1219-96-1Relevant articles and documents
Catalyst-free solventless synthesis of polysubstituted urea Method for preparing thioureas and chiral ureas and thiourea compounds
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Paragraph 0105-0111, (2021/09/29)
The invention discloses a method for synthesizing polysubstituted urea, thiourea and chiral urea and thiourea compounds without catalyst without solvent, and the method comprises A contact reaction of an amine compound with a structure shown B as shown first in a non-catalyst and a solventless condition to prepare a polysubstituted urea or thiourea compound with a structure as shown C. R1 And R2 Each independently selected from a hydrocarbyl or substituted hydrocarbyl group, R3 The method is selected from H, hydrocarbyl or substituted hydrocarbyl, X is S or o. The method solves the defect that a catalyst and/or a solvent need to be used in the synthesis of urea and thiourea compounds in the prior art.
Tunable NIR-II emitting silver chalcogenide quantum dots using thio/selenourea precursors: Preparation of an MRI/NIR-II multimodal imaging agent
Basel, Siddhant,Bhardwaj, Karishma,Borthakur, Sukanya,Brito, Beatriz,Clarke, Mitchell,Pariyar, Anand,Pradhan, Sajan,Roy, Pankaj,Saikia, Lakshi,Shankar, Amit,Stasiuk, Graeme J.,Tamang, Sudarsan,Thapa, Surakcha
supporting information, p. 15425 - 15432 (2020/11/18)
Aqueous-stable, Cd- and Pb-free colloidal quantum dots with fluorescence properties in the second near-infrared region (NIR-II, 1000-1400) are highly desirable for non-invasive deep-tissue optical imaging and biosensing. The low band-gap semiconductor, silver chalcogenide, offers a non-toxic and stable alternative to existing Pd, As, Hg and Cd-based NIR-II colloidal quantum dots (QDs). We report facile access to NIR-II emission windows with Ag2X (X = S, Se) QDs using easy-to-prepare thio/selenourea precursors and their analogues. The aqueous phase transfer of these QDs with a high conservation of fluorescence quantum yield (retention up to ~90%) and colloidal stability is demonstrated. A bimodal NIR-II/MRI contrast agent with a tunable fluorescence and high T1 relaxivity of 408 mM-1 s-1 per QD (size ~ 2.2 nm) and 990 mM-1 s-1 per QD (size ~ 4.2 nm) has been prepared by grafting 50 and 120 monoaqua Gd(iii) complexes respectively to two differently sized Ag2S QDs. The size of the nanocrystals is crucial for tuning the Gd payload and the relaxivity.
Unclicking of thioureas: Base catalyzed elimination of anilines and isothiocyanates from thioureas
Vlatkovi?, Matea,Feringa, Ben L.
, p. 2188 - 2192 (2019/03/05)
Bisaromatic thioureas are widely used in e.g. asymmetric organocatalysis and considered to be robust compounds. Herein we show, in strong contrast to common notion, that thioureas dissociate to amines and isothiocyanates in a base catalyzed reaction under mild conditions. This ‘unclicking’ process can occur in the presence of weak organic bases even at moderate temperatures. The influence of the substituents at the aromatic rings of the thiourea on the regioselectivity of this unclicking process is also shown.