Interaction of boron trichloride with chloro-alcohols and with cyclic ethers

Abstract

Studies on boron trichloride-alcohol systems have been extended to include examples in which the alkyl group contains chlorine. By interaction in appropriate proportion of the respective alcohols with boron trichloride, tri-2-chloroethyl and tri-kchlorobutyl borate, di-2-chloroethyl chloroboronate, and 2-chloroethyl and 4-chlorobutyl dichloroboronites were prepared. The alkoxyboron chlorides disproportionate reversibly and form adducts with pyridine. 4-Chlorobutyl dichloroboronite unlike the 2-chloroethoxyboron chlorides, but like other alkoxyboron chlorides, decomposes to form the chloroalkane, boron trichloride, and boron trioxide. Ethylene oxide and boron trichloride gave no 1 : 1 adduct even a t -80°, but afforded 2-chloroethyl dichloroboronite. From the tetrahydrofuran-boron trichloride complex, 4-chlorobutyl dichloroboronite (or its decomposition products) was obtained only on heating. Reactions are described which differentiate dichloroboronites from their isomeric 1 : 1 complexes. TRI-2-CHLOROETKYL borate and tri-4-chlorobutyl borate have been obtained quantitatively by the interaction of boron trichloride (1 mol.) with 2-chloroethanol (3 mols.) and 4-chlorobutan-1-01 (3 mols.) respectively. In the 2-chloroethyl series, the intermediate alkoxyboron chlorides, RO*BCl, and (RO),BCI, were prepared by the appropriate reaction (1)-( 4) :(1)

The Interhalogen Cations [Br2F5]+ and [Br3F8]+

“…The observed Br–F distances compare nicely with those determined in compounds containing “isolated” [BrF 2 ] + cations. So far, only [BrF 2 ][AuF 4 ], [BrF 2 ][SbF 6 ], and [BrF 2 ] 2 [GeF 6 ] have been characterized by single‐crystal X‐ray diffraction. The Br–F distances are approximately 1.69(2) Å in these cases.…”

Reactions Of Boron Trichloride With Organic Compounds

“…in an inert solvent such as n-pentane. It has been demonstrated with a selection of primary [R = n-C3H7 (64); n-C4H9, f-C4H9 (61); n-C5Hu (2); ¿-C4H9CH2, n-C8H17 (64); = 2, CH2=C(CH3)CH2 (71); CH3CH=CHCH2, CH2=CHCH2CH2 (74); CH=CCH2 (71); C1(CH2)2 (46); C1(CH2)3 (2); C1(CH2)« (46); C1(CH2)5, CH2C1CHC1CH2 (2); CC13 (22); CF,CH2 (4); C2H6OOCCH2, C2H6OOC(CH2)2 (52)] and also secondary alcohols [R = s-C4H9 (61); f-C3H7(CH3)CH, ¿-C4H9(CH3)CH (64); n-C6H13(CH3)CH (60); CH2=CH(CH3)CH ( 74 Exceptions were those alcohols [R = C6H5CH2 (7), CeHs(CH3)CH (60)] which have a propensity for preionization, when the major product was the alkyl chloride (equation 3), this being the exclusive stoichiometry for an unsubstituted tertiary alcohol (R = ¿-C4H9 ( 61)). Boron trichloride may, however, be used for the preparation of tert-alkyl (as well as less highly branched) borates, by adding the trichloride (1 mole) to a mixture of the alcohol and pyridine (3 moles of each) in an inert solvent such as n-pentane, chloroform, or methylene dichloride at low temperature ( -10°to -80°C.…”

“…BC13 + 3ROH -> 3RC1 + B(OH)3 In general, methods according to equations and 6 are available for obtaining dialkyl chloroboronates and alkyl dichloroboronites, respectively, in almost quantitative yield, the reaction conditions being similar to those described for equation 2. Reactions 5 [R = C2H5 (2, 141), n-C3H7 (101), n-C4H9 (61), n-CeHn (2), n-CsH17 (101), f-C4H9 (61), ¿-C4H9CH2 (101), C1(CH2)2 (46); C1(CH2)3, C1(CH2)4, C1(CH2)s (2);s-C4H9, ¿-C4H9(CH3)CH, n-C6H13(CH3)CH ( 101)] and 6 [R = C2H6 (2, 141), n-C3H7 (64), n-C4H9 (61), n-C6Hn (2), n-C8H17 (64), f-C4H9 (61), ¿-C4H9CH2 (64), C1(CH2)2 (46), C1(CH2)3 (2), C1(CH2)4 (46), C1(CH2)6 (2)]…”

“…The dialkyl chloroboronates have available three possible modes of reaction: an alkyl chloride-producing decomposition (equation 13) (61,101,104), accompanied, to a relatively small extent, by an olefin-producing elimination (equation 14), and disproportionation (reverse of equations 11 and 12) (101). Disproportionation is encouraged by a reduction of pressure or distillation because the products contain the most volatile components of the equilibria, or alternatively by structural factors which inhibit the competing reactions (equations 13 and 14) [e.g., R = C1(CH2)2 (46)]. Reaction 13 has been utilized for the preparation (100 per cent yield) of a number of alkyl metaborates (104).…”

“…Reactions of boron trichloride have been studied with ethers having one oxygen atom in the molecule [ethylene oxide (46,47,85), propylene oxide (47, 85), epichlorohydrin (l-chloro-2,3-epoxypropane) (47), trimethylene oxide, tetrahydrofuran (46, 47, 85), and tetrahvdropyran (47, 85)] and with two in the molecule [1,3-dioxalane (54), 1,4-dioxan (54, 91, 98), and catechol methylene, dimethylene, propylene, and trimethylene ethers (54)]. Perfluoro-l-butyltetrahydrofuran, CsFieO, did not react with the trichloride even at 350°C.…”