Lithiation of η6-fluorobenzenetricarbonylchromium(0) and reaction with dialkyl disulfides: synthesis of η6-1,2-bis- and 1,2,3-tris-alkylsulfanylbenzenetricarbonylchromium(0) complexes

Directed lithiation of η6-fluorobenzenetricarbonylchromium(0) and reaction with dialkyl disulfides affords η6-1,2-bis-alkylsulfanylbenzenetricarbonylchromium(0) complexes by electrophilic addition of an alkylthio group at C-2 of the benzene ring, and subsequent SNAr reaction with displacement of fluoride by the alkanethiolate generated in the first step. 1,2,3-tris-Alkylsulfanylbenzene complexes are formed as by-products. The structures of four of the new complexes have been confirmed by X-ray crystallography, one using synchrotron radiation

Studies on the double alkylation of 2,2-disubstituted-1,3-dithiacycloalkane-S-oxides: synthesis of tertiary thiol derivatives

Di-alkylation of 2,2-dimethyl-1,3-dithiacycloalkane-S-oxides has been achieved allowing the synthesis of two tertiary thiol centres. The diastereoisomers of the mono-alkylated products have been shown to react at different rates. The X-ray crystal structures of three substituted dithiane-S-oxides have been determined, and the conversion of the dialkylated products into cyclic disulfide derivatives of tertiary thiols (1,2-dithiolanes) has been achieved by treatment with acid

Synthesis of fluorinated fused benzofurans and benzothiophenes: smiles-type rearrangement and cyclisation of perfluoro(het)aryl ethers and sulfides

Lithium–bromine exchange in 2-bromophenyl perfluoroaryl ethers or sulfides affords fused fluorinated benzofurans or benzothiophenes respectively by SNAr substitution of the adjacent fluorine in the perfluoroaryl substituent. The structures of the new compounds were confirmed by NMR spectroscopy and single crystal X-ray diffraction analysis. In the case of 2-bromophenyl tetrafluoropyrid-4-yl ether, lithiation promoted a Smiles-type rearrangement which led to formation of 4-(2-hydroxyphenyl)tetrafluoropyridine, for which the structure was confirmed by X-ray crystallography

Digital laser-dyeing for polyester fabrics

Surface polyester fibers modified by laser beam energy have been found to display improved dye uptake (Lau et al. 1997; Kamel et al. 2012; Shahidi et al. 2013). This research considers “laser-dye” patterning as an alternative coloration method within a textile design context. In this study, standardized polyester (PET) knitted jersey and plain, woven fabrics were modified with CO2 laser technology to engineer dye onto the fabric with high-resolution graphics. The work considered the aesthetic possibilities, production opportunities, and environmental potential of the process compared to traditional and existing surface design techniques. Laser-dyed patterns were generated by a digital dyeing technique involving CAD, laser technology, and dye practices to facilitate textile coloration and patterning. An understanding of energy density was used to define the tone of a dye in terms of color depth in relation to the cloth. In so doing, a system for calibrating levels of color against laser energy in order to build a tonal image was found. Central to the investigation was the consideration of the laser beam spot as a dots-per-inch tool, drawing on the principles used in digital printing processes. It was therefore possible to utilize the beam as an image-making instrument for modifying textile fibers with controlled laser energy. Quantitative analysis of the outcomes alongside creative exploration facilitated both a tacit understanding of, and ability to control, processing parameters. This enabled repeatability of results parallel to design development and has established the potential to apply the technique commercially. Sportswear prototypes produced in the study suggest a suitable market for processing polyester garments in this way

An alternative method for the vulcanization of rubber articles

Zinc oxide was treated with a sulfenamide accelerator by vacuum evaporation of a suspension of ZnO in a solution of the accelerator in dichloromethane to provide a convenient single material component to use as additive. The optimum quantity of the accelerator in the additive was found to be 350 mg/g. A large batch of the surface-modified zinc oxide with this composition (referred to as the ‘TBBS/ZnO powder’) was then prepared. The effect of an increasing loading of the TBBS/ZnO powder on the cure properties of ethylene-propylene-diene rubber (EPDM) and polybutadiene rubber (BR) containing elemental sulfur was subsequently measured. When the loading of the TBBS/ZnO powder in the rubbers was raised progressively, the scorch time was unaffected and the optimum cure time reduced. The rate of cure kept rising until it reached an optimum. The crosslink density increased substantially as the loading of the TBBS/ZnO powder in the rubber was raised progressively. All the indications are that the use of the TBBS/ZnO powder in combination with sulfur in the cure system improves efficiency of the vulcanization process, reduces cost and harmful effects while also shortening the cure cycle. The surface modified TBBS/ZnO powder is a viable alternative chemical additive for the sulfur vulcanization of rubber

CO₂ laser dye patterning for textile design and apparel manufacture

Digital dyeing technique, described as ‘Digital Laser Dyeing’ (DLD) was studied in this research using CO2 laser technology, synthetic textiles, workshop coloration methods and industry standard dyes and dyeing procedures. Laser beam energy was used as an image creation tool to modify surface fibres with graphic patterns and coloured dyed effects through a Computer Aided Design (CAD) approach. The research was supported by a textile design perspective in order to explore the creative potential of DLD methods for textile processing, fabric finishing, fashion design and apparel manufacture. Combined technical and scientific inquiry ensured experimental rigor in terms of the repeatable methods employed and reliable results achieved using an energy density (J/cm2) approach. Outcomes of the study identified CO2 laser-dye patterning as an innovative alternative textile coloration approach and dye on demand manufacturing process relevant to textile and clothing production. Explorations with polyester/elastane sportswear and intimate garments in this study suggest a potential sector for the development of on demand processing for synthetic textiles and clothing

New rubber compound

Ethylene-propylene-diene rubber cured with a new single chemical additive and reinforced with mineral kaolin is a suitable compound for possible use in tires

Pyridone functionalization: regioselective deprotonation of 6-methylpyridin-2(1H)- and -4(1H)-one derivatives

Selective functionalization at the α-methyl group of 1-substituted pyridin-2(1H)- and 4(1H)-ones (2- and 4-pyridones) can be achieved by appropriate choice of base. n-Butyllithium was found to effect clean 6(2)-methyl deprotonation of 1-benzyl-2- and -4-pyridone derivatives, while potassium hexamethyldisilazide (KHMDS) was the preferred reagent for methyl deprotonation of the corresponding 1-methyl-2- and -4-pyridones. Deprotonation proceeds smoothly at –78 °C, and the resulting anions react readily with a wide range of electrophiles (aldehydes, ketones, alkylating reagents, and an azo compound) under precise temperature control to form usefully functionalized 2- and 4-pyridones and quinolizinones

A novel method for the optimization of sulfur cure systems for rubber using software

The goal of this study was to find a software approach that would make the optimization of the vulcanization system more efficient. For this purpose, a natural rubber (NR) was mixed with different amounts of elemental sulfur at ambient temperature to produce rubber compounds. Zinc oxide was treated with an organic accelerator to produce a convenient single material component to use as additive. The effect of an increasing loading of the surface modified zinc oxide on the cure properties of the sulfur-filled rubber compounds was subsequently measured at a high temperature in a curemeter. Using a JavaScript program, the cure test results were processed to develop a highly efficient method for optimizing sulfur cure systems for rubber. All the essential information such as scorch and optimum cure times, rate of cure, crosslink density changes in the rubber, and chemical curatives requirement at a given loading of sulfur were subsequently provided for the user. This method removes the need to mix and test the raw rubber with chemical curatives repeatedly to find a compound with ideal cure properties for industrial applications

Ein alternatives Verfahren zur Vulkanisation von Gummiartikeln

Durch die Oberflächenmodifikation von Zinkoxid mit einem Beschleuniger wurde ein Einkomponentenadditiv für ein Schwefelvulkanisationssystem hergestellt. Dazu wurde eine Dichlormethanlösung von ZnO und einem Sulfenamidbeschleuniger im Vakuum verdampft. Der optimale Beschleunigeranteil wurde mit 350 mg/g bestimmt. Es wurde ein großer Ansatz des oberflächenmodifizierten ZnO mit dieser Zusammensetzung hergestellt (im Folgenden als „TBBS/ZnO-Pulver“ bezeichnet) und der Einfluss des Anteils an TBBS/ZnO-Pulver auf die Vernetzungseigenschaften eines Ethylen-Propylen-Dien-Kautschuks (EPDM) und eines Polybutadienkautschuks (BR) bei der Schwefelvulkanisation untersucht. Mit ansteigendem Anteil an TBBS/ZnO-Pulver im Kautschuk nahm die optimale Vulkanisationszeit ab. Die Anvulkanisationszeit blieb jedoch unverändert. Die Vulkanisationsgeschwindigkeit nahm zu, bis sie ein Optimum erreicht hatte. Der Vernetzungsgrad nahm mit steigendem TBBS/ZnO-Pulveranteil deutlich zu. All das deutet darauf hin, dass der Einsatz des TBBS/ ZnO-Pulvers in einem Vulkanisationssystem mit Schwefel die Effizienz des Vulkanisationsprozesses erhöht und die Zykluszeit verkürzt und damit die Kosten und schädliche Auswirkungen der Vulkanisation reduziert. Das TBBS/ZnO-Pulver wäre damit ein mögliches alternatives Additiv für die Schwefelvulkanisation von Kautschuk. Zinc oxide was treated with a sulfenamide accelerator by vacuum evaporation of a suspension of ZnO in a solution of the accelerator in dichloromethane to provide a convenient single material component to use as additive. The optimum quantity of the accelerator in the additive was found to be 350 mg/g. A large batch of the surface-modified zinc oxide with this composition (referred to as the ‘TBBS/ ZnO powder’) was then prepared. The effect of an increasing loading of the TBBS/ZnO powder on the cure properties of ethylene-propylene-diene rubber (EPDM) and polybutadiene rubber (BR) containing elemental sulfur was subsequently measured. When the loading of the TBBS/ZnO powder in the rubbers was raised progressively, the scorch time was unaffected and the optimum cure time reduced. The rate of cure kept rising until it reached an optimum. The crosslink density increased substantially as the loading of the TBBS/ZnO powder in the rubber was raised progressively. All the indications are that the use of the TBBS/ZnO powder in combination with sulfur in the cure system improves efficiency of the vulcanization process, reduces cost and harmful effects while also shortening the cure cycle. The surface modified TBBS/ZnO powder is a viable alternative chemical additive for the sulfur vulcanization of rubber