Trichloride solvent system

A 1 2 mixture of l-methyl-3-ethylimidazolium chloride and aluminum trichloride, an ionic liquid that melts below room temperature, has been recommended recently as solvent and catalyst for Friedel-Crafts alkylation and acylation reactions of aromatics (Boon et al., 1986), and as solvent for UV/Vis- and IR-spectroscopic investigations of transition metal halide complexes (Appleby et al., 1986). The corresponding 1-methyl-3-ethylimidazolium tetrachloroborate (as well as -butylpyridinium tetrachlo-roborate) represent new molten salt solvent systems, stable and liquid at room temperature (Williams et al., 1986). 

When ruthenium dioxide or ruthenium trichloride is used to catalyze periodate cleavages, it is likely that Ru04 is first formed (equation 33) and then reacts with the double bond as depicted in equations (31) and (32). Sharpless and coworkers have demonstrated that the best solvent system for this reaction is a mixture of carbon tetrachloride, acetonitrile and water, in a volume ratio of 2 2 3. 

Reaction of quinazoline, benzoyl chloride, and trimethylsilyl cyanide in a 2 2 1 molar ratio in anhydrous dichloromethane affords l,3-dibenzoyl-2,4-dicyano-l,2,3,4-tetrahydroquinazoline in 25% yield. When the reaction of quinazoline with trimethylsilyl cyanide and benzoyl chloride or a,/ -unsaturated acid chlorides [molar ratio (1 2.2 2.2)] is carried out in the presence of a catalytic amount of anhydrous aluminum trichloride, a more vigorous reaction takes place and the quinazoline di-Reissert compounds 22 are obtained in higher yield. Attempted Reissert compound formation with benzoyl chloride and potassium cyanide using a dichloromethane/water solvent system leads to ring opening (cf. pp 84, 149). 

Some aromatic hydrocarbons (e.g. perylene) give cation radicals in (neat) antimony trichloride solutions at 75° (Porter et al., 1970 Johnson, 1971). However, the cation radicals are not formed in the absence of oxygen. In fact, molten antimony trichloride can be used as a solvent at 99° for the anodic oxidation of perylene, naphthacene, and other polynuclear aromatics, provided that the electrolyte (e.g. KC1) is highly dissociated (Bauer et al., 1971). When a more covalent electrolyte (e.g. A1C13) is used, the solvent system itself becomes the oxidant [(17) and (18)]. 

The height of formalism was reached by Wickert in his definitions of acids and bases in terms of the solvent system. He overlooks such experimental behavior as amphoterism in order to state his definitions wholly in terms of ions. Shatenstein also has pointed out one of the several inconsistencies in Wickert s presentation. Although Wickert defines an acid as an ionic compound the cation of which has an incomplete electronic configuration, he recognizes that ammonium salts are acids in ammonia. Another contradiction of the experimental facts is his listing of antimony trichloride but not aluminum chloride as an acid. 

Erom 1955—1975, the Ziegler-Natta catalyst (91), which is titanium trichloride used in combination with diethylaluminum chloride, was the catalyst system for propylene polymerization. However, its low activity, which is less than 1000 g polymer/g catalyst in most cases, and low selectivity (ca 90% to isotactic polymer) required polypropylene manufacturers to purify the reactor product by washing out spent catalyst residues and removing unwanted atactic polymer by solvent extraction. These operations added significantly to the cost of pre-1980 polypropylene. 

Alkanesulfinyl chlorides have been prepared by the action of thionyl chloride on alkanesulfinic acids and by the solvolysis of alkylsulfur trichlorides with water, alcohols, and organic acids. The present procedure, which appears to be general for the preparation of sulfinyl chlorides in either the aliphatic or the aromatic series, is based on an improvement in the solvolysis method whereby the use of inert solvent is eliminated and the reaction is carried out in a one-phase system. ... 

Conjugated olefinic systems have also been used in reaction with phosphorus-halogen species. For example, methylphosphonic dichloride adds regioselectively to acrylic acid in the presence of phosphorus trichloride (used as solvent), to produce the acid chloride 3-phosphonopropionyl chloride (Equation 4.35).158... 

The order in which the components of the catalytic system (a-titanium trichloride and trialkylaluminum), the solvent (n-heptane), and the olefin are brought together has no practical influence on the polymerization rate. 

To 68 g. (0.5 mole) of phenylacetic acid (Org. Syn. 2, 63) (Note 1) in a i-l. flask fitted with a reflux condenser and a system for absorbing hydrogen chloride (Org. Syn. 8, 27) (Note 2), is added 35 g. (0.25 mole) of phosphorus trichloride. The mixture is heated on a steam bath for one hour. While the contents of the flask are still warm, 400 cc. of dry benzene is added. The benzene solution of phenylacetyl chloride is decanted from the residue of phosphorous acid on 75 g. (0.56 mole) of anhydrous aluminum chloride in a dry, i-l. flask which can be fitted to the same condenser. The reaction is vigorous at first and cooling is necessary. The mixture is refluxed for one hour on a steam bath, then cooled and poured into a mixture of 500 g. of cracked ice and 200 g. of concentrated hydrochloric acid. The benzene layer is separated, and the aqueous layer is extracted once with a mixture of 100 cc. of benzene and 100 cc. of ether (Note 2). The ether-benzene solution is washed once with 100 cc. of water (Note 3), and then dried over 40-50 g. of calcium chloride. The solution is filtered (Note 4) with suction into a i-l. Claiscn flask and the solvent is removed by distillation under reduced pressure (Note 5) the residue consists of a brown oil which solidifies on cooling. 

Much work has been done to develop catalyst systems that optimize yield and reduce side reactions. The reaction has an induction period, which depends on the temperature and the amount of catalyst.8 An early patent from Bayer claims that a nearly quantitative yield can be achieved in the conversion of l,2-dibromo-1-chloro-l.2.2-trifluoroethane(5) into 1,1-di-bromo-l-chloro-2,2.2-trifluoroethane (6) when aluminum tribromide is used in 2-broino-2-chloro-1,1,1-trifluoroethane (4) as solvent.12 A Japanese patent26 describes the activation of aluminum trichloride or alumina by pretreatinent with l,L2-trichloro-l,2,2-trifluoroethane (1) (see discussion of compound 19, vide infra). A later patent claims that aluminum trichloride and tribromide can also be activated by complexing with 1,1-dichloro- (CF3CFC12) and 1,1-dibromo-1,2,2,2-tetrafluoroethane (CF3CFBr2), respectively 2 an example of the latter is shown in the formation of bromofluoroalkane 10. 

Although no direct oxygen transfer reactions from well-characterized rhodium-hydroperoxo or -alkylperoxo complexes to alkenes have yet been reported, these species are probably involved in the rhodium-copper catalyzed ketonization of terminal alkenes by 02, as previously shown in Section 61.3.2.1.3. Rhodium trichloride has been used to catalyze the ketonization of terminal alkenes by H202 or TBHP in alcoholic solvents, but these reactions occur less efficiently than with the Rh/Cu/02 system.207... 

Acidic chloroaluminate ionic liquids were used as reaction media for Friedel-Crafts reactions as early as 1976 [34], Systematic investigations into Friedel-Crafts alkylations of benzene with the same acidic systems followed in 1986 by Wilkes et al. [35]. The alkylation of benzene with alkenes in acidic imidazolium chloroaluminate melts was disclosed in a patent by BP Chemicals in 1994 [36]. Here, as advantages over the reaction with aluminum trichloride in organic solvents, claims are made regarding the easy isolation of the product, the practically total reusability of the liquid catalyst and the better selectivity to the desired products. 

Nitrogen trichloride is also produced by electrolysis of NH4CI solutions. The reaction is carried out in a buffer system because of the formed HCl. NCI3 can be extracted with organic solvents like carbon tetrachloride. Ammonium ions can be chlorinated with hypochloric acid at pH 3 -4 ... 

It has been pointed out that the initiating potential of the system MesAl-f-BuQ is hi in solvent methyl chloride, but nil in n entane. On the other hand, AIQ3 and alkylaluminium dichlorides can induce the polymerisation of isobutene in both solvents. These facts do not disprove our interpretation, since it can be readily argued that the chlorine-methyl exchanges between catalyst and cocatalyst are extremely slow in a medium of such alow dielectric constant as n-pentane and that the absence of polymerisation arises precisely from the lack of formation of di- and trichloride. 

The solvated ion pair [(C8Hi7)3NMe] [RhCl4]", formed from aqueous rhodium trichloride and Aliquat-336 in a two-phase liquid system, hydrogenates a,p-unsaturated ketones and esters selectively at the C==C double bond. The reduction of benzylideneacetone follows first-order kinetics in substrate below 0.2 M, and approaches second-order in hydrogen at partial pressures below 0.12 atm (1 atm = 101.3 kPa). The catalysis also depends on the nature of the solvent, the phase transfer catalyst and stirring rates. 

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