A transition‐metal‐free one‐pot synthesis of 3‐halo‐2‐organochalcogenylbenzobchalcogenophenes has been developed using 1‐(2‐organochalcogenylethynyl)‐2‐butylchalcogenylbenzenes generated in situ from ...1‐(2,2‐dibromovinyl)‐2‐organochalcogenylbenzenes and diorganoyl dichalcogenides. By this method, several 2,3‐disubstituted benzobchalcogenophenes were prepared in yields of 48–93%. The mechanistic investigation suggests that the formation of chalcogenoacetylenes containing an adjacent chalcogen atom in the first step of this one‐pot procedure involves acetylide anions formed from 1‐(2,2‐dibromovinyl)‐2‐organochalcogenylbenzenes and mild bases.
The structure of the title compounds 3-bromo-2-(phenyl-sulfan-yl)benzo
thiophene (C
H
BrS
;
), 3-iodo-2-(phenyl-sulfan-yl)benzo
thio-phene (C
H
IS
;
), 3-bromo-2-(phenyl-selan-yl)benzo
seleno-phene ...(C
H
BrSe
;
), and 3-iodo-2-(phenyl-selan-yl)benzo
seleno-phene (C
H
ISe
;
) were determined by single-crystal X-ray diffraction; all structures presented monoclinic (
2
/
) symmetry. The phenyl group is distant from the halogen atom to minimize the steric hindrance repulsion for all structures. Moreover, the structures of
and
show an almost linear alignment of halogen-selenium-carbon atoms arising from the intra-molecular orbital inter-action between a lone pair of electrons on the halogen atom and the anti-bonding σ*
orbital (
→σ*
). This inter-action leads to significant differences in the three-dimensional packing of the mol-ecules, which are assembled through π-π and C-H⋯π inter-actions. These data provide a better comprehension of the inter-molecular packing in benzo
chalcogenophenes, which is relevant for optoelectronic applications.
A variety of techniques have been employed in order to reduce problems caused by the crystallization of paraffin during the production and/or transportation of paraffin oils and derivatives. ...Methacrylate copolymers are known as additives which reduce the pour point of these oils. This paper describes the synthesis, characterization and performance evaluation of these copolymers, having as an initial step the synthesis of the alkyl methacrylate monomers by transesterification of methyl methacrylate (MMA) with C
14, C
16 and C
18 fatty alcohols. The copolymerization of these monomers with MMA was then performed, with molar ratios of 30:70, 50:50 and 70:30 for alkyl methacrylate:methyl methacrylate. All products were characterized by FTIR,
1H NMR and gel permeation chromatography (GPC). All the methacrylic copolymers lead to a large reduction in the pour point of samples of Brazilian diesel oil. Oil samples containing 50
ppm of the polymeric additive with ca. 70% octadecyl methacrylate units showed a 22
°C reduction in their pour points, thus establishing the large efficiency of the products synthesized in this work.
Bentonite is a technical term applied to layered silicates of very thin granulation, mainly composed by minerals of the smectites group. Montmorillonite, a phylossilicate with layers as thick as 1 ...nm, is the most common structure in the bentonite clay. The polarity of these materials is incompatible with most of the usual polymers and in order to overcome this problem, chemical modifications are often necessary. The purpose of this work is to evaluate the chemical and physical characteristics of different bentonites by comparing their product data sheets, their performance in the water Foster swelling and their response to chemical modifications of their surfaces structures. The samples were characterized by infrared spectroscopy and X-ray diffraction analysis. All bentonite samples showed effective intercalations of the modifying agent on their surface structures. This behavior showed the possibility of usage of these materials in the polymer layered silicates nanocomposites preparations.
In this work, we developed the first simple and eco-friendly mechanochemical solvent-free intercalation of imidazole into low-defect kaolinite. Results obtained by X-ray diffraction showed that ...imidazole could be intercalated by a co-grinding method with different intercalation ratios (InR) without loss of the stacking between the layers of the kaolinite after the co-grinding. An InR value of 92% was obtained for imidazole after 10 h of co-grinding using a ball mill. In addition, SEM and TEM results showed that the mechanical forces led to a decrease in particle size. The mechanochemical intercalation of imidazole into kaolinite was also investigated by Fourier transform infrared spectroscopy (FTIR) and density functional theory calculations, using a cluster model of Al10O38H46 and Si10O30H20 to represent both surfaces of the mineral. Results suggest that imidazole is stabilized into kaolinite interlayer surfaces mainly due to strong n(N)→σ∗(O–H) hydrogen bonding formation with the Al–O surface.
A hybrid organic-inorganic material was prepared by mechanochemical intercalation of imidazole into low-defect kaolinite using a simple solvent-free methodology without previous intercalation steps. Display omitted
A transition‐metal‐free one‐pot synthesis of 3‐halo‐2‐organochalcogenylbenzobchalcogenophenes has been developed using 1‐(2‐organochalcogenylethynyl)‐2‐butylchalcogenylbenzenes generated in situ from ...1‐(2,2‐dibromovinyl)‐2‐organochalcogenylbenzenes and diorganoyl dichalcogenides. By this method, several 2,3‐disubstituted benzobchalcogenophenes were prepared in yields of 48–93%. The mechanistic investigation suggests that the formation of chalcogenoacetylenes containing an adjacent chalcogen atom in the first step of this one‐pot procedure involves acetylide anions formed from 1‐(2,2‐dibromovinyl)‐2‐organochalcogenylbenzenes and mild bases.
The toughening of polypropylene PP with styrene–butadiene–styrene rubber SBS/montmorillonite MMT nanocomposites was investigated with respect to morphological, thermal, and mechanical properties. The ...MMT/SBS nanocomposites were prepared in an internal mixer, using an epoxidized SBS SBSe to investigate its effect as a compatibilizer. The MMT/SBS nanocomposite was added to PP up to 10 wt%, aiming at material toughening. Transmission electron microscopy (TEM) revealed MMT induced dispersed-phase reductions when compared to typical PP/SBS blends. In addition, changes in the PP crystallization process were observed in the presence of the nanocomposite. Surprisingly, the use of nanofiller, combined with SBSe compatibilizer agent, increased the PP impact strength by about 60%, with no reduction in the tensile module.
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