Cl Moieties Research Articles

Synthesis and X-ray structural characterization of the (chlorochalcogeno)phosphonium cations R2R′PSCl+ and R2R′PSeCl+ as their AuCl4− salts

Phosphine chalcogenides R2R'PE react with (tht)AuCl to form complexes of the type R2R'PEAuCl (E = S, Se); stepwise oxidation with PhICl2 leads first to R2R'PEAuCl3 and then to the (chlorochalcogeno)phosphonium salts R2R'PECl(+)AuCl4(-).

Ln2M complexes (M = Ru, Re) derived from a bismacrocyclic ligand containing a 4,4′-dimethyl-2,2′-bipyridyl bridging unit

Homodinuclear lanthanide complexes derived from a ligand featuring two DO3A chelating sites linked by a 4,4'-dimethyl-2,2'-bipyridyl spacer were prepared and characterized. The bipyridyl coordination site of 1 was used to introduce Ru(Bpy)(2) and Re(CO)(3)Cl moieties, leading to the formation of heterometallic d-f(2) complexes with general formulae [Ln(2)·1·Ru(Bpy)(2)](2+) (Ln = Nd, Eu, Tb, Yb and Lu) and [Ln(2)·1·Re(CO)(3)Cl] (Ln = Nd, Yb and Lu). The luminescence properties of the complexes were investigated by means of absorption spectroscopy and steady-state and time-resolved luminescence spectroscopy covering the visible and NIR regions. Both Ru and Re chromophores were shown to act as efficient sensitizers of the NIR emission of Yb and Nd in aqueous solutions. We also consider the unsaturated coordination spheres of the Ln cations in the Ln(2)·1 complexes, which form ternary complexes with bidentate anions without showing particular synergistic effects for polyanionic species.

Optimising BTP ligands by tuning their basicity

Abstract A novel approach for the optimisation of extractants for the actinide(III)/lanthanide(III) separation is presented. Two BTP ligands are synthesised carrying OMe or Cl moieties on the pyridine ring, thus altering the electronic structure of the aromatic system. The influence of functionalisation on the ligand basicity is determined both spectroscopically and by quantum chemical calculations. Furthermore, we show that both distribution ratios and separation factors for Am(III)/Eu(III) separation increase upon increase of ligand basicity.

New Insights into Factors Influencing BN Bonding in X:BH3−nFnand X:BH3−nClnfor X=N2, HCN, LiCN, H2CNH, NF3, NH3andn=0–3: The Importance of Deformation

Understanding the bonding in complexes X:BH(3-n)F(n) and X:BH(3-n)Cl(n), for X=N(2), HCN, LiCN, H(2)CNH, NF(3), NH(3) with n=0-3, is a challenging task. The trends in calculated binding energies cannot be explained in terms of any of the usual indexes, including π donation from the halogen lone pairs to the p(π) empty orbital on B, deformation energies, charge capacities, or LUMO energies, which are normally invoked to explain the higher Lewis acidity of BCl(3) relative to BF(3). The results of the high-level G3B3 ab initio calculations reported in this study suggest that the interaction energies of these complexes are determined by a combination of at least three factors. These include the decrease in the electron-accepting ability of B as a result of π donation by the halogen atom, the increase in the electron-acceptor capacity of B due to deformation of the acid, and the large increase in the deformation energy of the acid with increasing halogen substitution. The dominant effects are those derived from the electronic effects of acid deformation. Deformation not only has direct energetic consequences, which are reflected in the large differences between dissociation (D(0)) and interaction (E(int)) energies, but also leads to an enhancement of the intrinsic acidities of BH(3-n)F(n) and BH(3-n)Cl(n) moieties by lowering the LUMO energies to very different extents, consistent with the frontier orbital model of chemical reactivity. Although this lowering depends on both the number and the nature of the halogen substituents, binding energies do not systematically increase or decrease as the number of halogen atoms increases.

The Synthesis of Novel 2,4,6-Trisubstituted 1,3,5-Triazines: A Search for Potential MurF Enzyme Inhibitors

A series of new 2,4,6-trisubstituted 1,3,5-triazines, possessing a variety of substituents (-OH, -SH, -OMe, -Cl, -HNR, -SR and amino acid moieties), were synthesized and evaluated for the inhibition of the bacterial peptidoglycan biosynthesis enzyme MurF. Ethoxycarbonyl isothiocyanate successfully reacted with a variety of amidines, enabling an approach to 6-substituted-4-thioxo-1,3,5-triazin-2-ones. Also, a representative set of 2-thio-, 2-amino-, and 2-oxo-substituted 1,3,5-triazines was synthesized by the S N Ar reaction, employing 2,4,6-trichloro-1,3,5-triazine and 2-chloro-4,6-dimethoxy-1,3,5-triazine as the starting materials. One compound displayed notable inhibitory activity against MurF from Escherichia coli.

Practical Access to Amines by Platinum-Catalyzed Reduction of Carboxamides with Hydrosilanes: Synergy of Dual Si−H Groups Leads to High Efficiency and Selectivity

The synergetic effect of two Si-H groups leads to efficient reduction of carboxamides to amines by platinum catalysts under mild conditions. The rate of the reaction is dependent on the distance of two Si-H groups; 1,1,3,3-tetramethyldisiloxane (TMDS) and 1,2-bis(dimethylsilyl)benzene are found to be an effective reducing reagent. The reduction of amides having other reducible functional groups such as NO(2), CO(2)R, CN, C horizontal lineC, Cl, and Br moieties proceeds with these groups remaining intact, providing a reliable method for the access to functionalized amine derivatives. The platinum-catalyzed reduction of amides with polymethylhydrosiloxane (PMHS) also proceeds under mild conditions. The reaction is accompanied by automatic removal of both platinum and silicon wastes as insoluble silicone resin, and the product is obtained by simple extraction. A mechanism involving double oxidative addition of TMDS to a platinum center is discussed.

N-Halamine-coated cotton for antimicrobial and detoxification applications

A new N-halamine precursor, 3-(2,3-dihydroxypropyl)-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione (TTDD diol), was synthesized and bonded onto cotton fabrics. Fabrics with variable amounts of chlorine loading were prepared by using several concentrations of TTDD diol. A second N-halamine precursor, 3-(3-triethoxysilylpropyl)-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione (TTDD siloxane), was also synthesized and bound to cotton for comparison purposes. The coated cotton fabrics contained two types of N–Cl moieties after chlorination of the amine and amide groups. Swatches with variable chlorine loadings were challenged with Staphylococcus aureus and Escherichia coli O157:H7 as a function of contact time. The biocidal test results showed that the chlorine loadings and surface hydrophobicities influenced the antimicrobial efficacies. The chlorinated swatches have also been employed to oxidize the simulant of chemical mustard to the less toxic sulfoxide derivative.

Antimicrobial efficacy and light stability of N-halamine siloxanes bound to cotton

N-halamine silane syntheses and coatings of cotton fabrics as siloxanes were addressed for a series of silanes. The coated fabrics were chlorinated by exposure to dilute sodium hypochlorite with a range of chlorine loadings from 0.20% to 0.26%. Two types of N–Cl moieties were involved in the N-halamine siloxanes, amine and amide. The siloxane-coated cotton swatches were very effective in inactivating Escherichia coli O157:H7 and Staphylococcus aureus, each in 10 min contact time. The N–Cl bond and compound stabilities under UV irradiation and ambient light exposure were also investigated. Both UV and laboratory light stability tests show that most of the chlorine on cotton coated with 3-(3-triethoxysilylpropyl)-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione could be regenerated after irradiation, while most of the lost chlorine from 5,5-dimethyl-3-(3′-triethoxysilylpropyl)hydantoin and 4-[3-triethoxysilylpropoxyl]-2,2,6,6-tetramethylpiperidine could not be recovered upon rechlorination.

Syntheses, structures and reactions of a series of β-diketiminatoyttrium compounds

This paper describes the synthesis and selected reactions of a series of crystalline mono(beta-diiminato)yttrium chlorides 3a, 3b, 4a, 4b, 5a, 5b, 5c and 9. The X-ray structure of each has been determined, as well as of [YCl(L4)(2)] (6), [Y(L1)(2)OBu(t)] (7) and [Y{CH(SiMe(3))(2)}(thf)(mu-Cl)(2)Li(OEt(2))(2)(mu-Cl)](2) (8). The N,N'-kappa(2)-beta-diiminato ligands were [{N(R)C(Me)}(2)CH](-) [R = C(6)H(4)Pr(i)-2 (L1); R = C(6)H(4)Bu(t)-2 (L2); R = C(6)H(3)Pr(i)(2)-2,6 (L3)], [{N(SiMe(3))C(Ph)}(2)CH)](-) (L4) and [{N(C(6)H(3)Pr(i)(2)-2,6)C(H)}(2)CPh](-) (L5). Equivalent portions of Li[L(x)] and YCl(3) in Et(2)O under mild conditions yielded [Y(mu-Cl)(L(x))(mu-Cl)(2)Li(OEt(2))(2)](2) [L(x) = (L1(3a)) or (L1(3b))] and [Y(mu-Cl)(L3)(mu-Cl)Li(OEt(2))(2)(mu-Cl)](2) (4a) or its thf (instead of Et(2)O) equivalent 4b. Each of the Li(OEt(2))(2)Cl(2) moieties is bonded in a terminal (3) or bridging (4) mode with respect to the two Y atoms; the difference is attributed to the greater steric demand of L3 than L1 or L2. Under slightly more forcing conditions, YCl(3) and Li(L2) (via 3b) gave the lithium-free complex [YCl(2)(L2)(thf)(2)] (5b). Two isoleptic compounds 5a and 5c (having in place of L2 in 5b, L3 and L5, respectively) were obtained from YCl(3) and an equivalent portion of K[L3] and Na[L5], respectively; under the same conditions using Na[L4], the unexpected product was [YCl(L4)(2)] (6) (i.e. incorporating only one half of the YCl(3)). A further unusual outcome was in the formation of 8 from 3a and 2 Li[CH(SiMe(3))(2)]. Compound [Y(L5){N(H)C(6)H(3)Pr(i)(2)-2,6}(thf)(mu(3)-Cl)(2)K](2).4Et(2)O (9), obtained from and K[N(H)C(6)H(3)Pr(i)(2)-2,6], is noteworthy among group 3 or lanthanide metal (M) compounds for containing MClKCl (M = Y) moieties.

Cyclodiphosphazane cis‐{(o‐MeOC6H4O)P(μ‐NtBu)}2 as a Bridging Bidentate Ligand: Synthesis, Structures of Heterometallic Complexes, and Halogen Exchange Between Rh–Cl and Cu–X (X = Br, I)

AbstractThe mononuclear rhodium complexes of cyclodiphosphazane [(cod)RhCl{L‐κP}] (1a) (L = cis‐{(o‐MeOC6H4O)P(μ‐NtBu)}2) and trans‐[Rh(CO)Cl{L‐κP}2] (1b) react in a 1:1 molar ratio with [AuCl(SMe2)] to form the heteronuclear complexes [(cod)RhCl{μ‐L‐κP,κP}AuCl] (2) and trans‐[Rh(CO)Cl{μ‐L‐κP,κP}2(AuCl)2] (7), respectively, in quantitative yield. The reaction between 1a and CuCl afforded a tetranuclear complex [(cod)RhCl{μ‐L‐κP,κP}Cu(μ‐Cl)]2 (3). Under similar reaction conditions 1 reacts with 2 equiv. of CuX (X = Br, I) to produce the heteronuclear complexes [(cod)RhBr{μ‐L‐κP,κP}Cu(μ‐Br)]2 (4) and [((cod)RhI{μ‐L‐κP,κP})2Cu(μ‐X)2Cu] (X ≈ 1:1 mixture of Cl and I disordered over both sites) (5), respectively, in which two molecules of 1a are bridged by the rhombic, disordered, mixed halide [Cu(μ‐X)2Cu] (5: X = Br; 6: X = Cl, I) unit. The crystal structures of 4 and 5 confirm the halogen exchange between the Rh–Cl and CuX (X = Br, I) moieties which leads to the formation of Rh–Br and Rh–I bonds. The heterodinuclear RhI/PdII complex [(cod)RhCl{μ‐L‐κP,κP}PdCl(η3‐C3H5)] (6) was synthesized by the reaction of 1a with [PdCl(η3‐C3H5)]2 in a 2:1 ratio. Reaction of 1b with CuI leads to the formation of the tetranuclear complex [Rh(CO)I{μ‐L‐κP,κP}2Cu(μ‐I)]2 (8) containing two terminal uncoordinated phosphorus(III) centers irrespective of reactant ratio and reaction conditions. Halogen exchange reaction which leads to the formation of the Rh–I bond was also observed during the preparation of complex 8. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

2D and 3D supramolecular assemblies of double cyclopalladated azobenzenes realized by C–H⋯Cl–Pd, π⋯π and C–H⋯π interactions

The double cyclopalladated complex with azobenzene, μ-[( E)-1,2-diphenyldiazene- C 2,8, N 1,2]-di-[chloro(dimethylsulfoxide)palladium(II)]; (DMSO)PdCl(μ-C 6H 4N NC 6H 4)(DMSO)PdCl ( 1) and its analogous complex with DMF as ancillary ligand, (DMF)PdCl(μ-C 6H 4N NC 6H 4)(DMF)PdCl; μ-[( E)-1,2-diphenyldiazene- C 2,8, N 1,2]-di-[chloro(dimethylformamide)palladium(II)] ( 2a) were synthesized and the function of cyclopalladated moiety in molecular assembling in the solid state is illustrated by their crystal packings. The polymorphism of 2a and 2b is discussed. The crystal structures reveal assemblies with molecular components self-organized by C–H⋯Cl–Pd hydrogen bonds, π⋯π, and C–H⋯π interactions. The double cyclopalladated complexes of azobenzene, with two Pd–Cl moieties participating in the hydrogen bond formation and π-conjugated system involved in the π⋯π or C–H⋯π interactions, represent a new class of building blocks for construction of solid state supramolecular assemblies.

μ‐Coordination Chemistry of NO Ligands: Adducts of trans‐Mo(dmpe)2(Cl)(NO) with Lithium Salts

AbstractReaction of trans‐Mo(dmpe)2(Cl)(NO) (1) [dmpe = bis(dimethylphosphanyl)ethane] with lithium triethylborohydride and lithium bis(trimethylsilyl)amide affords the adducts [Mo(dmpe)2(Cl)(NO)(LiHBEt3)]n (2) and {Mo(dmpe)2(Cl)(NO)[LiN(SiMe3)2]2}n (3), respectively, and the reaction of 1 with n‐butyllithium and iodomethane generates the complex [Mo(dmpe)2(Cl)(NO)]3(LiI)2 (4). Complexes 2–4 have been characterized by elemental analysis, IR spectroscopy, NMR spectroscopy, and single‐crystal X‐ray diffraction analysis. The structure of 2 shows an infinite one‐dimensional “zigzag” chain constructed from an alternating arrangement of Mo(dmpe)2(Cl)(NO) and LiHBEt3 moieties, whereas the structure of 3 exhibits an infinite linear chain generated by the alternating arrangement of the Mo(dmpe)2(Cl)(NO) moiety and the dimeric [LiN(SiMe3)2]2 unit. In both compounds, the Mo(dmpe)2(Cl)(NO) moieties act as bridging ligands by coordination of the nitrosyl oxygen atom and the chlorine atom to the lithium ions. Complex 4 displays a discrete structure formed by two separate monomeric LiI units that are bridged by the nitrosyl oxygen atoms of three Mo(dmpe)2(Cl)(NO) moieties. The chlorine atoms of 4 are not involved in coordination. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Sulfate-Enhanced Catalytic Destruction of 1,1,1-Trichlorethane over Pt(111)

The catalytic destruction of 1,1,1-trichloroethane (TCA) over model sulfated Pt(111) surfaces has been investigated by fast X-ray photoelectron spectroscopy and mass spectrometry. TCA adsorbs molecularly over SO4 precovered Pt(111) at 100 K, with a saturation coverage of 0.4 monolayer (ML) comparable to that on the bare surface. Surface crowding perturbs both TCA and SO4 species within the mixed adlayer, evidenced by strong, coverage-dependent C 1s and Cl and S 2p core-level shifts. TCA undergoes complete dechlorination above 170 K, accompanied by C-C bond cleavage to form surface CH3, CO, and Cl moieties. These in turn react between 170 and 350 K to evolve gaseous CO2, C2H6, and H2O. Subsequent CH3 dehydrogenation and combustion occurs between 350 and 450 K, again liberating CO2 and water. Combustion is accompanied by SO4 reduction, with the coincident evolution of gas phase SO2 and CO2 suggesting the formation of a CO-SOx surface complex. Reactively formed HCl desorbs in a single state at 400 K. Only trace (<0.06 ML) residual atomic carbon and chlorine remain on the surface by 500 K.

Facile generation of platinum(IV) compounds with mixed labile moieties. Hydrogen peroxide oxidation of platinum(II) to platinum(IV) compounds

Hydrogen peroxide oxidation of platinum(II) compounds containing labile groups such as Cl, OH, and alkene moieties has been carried out and the products characterized. The reactions of [PtII (X)2 (N–N)] (X = Cl, OH, X2 = isopropylidenemalorate (ipm); N–N 2,2-dimethyl-1,3-propanediamine [(dmpda), N-isopropyl-1,3-propanediamine (ippda)] with hydrogen peroxide in an appropriate solvent at room temperature affords [PtIV (OH)(Y)(X)2(N–N)] (Y = OH, OCH3). The crystal structures of [PtIV(OH)(OCH3)(Cl)2(dmpda)]·2H2O (P-1 bar, a = 6.339(2) A , b = 9.861(1) A, c = 11.561(1) A, a = 92.078(9)°, β = 104.78(1)°, γ=100.54(1)°, V = 684.3(2) A3, Z = 2R = 0.0503) and [PtIV(OH)2(ipm)(ippda)]·3H2O (C 2/c, a = 27.275(6) A, b=6.954(2) A, c = 22.331(4) A, β = 118.30(2)°, V = 3729(2) A3, Z = 8, R = 0.0345) have been solved and refined. The local geometry around the platinum(IV) atom approximates to a typical octahedral arrangement with two added groups (OH and OCH3; OH and OH) in a transposition. The platinum(IV) compounds with potential labile moieties may be important intermediate species for further reactions.

In vivo biocompatibilty and degradation behavior of elastic poly( l-lactide- co- ε-caprolactone) scaffolds

Tubular scaffolds were fabricated from very elastic poly( l-lactide- co- ε-caprolactone) (PLCL, 50:50). The scaffolds were seeded with smooth muscle cells (SMCs) and implanted in nude mice to investigate the tissue compatibility and in vivo degradation behavior. Histological examination of all the implants with haematoxylin and eosin staining, masson trichrome staining, SM α-actin antibody, and CM-DiI labeling confirmed that the regular morphology and biofunction of the SMCs seeded and the expression of the vascular smooth muscle matrices in PLCL scaffolds. The implanted PLCL scaffolds displayed a slow degradation on time, where caprolactone units were faster degraded than lactide did. This could be explained by the fact that amorphous regions composed of mainly CL moieties degraded earlier than hard domains where most of the LA units were located. From these results, the scaffolds applied in this study were found to exhibit excellent tissue compatibility to SMCs and might be very useful for vascular tissue engineering.

Hydrogen-Bonded Assemblies as a Scaffold for Metal-Containing Nanostructures: From Zero to Two Dimensions

We report on the synthesis and characterization of metal-containing multicomponent, hydrogen-bonded rosette assemblies and their ordered arrangement on graphite surfaces. The introduction of gold atoms into the architecture of double rosettes was achieved using the coordination of phosphane groups to Au(I)Cl moieties. Transmission electron microscopy studies on gold-functionalized double rosettes deposited from dilute solution onto amorphous graphite revealed isolated features with a diameter of 1.0-1.2 nm, assigned to individual double rosettes. Highly ordered 2-D nanorod domains with an inter-row spacing of 5.1 ± 0.1 nm were obtained by deposition of the gold-labeled double rosettes on highly oriented pyrolytic graphite, as demonstrated by atomic force microscopy (AFM) experiments. Two sets of domains with different mutual orientations were resolved in high-resolution images, indicating the resolution of the racemic rosette mixture into enantiomerically pure domains on the substrate. Our strategy for the formation of metal-containing nanorod arrays, involving well-defined surface-immobilized self-assembled systems as scaffolds, will contribute to the development of templated functional nanoarchitectures via bottom-up approaches.

Adamantane-like cluster complexes of mixed-valent copper-copper and nickel-copper thiolates.

Square-planar copper(II) and nickel(II) derivatives of the cis-dithiolate N(2)S(2) ligand bis(N,N'-2-mercapto-2-methylpropyl)-1,5-diazocyclooctane, (bme*daco)M, nucleate four Cu(I)Cl moieties, forming M(II)(2)Cu(I)(4)S(4) clusters with unusual triply bridging thiolates, mu(3)-SR, in the topological form of adamantane. As determined by X-ray crystallography, the (bme*daco)M (M = Cu or Ni) metallothiolate serves as a bidentate ligand that bridges four Cu(I) ions, utilizing all lone pairs on sulfurs. Further characterization by electrochemical and electronic spectral measurements suggests greater electron delocalization in the all-copper complex as compared to the NiCu heterometallic complex. Mass spectral data imply that the mixed-metal Ni(II)(2)Cu(I)(4)S(4) is more stable toward CuCl loss than Cu(II)(2)Cu(I)(4)S(4), a result that is corroborated by extraction of Cu(I) by 1,2-bis(diphenylphosphino)ethane in the latter but not the former.

A new water-based chemical treatment based on sodium dichloroisocyanurate (DCI) for rubber soles in the footwear industry

A new water-based chemical treatment based on sodium dichloroisocyanurate (DCI) solutions for rubber soles of different natures is reported in this study. Different concentrations (1-5 wt%) of DCI and two rubber formulations (vulcanized styrene-butadiene rubber, R2; thermoplastic rubber, TR) were considered. The effects produced by treatment of the rubber soles with DCI were compared with the standard halogenation method using trichloroisocyanuric acid (TCI) solutions in an organic solvent (ethyl acetate). The effects of chlorination on the rubber surfaces were studied using contact angle measurements, ATR-IR spectroscopy, and scanning electron microscopy. The adhesion strength was obtained from T-peel strength tests on canvas/PUD adhesive/treated rubber joints. The adhesive used throughout this study was a water-based polyurethane dispersion (PUD). The surface treatment with aqueous DCI solutions modified the surface chemistry of both the TR and R2 rubbers, creating C—Cl moieties on the surface and removing the zinc stearate from the R2 rubber surface. The use of a low DCI concentration in water was less effective in modifying the TR rubber, but was sufficient to obtain good T-peel strength values for the R2 rubber joints. On the other hand, heterogeneities and cracks were created on the rubber surface (mainly on the R2 rubber surface), which may contribute to an increase in the mechanical interlocking with the adhesive. A noticeable increase in the T-peel strength and a cohesive failure in the rubber for the joints produced with TR rubber were obtained when the rubber was treated with aqueous DCI solutions. For the canvas/PUD adhesive/chlorinated R2 rubber joint, the failure was located in a thin surface layer on the canvas. Finally, the surface treatment with TCI in ethyl acetate produced a more significant surface modification on both the TR and the R2 rubber, creating deeper roughness on the R2 rubber surface. Consequently, higher peel strength values were obtained using TCI solutions in ethyl acetate. Furthermore, the T-peel strength values were high in all joints produced with TR rubber treated with either TCI solution in ethyl acetate or aqueous DCI solution.

The structure of N-methylbenzothiazole-2-selone dichloride: a novel ‘zipper’ arrangement of T-shaped molecules linked via intermolecular Cl–Cl contacts

The reaction of 1 mole equivalent of sulfuryl chloride with N-methylbenzothiazole-2-selone, mbts, produces the yellow 1:1 addition compound, mbts·Cl 2 ( 1), which exhibits a T-shaped geometry with intermolecular Cl–Cl interactions. These give rise to a novel ‘zipper’ packing arrangement of linear chains of ClSeClClSeCl atoms in the crystalline state. Both T-shaped ClSeCl and linear SeCl⋯Cl moieties can be observed because of this; the latter interaction being essentially ionic rather than charge transfer. FT-Raman studies imply the presence of a green metastable isomer ( 2) of 1. Compound 1 represents the first structurally characterised 1:1 dichloride adduct of the form R 2CSeCl 2.

Chlorination of vulcanized SBR rubber by immersion or brushing in TCI solutions

The effectiveness of the chlorination treatment of synthetic vulcanized styrene-butadiene rubbers is determined by several experimental variables. In this study, trichloroisocyanuric acid (TCI) solutions in butanone have been used as chlorinating agents for a difficult-to-bond vulcanized styrene-butadiene rubber (R2). The influence of the TCI concentration (0.5 and 2 wt% TCI/MEK) was studied and a comparison between the immersion and brushing procedures to apply the chlorinating agent has been carried out. Characterization of the chlorinated surfaces was carried out using contact angle measurements (water, 25°C), ATR-IR spectroscopy, and scanning electron microscopy (SEM). T-peel tests on similarly treated R2 rubber/polyurethane adhesive joints were carried out to quantify adhesion. The chlorination by immersion of R2 rubber with TCI/MEK solutions was less effective than using a brush. The effects of the chlorination were similar using both procedures (creation of roughness, improved wettability, C Cl moieties formation and deposition of TCI particles), but the extent of the modifications was more marked when using a brush. The higher concentration of chlorinating agent allows a higher degree of chlorination. Peel strength values were lower for brush-chlorinated R2 rubber because the migration of wax (which created a weak layer on the rubber surface) from the bulk to the R2 rubber surface was favoured. However, the presence of waxes on the R2 rubber surface still allowed a reasonable level of adhesion due to the predominance of polar moieties.