- Steric Hindrance Underestimated: It is a Long, Long Way to Tri- tert-alkylamines
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Ten different processes (Methods A-J) were tested to prepare tertiary amines bearing bulky alkyl groups. In particular, SN1 alkylation of secondary amines with the help of 1-adamantyl triflate (Method D) and reaction of N-chlorodialkylamines with organometallic reagents (Method H), but also attack of the latter reagents at iminium salts, which were generated in situ by N-alkylation of imines (Method J), led to trialkylamines with unprecedented steric congestion. These products showed a restriction of the rotation about the C-N bond. Consequently, equilibration of rotamers was slow on the NMR time scale resulting in distinguishable sets of NMR data at room temperature. Furthermore, tertiary amines with bulky alkyl substituents underwent Hofmann-like elimination when heating in toluene to form an olefin and a secondary amine. Since the tendency to take part in this decay reaction correlated with the degree of steric hindrance around the nitrogen atom, Hofmann elimination at ambient temperature, which made the isolation of the tertiary amine difficult, was observed in special cases.
- Banert, Klaus,Heck, Manuel,Ihle, Andreas,Kronawitt, Julia,Pester, Tom,Shoker, Tharallah
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- THE INFLUENCE OF INTERLAYER WATER ON CLAY CATALYSTS. INTERLAMELLAR CONVERSION OF 2-METHYLPROPENE
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Evidence is provided for two alternative pathways for the reactions undergone by 2-methylpropene between the layers of a sheet silicate catalyst (Al3+-exchanged montmorillonite).This clay, when it initially contains ca. 12percent interlayer water, catalyses the addition of either water or methanol to 2-methylpropene to yield, respectively, t-butanol or 2-methoxy-2-methyl propane (methyl tertiary butyl ether, MTBE), whereas the same clay following deliberate dehydration acts as an effective catalyst for the oligomerisation of 2-methylpropene.Similar results are obtained with an Al3+-exchanged synthetic hectorite.
- Ballantine, James A.,Jones, William,Purnell, J. Howard,Tennakoon, Dayananda T. B.,Thomas, John M.
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- Byproducts formation in the ethyl tert-butyl ether (ETBE) synthesis reaction on macroreticular acid ion-exchange resins
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Ethyl tert-butyl ether (ETBE) production is one of the industrial processes of major importance today in Europe. However, the study of side reactions in this synthesis reaction appears scarcely in the open literature. Side reactions take place along with the etherification of C4 olefinic cuts with ethanol, catalyzed by acidic ion-exchange resins. In this work, byproducts formation is studied in a batch reactor. The presence of diethyl ether (DEE), ethyl sec-butyl ether (ESBE), dimers of isobutene (2,4,4-trimethyl-1-pentene (TMP-1) and 2,4,4-trimethyl-2-pentene (TMP-2)) and tert-butyl alcohol (TBA) has been studied in terms of production and selectivity. The effect of temperature, ranging from 323 to 383 K, and the influence of initial molar ratio ethanol/isobutene (R A/O), ranging from 0.5 to 2.0, on byproducts formation have been analyzed. All byproducts formation was favored by high temperatures. A low initial molar ratio ethanol/isobutene favored the formation of DEE, ESBE, TMP-1 and TMP-2, whereas high molar ratios favored TBA formation.
- Badia,Fité,Bringué,Ramírez,Cunill
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- Selective and unexpected transformations of 2-methylpropane to 2,3-dimethylbutane and 2-methylpropene to 2,3-dimethylbutene catalyzed by an alumina-supported tungsten hydride
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2-Methylpropane and 2-methylpropene, in the presence of the W(H) 3/Al2O3 catalyst, are unexpectedly transformed to 2,3-dimethylbutane and 2,3-dimethylbutenes, respectively, with high selectivity; in case of 2-methylpropane
- Merle, Nicolas,Stoffelbach, Francois,Taoufik, Mostafa,Le Roux, Erwan,Thivolle-Cazat, Jean,Basset, Jean-Marie
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- THERMISCHER ZERFALL VON Β-PHENYL UND Β,Β-DIPHENYL-NITROALKANEN
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Elimination of nitrous acid is the exclusive reaction path for the thermal decomposition of the nitroalkanes 1, 2 and 5.Homolytic CC-cleavage cannot compete.A concerted β-elimination is the favoured mechanism.
- Fritzsche, Katharina,Beckhaus, Hans-Dieter,Ruechardt, Christoph
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- Sulfated SnO2 as a high-performance catalyst for alkene oligomerization
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Nanoparticulate (3-5 nm) sulfated tin dioxide shows high catalytic activity for the oligomerization of isobutylene, hexene-1, and cyclohexene. The acidity (Hammett acidity function H0) of sulfated stannia reaches H 0 = -16.04. We have studied the effect of synthesis conditions on the physicochemical and functional properties of sulfated SnO2.
- Yurkova, L. L.,Lermontov, S. A.,Kazachenko, V. P.,Ivanov, V. K.,Lermontov, A. S.,Baranchikov, A. E.,Vasil'Eva, L. P.
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- Structural effects on the Grunwald-Winstein correlations in the solvolysis of some simple tertiary alkyl chlorides
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The rates of solvolysis in various solvents at 25 °C were determined for five tertiary alkyl chlorides: 2-chloro-2,4,4-trimethylpentane (4), 2-chloro-2,4-dimethylpentane, 2-chloro-2-methylpentane, 1-chloro-1,3,3-trimethyl-cyclopentane (7) and 1-chloro-1-methylcyclopentane. The rate data were analysed on the basis of the original and extended Grunwald-Winstein-type equation [log(k/k0)=myc1+c and log(k/k0)=lNT+mYc1+c] and the results were compared with those reported for 2-chloro-2-methylpropane (1) and 2-chloro-2,3,3-trimethylbutane (3). The rate data for 4 in 18 solvents give an excellent correlation with l=0·00±0·02 and m=0·74±0·01. The neopentyl group in 4 more effectively shields the rear-side of the reaction center than the tert-butyl group in 3 that is correlated by l=0·10±0·04 and m=0·81±0·04. The rate ratio between 4 and 1 at 25 °C is 275 in TFE and predicted to increase to 950 in TFA. The previous 4/1 rate ratio of 21 in 80% ethanol evidently underestimates the B-strain effect on the solvolysis rate of 4 by a factor of at least 40. The remote methyl groups in 7 works to increase rear-side shielding without increasing B-strain. The marked difference in the effect of the remote methyl groups between 4 and 7 suggests that the leaving chloride ion in 4 takes a locus that is nearly antiperiplanar to the tert-butyl group.
- Takeuchi, Ken'ichi,Ohga, Yasushi,Ushino, Takuhiro,Takasuka, Masaaki
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- Etherification of glycerol by isobutylene: Tuning the product composition
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Etherification of glycerol by isobutylene was conducted in a batch mode using acidic and partially neutralized Amberlyst-15 ionic resin, p-toluenesulfonic acid, silicotungstic acid, cesium salt of silicotungstic acid, and ionic liquid containing sulfonic acid groups. All the catalysts are comparable in terms of the initial rate of glycerol conversion into mono-ether (except cesium salt of heteropolyacid), but differ substantially with respect to the yields of higher ethers of glycerol. Ionic liquid and heteropolyacid are immiscible/insoluble in higher ethers of glycerol. As a result they have unique capability of suppressing the formation of tri-ether during the initial stage of glycerol conversion. Acidic Amberlyst-15 in the form of fine powder has the highest activity per unit weight for glycerol etherification and relatively high activity in isobutene oligomerization. Partial exchange of acidic protons with cations Na+, Ag+, Mg2+, and Al3+ decreases the rates of all the processes, but isobutylene oligomerization is suppressed more efficiently. Ag+- and Al3+-modified Amberlyst demonstrates higher yields of tri-ether and has specific pattern of interaction with gaseous isobutene distinctive to other metal-substituted Amberlysts.
- Lee, Hee Jong,Seung, Doyoung,Jung, Kwang S.,Kim, Hwayong,Filimonov, Igor N.
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- Synthesis of Trialkylamines with Extreme Steric Hindrance and Their Decay by a Hofmann-like Elimination Reaction
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A number of amines with three bulky alkyl groups at the nitrogen, which surpass the steric crowding of triisopropylamine considerably, were prepared by using different synthetic methods. It turned out that treatment of N-chlorodialkylamines with organometallic compounds, for example, Grignard reagents, in the presence of a major excess of tetramethylenediamine offered the most effective access to the target compounds. The limits of this method were also tested. The trialkylamines underwent a dealkylation reaction, depending on the degree of steric stress, even at ambient temperature. Because olefins were formed in this transformation, it showed some similarity with the Hofmann elimination. However, the thermal decay of sterically overcrowded tertiary amines was not promoted by bases. Instead, this reaction was strongly accelerated by protic conditions and even by trace amounts of water. Reaction mechanisms, which were analyzed with the help of quantum chemical calculations, are suggested to explain the experimental results.
- Banert, Klaus,Hagedorn, Manfred,Heck, Manuel,Hertel, Raphael,Ihle, Andreas,Müller, Ioana,Pester, Tom,Shoker, Tharallah,Rablen, Paul R.
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- The competitive reactions between electron transfer and radical addition in free radical reactions
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The photolytic reactions of 2-substituted allyl chloride with t-BuHgCl in different solvents were investigated. The reactions proceed the SH2′ reaction mechanism except the substituent is a strong electron-releasing group. The electron transfer process becomes more competitive with the radical addition process when the substituent is a strong electron-releasing group. When the substituent is a strong electron-releasing group such as -CH2SiMe3, the reaction in CH3CN shows pronounced electron transfer process while the reaction in DMSO or THF involves both of the SH2′ and the electron transfer processes. The reaction is solvent dependent. An electron transfer mechanism is discussed.
- Wu, Yuh-Wern,Lu, Cheng-Yi
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- Disproportionation-Combination Reactions of Caged Geminate Radical Pairs Formed from the Photodecomposition of 2,2'-Azoisobutane. Anisotropic Reorientation of tert-Butyl Radicals in Viscous Media and Birth Effects in Very Viscous Media
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The solvent viscosity dependence of the self-termination reactions of tert-butyl radical pairs generated from the photolysis of 2,2'-azoisobutane, in a number of inert solvents admixed with thiophenol, shows a linear relationship between the cage efficiency, 1/cage yield, and fluidity, 1/η, of the solvent.The viscosity dependence of the ratio of disproportionation/combination rate constants, kd/kc, for these cage reactions was compared to the values observed for the reactions of encounter pairs generated by the photolysis of di-tert-butyl ketone.At viscosities between 0.5 and 2.7 cP the kd/kc ratios obtained for geminate radical pairs were the same as those obtained from the reaction of the encounter pairs, while at higher viscosities of 12-808 cP the orientation of the geminately formed radicals at birth appeared to bias the radicals to undergo a higher proportion of combination.
- Tanner, Dennis D.,Rahimi, Parviz M.
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- Fluorinated metal oxide-assisted oligomerization of olefins
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Fluorinated alumina is an efficient catalyst for hex-1-ene, cyclohexene and isobutene oligomerization, whereas fluorinated titania and zirconia are inactive.
- Lermontov, Sergey A.,Malkova, Alena N.,Yurkova, Lyudmila L.,Ivanov, Vladimir K.,Baranchikov, Alexander E.,Vasilyeva, Larisa P.
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- Contra-thermodynamic Olefin Isomerization by Chain-Walking Hydrofunctionalization and Formal Retro-hydrofunctionalization
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We report a contra-thermodynamic isomerization of internal olefins to terminal olefins driven by redox reactions and formation of Si-F bonds. This process involves chain-walking hydrosilylation of internal olefins and subsequent formal retro-hydrosilylation. The process rests upon the high activities of platinum hydrosilylation catalysts for isomerization of metal alkyl intermediates and a new, metal-free process for the conversion of alkylsilanes to alkenes. By this approach, 1,2-disubstituted and trisubstituted olefins are converted to terminal olefins.
- Hanna, Steven,Butcher, Trevor W.,Hartwig, John F.
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- Coke Formation and Its Effects on Shape Selective Adsorptive and Catalytic Properties of Ferrierite
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Channels or cavities of ferrierite are blocked by carbonaceous deposits (coke) which are formed during butene treatments.The pore blocking inside ferrierite/alumina catalysts affects the yield and selectivity to isobutylene in the catalytic reaction of butene isomerization.Pore size distribution experiments show that the blocking of 10-member ring channels (4.2 x 5.4 Angstroem) and 8-member ring channels (3.5 x 4.8 Angstroem) of ferrierite by coke reduces the channel size smaller than that of the nitrogen molecule (4.09 Angstroem).TPD data show that ammonia uptake for coked samples of different times on stream is decreased from about 62percent to 35percent of that for the fresh sample.This suggests that channels in coked ferrierites are at least larger than the size of the ammonia molecule (2 Angstroem).Uptakes for more bulky molecules such as 1-butene (2.99 x 4.71 Angstroem) and isobutylene (3.28 x 4.14 Angstroem) are severely reduced by coke formation ( +(XL), H+(L), and H+(S) (XL = extra large, L = large, S = small) from a structural point of view.These three kinds of acid sites were successfully probed with ammonia, 1-butene, and isobutylene.These experiments suggest that the adsorption of probe molecules on ferrierite is also a shape selective process.
- Xu, Wen-Qing,Yin, Yuan-Gen,Suib, Steven L.,O'Young, Chi-Lin
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- The solvent effect on the reaction constants of tert-butyl radical addition to 2-substituted allyl chlorides
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The ρ values of free radical SH2′ reactions have been determined in various solvents. The correlation of Hammett ρ with Taft's π* gives a W value of 0.70. The W value is a measure of susceptibility of the reaction constant to change in solvent polarity. However, the W value is 2.64 in the dissociation reactions of substituted benzoic acids. The free radical reactions are less susceptible to the solvent effect than ionic reactions and this could be rationalized in terms of the partial charge formed in the transition state of free radical reaction is less than that of heterolytic reaction. The ρ values in SH2′ reactions might not reflect truly the partial charge separation at transition state, however, it might be a measure of the susceptibility of the reaction to the electronic effect of the substituents.
- Wu, Yuh-Wern,Huang, Hsu-Ting,Huang, Zhau-Jie,Huang, Huang-Ming,Yang, Jyh-Ferng
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- Screening of solid acid catalysts for etherification of glycerol with isobutene under identical conditions
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We compared the performance of more than 70 solid acid catalysts with Br?nsted acid function for the etherification of glycerol with isobutene under identical reaction conditions of 75 °C, 10 bar, 6 h and with an isobutene/glycerol molar ratio of 3/1. The catalysts were selected from a wide range of solid acid catalysts including ion exchange resins, zeolites, silica, and heteropolyacids, and their counterparts modified by simple treatments, with more than half of them being investigated for the first time for this reaction. For the modified commercial acid catalysts, the desired glycerol tertiary butyl ether (DTBGE and TTBGE) selectivity improved from 75 to 87 wt% upon partial cation exchange of the sulfonic acid protons in Amberlyst type ion exchange resins with Na+ cations; from 66 to 85 wt% by hydrothermal steam treatment of zeolite H-Y (SiO2/Al2O3 = 80); and from 75 to 80 wt% with partial La+-exchange of zeolite H-Beta (SiO2/Al2O3 = 300), all at high (90–100%) glycerol conversion. Impregnation of the heteropolyacids, tungstosilicic acid (TSA) and tungstophosphoric acid (TPA), on silica at a loading of 50 wt% provided a glycerol conversion of higher than 65 wt% and with a desired ether selectivity in the range of 62 to 76 wt%. In general, total ether selectivity increased with decreasing acid capacity for ion exchange resins, while the desired ether selectivity was enhanced with increasing acid strength for zeolites and supported heteropolyacids on mesoporous silica. Data present a detailed guideline for the selection of solid acid catalysts for the etherification of glycerol with isobutene.
- Bozkurt, ?zge Deniz,Ba?lar, Nur,?elebi, Serdar,Uzun, Alper
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- Unique mesoporous silicoaluminophosphate assembled from faujasite-type SAPO-37 precursor: A potential catalyst for isomerization
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Unique mesoporous silicoaluminophosphate (MESO-SAPO-37) with uniform pores (3 nm) was synthesized for the first time by using a faujasite-type microporous SAPO-37 precursor. MESO-SAPO-37 contains hierarchical mesopores with a microporous secondary building unit. It possesses strong acidity and shows high catalytic activity for the conversion of 1-octene, with the exclusive formation of isomerized products (84%).
- Yadav, Rekha,Singh, Arvind Kumar,Sakthivel, Ayyamperumal
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- Insight into the active site nature of zeolite H-BEA for liquid phase etherification of isobutylene with ethanol
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The nature of active acid sites of zeolite H-BEA with different Si/Al ratios (15-407) in liquid phase etherification of isobutylene with ethanol in a continuous flow reactor in the temperature range 80-180 °C has been explored. We describe and discuss data concerning the strength and concentration of acid sites of H-BEA obtained by techniques of stepwise (quasi-equilibrium) thermal desorption of ammonia, X-ray diffraction, low-Temperature adsorption of nitrogen, FTIR spectroscopy of adsorbed pyridine and solid-state 27Al MAS NMR. The average values of the adsorption energy of NH3 on H-BEA were experimentally determined as 63.7; 91.3 and 121.9 mmol g-1 (weak, medium, and strong, respectively). In agreement with this, a correlation between the rate of ethyl-Tert-butyl ether synthesis and the concentration of weak acid sites (ENH3 = 61.6-68.9 kJ mol-1) has been observed. It was concluded that the active sites of H-BEA for this reaction are Br?nsted hydroxyls representing internal silanol groups associated with octahedrally coordinated aluminum in the second coordination sphere.
- Vlasenko, Nina V.,Kochkin, Yuri N.,Telbiz, German M.,Shvets, Oleksiy V.,Strizhak, Peter E.
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- Identification of the strong Br?nsted acid site in a metal–organic framework solid acid catalyst
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It remains difficult to understand the surface of solid acid catalysts at the molecular level, despite their importance for industrial catalytic applications. A sulfated zirconium-based metal–organic framework, MOF-808-SO4, was previously shown to be a strong solid Br?nsted acid material. In this report, we probe the origin of its acidity through an array of spectroscopic, crystallographic and computational characterization techniques. The strongest Br?nsted acid site is shown to consist of a specific arrangement of adsorbed water and sulfate moieties on the zirconium clusters. When a water molecule adsorbs to one zirconium atom, it participates in a hydrogen bond with a sulfate moiety that is chelated to a neighbouring zirconium atom; this motif, in turn, results in the presence of a strongly acidic proton. On dehydration, the material loses its acidity. The hydrated sulfated MOF exhibits a good catalytic performance for the dimerization of isobutene (2-methyl-1-propene), and achieves a 100% selectivity for C8 products with a good conversion efficiency.
- Trickett, Christopher A.,Osborn Popp, Thomas M.,Su, Ji,Yan, Chang,Weisberg, Jonathan,Huq, Ashfia,Urban, Philipp,Jiang, Juncong,Kalmutzki, Markus J.,Liu, Qingni,Baek, Jayeon,Head-Gordon, Martin P.,Somorjai, Gabor A.,Reimer, Jeffrey A.,Yaghi, Omar M.
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- HYDROTHERMAL PRODUCTION OF ALKANES
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Synthesizing an alkane includes heating a mixture including an alkene and water at or above the water vapor saturation pressure in the presence of a catalyst and one or both of hydrogen and a reductant, thereby hydrogenating the alkene to yield an alkane and water, and separating the alkane from the water to yield the alkane. The reductant includes a first metal and the catalyst includes a second metal.
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Paragraph 0022
(2021/04/17)
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- PROCESS AND CATALYSTS FOR THE PRODUCTION OF DIESEL AND GASOLINE ADDITIVES FROM GLYCEROL
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A method of producing one or more glycerol ethers, the method comprising contacting glycerol and tertiary butanol (TBA) in the presence of an acidic catalyst to produce one or more glycerol ethers selected from mono-tert butyl glycerol ethers, di-tert butyl glycerol ethers, tri-tert butyl glycerol ethers, or a combination thereof; separating water and a stream comprising isobutylene, unreacted TBA, or a combination thereof from the one or more glycerol ethers; and recycling at least a portion of the stream comprising isobutylene, unreacted TBA, or a combination thereof to the contacting. Also disclosed is a process of co-producing isooctene, wherein the process involves contacting glycerol and tertiary butanol in the presence of a dehydrating catalyst and dimerizing/oligomerizing the dehydrated products in the presence of an oligomerizing catalyst to form isooctene, a precursor of isooctane and isomers thereof.
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Paragraph 0043-0045
(2020/01/24)
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- Olefin oligomerization via new and efficient Br?nsted acidic ionic liquid catalyst systems
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Olefin oligomerization reaction catalyzed by new catalyst systems (a Br?nsted-acidic ionic liquid as the main catalyst and tricaprylylmethylammonium chloride as the co-catalyst) has been investigated. The synthesized Br?nsted acidic ionic liquids were characterized by Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV), 1H nuclear magnetic resonance (NMR), and 13C NMR to analyze their structures and acidities. The influence of different ionic liquids, ionic liquid loading, different co-catalysts, catalyst ratios (mole ratio of ionic liquid to co-catalyst), reaction time, pressure, temperature, solvent, source of reactants, and the recycling of catalyst systems was studied. Among the synthesized ionic liquids, 1-(4-sulfonic acid)butyl-3-hexylimidazolium hydrogen sulfate ([HIMBs]HSO4) exhibited the best catalytic activity under the tested reaction conditions. The conversion of isobutene and selectivity of trimers were 83.21% and 35.80%, respectively, at the optimum reaction conditions. Furthermore, the catalyst system can be easily separated and reused; a feasible reaction mechanism is proposed on the basis of the distribution of experimental products.
- Wang, Guoqin,Song, Heyuan,Li, Ruiyun,Li, Zhen,Chen, Jing
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p. 1110 - 1120
(2018/05/28)
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- Preparation method for 2,4,4-trimethyl-1-amylene
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The invention belongs to the field of chemical engineering and specifically relates to a preparation method for 2,4,4-trimethyl-1-amylene. The method comprises the following steps: taking tertiary butanol or isobutyl alcohol as a raw material; taking sulfuric acid or strong acid type macromolecule resin as a catalyst; closing and reacting at 60-95 DEG C, thereby acquiring the 2,4,4-trimethyl-1-amylene. The raw materials are low-cost and are easily acquired; the operation is simple and convenient; the distilling refining is not required; the yield can reach up to 95%.
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Paragraph 0018; 0019; 0024; 0025; 0030; 0031
(2017/09/02)
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- The feeding at the same time containing butene dimerization and hydrated method (by machine translation)
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The present invention provides a mixed butene by acid catalysts containing hydrocarbon feed of manufacturing and method of the oligomer at the same time. Furthermore, embodiments of the present invention also provides the preparation of the mixed olefin containing the alcohol and the oligomer process for the preparation of the fuel composition, in certain embodiments, the catalyst can include two-phase catalyst system, the catalyst system includes a water-soluble acid catalyst and solid acid catalyst. (by machine translation)
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Paragraph 0071-0077
(2017/03/22)
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- Double-modified mesoporous molecular sieve catalytic SBA method for preparing carboxylic acid T-butyl ester
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The invention discloses a method for preparing tert-butyl carboxylate by using a dual-modified SBA mesoporous molecular sieve catalyst. According to the method, carboxylic acid and isobutylene are subjected to addition esterification by using a dual-modified SBA mesoporous molecular sieve as a catalyst to synthesize the tert-butyl carboxylate. The molecular sieve catalyst is a metal-doped sulfonate-grafted dual-modified SBA mesoporous molecular sieve catalyst prepared by a one-step cocondensation process. When the dual-modified SBA mesoporous molecular sieve catalyst is used in the addition esterification reaction process of synthesizing tert-butyl carboxylic acid from carboxylic acid and isobutylene, no polar solvent (such as tert-butyl alcohol, methyl tert-butyl ether or the like) is needed as an isobutylene polymerization inhibitor, and the quantity of the carboxylic acid is not excessive, thereby reducing the energy consumption for separating the reaction product. The catalyst has the advantages of high conversion rate, high selectivity, non-homogeneous phase, no corrosiveness, adjustable acid quantity and acid center and the like, and is recyclable.
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Paragraph 0059
(2016/11/21)
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- PROCESS FOR DIMERIZATION OF OLEFINS
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The present invention relates to a process for the dimerization of branched olefins or a mixture of olefins and paraffins, wherein said olefins and paraffins have between 3 to 10 carbon atoms, comprising contacting a feedstream comprising said olefin or mixture of olefins and paraffins with a catalyst composition comprising a medium pore aluminosilicate zeolite having a pore size of between more than 5 ? but less than 6 ? and up to 5 wt-% of one or more elements selected from the group consisting of molybdenum (Mo), tungsten (W), seaborgium (Sg), cobalt (Co), rhodium (Rh), iridium (Ir) and meinerium (Mt).
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Paragraph 0066; 0067
(2015/09/22)
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- Substituent-controlled selective synthesis of N -Acyl 2-aminothiazoles by intramolecular zwitterion-mediated C-N bond cleavage
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The cleavage of C-N bonds is an interesting and challenging subject in modern organic synthesis. We have achieved the first zwitterion-controlled C-N bond cleavage in the MCR reaction among lithium alkynethiolates, bulky carbodiimides, and acid chlorides to construct N-acyl 2-aminothiazoles. This is a simple, highly efficient, and general method for the preparation of N-acyl 2-aminothiazoles with a broad range of substituents. The selective synthesis of N-acyl 2-aminothiazoles significantly depends on the steric hindrance of carbodiimides. The result is in striking contrast with our previous convergent reaction giving 5-acyl-2-iminothiazolines via 1,5-acyl migration. It is indeed interesting that the slight change of the substituents on the carbodiimides can completely switch the product structure. Experimental and theoretical results demonstrate the reason why the C-N bond cleavage in the present system is prior to the acyl migration. The intramolecular hydrogen relay via unprecedented Hofmann-type elimination is essential for this totally new zwitterion-controlled C-N bond cleavage.
- Wang, Yang,Zhao, Fei,Chi, Yue,Zhang, Wen-Xiong,Xi, Zhenfeng
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p. 11146 - 11154
(2015/01/08)
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- Sulfated SnO2 as a high-performance catalyst for alkene oligomerization
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Nanoparticulate (3-5 nm) sulfated tin dioxide shows high catalytic activity for the oligomerization of isobutylene, hexene-1, and cyclohexene. The acidity (Hammett acidity function H0) of sulfated stannia reaches H 0 = -16.04. We have studied the effect of synthesis conditions on the physicochemical and functional properties of sulfated SnO2.
- Yurkova,Lermontov,Kazachenko,Ivanov,Lermontov,Baranchikov,Vasil'Eva
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p. 1012 - 1019
(2013/01/15)
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- A new disilene with π-accepting groups from the reaction of disilyne RSi≡SiR (R = SiiPr[CH(SiMe3)2]) with isocyanides
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The reaction of 1,1,4,4-tetrakis[bis(trimethylsilyl)methyl]-1,4- diisopropyltetrasila-2-yne (1) with tert-butylisocyanide or tert-octylisocyanide produced the corresponding disilyne-isocyanide adducts [RSiSiR(CNR′) 2] (R = SiiPr[CH(SiMe3)2] 2, R′ = tBu (2a) or CMe2CH 2tBu (2b)), which are stable below -30 °C and were characterized by spectroscopic data and, in the case of 2a, X-ray crystallography. Upon warming to room temperature, 2 underwent thermal decomposition to produce 1,2-dicyanodisilene R(NC)Si=Si(CN)R (3) and 1,2-dicyanodisilane R(NC)HSiSiH(CN)R (4) via C-N bond cleavage and elimination of an alkane and an alkene. The 1,2-dicyanodisilene derivative 3 was characterized by X-ray crystallography.
- Takeuchi, Katsuhiko,Ichinohe, Masaaki,Sekiguchi, Akira
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supporting information; experimental part
p. 2954 - 2957
(2012/04/10)
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- DIMERIZATION PROCESS
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A process for the dimerization of isoolefins is disclosed. The process may include: contacting an isoolefin with sulfurous acid in a reaction zone at conditions of temperature and pressure sufficient to dimerize at least a portion of the isoolefin
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Page/Page column 4-5
(2011/04/18)
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- Diisobutylene process
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This invention is a process for producing diisobutylene from isobutylene. The process comprises first contacting a sulfonic acid resin with a reaction feed comprising isobutylene and tertiary butyl alcohol to produce a product stream comprising diisobutylene, isobutylene, tertiary butyl alcohol, and water. The product stream is distilled to produce a first overhead stream comprising water and isobutylene and a first bottoms stream comprising diisobutylene and tertiary butyl alcohol. Water is separated from the first overhead stream, and the resulting isobutylene-enriched stream is recycled back to the reaction step. The first bottoms stream is distilled to produce a second overhead stream comprising tertiary butyl alcohol and a bottoms product stream comprising diisobutylene.
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Page/Page column 3
(2009/12/23)
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- Diisobutene process
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A process comprising reacting a feed comprising isobutene and a modifier in the presence of an acidic solid catalyst to produce diisobutene is disclosed. The amount of the modifier in the feed is reduced as the catalyst ages. Lower reaction temperature is maintained throughout the catalyst life, which is less likely to corrode the reactor. When an alcohol is used as a modifier, a lower reaction temperature causes lower degree of dehydration of the modifier, thus lower water concentration is maintained, which in turn reduces the likelihood of reactor corrosion.
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Page/Page column 2
(2009/06/27)
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- Process for manufacturing neohexene
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The present invention relates to a process for manufacturing neohexene, comprising contacting isobutene with a supported catalyst comprising a tungsten compound chosen from tungsten hydrides, organometallic tungsten compounds and organometallic tungsten hydrides, and a support comprising an oxide of aluminium, so as to form a reaction mixture comprising neohexene, and preferably separating neohexene from the reaction mixture, so as to isolate it. The contacting leads to the direct production of neohexene, in particular in a single (reaction) stage and with a high molar selectivity for neohexene. The contacting can be performed at a temperature of 50 to 600 °C, under a total absolute pressure of 0.01 to 100 MPa.
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Page/Page column 15
(2008/12/06)
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- PREPARING METHOD OF LIGHT OLEFIN TRIMERS AND PRODUCTION OF HEAVY ALKYLATES BY USING THEREOF
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The present invention relates to a preparation method of olefin oligomers, and more particularly, to a preparation method of olefin trimers with high selectivity. The oligomerization is performed with a catalyst such as a zeolite having cross linking pores; a composite acid catalyst having both Br?nsted acid and Lewis acid; or a composite catalyst post-treated by calcination and/or water-washing. Furthermore, the present invention relates to a preparation method of heavy alkylates by hydrogenating olefin trimers thus formed.
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Page/Page column 18
(2008/06/13)
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- OLIGOMERISATION
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The application discloses novel processes for the oligomerisation of unsaturated hydrocarbons, and more specifically the use of selected ionic liquids in the oligomerisation of unsaturated hydrocarbons, which allows for selection of the oligomers formed.
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Page/Page column 38-39
(2008/06/13)
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- Process and apparatus for oligomerization in multiple stages with single fractionation column
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In an oligomerization process comprising at least two oligomerization reactors, at least portions of product streams from two reactors are separated in the same separator vessel. In an embodiment, a liquid product stream from the first oligomerization reactor is fed to a fractionation column and a side cut from the fractionation column feeds the second oligomerization reactor.
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Page/Page column 4
(2008/06/13)
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- Diisobutylene process
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This invention is a process for producing diisobutylene from isobutylene. The process comprises first forming dry sulfonic acid resin by contacting water wet sulfonic acid resin catalyst with a first reaction feed comprising isobutylene under conditions effective to produce tertiary butyl alcohol from the reaction of isobutylene and water, and then contacting the dry sulfonic acid resin with a second reaction feed comprising isobutylene under conditions effective to oligomerize isobutylene to produce diisobutylene.
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Page/Page column 2
(2008/06/13)
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- Diisobutylene process
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This invention is a process for producing diisobutylene from isobutylene. The process comprises contacting isobutylene with a solid adsorbent to remove sulfur and/or nitrogen impurities from the isobutylene, followed by oligomerizing the isobutylene to diisobutylene using a sulfonic acid-type ion exchange resin. The solid adsorbent removes sulfur and/or nitrogen impurities from the isobutylene and surprisingly increases both catalyst activity and catalyst life of the sulfonic acid-type ion exchange resin.
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Page/Page column 2-3
(2008/06/13)
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- Diisobutylene process
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This invention is a process for producing diisobutylene from isobutylene. The process comprises first oligomerizing isobutylene to diisobutylene using a sulfonic acid-type ion exchange resin. The oligomerization step is followed by contacting the diisobutylene product with an adsorbent to remove sulfur impurities produced during the oligomerization step. The adsorbent is a large pore zeolite such as zeolite X and zeolite Y. Optionally, the purified diisobutylene may be hydrogenated to isooctane using a hydrogenation catalyst.
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Page/Page column 2,3
(2008/06/13)
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- COMPOSITE CATALYST FOR THE SELECTIVE OLIGOMERIZATION OF LOWER ALKENES AND THE PRODUCTION OF HIGH OCTANE PRODUCTS
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The present invention relates to a) a catalytic composite comprising a support structure and a catalytic species that is deposited on the support structure, b) a process for the selective oligomerization of lower alkenes and mixtures of alkenes, which process comprises contacting the lower alkenes with the catalytic composite in a catalytic distillation apparatus and under catalytic distillation conditions, and c) a process for producing high octane products, which process comprises hydrogenating one or more catalytic distillation apparatus and under catalytic distillation conditions.
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Page/Page column 48-52
(2008/06/13)
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- Production of diisobutene from tertiary butyl alcohol
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A process for the production of diisobutene is disclosed wherein tertiary butyl alcohol is dehydrated to isobutene in a distillation column reactor containing an acid cation exchange resin catalyst in the form of catalytic distillation structure. The isobutene reacts with itself in the presence of the catalyst to form primarily diisobutene which is removed as bottoms from the distillation column reactor with the bulk of the water. Unreacted isobutene along with an azeotrope of water is removed as overheads with the water being separated and removed from the unreacted isobutene. A portion or all of the unreacted isobutene may be returned to the distillation column reactor as reflux.
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- Ester preparation
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An olefin such as isobutylene is reacted with a carboxylic acid to produce the ester in the presence of an alkanol modifying agent effective to suppress olefin polymerization, at least part of the modifying agent being formed in situ by reaction of the olefin and water.
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- Ester preparation
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An olefin such as isobutylene is reacted with a carboxylic acid to produce the ester in the presence of an alkanol modifying agent effective to suppress olefin polymerization, at least part of the modifying agent being formed in situ by reaction of the olefin and water.
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- The Grunwald-Winstein type correlation for 2-chloro-2,4,4- trimethylpentane: A simple tertiary alkyl chloride that shows essentially limiting behaviour in solvolysis
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Evaluation of the rates of solvolysis of 2-chloro-2,4,4-trimethylpentane (4) in 17 solvents on the basis of the Grunwald-Winstein type equation [log(k/k0)= lNT+mYC1 + c] gives an excellent correlation with l=-0·01±0·02 and m = 0·74±0·01. The neopentyl group in 4 more effectively shields the rear side of the reaction center than the tert-butyl group in 2-chloro-2,3,3-trimethylbutane. The rate ratio between 4 and 2-chloro-2-methylpropane (3) at 25°C is 275 in trifluoroethanol and predicted to increase to 950 in trifluoroacetic acid. The previous 4:3 rate ratio of 22 in 80% ethanol evidently underestimated the B-strain effect on the solvolysis rate of 4 by a factor of at least 40.
- Takeuchi, Ken'Ichi,Ohga, Yasushi,Ushino, Takuhiro,Takasuka, Masaaki
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p. 777 - 779
(2007/10/03)
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- Synthesis, thermochemistry, and reactions of vicinal bis(azoalkanes). The chemistry of α- and β-azo radicals
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Two vicinal bis(azo)alkanes, 8P and 8B, were prepared from acetone phenylhydrazone (APH) and acetone tert-butylhydrazone (ATBH), respectively. Thermolysis of 8P above 130°C in the presence of thiophenol affords APH in quantitative yield, showing that the central C-C bond of 8P cleaves in preference to the usual C-N homolysis of azoalkanes. The resulting radicals 9P recombine to the C-N dimer 16P about 40 times faster than to the more stable C-C dimer 8P. From the combustion heat of 8P, we deduce that its strain enthalpy Hs is 5.5 kcal/mol, while the resonance stabilization energy (RSE) of 9P is 15.3 kcal/mol. The tert-butyl analog 8B loses 2 mol of N2, showing that C-N homolysis greatly dominates over C-C homolysis. Nevertheless, we estimate that the latter process would occur with ΔG* (150°C) > 40.3 kcal/mol, which implies that the RSE of aliphatic hydrazonyl radical 9B is at least 6 kcal/mol below that of 9P and is little or no more than the RSE of the 1,1-dimethylallyl radical.
- Engel, Paul S.,Wang, Chengrong,Chen, Yanqin,Rüchardt, Christoph,Beckhans, Hans-Dieter
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- Reaction of Azoalkanes with Isolable Cation Radical Salts
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Three tertiary azoalkanes related in the sense acyclic, cyclic, and bicyclic are shown to evolve nitrogen upon oxidation with stable cation radical salts.Thus azo-tert-octane (ATO), 3,3,6,6-tetramethyl-1,2-diazacyclohexene (TMDAC), and 1,4-dimethyl-2,3-diazabicyclooct-2-ene (Me2DBO) react rapidly with thianthrenium perchlorate (Th(.1+)ClO4(1-)), tris(p-bromophenyl)aminium hexachloroantimonate (TBPA(.1+)SbCl6(1-)), and TBPA(.1+)SbF6(1-).The ether and olefin products, which are formed in high yield in CH2Cl2/MeOH solvent, are not those expected from the usual free-radical decomposition of azoalkanes but instead implicate carbocations.Althrough the reaction stoichiometry clearly requires 2 equiv of cation radical salt to one of azoalkane, the mechanism is not yet clearly defined.A complication in these studies is found in the ability of certain cation radical salts to oxidize more azoalkane than expected based on the 2:1 stoichiometry.
- Engel, Paul S.,Robertson, Donald M.,Scholz, John N.,Shine, Henry J.
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p. 6178 - 6187
(2007/10/02)
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- Allylic and Propargylic Substitution Reactions Involving Radicals Generated from Alkylmercury Halides
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Addition of alkyl radicals to allyl or propargyl derivatives forms adduct radicals which can undergo β-elimination with substituents such as halogen, PhS, PhSO2, Bu3Sn, or HgCl to form the alkyl-substituted propene or allene and an eliminated radical which regenerates the alkyl radical by displacement from an alkylmercurial.With β-oxy substituents, such as O2CR, OP(O)(OEt)2, O3SAr, OPh, OSiMe3, or OH, the adduct radicals can displace the alkyl radical from the alkylmercurial to yield β-substituted alkylmercurials which spontaneously, or in the presence of nucleophiles, undergo an elimination reaction to yield the alkene or allene.Relative reactivities toward tert-butyl radical attack, such as k(allyl chloride)/k(propargyl chloride) = ca. 10, have been determined.A similar relative reactivity is observed in reaction with (t-Bu)2CuLi implicating attack by free tert-butyl radicals.With allyl or propargyl iodide, radical attack leads to iodine atom abstraction.Reaction of propargyl iodide with t-BuHgCl/hν, (t-Bu)2CuLi, or (t-Bu)3ZnLi leads to a mixture of hydrocarbons in which tert-butylallene is present in only trace amounts.Benzene is an important reaction product which seems to be formed via the cyclodimerization of two "propargyl" (C3H3.) radicals.
- Russell, Glen A.,Ngoviwatchai, Preecha,Wu, Yuh Wern
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p. 4921 - 4927
(2007/10/02)
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- Acid catalyzed reactions of monovinyl aromatic compounds
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The self condensation of monovinyl aromatic compounds to acyclic dimers, the cross-reaction of monovinyl aromatic compounds with olefins in the presence of acid catalysts to produce cyclialkylated aromatic compounds, and the production of cyclialkylated aromatic compounds by reaction of olefins with acyclic dimers of monovinyl aromatic compounds in the presence of acid catalysts is improved by employing a tetrahydrothiophene 1,1-dioxide solvent.
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