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Convenient Syntheses of a Family of Easily Recoverable Fluorous Primary, Secondary, and Tertiary Aliphatic Amines NH 3 − x [(CH 2 ) m (CF 2 ) 7 CF 3 ] x ( m = 3−5; x = 1−3) − Fine Tuning of Basicities and Fluorous Phase Affinities
Author(s) -
Rocaboy Christian,
Bauer Walter,
Gladysz John A.
Publication year - 2000
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200007)2000:14<2621::aid-ejoc2621>3.0.co;2-h
Subject(s) - chemistry , protonation , aldehyde , reagent , toluene , amine gas treating , primary (astronomy) , medicinal chemistry , tertiary amine , organic chemistry , catalysis , ion , physics , astronomy
The alcohols HOCH 2 (CH 2 ) m −1 (CF 2 ) 7 CF 3 [ m = 3−5; (CF 2 ) 7 CF 3 = R f8 ] are oxidized to aldehydes O=CH(CH 2 ) m −1 R f8 (Dess−Martin reagent, 90−96%), which are condensed with NH 2 CH 2 C 6 H 5 and Na(AcO) 3 BH to give benzylamines NH(CH 2 C 6 H 5 )[(CH 2 ) m R f8 ] (excess amine, 88−90%) or N(CH 2 C 6 H 5 )[(CH 2 ) m R f8 ] 2 (excess aldehyde, 85−91%). Subsequent hydrogenolyses (Pd/C, 1 atm H 2 ) give the title primary amines NH 2 [(CH 2 ) m R f8 ] ( 10−12 ; 98−99%) or secondary amines NH[(CH 2 ) m R f8 ] 2 ( 13−15 ; 92−99%). The aldehyde condensations are repeated with 13−15 to give tertiary amines N[(CH 2 ) m R f8 ] 3 ( 16−18 ; 86−97%) with very high fluorous phase affinities. These decrease monotonically as the numbers of CH 2 groups increase or R f8 groups decrease (CF 3 C 6 F 11 /toluene, 24 °C, 16/17/18/13/14/15/10/11/12 : >99.7:<0.3, >99.7:<0.3, 99.5:0.5, 96.5:3.5, 95.1:4.9, 93.0:7.0, 70.0:30.0, 63.2:36.8, 56.9:43.1). The relative basicities towards CF 3 CO 2 H are probed by NMR in CDCl 3 . Competitions between N(CH 2 CH 3 ) 3 or N[(CH 2 ) 11 CH 3 ] 3 and 16−18 show 100% or >95%, >95% or 85−90%, and 85−90 or 65−70% protonation of the former. Competitions between 16/17 , 17/18 , and 16/18 show 60%, 85−90%, and >95% protonation of the latter. Thus, an inductive effect of the R f8 group is still detected through five CH 2 groups.