Chloride complexes

There appear to be at least two zinc chloride complexes of pyridine, one of m.p. 207 and composition 2CsH,N,ZnCh, sind the other of m.p. 152° and probable composition 2C,H,N,ZnClt,HCl. The former is slightly soluble in water and in hot ethyl alcohol the latter passes into the former in aqueous solution, is readily soluble in hot absolute ethanol and can therefore be readily recrystaUised from this solvent. 

Secondary alkyl halides react by a similar mechanism involving attack on benzene by a secondary carbocation Methyl and ethyl halides do not form carbocations when treated with aluminum chloride but do alkylate benzene under Friedel-Crafts conditions The aluminum chloride complexes of methyl and ethyl halides contain highly polarized carbon-halogen bonds and these complexes are the electrophilic species that react with benzene... 

The use of silver fluoroborate as a catalyst or reagent often depends on the precipitation of a silver haUde. Thus the silver ion abstracts a CU from a rhodium chloride complex, ((CgH )2As)2(CO)RhCl, yielding the cationic rhodium fluoroborate [30935-54-7] hydrogenation catalyst (99). The complexing tendency of olefins for AgBF has led to the development of chemisorption methods for ethylene separation (100,101). Copper(I) fluoroborate [14708-11-3] also forms complexes with olefins hydrocarbon separations are effected by similar means (102). 

Ai lepiesents an aiyl group. Diaiyl products are obtained after long reaction times. Other Friedel-Crafts catalysts, eg, ZnCl2, FeCl2, FIF, and BF, can also be used. In most cases, stoichiometric amounts of the catalyst ate requited. Flowever, strong complexation of the phosphine by the catalyst necessitates separation by vacuum distillation, hydrolysis, or addition of reagents such as POCl to form more stable aluminum chloride complexes. Whereas yields up to 70—80% are possible for some aryl derivatives, yields of aliphatic derivatives are generally much less (19). 

Aluminum chloride dissolves readily in chlorinated solvents such as chloroform, methylene chloride, and carbon tetrachloride. In polar aprotic solvents, such as acetonitrile, ethyl ether, anisole, nitromethane, and nitrobenzene, it dissolves forming a complex with the solvent. The catalytic activity of aluminum chloride is moderated by these complexes. Anhydrous aluminum chloride reacts vigorously with most protic solvents, such as water and alcohols. The ability to catalyze alkylation reactions is lost by complexing aluminum chloride with these protic solvents. However, small amounts of these "procatalysts" can promote the formation of catalyticaHy active aluminum chloride complexes. 

A quinoline—bromine adduct in hot carbon tetrachloride containing pyridine gives a 90% yield of 3-bromoquinoline (21) 3-chloroquinoline [612-59-9] is prepared by an analogous route, but in poorer yield. A quinoline—aluminum chloride complex heated with bromine gives a 78% yield of 5-bromoquinoline [165-18-3] (22). Equal quantities of 5- and 8-bromoquinoline [16567-18-3] are formed when quinoline is treated with one equivalent of bromine in concentrated sulfuric acid containing silver sulfate (23). 

A number of improvements have been made in these syntheses. For example, the use of ethanoHc ferric chloride and zinc chloride produces a good yield of 2-isopropylquinoline [17507-24-3] from isovaleraldehyde (46). The purification of 2-methylquinoline is facHitated through precipitation. A cmde quinaldine—hydrochloride and zinc chloride complex is prepared and then treated with aqueous base (47). 

The reaction of higher alkyl chlorides with tin metal at 235°C is not practical because of the thermal decomposition which occurs before the products can be removed from the reaction zone. The reaction temperature necessary for the formation of dimethyl tin dichloride can be lowered considerably by the use of certain catalysts. Quaternary ammonium and phosphonium iodides allow the reaction to proceed in good yield at 150—160°C (109). An improvement in the process involves the use of amine—stannic chloride complexes or mixtures of stannic chloride and a quaternary ammonium or phosphonium compound (110). Use of these catalysts is claimed to yield dimethyl tin dichloride containing less than 0.1 wt % trimethyl tin chloride. Catalyzed direct reactions under pressure are used commercially to manufacture dimethyl tin dichloride. 

BenZotrichloride Method. The central carbon atom of the dye is supphed by the trichloromethyl group from iJ-chlorobenzotrichloride. Both symmetrical and unsymmetrical triphenyhnethane dyes suitable for acryhc fibers are prepared by this method. 4-Chlorobenzotrichloride is condensed with excess chlorobenzene in the presence of a Lewis acid such as aluminium chloride to produce the intermediate aluminium chloride complex of 4,4, 4"-trichlorotriphenylmethyl chloride (18). Stepwise nucleophihc substitution of the chlorine atoms of this intermediate is achieved by successive reactions with different arylamines to give both symmetrical (51) and unsymmetrical dyes (52), eg, N-(2-chlorophenyl)-4-[(4-chlorophenyl) [4-[(3-methylphenyl)imino]-2,5-cyclohexadien-l-yhdene]methyl]benzenaminemonohydrochloride [85356-86-1J (19) from. w-toluidine and o-chloroaniline. 

The most useful general method for the C-acylation of pyrroles is the Vilsmeier-Haack procedure in which pyrrole is treated with the phosphoryl chloride complex (55a, b) of an AiA-dialkylamide (54). The intermediate imine salt (56) is hydrolyzed subsequently under mildly alkaline conditions to give the acylated pyrrole (57). On treatment of the imminium salt (56 R =H) with hydroxylamine hydrochloride and one equivalent of pyridine and heating in DMF, 2-cyanopyrrole (58) is formed (80CJC409). 

Porphyrin, octaethyl-, thallium chloride complex cyclic voltammetry, 4, 399 <73JA5140)... 

Thermodynamic data show that the stabilities of the caesium chloride-metal chloride complexes are greater than the conesponding sodium and potassium compounds, and tire fluorides form complexes more readily tlrair the chlorides, in the solid state. It would seem that tire stabilities of these compounds would transfer into tire liquid state. In fact, it has been possible to account for the heats of formation of molten salt mixtures by the assumption that molten complex salts contain complex as well as simple anions, so tlrat tire heat of formation of the liquid mixtures is tire mole fraction weighted product of the pure components and the complex. For example, in the CsCl-ZrCU system the heat of formation is given on each side of tire complex compound composition, the mole fraction of the compound... 

Diethyl sulfide [352-93-2] M 90.2, m 0 /15mm, 90.1 /760mm, d 0.837, n 1.443. Washed with aq 5% NaOH, then water, dried with CaCl2 and distd from sodium. Can also be dried with MgS04 or silica gel. Alternative purification is via the Hg(II) chloride complex [(Et)2S.2HgCl2] (see dimethyl sulfide). 

Tetrahydrothiophene [110-01-0] M 88.2, m -96 , b 14.5 /10mm, 120.9 /760mm, d 0.997, n 1.5289. Crude material was purified by crystn of the mercuric chloride complex to a constant melting point. It was then regenerated, washed, dried, and fractionally distd. [Whitehead et al. 7 Am Chem Soc 73 3632 7957.] It has been dried over Na2S04 and distd in a vacuum [Roberts and Friend J Am Chem Soc 108 7204 1986]. 

Bicyclo[2.2.1]hepta-2,5-diene rhodium (I) chloride dimer (norbornadiene rhodium chloride complex dimer) [12257-42-0] M 462, m 240°(dec). Recrystd from hot CHCl3-pet ether as fine crystals soluble in CHCI3 and C H but almost insoluble in Et20 or pet ether. [7 Chem Soc 3178 1959.]... 

Cobalt (II) meso-5.10,15,20-tetraphenylporphine complex [14172-90-8] M 671.7. Brown crystals from Et20 or CHCl3-MeOH (cf iron chloride complex). Recrystd by extraction (Soxhlet) with CgHg. Sol in most organic solvents except MeOH and pet ether. [UV, IR J Am Chem Soc 70 1808 7948 81 5111 7959.]... 

Iron (III) meso-5,10,15,20-tetraphenylporphine chloride complex [16456-81-8] M 704.0. Crystallise by extraction from a thimble (Soxhlet) with CHCI3. Concentrate the extract to ca lOmL and add ca 80mL of hot MeOH. Dark blue crystals separate on cooling. It can be recrystallised several times from CHCl3-MeOH. Avoid prolonged heating. It is quite soluble in organic solvents but insoluble in pet ether. [J Am Chem Soc 70 1808 1948 UV 73 4315 7957.]... 

Nuclear halogenation of acetophenone depends on formation of the aluminum chloride complex. If less than one equivalent of aluminum chloride is used, side-chain halogenation occurs. 3-Bromoacetophenone has been prepared from 3-aminoaceto-phenone by the Sandmeyer reaction. The synthesis described here has been taken from work of the submitters, who have used it to prepare many 3-bromo- and 3-chloroacetophenones and benzaldehydes, as well as more highly halogenated ones (Notes 7 and 8). 

Methylene dianiline is normally a very reactive diamine in the presence of diisocyanates. However, a sodium chloride complex that is relatively unreactive at room temperature is commercially available. When the complex is heated to 21°C, it activates to quickly cure the urethane [76]. 

The next step in the calculations involves consideration of the allylic alcohol-carbe-noid complexes (Fig. 3.28). The simple alkoxide is represented by RT3. Coordination of this zinc alkoxide with any number of other molecules can be envisioned. The complexation of ZnCl2 to the oxygen of the alkoxide yields RT4. Due to the Lewis acidic nature of the zinc atom, dimerization of the zinc alkoxide cannot be ruled out. Hence, a simplified dimeric structure is represented in RTS. The remaining structures, RT6 and RT7 (Fig. 3.29), represent alternative zinc chloride complexes of RT3 differing from RT4. Analysis of the energetics of the cyclopropanation from each of these encounter complexes should yield information regarding the structure of the methylene transfer transition state. 

The activation energy for the favored transition state TS4 (22.8 kcal mol ) is still somewhat high. Still, the qualitative predictions of enhanced reactivity of the zinc alkoxide-zinc chloride complexes are in full agreement with contemporary ideas about this reaction and represent a major advance in the theoretical understanding of the cyclopropanation process. 

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