40921-86-6

Basic information

• Product Name: Polyisobutane
• Synonyms: Polyisobutane
• CAS NO: 40921-86-6
• Molecular Formula: C4H10
• Molecular Weight: 58.12
• Mol File: 40921-86-6.mol
• Article Data: 448

Chemical Properties

• Appearance: /
• CAS DataBase Reference: Polyisobutane(CAS DataBase Reference)
• NIST Chemistry Reference: Polyisobutane(40921-86-6)
• EPA Substance Registry System: Polyisobutane(40921-86-6)

Safety Data

• Hazardous Substances Data: 40921-86-6(Hazardous Substances Data)

Upstream product

• 563-80-4 3-methyl-butan-2-one 
• 677-22-5 tert-butylmagnesium chloride 
• 253185-03-4 tert-butylbenzene 
• 2229-07-4 methyl radical 
• 74-98-6 propane 
• 2465-56-7 methylene 
• 74-85-1 ethene 
• 110-54-3 hexane 
• 142-82-5 n-heptane 
• 513-38-2 Isobutyl iodide 
• 101082-11-5 3-tert-butyl-2,2-dimethyl-nonan-3-ol 
• 585-34-2 3-tert-butylphenyol 
• 630-19-3 pivalaldehyde 
• 78-84-2 isobutyraldehyde 

Downstream Products

• 35432-36-1 2-methylpropane-1-sulfonyl chloride 
• 187737-37-7 propene 
• 4749-31-9 1,1,1,2,3-pentachloro-2-methyl-propane 
• 98-51-1 4-tert-butyltoluene 
• 1075-38-3 m-t-butyltoluene 
• 46030-99-3 4,7-dimethylazulene 
• 676-55-1 methane-d2 
• 5505-49-7 ethane-d 
• 5177-75-3 ethane-1,1-d2 
• 1688-17-1 1-chloro-2,2-dimethyl-1-phenylpropane 
• 253185-03-4 tert-butylbenzene 
• 13183-68-1 2-methylpropane-2-d1 
• 75-28-5 tert-Butyl radical 
• 5674-02-2 2-methylpropylmagnesium chloride 

Relevant articles and documents

Hydrogenolysis of Alkanes. Part 4. - Hydrogenolysis of Propane, n-Butane and Isobutane over Pt/Al2O3 and Pt-Re/Al2O3 Catalysts

The hydrogenolysis of propane, n-butane and isobutane on Pt/Al2O3 (0.3 and 0.6 percent Pt) and on Pt-Re/Al2O3 (0.3 percent Pt, 0.3 percent Re) has been investigated by a thermal cycling technique that permits evaluation of initial rates of deactivation and of consequential changes in product distributions.Less deactivation is found with propane than with the butanes; with n-butane on Pt/Al2O3 catalysts, two types of sites are apparent, one of which, having a higher probability of giving central C-C bond fission, is selectively deactivated.However, the relative chances of desorption and of further hydrogenolysis of the adsorbed intermediates are the same at both types of site.With the Pt-Re/Al2O3 catalyst, further bond-breaking in the adsorbed species formed from all three alkanes is relatively more favoured than with the Pt/Al2O3 catalysts, and with n-butane the chance of central bond-fission is enhanced.No changes in product distribution result from initial deactivation, which is comparable to that found with Pt/Al2O3 catalysts.Isomerisation of n-butane is slight (3 percent) on all three catalysts.Multiply adsorbed species are suggested as possible intermediates, and differences in product selectivities are attributed chiefly to variations in electron density at the active site.

In situ study of the interaction between tert-butyl chloride and aluminum activated with liquid in-ga eutectic

The interaction between tert-butyl chloride and activated aluminum was studied by attenuated total reflectance Fourier transform infrared spectroscopy near room temperature (18-25°C). A long induc- tion period of ?240-260 min was observed. The AlCl4- ionic aluminum chloride complexes [AlnCl3n+1]-(n = 1, 2) and the molecular species AlCl3 were identified at the activated aluminum/tert-butyl chloride interface during the reaction. The formation of the ion in the liquid medium and the presence of the same ion and a molecular AlCl3 -tert-butyl chloride complex in the resinous products of the reaction were confirmed by 27Al NMR spectroscopy. The reaction products were analyzed qualitatively by GC/MS. The reactivities of activated aluminum and anhydrous aluminum chloride toward tert-butyl chloride under the same conditions were compared. A distinctive feature of the interaction activated aluminum and tert-butyl chloride is the dominant formation of the AlCl4 -ion. By contrast, the interaction between aluminum chloride and tert-butyl chloride yields the polynuclear ion and,Al2Cl7 - likely,Al3Cl10-. Pleiades Publishing, Ltd., 2010.

The Mechanism of the Reaction between Silyl Radicals and Chloroethylenes: A Case Study of the Et3Si-C2Cl4 Reaction

The photolysis and radiolysis of C2Cl4 solutions in Et3SiH were studied at 298 K.The main products, Et3SiCl and C2Cl3H, are formed in equal yields and via a free radical chain mechanism, as indicated by the high quantum yields (ca.500) and G values (ca.1600).The reactions C2Cl3+Et3SiH->C2Cl3H+Et3Si (3) and Et3Si+C2Cl4->Et3SiCl+C2Cl3 (4) constitute the chain propagation step.Competitive studies yield k4/k11 of 0.18+/-0.01 (2?) where Et3Si+t-BuCl->Et3SiCl+t-Bu (11).The mechanistic implications and consequences of the observation that the reaction of Et3Si radicals with C2Cl4 results almost exclusively in Cl transfer rather than addition are discussed, and the conclusions are generalized for similar reactions of other chloroethylenes.

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A highly active solid superacid catalyst for n-butane isomerization: Persulfate modified Al2O3-ZrO2

A new solid superacid catalyst of persulfate modified Al2O3ZrO2 has been prepared for the first time; it displays extraordinarily high catalytic activity and stability for the isomerization of n-butane.

Hydrogen Activation and Hydrogenolysis Facilitated by Late-Transition-Metal-Aluminum Heterobimetallic Complexes

Previously reported heterobimetallic rhodium-aluminum and iridium-aluminum alkyl complexes are shown to activate hydrogen, generating the corresponding alkane. Kinetic data indicate a mechanistic difference between the iridium- A nd rhodium-based systems. In both cases the transition metal is an active participant in the release of alkane from the aluminum center. For iridium-aluminum species, experimental mechanistic data suggest that multiple pathways occur concomitantly with each other: One being the oxidative addition of hydrogen followed by proton transfer resulting in alkane generation. Computational data indicate a reasonable barrier to formation of an iridium dihydride intermediate observed experimentally. In the case of the rhodium-aluminum species, hydrides are not observed spectroscopically, though a reasonable barrier to formation of this thermodynamically unstable species has been calculated. Alternative mechanistic possibilities are discussed and explored computationally. Cooperative hydrogenolysis mechanisms are computed to be energetically unfeasible for both metal centers.

Skeletal isomerization of n-pentane in the presence of an AlCl 3-based ionic liquid

The skeletal isomerization of n-pentane in the presence of a trimethylamine hydrochloride-aluminum chloride ionic liquid has been studied at 20°C. It has been found that the catalytic activity of the ionic liquid in n-pentane isomerization increases with an increase in the trimethylamine hydrochloride: aluminum chloride molar ratio. The optimum ratio of the catalyst complex components at the highest yields of the desired isoparaffins attained has been determined. The catalytic activity of the ionic liquid increased when a copper salt was added. The maximum total yield of isoparaffins is achieved with copper(II) chloride as an activating additive for the ionic liquid, whereas the maximum yield of isopentane is attained when copper(II) sulfate is introduced.

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The reinvestigation of the kinetics of the metathesis reactions t-C 4H9?+ HBr (HI) → i-C 4H10+ Br?(I?) and of the t-C4H9?free radical thermochemistry

A reinvestigation of the absolute rate constant of the metathesis reactions t-C4H9?+ HBr → i-C4H 10+ Br?(1) and t-C4H9 ?+ HI → i-C4H10+ I ?(2) was performed thanks to a recently developed apparatus consisting of a Knudsen reactor coupled to detection based on single-photon (VUV) photoionization mass spectrometry (SPIMS). It enables the generation of thermalized hydrocarbon free radicals owing to a source upstream of and external to the Knudsen reactor. The following Arrhenius expressions were obtained: k1= 5.6(±1.4) × 10-12exp(-6.76(±0.94)/ (RT)) and k2= 2.0(±0.6) × 10-11exp(-8. 48(±0.94)/(RT)) with R = 8.314 J mol-1K-1over the range 293 to 623 K. The mass balance of the reaction system based on closed shell product detection (CSPD) was checked in order to ensure the accuracy of the used reaction mechanism and as an independent check of k1and k2The wall-loss rate constants of the t-butyl free radical, kwC4H9 were measured and found to be low compared with the corresponding escape rate constant, keC 4H9for effusion of t-C4H9 ?out of the Knudsen reactor. On the basis of the present results, the free radical standard heat of formation Δ fH298°t-C4H9?44.3 ± 1.7 kJ mol-1was obtained when combined with the kinetics of the inverse halogenation reaction taken from the literature and using S298° (t-C4H9?) = 322.2 J K-1mol -1following a "Third Law" evaluation method. The standard enthalpy for t-butyl free radical is consistent for both the bromination and iodination reactions within the statduncertainties.

Kinetics of the Reaction of Alkyl Radicals with HBr and DBr

Time-resolved resonance fluorescence detection of Br atom appearance following laser flash photolysis of RI (R = CH3, CD3, C2H5, t-C4H9) or Cl2/RH (R = CH3, C2H5) has been employed to study the kinetics of the reactions CH3 + HBr (1), CD3 + HBr (2), CH3 + DBr (3), C2H5+ HBr (4), C2H5 + DBr (5), t-C4H9 + HBr (6), and t-C4H9 + DBr (7) as a function of temperature (257-430 K) and pressure (10-300 Torr of N2).The rates of all reactions are found to increase with decreasing temperature; i.e., activation energies are negative, and 298 K rate coefficients for reactions 1 and 3-7 are found to be significantly faster than previously thought.Arrhenius expressions for reactions 1, 3, 4, and 6 in units of 10-12 cm3 molecule-1 s-1 are k1 = (1.36 +/- 0.10) exp, k3 = (1.07 +/- 0.17) exp, k4 = (1.33 +/- 0.33) exp, and k6 = (1.07 +/- 0.34) exp; errors are 2? and represent precision only.Normal kinetic isotope effects are observed (kHBr > kDBr), although the ratio kHBr/kDBr decreases in magnitude with decreasing activation energy; i.e., kHBr/kDBr is largest for R = CH3 and smallest for R = t-C4H9.Combining our results with the best available kinetic data for the reverse reactions (Br + RH) yields the following 298 K alkyl radical heats of formation in units of kcal mol-1: CH3, 35.3 +/- 0.6; C2H5, 29.1 +/- 0.6; t-C4H9, 12.1 +/- 0.8; errors are 2? and represent estimates of absolute accuracy.

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Laser Flash Photolysis Study of the Br + i-C4H10 HBr + t-C4H9 Reaction. Heat of Formation of t-C4H9

The heat of formation of the tert-butyl radical has been determined in two independent ways using laser flash photolysis coupled with detection of Br by resonance fluorescence.The t-C4H9 + HBr reaction was studied by monitoring the rise of the Br product at room temperature following photolysis of (t-C4H9)2N2 at 351 nm.Combination of the rate constant with k(Br+i-C4H10) gives ΔHf,298(t-C4H9) = 50.9 +/- 3.5 kJ mol-1.The measured value of k(t-C4H9+HBr) ((3.2 +/- 1.0) x 10-11 cm3 molecule-1 s-1) is in reasonable agreement with the measurements of Russell et al. and of Richards et al.Equilibration in the reaction system Br + i-C4H10 HBr + t-C4H9 was studied by generating Br by photolysis of CF2Br2 at 248 nm in the presence of i-C4H10 and HBr and observing the relaxation of .These experiments were conducted at 573 and 641 K.The measurements yield data for both forward and reverse rate constants, for the equilibrium constant, and hence for ΔHf,298(t-C4H9), giving values of 44.2 +/- 4.0 and 48.1 +/- 4.0 kJ mol-1 at the respective temperatures.Combination of the three independent estimates gives ΔHf,298(t-C4H9) = 47.3 +/- 3.5 kJ mol-1.The values for k(t-C4H9+HBr) at these elevated temperatures agree with the data of Russell et al. and demonstrate a negative temperature dependence in the rate constant.

On the superacidity of sulfated zirconia catalysts for low-temperature isomerization of butane

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Conversion of n-Heptane, n-Butane, and Their Mixtures on Catalytic Systems Al2O3/WO 42– ?ZrO2 and HMOR/WO 42– ?ZrO2

The conversion of n-C7H16, n-C4H10 and mixtures of C7H16: n-C4H10 = 1: 0.3 on the composite catalysts Al2O3/WO42– ?ZrO2 (A-WZ) and HMOR/ WO42– ? ZrO2 (M-WZ) at atmospheric pressure, H2/hydrocarbon = 3 and temperatures of 140°C-200°C was studied. A mixture of C7H16: n-C4H10 on M-WZ with high selectivity was converted into C5–C6 isomers. Systems, e.g., M-WZ can be promising catalysts for the joint processing of associated petroleum gas and gasoline into ecologically clean high-octane gasolines without aromatic components. However, the bifunctional interaction of n-heptane:n-butane was realized at certain lower temperatures.

WO3 monolayer loaded on ZrO2: Property-activity relationship in n-butane isomerization evidenced by hydrogen adsorption and IR studies

The property-activity relationship of WO3 supported on ZrO 2 (WZ) was evaluated in n-butane isomerization for a series of catalysts with WO3 loading ranging from 5 to 20 wt% on ZrO 2. The catalysts were prepared by incipient-wetness impregnation of Zr(OH)4 with an aqueous solution of (NH4) 6[H2W12O40·nH2O], followed by drying and calcination at 1093 K. The introduction of WO3 continuously increased the tetragonal phase of ZrO2, WO3 surface density and coverage. The specific surface area and total pore volume passed through a maximum of WO3 loading at 13 wt%; this loading corresponds to 5.9 WO3/nm2 and is near the theoretical monolayer-dispersed limit of WO3 on ZrO2. The IR results indicate that the presence of WO3 eroded the absorbance bands at 3738 and 3650 cm-1 corresponding to bibridged and tribridged hydroxyl groups up to near the monolayer-dispersed limit of WO3. A new broad and weak band appeared, centered at 2930 cm-1, indicating the presence of bulk crystalline WO3 for WO3 coverage exceeding the theoretical monolayer-dispersion limit. In addition to the band at 2930 cm-1, two WO stretching bands were observed at about 1021 and 1014 cm-1 for all WZ catalysts, confirming the existence of WO connected to coordinative unsaturated (cus) Zr4+ through O and to the other W through O, respectively. Pyridine adsorbed IR and NH3-TPD revealed that the presence of WO3 modified the nature and concentration of acidic sites. The highest acidity was observed with 13 wt% loading WO3. The decrease in the intensity of peaks due to increasing WO3 loading was much higher on Lewis acid sites than on Bronsted acid sites. Hydrogen adsorption isotherms and the IR results for hydrogen adsorption on preadsorbed pyridine were used to evaluate the formation of active protonic acid sites from molecular hydrogen. The catalyst with 13 wt% WO 3 loading showed the maximum hydrogen uptake capacity and formation of protonic acid sites. These results show a direct correlation with the activity of WZ in n-butane isomerization at 573 K in which 13 wt% WO3 loading on ZrO2 yielded the highest amount of isobutane. It is suggested that the presence of strong Lewis acid sites on monolayer-dispersed WO3 facilitates the formation of protonic acid sites from hydrogen in the gas phase which act as active sites in n-butane isomerization. The presence of permanent Bronsted acid sites could not be directly associated with activity. In fact, no isomerization activity was observed in the absence of hydrogen.

ISOMERIZATION OF BUTANE CATALYZED BY CH3COX*2AlX3

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Activation of sulfated zirconia catalysts Effect of water content on their activity in n-butane isomerization

The effect of water content in sulfated zirconia catalysts on their activities for n-butane isomerization was investigated using catalytic testing, Fourier transform infrared (FTIR) spectroscopy and thermogravimetry analysis. It was found that minor amounts of water promote the catalytic activity while excess water diminishes it. The FTIR spectrum of pyridine adsorbed on the catalysts showed that a decrease in water content resulted in a decrease in Bronsted acidity with a concurrent increase in Lewis acidity. In the most active catalyst, approximately two-thirds of the acid sites are Bronsted sites, and the rest are Lewis sites; an appropriate amount of water is needed to produce this ratio. The Bronsted acid sites presumably contribute to the catalysis by protonating butene formed at redox sites on the catalyst to create carbocations. The high catalytic capability of the Bronsted acid sites requires the presence of adjacent Lewis acid sites, which withdraw electrons from bisulfate SO - H bonds through an induction effect, giving rise to more acidic protons.

A Skeletal Rearrangement Study of Labelled Butanes on a Solid Superacid Catalyst : Sulfuric Acid Treated Zirconium Oxide

The reactions of n-butane and isobutane have been studied in a flow system in the presence of hydrogen at 250 deg C using sulfuric acid treated zirconia as catalyst.The conversion of the butanes occurs with high selectivity in isomerization.The branched isomer reacts much faster than the linear one.The use of 13C labelled starting material and analysis of the isotope distribution in the products show that the rearrangement is of intramolecular nature in accord with the superacidic properties of the catalyst.

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A Highly Active Solid Superacid Catalyst for n-Butane Isomerization: a Sulfated Oxide Containing Iron, Manganese and Zirconium

A porous sulfated metal oxide containing Fe, Mn and Zr is described; it is the most active nonhalide superacid catalyst yet reported, catalysing the isomerization of n-butane at 301 K and being about three orders of magnitude more active than sulfated ZrO2.

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Rational Preparation of Well-Defined Multinuclear Iridium-Aluminum Polyhydride Clusters and Comparative Reactivity

We report an original alkane elimination approach, entailing the protonolysis of triisobutylaluminum by the acidic hydrides from Cp*IrH4. This strategy allows access to a series of well-defined tri- and tetranuclear iridium aluminum polyhydride clusters, depending on the stoichiometry: [Cp*IrH3Al(iBu)2]2(1), [Cp*IrH2Al(iBu)]2(2), [(Cp*IrH3)2Al(iBu)] (3), and [(Cp*IrH3)3Al] (4). Contrary to most transition-metal aluminohydride complexes, which can be considered as [AlHx+3]x-aluminates and LnM+moieties, the situation here is reversed: These complexes have original structures that are best described as [Cp*IrHx]n-iridate units surrounding cationic Al(III) fragments. This is corroborated by reactivity studies, which show that the hydrides are always retained at the iridium sites and that the [Cp*IrH3]-moieties are labile and can be transmetalated to yield potassium ([KIrCp*H3], 8) or silver (([AgIrCp*H3]n, 10) derivatives of potential synthetic interest. DFT calculations show that the bonding situation can vary in these systems, from 3-center 2-electron hydride-bridged Lewis adducts of the form Ir-H←Al to direct polarized metal-metal interaction from donation of d-electrons of Ir to the Al metal, and both types of interactions take place to some extent in each of these clusters.

Impact of the Spatial Organization of Bifunctional Metal–Zeolite Catalysts on the Hydroisomerization of Light Alkanes

Improving product selectivity by controlling the spatial organization of functional sites at the nanoscale is a critical challenge in bifunctional catalysis. We present a series of composite bifunctional catalysts consisting of one-dimensional zeolites (ZSM-22 and mordenite) and a γ-alumina binder, with platinum particles controllably deposited either on the alumina binder or inside the zeolite crystals. The hydroisomerization of n-heptane demonstrates that the catalysts with platinum particles on the binder, which separates platinum and acid sites at the nanoscale, leads to a higher yield of desired isomers than catalysts with platinum particles inside the zeolite crystals. Platinum particles within the zeolite crystals impose pronounced diffusion limitations on reaction intermediates, which leads to secondary cracking reactions, especially for catalysts with narrow micropores or large zeolite crystals. These findings extend the understanding of the ??intimacy criterion” for the rational design of bifunctional catalysts for the conversion of low-molecular-weight reactants.

Decarbonylative ether dissection by iridium pincer complexes

A unique chain-rupturing transformation that converts an ether functionality into two hydrocarbyl units and carbon monoxide is reported, mediated by iridium(i) complexes supported by aminophenylphosphinite (NCOP) pincer ligands. The decarbonylation, which involves the cleavage of one C-C bond, one C-O bond, and two C-H bonds, along with formation of two new C-H bonds, was serendipitously discovered upon dehydrochlorination of an iridium(iii) complex containing an aza-18-crown-6 ether macrocycle. Intramolecular cleavage of macrocyclic and acyclic ethers was also found in analogous complexes featuring aza-15-crown-5 ether or bis(2-methoxyethyl)amino groups. Intermolecular decarbonylation of cyclic and linear ethers was observed when diethylaminophenylphosphinite iridium(i) dinitrogen or norbornene complexes were employed. Mechanistic studies reveal the nature of key intermediates along a pathway involving initial iridium(i)-mediated double C-H bond activation. This journal is