electrophilic substitution
Autorzy:
Mąkosza, M.
Powiązania:
https://bibliotekanauki.pl/articles/171966.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
podstawienie elektrofilowe
podstawienie nukleofilowe
pierścienie aromatyczne
nitroarenes
nucleophilic substitution
oxidation
vicarious substitution
Opis:
Nucleophiles add to electron-deficient arenes, also those containing halogens, initially in positions occupied by hydrogen to form óH adducts. This addition is faster than addition in similarly activated positions occupied by halogens. Formation of the óH adducts is a reversible process, thus they dissociate and slower addition in positions occupied by halogens results in formation of óH adducts followed by fast departure of X– to form products of nucleophilic substitution of halogen, SNAr. In the review it is shown that there are a few ways for fast further conversion of initially formed óH adducts into products of nucleopilic substitution of hydrogen such as oxidative substitution, vicarious substitution, etc. Since formation of óH adducts is faster than óH adducts and the former undergo fast transformations into products of nucleophilic substitution of hydrogen we should accept than this is the major, primary reaction whereas conventional nucleophilic substitution of halogens, SNAr reaction “ipso” substitution is just a secondary process. In modern textbooks only SNAr reactions are discussed whereas nucleophilic substitution of hydrogen is not mentioned, thus it is necessary to introduce proper corrections in textbooks and teaching of this chapter of chemistry of arenes.
Źródło:
Wiadomości Chemiczne; 2011, 65, 9-10; 795-819
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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