- Batch versus flow photochemistry: A revealing comparison of yield and productivity
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The use of flow photochemistry and its apparent superiority over batch has been reported by a number of groups in recent years. To rigorously determine whether flow does indeed have an advantage over batch, a broad range of synthetic photochemical transformations were optimized in both reactor modes and their yields and productivities compared. Surprisingly, yields were essentially identical in all comparative cases. Even more revealing was the observation that the productivity of flow reactors varied very little to that of their batch counterparts when the key reaction parameters were matched. Those with a single layer of fluorinated ethylene propylene (FEP) had an average productivity 20% lower than that of batch, whereas three-layer reactors were 20% more productive. Finally, the utility of flow chemistry was demonstrated in the scale-up of the ringopening reaction of a potentially explosive [1.1.1] propellane with butane-2,3-dione.
- Elliott, Luke D.,Knowles, Jonathan P.,Koovits, Paul J.,Maskill, Katie G.,Ralph, Michael J.,Lejeune, Guillaume,Edwards, Lee J.,Robinson, Richard I.,Clemens, Ian R.,Cox, Brian,Pascoe, David D.,Koch, Guido,Eberle, Martin,Berry, Malcolm B.,Booker-Milburn, Kevin I.
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- Potent Bacterial Mutagens Produced by Chlorination of Simulated Poultry Chiller Water
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Hypochlorite treatment of a simulated food-processing mixture produces 3,4-dichloromaleimide and 3,3-dichloro-4-(dichloromethylene)-2,5-pyrrolidinedione (C5HCl4NO2). The tetrachloro compound and two analogs, which can be synthesized from citraconic anhydride and itaconic anhydride, are direct-acting Ames mutagens in Salmonella typhimurium TA100 tester strain. These novel five-carbon cyclic imides are structurally similar to 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), the principal mutagenic compound present in paper pulp bleaching liquors. Molecular structure analysis of the mutagens was based on X-ray crystallography, 13C NMR, and mass spectrometry of synthetic chlorinated imides with identical mass spectra and gas chromatographic retention indices. The tetrachloroimide accounts for much of the mutagenicity of the dichloromethane-extractable pH 2 fraction from chlorination of a simulated food-processing system consisting of chicken frankfurters. In the Ames TA100 tester strain it has a molecular mutagenicity of 1450 revertants/ nmol without microsomal activation, making it the second most potent mutagen reported from a chlorination process.
- Haddon, William F.,Binder, Ronald G.,Wong, Rosalind Y.,Harden, Leslie A.,Wilson, Robert E.,Benson, Mabry,Stevens, Kenneth L.
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- Natural product-based pesticide discovery: Design, synthesis and bioactivity studies of N-amino-maleimide derivatives
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Natural products are an important source of pesticide discovery. A series of N-amino-maleimide derivatives containing hydrazone group were designed and synthesized based on the structure of linderone and methyllinderone which were isolated from Lindera erythrocarpa Makino. According to the bioassay results, compounds 2 and 3 showed 60% inhibition against mosquito (Culex pipiens pallens) at 0.25 μg·mL?1. Furthermore, the results of antifungal tests indicated that most compounds exhibited much better antifungal activities against fourteen phytopathogenic fungi than linderone and methyllinderone and some compounds exhibited better antifungal activities than commercial fungicides (carbendazim and chlorothalonil) at 50 μg·mL?1. In particular, compound 12 exhibited broad-spectrum fungicidal activity (>50% inhibitory activities against 11 phytopathogenic fungi) and compounds 12 and 14 displayed 60.6% and 47.9% inhibitory activity against Rhizoctonia cerealis at 12.5 μg·mL?1 respectively. Furthermore, compound 17 was synthesized, which lacks N-substituent at maleimide and its poor antifungal activity against Sclerotinia sclerotiorum and Rhizoctonia cerealis at 50 μg·mL?1 showed that the backbone structure of N-amino-maleimide derivatives containing hydrazone group was important to the antifungal activity.
- Song, Xiangmin,Liu, Chunjuan,Chen, Peiqi,Zhang, Hao,Sun, Ranfeng
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- Benzopyrazinoisoindigo or Its Reduced Form? Synthesis, Clarification, and Application in Field-Effect Transistors
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Benzopyrazinoisoindigo, a pigment reported 40 years ago, should be a good candidate for n-type semiconductors if the reported structure is correct. Reinvestigation of this molecule revealed that it is actually (4H,4′H)-benzopyrazinoisoindigo, which could be considered as the reduced form of benzopyrazinoisoindigo, and hence, it is a good candidate for p-type semiconductors. The route toward the synthesis of this molecule was optimized, and a mechanism was accordingly proposed. A field-effect transistor based on this material showed a hole mobility up to 2.5 × 10-2 cm2 V-1 s-1. An expedient route for the synthesis of unexpectedly alkylated (4H,4′H)-benzopyrazinoisoindigo is developed, which also clarifies the previously reported structure. A mechanism is accordingly proposed. A field-effect transistor based on this material shows a hole mobility up to 2.5 × 10-2 cm2 V-1 s-1.
- Wang, Xiao,Zhao, Zhiyuan,Ai, Na,Pei, Jian,Liu, Yunqi,Wan, Xiaobo
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supporting information
p. 2603 - 2607
(2016/06/08)
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- Pyrazine-2,3-dicarbonitriles substituted with maleimide derivatives
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Syntheses and spectroscopic characteristics are reported for eight pyrazine-2,3-dicarbonitriles substituted with maleimide residue in addition to phenyl, 2-thienyl, or 2-furyl substituent.
- Morkved
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p. 1197 - 1201
(2008/09/19)
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- Photocycloadditions of Dichloromaleimide and Dichloromaleic Anhydride to Cyclic Olefins
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The photocycloaddition of dichloromaleimide to cyclohexadiene, cyclopentadiene, and cyclopentene on direct photolysis gave addition products with the cis,endo- and cis,exo-configurations as the major products.However, a similar photocycloaddition to cyclohexene yielded the trans-fused cycloaddition product (between the four- and six-membered rings) as the major product in addition to the cis,endo- and cis,exo-isomers.The photocycloadditions of dichloromaleic anhydride to cyclopentadiene and cyclohexadiene were reinvestigated; two major products were obtained which were identified as the cis,endo- and cis,exo-addition products, while the reported trans-fused isomers were not isolated.The structures of these photoaddition products were investigated by 400 MHz n.m.r. spectroscopy to ascertain the configuration of the ring fusion.An X-ray crystallographic analysis established the stereochemistry of one product.
- Chow, Yuan L.,Naguib, Yousry M. A.
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p. 1165 - 1172
(2007/10/02)
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- Acylation of Amines with Dichloromaleoyl Chloride
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The reaction of dichloromaleoyl chloride (2) with ammonia in ether yields the ammonium salt of (Z)-2,3-dichloro-3-cyanoacrylic acid (6) and with aqueous ammonia the ammonium salt of (Z)-2-amino-3-chloro-3-cyanoacrylic acid (1).With primary aliphatic and aromatic amines dichloromaleamides 8 are obtained, the two chlorine atoms of which can be replaced with other amines to form after cis/trans isomerization diaminofumaramides 11.
- Bonse, Gerhard,Blank, Heinz Ulrich
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p. 1658 - 1664
(2007/10/02)
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