Alcohols Ishikawa reagent

Secondary and tertiary alcohols react with the Ishikawa reagent to give the corresponding fluorides and, usually, considerable amounts of alkenes or ethers [57] (Table 5]... 

V,A -Diethyl-l.l,2,3,3,3-hexafluoropropanamine (10, Ishikawa reagent) is a mild fluorinating agent which can convert primary, secondary and tertiary alcohols (which do not easily form carbanions) to their corresponding fluorides (see Table 3). It can also readily fluorinate carboxylic acids to their corresponding acid fluorides. 

The batch sheet for operation of the process was written to ensure that the correct amount of the alcohol intermediate (RCH2OH) was added to consume the Ishikawa reagent produced. 

Simple primary alcohols generally give high yields of the expected fluoro compounds when treated with the Yarovenko reagent, 2-chloro-Af,Af-diethyl-l,l,2-trifluorocthylamine (1). or the Ishikawa reagent, A, A-diethyl-l,l,2,3,3,3-hexafluoropropylamine (2) examples arc given in Tables 6 and 7. 

Table 7. Fluorination of Primary Alcohols with the Ishikawa Reagent (2)...

Some unusual behaviour was displayed by the benzodisilacyclobutane 84 as described by Ishikawa et al.95 When thermolyzed, it appeared to form the quinodimethane bis-silene species 85 shown in Scheme 13, as confirmed by trapping reactions with f-butyl alcohol, alkynes, or aldehydes, all of which added in a 1,4-manner (see Scheme 13). In the absence of a trapping reagent, 85 decomposed, but not to 86 as claimed earlier.95 ... 

Reaction of perfluoropropene with diethylamine yields (F)-fluoroenaminc 3 and fluoro-alkylamine 4 in a 1 1 or 3 1 mixture (depending on the reaction conditions used). This mixture is known as Ishikawa s reagent and can be used (without separation) for the transformation of alkyl alcohols to fluoroalkanes (see Vol. ElOb/Part 1. p99).218... 

The active fluorinating agent of the mixture is 2, while 3 alone docs not fluorinate alcohols however, 3 is converted into 2 by addition of the hydrogen fluoride which is liberated by reaction of 2 with an alcohol and thus is also consumed during the reaction. The use of dibutylamine and piperidine instead of diethylamine has also been described by Ishikawa. but there is no difference in the reactivity of the products as fluorinating reagents. 

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