Tert Butyl cation chloride

Step 3 Capture of tert butyl cation by chloride ion... 

The transition state for this step involves partial bond formation between tert butyl cation and chloride ion... 

FIGURE 4 11 Combi nation of tert butyl cation and chloride anion to give tert butyl chloride In phase overlap between a vacant p orbital of (CHbIbC and a filled p orbital of Cr gives a C—Cl (T bond... 

The major difference between the two mechanisms is the second step The second step m the reaction of tert butyl alcohol with hydrogen chloride is the ummolecular dis sociation of tert butyloxonium ion to tert butyl cation and water Heptyloxonium ion however instead of dissociating to an unstable primary carbocation reacts differently It IS attacked by bromide ion which acts as a nucleophile We can represent the transition state for this step as... 

These common features suggest that carbocations are key intermediates m alcohol dehydra tions just as they are m the reaction of alcohols with hydrogen halides Figure 5 6 portrays a three step mechanism for the acid catalyzed dehydration of tert butyl alcohol Steps 1 and 2 describe the generation of tert butyl cation by a process similar to that which led to its for matron as an intermediate m the reaction of tert butyl alcohol with hydrogen chloride... 

Both compounds react by an S l mechanism and their relative rates reflect their acti vation energies for carbocation formation Because the allylic chloride is more reactive we reason that it ionizes more rapidly because it forms a more stable carbocation Struc turally the two carbocations differ m that the allylic carbocation has a vinyl substituent on Its positively charged carbon m place of one of the methyl groups of tert butyl cation... 

Step 1 Once generated by the reaction of tert butyl chloride and aluminum chloride tert butyl cation attacks the TT electrons of benzene and a carbon-carbon bond is formed... 

FIGURE 4.10 Potential energy diagram for reaction of tert-butyl cation with chloride anion. 

Arnett and Hofelich measured heats of reaction of a variety of alcohols with SbF5/FS03H in sulfuryl chloride fluoride to form their respective carbocations at constant temperature (-40 °C). In this superacid medium there were no ion-pair complications and hence reliable calorimetric data were obtained for various cyclopropyl and phenyl substituted cations. The heats of reaction for the formation of tricyclopropylcarbinyl cation (-59.2 kcalmoT ), trityl cation ( 9.0 kcalmoT ) and tert-butyl cation (-35.5 kcalmol ) show that the relative order of the stabilization of the cationic center is cyclopropyl >... 

In the third step, the carbocation intermediate is captured by a chloride ion, and the energy barrier for this cation-anion combination is relatively low. The transition state is characterized by partial bond formation between the nucleophile (chloride anion) and the electrophile (tert-butyl cation). 

Great question First, let s review what led you to this question. In the unimolecular substitution reaction we looked at, an intermediate tert-butyl cation was formed, but in the bimolecular substitution reaction, the cation (this time a methyl cation, CH3+) was too high in energy. In this case the hydroxide ion directly displaced the chloride ion. 

Step 3 Reaction of tert-Butyl Cation with Chloride Ion... 

Physical organic studies have demonstrated that lerl-butylsulfonyl chloride decomposes cleanly to the tert-butyl cation in water over a pH range 3.5 to 13.0. Clean teri-butyl cation formation is also the only significant reaction in methanol-chloroform. The subsequent product spectrum is a function of the reaction conditions. tert-Butylsulfonyl chloride, is used for the tert-butylation of aromatic compounds in a Friedel-Crafts desulfonylative alkylation in the presence of aluminum chloride-nitromethane as catalyst at 25 °C (eq 1). Alkylation products were obtained free of contamination by the sulfonylation product. 

The mechanism for the reaction of tert-butyl chloride with water (Section 6.9) can be described in three steps. See the box Mechanism for the SnI Reaction below, with a schematic free-energy diagram highlighted for each step. Two distinct intermediates are formed. The first step is the slow step—it is the rate-determining step. In it a molecule of tert-butyl chloride ionizes and becomes a tert-butyl cation and a chloride ion. In the transition state for this step the carbon-chlorine bond of tert-butyl chloride is largely broken and ions are beginning to develop ... 

Cyclization takes place when tert-butylisocyanide, benzaldehyde, anilinium chloride, and carbonyl(dicyano)cyclopentadienyl ferrate are reacted, the carbene complex 42 being the result (95JOM(491)135). /50-butyraldehyde, tert-butyl isocyanide, ammonium hexafluorophosphate, and [(T -Cp)Fe(CO)(CN)2] give the cationic bis-carbene 43. 

With regard to the mechanism of these Pd°-catalyzed reactions, little is known in addition to what is shown in Scheme 10-62. In our opinion, the much higher yields with diazonium tetrafluoroborates compared with the chlorides and bromides, and the low yields and diazo tar formation in the one-pot method using arylamines and tert-butyl nitrites (Kikukawa et al., 1981 a) indicate a heterolytic mechanism for reactions under optimal conditions. The arylpalladium compound is probably a tetra-fluoroborate salt of the cation Ar-Pd+, which dissociates into Ar+ +Pd° before or after addition to the alkene. An aryldiazenido complex of Pd(PPh3)3 (10.25) was obtained together with its dediazoniation product, the corresponding arylpalladium complex 10.26, in the reaction of Scheme 10-64 by Yamashita et al. (1980). Aryldiazenido complexes with compounds of transition metals other than Pd are discussed in the context of metal complexes with diazo compounds (Zollinger, 1995, Sec. 10.1). 

There is direct evidence, from IR and NMR spectra, that the re/T-butyl cation is quantitatively formed when tert-butyl chloride reacts with AICI3 in anhydrous liquid HCl. In the case of alkenes, Markovnikov s rule (p. 984) is followed. Carbocation formation is particularly easy from some reagents, because of the stability of the cations. Triphenyhnethyl chloride and 1-chloroadamantane alkylate activated... 

Sometimes acylium ions lose carbon monoxide to generate an ordinary carbonium ion. It will be recalled that free acyl radicals exhibit similar behavior at high temperatures. Whether or not the loss of carbon monoxide takes place seems to depend on the stability of the resulting carbonium ion and on the speed with which the acylium ion is removed by competing reactions. Thus no decarbonylation is observed in Friedel-Crafts reactions of benzoyl chloride, the phenyl cation being rather unstable. But attempts to make pivaloyl benzene by the Friedel-Crafts reaction produce tert-butyl benzene instead. With compound XLIV cyclization competes with decarbonylation, but this competition is not successful in the case of compound XLV in which the ring is deactivated.263... 

Another differential reaction is copolymerization. An equi-molar mixture of styrene and methyl methacrylate gives copolymers of different composition depending on the initiator. The radical chains started by benzoyl peroxide are 51 % polystyrene, the cationic chains from stannic chloride or boron trifluoride etherate are 100% polystyrene, and the anionic chains from sodium or potassium are more than 99 % polymethyl methacrylate.444 The radicals attack either monomer indiscriminately, the carbanions prefer methyl methacrylate and the carbonium ions prefer styrene. As can be seen from the data of Table XIV, the reactivity of a radical varies considerably with its structure, and it is worth considering whether this variability would be enough to make a radical derived from sodium or potassium give 99 % polymethyl methacrylate.446 If so, the alkali metal intitiated polymerization would not need to be a carbanionic chain reaction. However, the polymer initiated by triphenylmethyl sodium is also about 99% polymethyl methacrylate, whereas tert-butyl peroxide and >-chlorobenzoyl peroxide give 49 to 51 % styrene in the initial polymer.445... 

Priola, and Ferraris [36] had done what was considered impossible, namely to prepare a stable crystalline product from tert-butyl chloride and A1C13, and that they had used it to initiate polymerisation. From our own experiments we concluded independently that stable tert. aliphatic cations can be prepared and our discussion has been based on this view throughout. Our conclusion is derived from the following argument ... 

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