107-39-1Relevant articles and documents
Steric Hindrance Underestimated: It is a Long, Long Way to Tri- tert-alkylamines
Banert, Klaus,Heck, Manuel,Ihle, Andreas,Kronawitt, Julia,Pester, Tom,Shoker, Tharallah
, p. 5138 - 5148 (2018)
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.
THE INFLUENCE OF INTERLAYER WATER ON CLAY CATALYSTS. INTERLAMELLAR CONVERSION OF 2-METHYLPROPENE
Ballantine, James A.,Jones, William,Purnell, J. Howard,Tennakoon, Dayananda T. B.,Thomas, John M.
, p. 763 - 766 (1985)
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.
Byproducts formation in the ethyl tert-butyl ether (ETBE) synthesis reaction on macroreticular acid ion-exchange resins
Badia,Fité,Bringué,Ramírez,Cunill
, p. 384 - 394 (2013)
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.
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
Merle, Nicolas,Stoffelbach, Francois,Taoufik, Mostafa,Le Roux, Erwan,Thivolle-Cazat, Jean,Basset, Jean-Marie
, p. 2523 - 2525 (2009)
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
THERMISCHER ZERFALL VON Β-PHENYL UND Β,Β-DIPHENYL-NITROALKANEN
Fritzsche, Katharina,Beckhaus, Hans-Dieter,Ruechardt, Christoph
, p. 2805 - 2808 (1988)
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.
Sulfated SnO2 as a high-performance catalyst for alkene oligomerization
Yurkova, L. L.,Lermontov, S. A.,Kazachenko, V. P.,Ivanov, V. K.,Lermontov, A. S.,Baranchikov, A. E.,Vasil'Eva, L. P.
, p. 1012 - 1019,8 (2012)
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.
Structural effects on the Grunwald-Winstein correlations in the solvolysis of some simple tertiary alkyl chlorides
Takeuchi, Ken'ichi,Ohga, Yasushi,Ushino, Takuhiro,Takasuka, Masaaki
, p. 717 - 724 (1997)
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.
Etherification of glycerol by isobutylene: Tuning the product composition
Lee, Hee Jong,Seung, Doyoung,Jung, Kwang S.,Kim, Hwayong,Filimonov, Igor N.
, p. 235 - 244 (2010)
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.
Synthesis of Trialkylamines with Extreme Steric Hindrance and Their Decay by a Hofmann-like Elimination Reaction
Banert, Klaus,Hagedorn, Manfred,Heck, Manuel,Hertel, Raphael,Ihle, Andreas,Müller, Ioana,Pester, Tom,Shoker, Tharallah,Rablen, Paul R.
, p. 13630 - 13643 (2020)
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.
The competitive reactions between electron transfer and radical addition in free radical reactions
Wu, Yuh-Wern,Lu, Cheng-Yi
, p. 1129 - 1134 (2001)
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.
