China 
Africa 
Explore chapters and articles related to this topic
Atom Economy
Published in Aidé Sáenz-Galindo, Adali Oliva Castañeda-Facio, Raúl Rodríguez-Herrera, Green Chemistry and Applications, 2020
Kunnambeth M. Thulasi, Sindhu Thalappan Manikkoth, Manjacheri Kuppadakkath Ranjusha, Padinjare Veetil Salija, Nisha Vattakkoval, Shajesh Palantavida, Baiju Kizhakkekilikoodayil Vijayan
In the Mitsunobu reaction of conversion of secondary alcohols to ester, diethyl azodicarboxylate and triphenyl phosphine are used as reagents. Diethyl azocarboxylate is unstable and explosive in nature. The byproducts of the reactions also have considerable mass. Therefore the reaction is not ideal and has low atom economy. Instead of these reagents, Barret in 1998 used imidate esters (Barrett et al., 1998), produced from DMF and oxalyl chloride. This, on reaction with potassium benzoate leads to SN2 substitution reaction of secondary alcohols. This reaction, given in Scheme 2.10 minimizes the quantity of nucleophile which improves atom economy. Moreover, the side products (DMF and KCl) can be removed easily.
Polymeric Second-Order Nonlinear Optical Materials and Devices
Published in Sam-Shajing Sun, Larry R. Dalton, Introduction to Organic Electronic and Optoelectronic Materials and Devices, 2016
In general, two different processes are used for the synthesis of PEIs, nitrogen-displacement of anhydride and imidization of polyamicacid. However, such synthetic method is not applicable for a side-chain NLO PEI because of harsh reaction conditions. The alternative synthetic approach for making the NLO polyetherimides is the use of the single-step reaction of NLO chromophores with terminal diol and diimide by the Mitsunobu reaction using diethyl azodicarboxylate (DEAD) and triphenylphosphine in tetrahydrofuran. In this method, the polyimide structure is directly formed during mild condensation polymerization without a thermal imidization step [26].
Anisotropic derivatives of (-)-L-lactic acid and their nanocomposites
Published in Liquid Crystals, 2018
V. S. Bezborodov, S. G. Mikhalyonok, N. M. Kuz’menok, A. S. Arol, G. A. Shandryuk, A. S. Merekalov, O. A. Otmakhova, G. N. Bondarenko, R. V. Talroze
It was also found that 3,6-disubstituted cyclohex-2-enones (Ia, b) under the action of various reagents can be aromatised and modified to various derivatives of biphenyl, terphenyl and quaterphenyl (VIII-XI) [14,15] (see Scheme 2). Taking into account these data, we synthesised 6-octyl-3-(4-ethoxyphenyl)cyclohex-2-enone (1) and 6-(4-methoxyphenyl)-3-(4-substituted phenyl)cyclohex-2-enones (2a-c) by the condensation of 2-octyl acetoacetic ether (3) with 4-ethoxy-3-(N,N-dimethylamino)propiophenone hydrochloride (5) and 4-methoxyphenylacetone (6) with 4-hexyl-3-(N,N-dimethylamino)propiophenone (5a), 4-(trans-butylcyclohexyl)-3-(N,N-dimethylamino)propiophenone (5b), 1-(4-octyldiphenyl-4ʹ)-3-(N,N-dimethylamino)propan-1-one (5c) hydrochlorides (see Scheme 3) and used them to prepare new chiral anisotropic compounds with a high optical activity and the presence of functional groups. The following aromatisation of the condensation products (1, 2a-c) under the action of phosphorus pentachloride, dealkylation of chloroarenes (7a-d) in boiling acetic acid in the presence of iodide, reaction of hydroxy derivatives (8a-d) with optically active ethyl ester of (-)-L-lactic acid in the presence of diethyl azodicarboxylate and triphenylphosphine (Mitsunobu reaction) gave ethyl esters of (R)-2-aryloxypropionic acids (9a-d), which by alkaline hydrolysis in the presence of lithium hydroxide in aqueous tetrahydrofuran was converted to the corresponding optically active acids (10a-c) (see Scheme 4). Additionally the conditions of the preparation of optically active ethyl ω-halogenealkyl lactates (11a,b), which are promising for the creation of nanocomposite materials, were also studied and optimised (see Scheme 5).