Kinetic study on the dehydration of tert‐butyl alcohol catalyzed by ion exchange resins

The dehydration of tert‐butyl alcohol (TBA) in the liquid phase was studied by using an ion exchange resin, Amberlyst 15 (A15) in the H⁺ form. Experiments were carried out both in a semi‐batch reactor and in a continuous stirred tank reactor (CSTR) with wet or dry resins. The results with the dry resin in the semi‐batch reactor were different from those with the wet resin due to the swelling of resin in the presence of water. However, the results in CSTR agreed well with those in the semi‐batch reactor using the wet resin. A rate equation that considered the inhibition of water was formulated. The experimental results agreed well with the calculated ones. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 854–859, 1999     

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     

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.     

Photocatalytic Degradation of Ethyl tert‐Butyl Ether in Aqueous Solution Mediated by TiO2 Suspensions: Parameter and Reaction Pathway Investigations

Degradation of ethyl tert‐butyl ether (ETBE) with UV/TiO₂ was studied by solid‐phase microextraction and gas chromatography‐mass spectrometry. The complete removal of 0.1 g L^?1 of ETBE was achieved after 20 h of treatment. Factors such as pH of the system, catalyst and substrate concentration, and the presence of anions influenced the degradation rate. Establishment of the degradation pathway was made possible by a thorough analysis of the reaction mixture, which identified the main intermediate products generated. The possible degradation pathways were proposed and discussed in this research. The attack on the C–H bond in ETBE by ·OH forms an alkyl radical, which consequently produces a peroxyl radical upon reaction with oxygen. Peroxyl radicals react with one another and produce an alkoxy radical. The β‐bond fragmentation of the alkoxy radical produces different intermediates.     

Synthesis and biological activity of novel N‐benzoyl‐N‐tert‐butyl‐N′‐(β‐triphenylgermyl)propionylhydrazines

A series of new N‐benzoyl‐N‐tert‐butyl‐N′‐(β‐triphenylgermyl)propionylhydrazines were synthesized by the condensation reaction of β‐triphenylgermyl propanoic acid with N‐benzoyl‐N‐tert‐butylhydrazines in good yields by using N,N′‐dicyclohexylcorbodiimide as dehydrating agent. These title compounds were evaluated for molting hormone mimicking activity. The results of bioassay showed that the compounds exhibit moderate larvicidal activity, and toxicity assays indicated that the title compounds can induce a premature, abnormal and lethal larval molt. We found that the title compounds possess potential anticancer activities in vitro. Copyright © 2002 John Wiley & Sons, Ltd.     

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.     

tert‐Butyl (6S)‐4‐hydroxy‐6‐isobutyl‐2‐oxo‐1,2,5,6‐tetra­hydropyridine‐1‐carboxyl­ate and tert‐butyl (4R,6S)‐4‐hydroxy‐6‐iso­butyl‐2‐oxopiperidine‐1‐carboxyl­ate

X‐ray studies reveal that tert‐butyl (6S)‐6‐iso­butyl‐2,4‐dioxo­piperidine‐1‐carboxyl­ate occurs in the 4‐enol form, viz. tert‐butyl (6S)‐4‐hydroxy‐6‐iso­butyl‐2‐oxo‐1,2,5,6‐tetra­hydropyri­dine‐1‐carboxyl­ate, C₁₄H₂₃NO₄, when crystals are grown from a mixture of di­chloro­methane and pentane, and has an axial orientation of the iso­butyl side chain at the 6‐position of the piperidine ring. Reduction of the keto functionality leads predominantly to the corresponding β‐hydroxy­lated δ‐lactam, tert‐butyl (4R,6S)‐4‐hydroxy‐6‐iso­butyl‐2‐oxo­piperidine‐1‐car­boxyl­ate, C₁₄H₂₅NO₄, with a cis configuration of the 4‐hydroxy and 6‐iso­butyl groups. The two compounds show similar molecular packing driven by strong O—H⋯O=C hydrogen bonds, leading to infinite chains in the crystal structure.     

Synthesis of tetracyclic system of 2,4‐di(tert‐butyl)‐6,7‐dihydrofuro[2′,3′:3,4]cyclohepta[1,2‐b]indole

For the first time, tetracyclic compounds, namely, furo[2′,3′:3,4]cyclohepta[1,2‐b]indoles were synthesized by recyclization of ortho‐substituted aryldifurylmethanes containing tert‐butyl groups at C5 positions of the furan rings. It was shown that [2‐(benzoylamino)phenyl]bis(5‐tert‐butyl‐2‐furyl)methanes 12 are transformed into tetracycles 15 at room temperature under treatment with POCl₃ in benzene solution containing some drops of water. The reaction proceeds via the intermediate formation of 1‐benzoylamino‐3‐(5‐tert‐butyl‐2‐furyl)‐2‐(4,4‐dimethyl‐3‐oxopentyl)indoles 14 which can be isolated from the reaction mixture. The method is very simple but its application is restricted due to side reactions if electron‐releasing groups are present in 12 . On the other hand, the decrease of electron density on furan ring in the starting compounds (for example, the use of [2‐X‐phenyl]difurylmethanes (where X = tosylamino or hydroxy group) prevents cyclization under the studied reaction conditions. As a result, corresponding ketones are formed as products of recyclization. J. Heterocyclic Chem., (2011).     

Zur Hydrolyse von 2,3‐Dihydro‐1,3‐di‐tert‐butyl‐4,5‐dimethylimidazol‐2‐yliden. Die Kristallstruktur von 1,3‐Di‐tert‐butyl‐4,5‐dimethylimidazoliumhydrogencarbonat

On the Hydrolysis of 2,3‐Dihydro‐1,3‐di‐tert‐butyl‐4,5‐dimethylimidazol‐2‐ylidene. The Crystal Structure of 1,3‐Di‐tert‐butyl‐4,5‐dimethylimidazolium Bicarbonate 1,3‐Di‐tert‐butyl‐4,5‐dimethylimidazolium bicarbonate ( 7 ), formed on the exposure of 2,3‐dihydro‐1,3‐di‐tert‐butyl‐4,5‐dimethylimidazol‐2‐ylidene ( 6 ) towards air, is prepared on the reaction of 6 with ammonium bicarbonate; its crystal structure analysis reveals the presence of dimeric bicarbonate anions linked to each other and to the imidazolium ions with hydrogen bonds.     

Acid Catalyzed tert‐Butylation and Tritylation of 4‐Nitro‐1,2,3‐triazole: Selective Synthesis of 1‐Methyl‐5‐nitro‐1,2,3‐triazole via 1‐tert‐Butyl‐4‐nitro‐1,2,3‐triazole

4‐Nitro‐1,2,3‐triazole was found to react with tert‐butanol in concentrated sulfuric acid to yield 1‐tert‐butyl‐4‐nitro‐1,2,3‐triazole as the only reaction product, whereas tert‐butylation and tritylation of 4‐nitro‐1,2,3‐triazole in presence of catalytic amount of sulfuric acid in benzene was found to provide mixtures of isomeric 1‐ and 2‐alkyl‐4‐nitro‐1,2,3‐triazoles with predominance of N2‐alkylated products. A new methodology for preparation of 1‐alkyl‐5‐nitro‐1,2,3‐triazoles from 1‐tert‐butyl‐4‐nitro‐1,2,3‐triazole via exhaustive alkylation followed by removal of tert‐butyl group from intermediate triazolium salts was demonstrated by the example of preparation of 1‐methyl‐5‐nitro‐1,2,3‐triazole.     

2,4,6‐Tri‐tert‐butylphenyl and 2,4‐di‐tert‐butyl‐6‐methylphenyl groups: Look similar,react differently

The crystal structures of molecules with two phosphaalkene groups have been determined. Differences in the stabilization of the PC π‐bond by the 2,4,6‐tri‐tert‐butylphenyl and 2,4‐di‐tert‐butyl‐6‐methylphenyl groups were observed. It has been found that lithium supermesityl(trimethylsilyl)phosphide could be a very efficient base to remove a proton from acetonitrile.© 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:662–666, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10083     

Reactions of sterically congested 1,6‐ and 1,7‐bis(diazo)alkanes with elemental sulfur and selenium: Formation of cyclohexene, 1,2‐dithiocane, 1,2‐diselenocane,and 1,2,3‐triselenecane derivatives

The reaction of 3,8‐bis(diazo)‐2,2,4,4,7,7,9,9‐octamethyldecane ( 5 ) with elemental selenium in 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) at 130°C yielded 1,2‐di‐tert‐butyl‐3,3,6,6‐tetramethylcyclohexene ( 1 ) (64%) and trans‐3,8‐di‐tert‐butyl‐4,4,7,7‐tetramethyl‐1,2‐diselenocane ( 8 ) (13%), while that of 5 with elemental sulfur in DBU gave trans‐3, 8‐di‐tert‐butyl‐4,4,7,7‐tetramethyl‐1,2‐dithiocane ( 9 ) (77%). The reaction of 3,9‐bis(diazo)‐2,2,4,4,8,8,10,10‐octamethylundecane ( 6 ) with elemental selenium in DBU at 80°C gave a cyclic triselenide, cis‐4,10‐di‐tert‐butyl‐5,5,9,9‐tetramethyl‐1,2,3‐triselenecane ( 11 ), in 15% yield as the only identifiable product. The structures of 9 and 11 were confirmed by X‐ray crystallography. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:351–356, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10046     

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     

Copper(I)‐Catalyzed 3‐Position Methylation of Coumarins by Using Di‐tert‐butyl Peroxide as the Methylation Reagents

The copper‐catalyzed methylation of coumarin by using di‐tert‐butyl peroxide (DTBP) has been described. The reaction provides direct access to a wide range of 3‐methylcoumarins in moderate to good yields. In this procedure, it is noteworthy that DTBP was employed not only as the oxidant, but also as the methyl source.     

Synthesis of poly(tert‐butyl acrylate‐block‐vinyl acetate) copolymers by combining ATRP and RAFT polymerizations

The synthesis of poly(tert‐butyl acrylate‐block‐vinyl acetate) copolymers using a combination of two living radical polymerization techniques, atom transfer radical polymerization (ATRP) and reversible addition‐fragmentation chain transfer (RAFT) polymerization, is reported. The use of two methods is due to the disparity in reactivity of the two monomers, viz. vinyl acetate is difficult to polymerize via ATRP, and a suitable RAFT agent that can control the polymerization of vinyl acetate is typically unable to control the polymerization of tert‐butyl acrylate. Thus, ATRP was performed to make poly(tert‐butyl acrylate) containing a bromine end group. This end group was subsequently substituted with a xanthate moiety. Various spectroscopic methods were used to confirm the substitution. The poly(tert‐butyl acrylate) macro‐RAFT agent was then used to produce (tert‐butyl acrylate‐block‐vinyl acetate). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7200–7206, 2008     

Synthesis of p‐tert‐Butyl‐calix[6] ‐biscrown‐3 via Intramolecular Ring‐closure of 1,4‐Bis (2‐(2‐chloroethoxy) ethoxy) ‐p‐tert‐butyl‐calix[6]arene

With a variation in reaction conditions, 1, 4‐bis (2‐(2‐chloroethoxy)ethoxy)‐calix[6]arene (3) and l,3,5‐tris(2‐(2‐chloroethoxy) ethoxy)‐calix [6] arene (4) or 4 and 4‐chloroethoxyethoxy‐calix[6]crown‐3 (5) were selectively synthesized from p‐tert‐butyl‐calix [6] arene and 2‐(2‐chloroethoxy)ethyltosylate. l,3–4,6‐p‐tert‐butylcalix[6]‐bis‐crown‐3 (6) with (u,u,u,d,d,d) conformation and 1,3–4,5‐p‐tert‐butylcalix[6]‐biscrown‐3 (7) with self‐anchored (u,u, u, u, u, d) conformation were synthesized through an intramolecularly ring‐closing condensation of 1, 4‐bis (2‐(2‐chloroethoxy)ethoxy)‐p‐tert‐butyl‐calix[6]arene (3) in 25% and 15% yield, respectively. Using 5 instead of 3, only 7 was obtained in 65% high yield. 6 and 7 show different complexation properties toward alkali metal and ammonium ions.     

Poly[(cis‐3‐(ethanesulfonyloxy)‐2‐pinanyl methacrylate)‐co‐(tert‐butyl methacrylate)] as an acid‐amplifying photoresist

Synthesis and characteristics of novel copolymers bearing both acid amplifier and acid‐sensitive units are described. The acid amplifier units in the polymer side chains were acidolytically transformed to sulfonic acid residues, leading to the deprotection of the acid‐labile tert‐butyl ester side chains introduced as a comonomer unit. The copolymer was 3.2 times more sensitive than poly(tert‐butyl methacrylate) in the presence of a photoacid generator and, therefore, provides practical applicability for photoimaging.     

Synthesis and complexing properties of double armed diaza‐15‐crown‐5 and diaza‐18‐crown‐6 ethers having 4′‐hydroxy‐3′,5′‐disubstituted benzyl groups

A series of double armed diaza‐15‐crown‐5 ethers (9a ‐ 16a) and diaza‐18‐crown‐6 ethers (9b ‐ 16b) have been prepared by the Mannich reaction of 2,6‐disubstituted phenols with the corresponding N,N'‐dimethoxymethyldiaza‐crown ethers in benzene. The crystal structures of the diaza‐18‐crown‐6 ethers having iso‐propyl (10b) , tert‐butyl (11b) , and mixed methyl and tert‐butyl groups (12b) at positions 3′ and 5′ of the phenolic side arms were determined using X‐ray diffraction methods. Competitive transport by these ligands for sodium, potassium and cesium cations were measured under basic‐source phase and acidic‐receiving phase conditions.     

Novel C60‐Anchored Two‐Armed Poly(tert‐butyl acrylate): Synthesis and Characterization

Summary: A multistep synthetic procedure for preparing novel C₆₀‐anchored two‐armed poly(tert‐butyl acrylate) was developed. First, two‐armed poly(tert‐butyl acrylate) bearing a malonate ester core with well‐controlled molecular weight was synthesized through atom transfer radical polymerization. The effective Bingel reaction between C₆₀ and the well‐defined polymer was then carried out to yield C₆₀‐anchored polymer. GPC, ¹H NMR, and UV‐vis spectroscopy indicated that the C₆₀‐anchored polymer was a monosubstituted and ‘closed’ 6,6‐ring‐bridged methanofullerene derivative.

Schematic of a novel C₆₀‐anchored two‐armed polymer.     

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