Lewis structure aluminum trichloride

The electrophile, an acyl cation, is generated in a manner similar to that outlined in Figure 17.4 for the generation of the carbocation electrophile from an alkyl halide. First the Lewis acid, aluminum trichloride, complexes with the chlorine of the acyl chloride. Then A1C14 leaves, generating an acyl cation. The acyl cation is actually more stable than most other carbocations that we have encountered because it has a resonance structure that has the octet rule satisfied for all of the atoms ... 

The reaction of aryl azides with alkenes in the presence of aluminum trichloride gave different products depending on the structure and the geometry of the alkene, the reaction proceeds via the intermediacy of an aziridine 8 complexed with the Lewis acid. Thus aziridines 9 were cleanly obtained from cycloheptene and (Z)-cyclooctene, however, from cyclopentene and cyclohexene a mixture of allylic amines 10 and /5-chloro amines 11 was produced86- 87. The use of 4-chlorophenyl azide in the reaction with cyclohexene gave only a tar. 

Regitz and co-workers have reported a spirocyclotrimerization of a stable phosphaalkyne with aluminum trichloride in a 3 1 molar ratio (Scheme 3) <92AG(E)1055>. The reaction gives a betaine with the incorporation of the Lewis acid and its structure, bearing a spiranic diphosphirene, was confirmed by x-ray crystal structure analysis (cf (4e), Table 1). 

Addition compounds of 1,3,5-triazine with several Lewis acids can also be formed in which one or two molecules of the Lewis acid are bound to one molecule of 1,3,5-triazine. The structures of the obtained adducts 4 depend on the nature of the metal cation examples of Lewis acids that can be used in this reaction are aluminum trichloride, titanium(IV) chloride, tin(IV) chloride and antimony(V) chloride.26 In inert solvents, boron trifluoride and 1,3,5-triazine produce a stable adduct with the appearance of fine needles.28... 

A mechanism for the final step is shown below. Overall, this step constitutes two subsequent electrophUic aromatic substitution reactions, resulting in the formation of two new B-C bonds. Addition of aluminum trichloride, a Lewis acid, serves to enhance the electrophilicity of the boron by forming a complex with one of the chlorine atoms. The boron is then attacked by one of the pendant arenes, with subsequent loss of AlCLt and formation of a resonance-stabilized sigma complex (several, but not all, of the many resonance structures are shown). Deprotonation with AlCl4 restores aromaticity, giving a neutral intermediate. An identical sequence of mechanistic steps (complexation with AICI3, attack of the arene, loss of AlCLt and deprotonation) results in fte formation of the second B-C bond, thus producing compound 3. 

Complex Formation. B-Trichloroborazine was reported to readily form crystalline adducts of uncertain structure with pyridine (131). The Lewis acids aluminum tribromide or gallium trichloride form 1 1 adducts with hexamethylborazine (eq. 36) in which the metal atom coordinates with a nitrogen with loss of planarity of the ring (132,133). 

Many ot-olefins were polymerized by the Ziegler-Natta catalysts to yield high polymers and many such polymers were found to be stereospecific and crystalline. Polymerizations of a-olefins of the general structure of CH2 = CH — (CH2) — R, where x is 0-3 and R denotes CH3, CH-(CH3)2, C(CH3)3, or CsHs, can be catalyzed by vanadium trichloride/triethyl aluminum [80]. The conversions are fairly high, though higher crystallinity can be obtained with titanium-based catalysts [81]. Addition of Lewis bases, such as ( 4119)20, (C4H9)3N, or ( 4119)3 , to the catalyst system further increases crystallinity [82]. 

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