In:
Chemistry – A European Journal, Wiley, Vol. 10, No. 19 ( 2004-10-04), p. 4886-4893
Abstract:
Imidazolium chlorides with one or two carboxylic acid substituent groups, 1‐methyl‐3‐alkylcarboxylic acid imidazolium chloride, [Me{(CH 2 ) n COOH}im]Cl ( n= 1, 3), and 1,3‐dialkylcarboxylic acid imidazolium chloride, [{(CH 2 ) n COOH} 2 im]Cl ( n= 1, 3), have been synthesized via their corresponding acid esters. Deprotonation of the carboxylic acid functionalized imidazolium chlorides with triethylamine affords the corresponding zwitterions [Me{(CH 2 ) n COO}im] ( n =1, 3) and [{(CH 2 ) n COOH}{(CH 2 ) n COO}im] ( n =1, 3). Subsequent reaction of the zwitterions with strong acids gives the new imidazolium salts [Me{(CH 2 ) n COOH}im]X ( n =1, 3; X=BF 4 , CF 3 SO 3 ) and [{(CH 2 ) n COOH} 2 im]X ( n =1, 3; X=BF 4 , CF 3 SO 3 ), which exhibit melting points as low as −61 °C. The solid‐state structures of two of the carboxylic acid functionalized imidazolium salts have been determined by single‐crystal X‐ray diffraction analysis. Extensive hydrogen bonding is present between the chloride and the imidazolium, with eight Cl⋅⋅⋅H interactions below 3 Å. The p K a values of all the salts, determined by potentiometric titration, lie between 1.33 and 4.59 at 25 °C.
Type of Medium:
Online Resource
ISSN:
0947-6539
,
1521-3765
DOI:
10.1002/chem.200400145
Language:
English
Publisher:
Wiley
Publication Date:
2004
detail.hit.zdb_id:
1478547-X
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