2-Chloroallyl cation

Dichlorination of tetramethylallene afforded 3-chloro-2,4-dimethyl-l,3-pentadiene as the single product, whereas the same reaction of 1,1-dimethylallene yielded a mixture of 2-chloro-3-methyl-l,3-butadiene, 2,3-dichloro-3-methyl-l-butene and 1,2-dichloro-3-methyl-2-butene, indicating the intermediacy of the 2-chloroallylic cationic intermediate 11 [13]. 

The 2-chloroallyl cation generated by matrix isolation has been studied by FT-IR spectroscopy and calculations [MP2(fc)/6-311G(d,p) level].235 Structure 78 of Cs symmetry with bridging chlorine, proposed earlier,162 was found to be less stable by 7.5 kcal mol 1 than cation 79 of C2v symmetry and could not be found by spectroscopy. Furthermore, in contrast to 1- or 3-chloroallyl cations, the centrally positioned chlorine does not contribute to charge delocalization through back-donation as a consequence of the Ji-orbital noninteraction between the n electrons of Cl and the LUMO of the allyl cation.236... 

The challenge of elucidating the structure of the 2-chloroaIlyl cation prompted Kidemet et al to embark on a combined computational and FT-IR investigation. In going from the 1-chloroallyl cation to the 2-chloroallyl cation the charge on chlorine decreases fi om 0.333 to 0.156 (NPA) or from 0.127 to —0.001 (AIM), respectively. Also, the C-Cl bond order, calculated by the AIM method changes fi om 1.445 in the tra s-l-chloroallyl cation to 1.183 in the 2-chloroallyl cation. 

In the first step, Ag+ promotes the departure of Cl- to give a cyclopropyl carbocation. This undergoes two-electron disrotatory electrocyclic ring opening to give the chloroallylic cation, in which the empty orbital is localized on Cl and C3. Then 09 can add to C3 desilylation then gives the product. 

Information has been obtained on the C—C stretching vibrations of various enyl carbenium ions. The IR spectrum of [CClj CCl CCl2] shows this penta-chloroallyl cation to have a planar structure, the antisymmetric stretching vibration of its C—C bonds displaying itself at 1350 cm and the symmetric, at 1040 cm ... 

Cationic surfactants contain a positively charged headgroup and are typically used as conditioners to improve hair manageability and reduce static. Cationic surfactants are especially irritating to eyes when used in high concentrations but are safe and useful in low amounts. Quatemium-15 (chloroallyl methanamine chloride, Fig. 7.9.4) is a cationic surfactant included in shampoo formulations... 

Figure 7.9.4 The cationic surfactant quatemium-15 (chloroallyl methanamine chloride).

CAS 4080-31-3 51229-78-8 EINECS/ELINCS 223-805-0 Synonyms Chlorallyl methenamine chloride N-(3-Chloroallyl) hexaminium chloride 1-(3-Chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride Methenamine 3-chloroallylochbride Ciassification Quaternary ammonium salt Empirical C,H,6CIN, Cl Formula C H,2N,(CH2CHCHCI)CI Properties Cationic Toxicology TSCA listed... 

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