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Crystallization and Structural Linkages of COFs
Published in Atsushi Nagai, Covalent Organic Frameworks, 2019
Nowadays, Schiff base chemistry or dynamic imine chemistry is profusely utilized for the synthesis of COFs. Imine is a functional group or chemical compound containing a carbon-nitrogen double bond and is typically prepared by the condensation of primary amines and aldehydes and less commonly ketones (Eq. 2.5). In terms of mechanism, such reactions proceed via nucleophilic addition, giving a hemiaminal –C(OH)(NHR)– intermediate, followed by the elimination of water to give the imine (–N=C–) compound. The equilibrium in this reaction usually favors the carbonyl compound and amine, so azeotropic distillation or use of a dehydrating agent, such as molecular sieves or magnesium sulfate, is required to push the reaction in favor of imine formation. In recent years, several reagents, such as tris(2,2,2-trifluoroethyl)borate, pyrrolidine, acetic acid, and titanium ethoxide, have been shown to catalyze imine formation. Especially, according to synthesis of COFs, aqueous acetic acid as a catalyst is most useful.
Organic Chemistry Nomenclature
Published in Arthur W. Hounslow, Water Quality Data, 2018
Thus, imines contain carbon to nitrogen double bonds. These compounds result from the reaction of primary amines with the carbonyl bonds of aldehydes and ketone. Imines derived from special types of amines are given names as follows: those derived from hydroxylamine (HO—NH2) are called oximes,those derived from Phenylhydrazine (C6H5—NH—NH2) are called phenylhydrazones, andthose derived from semicarbazide are called semicarbazones.
Antimicrobial studies of the Zn(II) complex of S-benzyl-β-(N-2-methyl-3-phenylallylidene)dithiocarbazate
Published in Journal of Coordination Chemistry, 2022
Rayees A. Bhat, Kaman Singh, D. Kumar, Ashok Kumar, Prashant Mishra
The classical synthesis of imines reported by Schiff involves the condensation of a carbonyl compound with an amine under azeotropic distillation. Freshly prepared solution of S-benzyl-β-(N-2-methyl-3-phenylallylidene)dithiocarbazate (HL) [52] (1.863 g, 5.7 mmol) in 21 mL boiling acetone was added to a hot solution of the zinc acetate dihydrate (2.85 g, 0.002 mmol) in acetone (12 mL) in 2:1 molar ratio [53]. For 42 min, the mixture was refluxed on a water bath, microcrystalline creamy-colored compound separated out, was collected by filtration, washed with cold ethanol several times and dried in vacuo over silica gel (Scheme 1). [Zn(L)2] was characterized by spectroscopic and physicochemical techniques, and the results were compared to quantum-chemical calculations.
Advances in self-crosslinking of acrylic emulsion: what we know and what we would like to know
Published in Journal of Dispersion Science and Technology, 2019
Sumit Parvate, Prakash Mahanwar
Nicola Kessel studied the fundamentals of the keto-hydrazide reaction and put forwarded for the first time, that the reaction yields an imine and not enamine.[79] While it was made known that primary amines and carbonyl groups gives imines, whereas enamines can be formed on the reaction of aldehydes and ketones with secondary amines. Furthermore, crosslinking reaction was acid catalyzed and the reaction rate was inversely proportional to pH of reaction. The factors like lower latex Tg, higher film formation temperature, and no crosslinking enhances surfactant exudation. Koukiotis et al. studied the effect of various polymerizable and non-polymerizable, free of alkylphenol ethoxylates (APEO-free) surfactants on film properties. They have testified that non-polymerizable surfactants showed very high coagulum, whereas polymerizable surfactant gave almost zero coagulum. In addition, crosslinking helped in the coalescence of the particles which resulted in better scratch resistance, low MFFT, and higher gloss. Water absorption was increased because of hydrophilicity of the ADH and might be due to possibility of unbounded groups (–NH–NH2) of ADH on DAAM [80]
Caffeine hydrogen sulfate: a recyclable solid acid catalyst for mechanochemical synthesis of 2-arylbenzothiazoles
Published in Journal of Sulfur Chemistry, 2022
Priyanka Kalal, Ayushi Sethiya, Jay Soni, Isha Patel, Divyani Gandhi, Shikha Agarwal
The plausible reaction mechanism is shown in Scheme 2. Initially, the aldehyde (2) was activated by the catalyst CHS and the carbonyl carbon became more electrophilic and facilitated the nucleophilic addition of the amine group of 2-aminobenzenethiol to form imine. Furthermore, CHS activated the nitrogen of imine, making it more electrophilic. This in turn facilitated the attack of SH group to imine which finally resulted into 2-arylbenzothiazole (3) with the release of CHS (Scheme 2).