Structures, internal rotor potentials, and thermochemical properties for a series of nitrocarbonyls, nitroolefins, corresponding nitrites, and their carbon centered radicals

Structures, enthalpy (Δ(f)H°(298)), entropy (S°(T)), and heat capacity (C(p)(T)) are determined for a series of nitrocarbonyls, nitroolefins, corresponding nitrites, and their carbon centered radicals using the density functional B3LYP and composite CBS-QB3 calculations. Enthalpies of formation (Δ(f)H°(298)) are determined at the B3LYP/6-31G(d,p), B3LYP/6-31+G(2d,2p), and composite CBS-QB3 levels using several work reactions for each species. Entropy (S) and heat capacity (C(p)(T)) values from vibration, translational, and external rotational contributions are calculated using the rigid-rotor-harmonic-oscillator approximation based on the vibration frequencies and structures obtained from the density functional studies. Contribution to Δ(f)H(T), S, and C(p)(T) from the analysis on the internal rotors is included. Recommended values for enthalpies of formation of the most stable conformers of nitroacetone cc(═o)cno2, acetonitrite cc(═o)ono, nitroacetate cc(═o)no2, and acetyl nitrite cc(═o)ono are -51.6 kcal mol(-1), -51.3 kcal mol(-1), -45.4 kcal mol(-1), and -58.2 kcal mol(-1), respectively. The calculated Δ(f)H°(298) for nitroethylene c═cno2 is 7.6 kcal mol(-1) and for vinyl nitrite c═cono is 7.2 kcal mol(-1). We also found an unusual phenomena: an intramolecular transfer reaction (isomerization) with a low barrier (3.6 kcal mol(-1)) in the acetyl nitrite. The NO of the nitrite (R-ONO) in CH(3)C(═O')ONO moves to the C═O' oxygen in a motion of a stretching frequency and then a shift to the carbonyl oxygen (marked as O' for illustration purposes).     

Di‐tert‐butyl ketone hydrazone and di‐tert‐butyl ketone triphenyl­phosphoranyl­idene­hydrazone

Reaction of di‐tert‐butyl ketone with hydrazine hydrate gives di‐tert‐butyl ketone hydrazone, C₉H₂₀N₂, which is dimerized by double hydrogen bonding in the solid state. Further reaction of this compound with dibromo­triphenyl­phospho­rane gives di‐tert‐butyl ketone triphenyl­phosphoranyl­idene­hydrazone, C₂₇H₃₃N₂P, in the structure of which double chains parallel to the c axis are formed through weak C—H⋯π and π–π stacking inter­actions. The hydrazone group is nearly planar in both cases. In the second compound, one of the aromatic rings is nearly coplanar with the hydrazone moiety, indicating possible π‐conjugation.     

Depolymerization kinetics of di(4‐tert‐butyl cyclohexyl) itaconate and Mark‐Houwink‐Kuhn‐Sakurada parameters of di(4‐tert‐butyl cyclohexyl) itaconate and di‐n‐butyl itaconate

Multipulse pulsed laser polymerization coupled with size exclusion chromatography (MP‐PLP‐SEC) has been employed to study the depropagation kinetics of the sterically demanding 1,1‐disubstituted monomer di(4‐tert‐butylcyclohexyl) itaconate (DBCHI). The effective rate coefficient of propagation, k, was determined for a solution of monomer in anisole at concentrations, c, 0.72 and 0.88 mol L^?1 in the temperature range 0 ≤ T ≤ 70 °C. The resulting Arrhenius plot (i.e., ln k vs. 1/RT) displayed a subtle curvature in the higher temperature regime and was analyzed in the linear part to yield the activation parameters of the forward reaction. In the temperature region where no depropagation was observed (0 ≤ T ≤ 50 °C), the following Arrhenius parameters for k_p were obtained (DBCHI, E_p = 35.5 ± 1.2 kJ mol^?1, ln A_p = 14.8 ± 0.5 L mol^?1 s^?1). In addition, the k data was analyzed in the depropagatation regime for DBCHI, resulting in estimates for the associated entropy (?ΔS = 150 J mol^?1 K^?1) of polymerization. With decreasing monomer concentration and increasing temperature, it is increasingly more difficult to obtain well structured molecular weight distributions. The Mark Houwink Kuhn Sakurada (MHKS) parameters for di‐n‐butyl itaconate (DBI) and DBCHI were determined using a triple detection GPC system incorporating online viscometry and multi‐angle laser light scattering in THF at 40 °C. The MHKS for poly‐DBI and poly‐DBCHI in the molecular weight range 35–256 kDa and 36.5–250 kDa, respectively, were determined to be K_DBI = 24.9 (10³ mL g^?1), α_DBI = 0.58, K_DBCHI = 12.8 (10³ mL g^?1), and α_DBCHI = 0.63. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1931–1943, 2007     

Favoured conformations of methyl isopropyl,ethyl isopropyl,methyl tert‐butyl,and ethyl tert‐butyl 2‐(triphenylphosphoranylidene)malonate

The conformations of organic compounds determined in the solid state are important because they can be compared with those in solution and/or from theoretical calculations. In this work, the crystal and molecular structures of four closely related diesters, namely methyl isopropyl 2‐(triphenylphosphoranylidene)malonate, C₂₅H₂₅O₄P, ethyl isopropyl 2‐(triphenylphosphoranylidene)malonate, C₂₆H₂₇O₄P, methyl tert‐butyl 2‐(triphenylphosphoranylidene)malonate, C₂₆H₂₇O₄P, and ethyl tert‐butyl 2‐(triphenylphosphoranylidene)malonate, C₂₇H₂₉O₄P, have been analysed as a preliminary step for such comparative studies. As a result of extensive electronic delocalization, as well as intra‐ and intermolecular interactions, a remarkably similar pattern of preferred conformations in the crystal structures results, viz. a syn–anti conformation of the acyl groups with respect to the P atom, with the bulkier alkoxy groups oriented towards the P atom. The crystal structures are controlled by nonconventional hydrogen‐bonding and intramolecular interactions between cationoid P and acyl and alkoxy O atoms in syn positions.     

Synthesis and solution properties of star‐shaped poly(tert‐butyl acrylate)

A series of star polymers consisting of poly(tert‐butyl acrylate) arms and an ethyleneglycol dimethacrylate (EGDMA) microgel core were synthesized using anionic polymerization. The effect of various parameters (precursor length, ratio [[EGDMA]/[Initiator], reaction time, and overall concentrations) on the average number of arms was investigated. Molecular weights were determined using GPC coupled with an online viscometer and MALLS. The exponents for the relation between intrinsic viscosity or radius of gyration and molecular weight, respectively, are extremely low, indicating that the dimensions of the star polymers only slightly increase with the number of arms. After a certain number of arms is reached the intrinsic viscosity even decreases with molecular weight. Computer simulations for star polymers were carried out where the radius of gyration was calculated as a function of the number of arms. The results are in good agreement with the experimental data.     

Mechanical properties of gradient copolymers of styrene and n‐butyl acrylate

The mechanical properties of linear and V‐shaped compositional gradient copolymer of styrene and n‐butyl acrylate with composition of around 55 wt % styrene were investigated by comparing with their block copolymer counterparts. Compared with their block copolymer counterparts, the gradient copolymers showed lower elastic modulus, much larger elongation at break, and similar ultimate tensile strength at room temperature. This performance could be ascribed to that the local moduli continuously change from the hardest nanodomains to the softest nanodomains in the gradient copolymer, which alleviates the stress concentration during tensile test. Compared with the V‐shaped gradient (VG) copolymer, the linear gradient copolymer showed much higher elastic modulus but lower elongation at break. The mechanical properties of the gradient copolymers were more sensitive to the change in temperature from 9 °C to 75 °C. With recovery temperature increased from 10 °C to 60 °C, the strain recovery of VG copolymer would change steadily from 40% to 99%. However, the elastic recovery of linear and triblock copolymer was poor even at 60 °C. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 860–868     

A di‐tert‐butyl acrylate monomer for controlled radical photopolymerization

A new di‐tert‐butyl acrylate (diTBA) monomer for controlled radical polymerization is reported. This monomer complements the classical use of tert‐butyl acrylate (TBA) for synthesis of poly(acrylic acid) by increasing the density of carboxylic acids per repeat unit, while also increasing the flexibility of the carboxylic acid side‐chains. The monomer is well behaved under Cu(II)‐mediated photoinduced controlled radical polymerization and delivers polymers with excellent chain‐end fidelity at high monomer conversions. Importantly, this new diTBA monomer readily copolymerizes with TBA to further the potential for applications in areas such as dispersing agents and adsorbents. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 801–807     

Laboratory studies of the ·OH‐initiated photooxidation of ethyl‐n‐butyl ether and di‐n‐butyl ether

Oxygenated compounds such as ethers and alcohols are used as gasoline additives and industrial solvents. However, despite their widespread use, the atmospheric reaction mechanisms of some of these compounds are unknown. This study examines the ^·OH‐initiated gas‐phase removal mechanisms of ethyl‐n‐butyl ether (ENBE) and di‐n‐butyl ether (DNBE) utilizing gas chromatography–mass spectrometry techniques. The primary products and molar yields from the hydroxyl‐radical–initiated photooxidation of ENBE in the presence of nitric oxide were acetaldehyde (0.173 ± 0.012), ethyl formate (0.219 ± 0.033), butyraldehyde (0.076 ± 0.004), butyl formate (0.241 ± 0.009), butyl acetate (0.032 ± 0.001), and ethyl butyrate (0.0044 ± 0.0006). From the calculated molar yields, approximately 45.5% of the reacted carbon were recovered. The primary products and molar yields from the DNBE and hydroxyl radical reaction in the presence of nitric oxide were propionaldehyde (0.379 ± 0.022), butyraldehyde (0.119 ± 0.003), butyl formate (0.410 ± 0.009), and butyl butyrate (0.019 ± 0.001). Approximately 47.7% of the reacted DNBE were recovered. The chemical mechanisms are presented to explain the formation of these products. In addition, the importance of the isomerization and nitrate/nitrite formation pathways in the reactions of large ethers are discussed. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 328–341, 2001     

Poly(butylene terephthalate‐co‐5‐tert‐butyl isophthalate) copolyesters: Synthesis,characterization, and properties

A series of poly(butylene terephthalate) copolyesters containing 5‐tert‐butyl isophthalate units up to 50 mol %, as well as the homopolyester entirely made of these units, were prepared by polycondensation from a melt. The microstructure of the copolymers was determined by NMR to be random for the whole range of compositions. The effect exerted by the 5‐tert‐butyl isophthalate units on thermal, tensile, and gas transport properties was evaluated. Both the melting temperature (T_m) and crystallinity were found to decrease steadily with copolymerization, whereas the glass‐transition temperature (T_g) increased and the polyesters became more brittle. Permeability and solubility slightly increased with the content in substituted isophthalic units, whereas the diffusion coefficient remained practically constant. For the homopolyester poly(5‐tert‐butyl isophthalate), all these properties were found to deviate significantly from the general trend displayed by copolyesters, suggesting that a different structure in the solid state is likely adopted in this case. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 92–100, 2005     

Synthesis,characterization, and rheological properties of hybrid titanium star‐shaped poly(n‐butyl acrylate)

The synthesis of hybrid star‐shaped polymers was carried out by atom transfer radical polymerization of n‐butyl acrylate from a well‐defined multifunctional titanium‐oxo‐cluster initiator. Conditions were identified to prevent possible side reactions among monomer, polymer, and the titanium‐oxo‐cluster ligands. Polymerizations provided linear first‐order kinetics and the evolution of the experimental molecular weight is also linear with the conversion. ¹H DOSY NMR and cleavage of the polymeric branches from the multifunctional initiator by hydrolysis were used to (i) prove the star‐shaped structure of the polymer, and (ii) demonstrate that the shoulder observed on size exclusion chromatograms is not due to a noncontrolled polymerization but to ungrafting of polymeric branches during analysis. Rheological properties of the hybrid star‐shaped poly(n‐butyl acrylate) were studied in the linear regime and show that the Ti‐oxo‐cluster not only increases significantly the viscosity of the polymer relative to its ungrafted arm but has a rheological signature which is qualitatively different from that of stars with organic cores suggesting that the Ti cluster reduces significantly the molecular mobility of the star. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Atmospheric chemistry of isopropyl formate and tert‐butyl formate

Formates are produced in the atmosphere as a result of the oxidation of a number of species, notably dialkyl ethers and vinyl ethers. This work describes experiments to define the oxidation mechanisms of isopropyl formate, HC(O)OCH(CH₃)₂, and tert‐butyl formate, HC(O)OC(CH₃)₃. Product distributions are reported from both Cl‐ and OH‐initiated oxidation, and reaction mechanisms are proposed to account for the observed products. The proposed mechanisms include examples of the α‐ester rearrangement reaction, novel isomerization pathways, and chemically activated intermediates. The atmospheric oxidation of isopropyl formate by OH radicals gives the following products (molar yields): acetic formic anhydride (43%), acetone (43%), and HCOOH (15–20%). The OH radical initiated oxidation of tert‐butyl formate gives acetone, formaldehyde, and CO₂ as major products. IR absorption cross sections were derived for two acylperoxy nitrates derived from the title compounds. Rate coefficients are derived for the kinetics of the reactions of isopropyl formate with OH (2.4 ± 0.6) × 10^?12, and with Cl (1.75 ± 0.35) × 10^?11, and for tert‐butyl formate with Cl (1.45 ± 0.30) × 10^?11 cm³ molecule^?1 s^?1. Simple group additivity rules fail to explain the observed distribution of sites of H‐atom abstraction for simple formates. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 479–498, 2010     

Viscoelastic and damping characteristics of poly(n‐butyl acrylate)‐poly(n‐butyl methacrylate) semi‐IPN latex films

This article reports the synthesis, characterization, and damping characteristics of semi‐interpenetrating (semi‐IPN) latex systems composed of poly n‐butyl acrylate (PBA) core and poly n‐butyl methacrylate (PBMA) shell. The IPN's were prepared by seeded emulsion polymerization using crosslinked PBA seeds with varying crosslinker (m‐diisopropenyl benzene) concentration. The polymer weight ratio in the first and second stage polymerization is maintained at 1:1 in all the cases. The particle size determined by dynamic light scattering shows a decrease in the shell thickness with increasing crosslinker concentration of the seed. The mechanical properties, like Shore A hardness of the films, increased from 18 to 65 when the crosslinker concentration is increased from 0 to 4.8 mol%. The dynamic mechanical studies show that the modulus value of the IPN's is below that of non‐crosslinked films, and the value depends upon the crosslink density of the seed. Mechanical models, such as the Kerner's model and the Takayanagi's model, were used to explain the variation in the dynamic mechanical properties with the degree of seed crosslinking. The study indicates lower bound (rubbery) behavior for the films with lightly crosslinked cores. The study also shows that, at lower crosslinker concentration enhanced phase separation and better damping properties are achieved but at higher cross linker concentration (>2 mol%) greater interpenetration of the shell monomer to the cores takes place and tough films, with reduced damping properties are formed. Copyright © 2007 John Wiley & Sons, Ltd.     

Simultaneous measurement of methyl tert‐butyl ether and tert‐butyl alcohol in human serum by headspace solid‐phase microextraction gas chromatography–mass spectrometry

The abundant production of methyl tert‐butyl ether (MTBE) and its widespread use have led to an increase in the potential for human exposure. This work described a simple, fast, sensitive, reliable and low‐cost method for the simultaneous measurement of MTBE and its metabolite, tert‐butyl alcohol (TBA) in human serum by headspace solid‐phase microextraction gas chromatography–mass spectrometry. Extraction conditions were optimized and 40 °C, 10 min, 250 rpm and 0.3 g NaCl for a 1 mL sample were the optimal conditions. This method showed good analytical performance in terms of sensitivity with limits of detection in serum (1 mL) of 0.03 µg/L for MTBE and 0.05 µg/L for TBA, accuracy (mean recovery values) from 75.8% to 85.8%, precision (relative standard deviations) <10% and sample stability (biodegradation) <10% after 28 days. A verification experiment proved the reproducibility and stability of this method as well. Finally the method was used to detect 212 specimens, and the internal dose levels for MTBE in human serum were presented in China. Copyright © 2015 John Wiley & Sons, Ltd.     

Order in amorphous di‐n‐alkyl itaconate polymers,copolymers, and blends

The presence of a main‐chain correlation distance (d_II) in the poly(di‐n‐alkyl itaconate)s was confirmed with small‐angle X‐ray scattering/wide‐angle X‐ray scattering measurements taken over the temperature range of 293–478 K. Data for a series of alkyl acrylate polymers were also obtained for comparison. The intensity of the itaconate d_II peak was significant and indicated a greater level of nanophase formation than in analogous systems. In the lower members of the series, nanophase formation appeared to be further enhanced in the temperature range above the glass‐transition temperature (T_g). This was ascribed to the rapidly increasing main‐chain mobility in this region. Macroscopically phase‐separated itaconate blends displayed the individual d_II nanospacings of each homopolymer component. Copolymers, on the other hand, showed more interesting behavior. Poly(methyl‐co‐di‐n‐butyl itaconate) followed an average behavior in which the d_II spacing and T_g changed progressively with the comonomer content. In contrast, the side‐chain pairing in poly(methyl‐co‐di‐n‐octyl itaconate) generated d_II spacings characteristic of separate methyl and octyl nanodomains. The observation of the dioctyl nanodomains, along with the dioctyl side‐chain lower T_g relaxation event, confirmed the concept of independent side‐chain‐domain relaxation in these polymers. The temperature behavior of the poly(methyl‐co‐di‐n‐octyl itaconate) small‐angle X‐ray scattering profiles and scattering correlation lengths indicated that the two nanodomains were not completely structurally independent. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4000–4016, 2004     

Synthesis and properties of photoalignable aromatic polyesters containing phenylenediacrylate units in their backbones and n‐alkyl moieties in their side groups

A series of poly[oxy(4‐n‐alkyl‐3,5‐benzoate)oxy‐1,4‐phenylenediacryloyl]s (PPDA‐CnBZ polymers) with high molecular weights was synthesized. These polymers exhibit excellent solubility in some common organic solvents and produce good quality films using conventional spin‐casting and drying processes. The polymers are thermally stable up to 357–362 °C in a nitrogen atmosphere; their glass transition temperatures are greater than 121 °C. The photoreactions and photoalignments of the polymers were investigated using ultraviolet‐visible and infrared spectroscopy, and their liquid crystal (LC) alignment properties were examined. The phenylenediacrylate (PDA) chromophores in the polyesters were found to mainly undergo photocyclization upon ultraviolet light irradiation. Irradiation of the polyester films with linearly polarized ultraviolet light (LPUVL) induces preferential orientation of the polymer main chains, while the unreacted PDA chromophores are aligned along the direction perpendicular to the electric vector of the LPUVL. All the films irradiated with LPUVL were found to align LCs in a direction perpendicular to the electric vector of the LPUVL. Moreover, these LC alignments persisted even on irradiated films annealed at temperatures up to 210 °C, which is much higher than the glass transition temperatures of the polyesters. These LC alignment characteristics are due to the anisotropic interactions of the LC molecules with the oriented polymer chains and with the unreacted PDA chromophores. LC alignments on the polyester film surfaces have homeotropic to homogeneous characteristics, depending on the length of the n‐alkyl side group, providing strong evidence that the n‐alkyl side groups of the polyesters play a critical role in determining the pretilt angles of the LCs. The LC pretilt angles were also found to be influenced by the thermal annealing history of the irradiated films. In summary, the excellent properties of the PPDA‐CnBZ polymers make them promising candidate materials for use as LC alignment layers in advanced LC display devices. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1322–1334, 2004     

Synthesis of n‐alkyl methacrylate polymers with pendant carbazole moieties and their derivatives

New methacrylate monomers with carbazole moieties as pendant groups were synthesized by multistep syntheses starting from carbazoles with biphenyl substituents in the aromatic ring. The corresponding polymers were prepared using a free‐radical polymerization. The novel polymers contain N‐alkylated carbazoles mono‐ or bi‐substituted with biphenyl groups in the aromatic ring. N‐alkyl chains in polymers vary by length and structure. All new polymers were synthesized to evaluate the structural changes in terms of their effect on the energy profile, thermal, dielectric, and photophysical properties when compared to the parent polymer poly(2‐(9H‐carbazol‐9‐yl)ethyl methacrylate). According to the obtained results, these compounds may be well suited for memory resistor devices. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 70–76     

Rate constants for the reactions of OH radicals and Cl atoms with Di‐n‐Propyl ether and Di‐n‐Butyl ether and their deuterated analogs

Using relative rate methods, rate constants for the gas‐phase reactions of OH radicals and Cl atoms with di‐n‐propyl ether, di‐n‐propyl ether‐d₁₄, di‐n‐butyl ether and di‐n‐butyl ether‐d₁₈ have been measured at 296 ± 2 K and atmospheric pressure of air. The rate constants obtained (in cm³ molecule⁻¹ s⁻¹ units) were: OH radical reactions, di‐n‐propyl ether, (2.18 ± 0.17) × 10⁻¹¹; di‐n‐propyl ether‐d₁₄, (1.13 ± 0.06) × 10⁻¹¹; di‐n‐butyl ether, (3.30 ± 0.25) × 10⁻¹¹; and di‐n‐butyl ether‐d₁₈, (1.49 ± 0.12) × 10⁻¹¹; Cl atom reactions, di‐n‐propyl ether, (3.83 ± 0.05) × 10⁻¹⁰; di‐n‐propyl ether‐d₁₄, (2.84 ± 0.31) × 10⁻¹⁰; di‐n‐butyl ether, (5.15 ± 0.05) × 10⁻¹⁰; and di‐n‐butyl ether‐d₁₈, (4.03 ± 0.06) × 10⁻¹⁰. The rate constants for the di‐n‐propyl ether and di‐n‐butyl ether reactions are in agreement with literature data, and the deuterium isotope effects are consistent with H‐atom abstraction being the rate‐determining steps for both the OH radical and Cl atom reactions. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 425–431, 1999     

Sulfobetaine zwitterionomers based on n‐butyl acrylate and 2‐ethoxyethyl acrylate: Physical properties

New materials with potential applications for adhesives and coatings, based on copolymers containing zwitterionic pendent groups, were investigated. n‐Butyl acrylate and 2‐ethoxyethyl acrylate were copolymerized with a series of five zwitterionic sulfobetaine monomers (SBMs). The structures of the SBMs were varied systematically in terms of (1) intercharge spacing in the zwitterionic moiety and (2) substituent bulkiness at the quaternary ammonium functionality. The effect of varying the sulfobetaine content and structure in the copolymers was investigated, with an emphasis on ion aggregation behavior and physical properties, with dynamic mechanical analysis. The zwitterionomers exhibited the expected biphasic morphology, with the appearance of an ion‐rich glass‐transition temperature. An increase in the storage modulus was observed with increasing SBM content in the rubbery and terminal regions, suggesting an increased degree of ionic crosslinking in the rubbery region and decreased chain mobility in the flow region. Intercharge spacing variation in the sulfobetaine moiety did not have a significant effect on the modulus–temperature curves, contrary to our expectations. Increases in the modulus were much less pronounced for the bulkier SBMs than for the other monomers, possibly because of hindered aggregation of the sulfobetaine moieties. Likewise, matrix polarity had a greater influence on the physical properties of these materials than intercharge separation in the SBMs. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2303–2312, 2002     

Phosphorylation of N‐iso‐propyl‐ and N‐tert‐butylpyrroles with phosphorus(III) halides

The investigation concerns the effect of a bulky substituent at the pyrrole nitrogen atom on the orientation and regioselectivity of pyrrole phosphorylation with phosphorus(III) halides. As shown, phosphorylation of N‐iso‐propylpyrrole with phosphorus tribromide or trichloride proceeds nonregioselectively at positions 2 and 3 but it is followed by the 2 → 3 migration of the dihalogenophosphine group which quantitatively yields the 3‐isomer. N‐tert‐butylpyrrole is regioselectively phosphorylated with halogenophosphines at position 3. The tert‐butyl substituent at the nitrogen atom does not preclude the binding of even two or three pyrrolyl residues to the phosphorus atom. The key compounds, 3‐pyrrolyldihalogenophosphines, were isolated in a pure state, characterized and used to obtain a number of stable phosphorus(V) derivatives. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:599–604, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20158     

Kinetics of liquid phase synthesis of ethyl tert‐butyl ether from tert‐butyl alcohol and ethanol catalyzed by β‐zeolite supported on monolith

This paper compared the performance of β‐zeolite and Amberlyst‐15 catalysts on a liquid phase synthesis of ethyl tert‐butyl ether (ETBE) from ethanol (EtOH) and tert‐butyl alcohol (TBA) β‐Zeolite was synthesized and deposited on monolith support. Its structure was confirmed by an XRD measurement and its composition was analyzed by an XRF measurement. It was found that even though the catalytic activity of β‐zeolite was lower than that of Amberlyst‐15, the selectivity of ETBE was much higher than that of Amberlyst‐15, resulting in almost the same level of ETBE yield. The dehydration of TBA to isobutene (IB) was the major side reaction. The kinetic study of the reaction catalyzed by β‐zeolite supported on monolith was carried out by using a semibatch reactor. The effect of external mass transfer was investigated by varying stirring speeds. The activity‐based rate expressions were developed taking into account of water inhibition. Three temperature levels of 323, 333, and 343 K were performed in the study to obtain the parameters in the Arrhenius's equation and the Van't Hoff's equation. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 292–299, 2002