Patent Application: US-67320008-A

Abstract:
this invention relates to ionic liquid solvents for chemical synthesis based on an alkyl - imidazolium cation core containing ionic liquids which have enhanced biodegradability and reduced toxicity relative to existing imidazolium bases ils such as 1 - butyl - 3 - methylimidazolium salts . many of the described ils produce a score of over 60 % biodegradability over 28 days in a biodegradability test such as the sturm test , the closed bottle test or the co 2 headspace test . the ils of the invention comprise an alkyl substituted imidazolium cationic core having a — c ═ ox — side chain in the 3 - position of the imidazole ring , wherein x ═ o , nh , n or s and an associated counteranion characterized in that the — c ═ ox side chain comprises at least one ether linkage . the biodegradable and non - toxic il may be used as green solvents for the chemical , pharmaceutical , biofuel and biomass industries . the ils of the invention are particularly useful in hydrogenation , pericyclic and metathesis reactions .

Description:
the present invention provides excellent candidates for ionic liquids , which are stable and liquid at room temperature , are readily biodegradable and have low toxicities and containing coordinating side - chains . the ils produced herein can be tailored with regard to properties such as viscosity , melting point , hydrophobicity , toxicity and biodegradability , these being key parameters for solvent applications . toxicity data and biodegradability data for the compounds of the present invention are set out below , as are examples of the use of some of the ionic liquids of the invention in chemical reactions , such as hydrogenation reactions where such use gives high percentage conversion and high product selectivity . cellulose dissolution data is also presented . a simple method to synthesize the family of ionic liquids has been developed which produced the ils in good yield for each step . a typical reaction scheme for synthesis of the achiral ils is shown in fig2 ( scheme a - c ). in brief , a bromo ester alkylating agent 3 is made from the alcohol of interest ( ils with thioester side chains or ils with amide side chains can be typically prepared by use of a halo amide 4 or halo thioester 5 alkylating agent respectively ). the bromo ester is then reacted with the imidazole of interest to form the bromide salt of the 2 - imidazolium ester . a wide range of achiral alcohols were found to be compatible with the synthetic methodology outlined in fig2 , including unsaturated unsubstituted alkyl species such as 1 - butanol and 1 - pentanol , ether or polyether substituted species such as 2 - ethoxyethanol and 2 -( 2 - ethoxyethoxy ) ethanol ( table 1 ). use of the former produces ils with unsubstituted alkyl ester side chains of desired length , whereas use of the latter provides unusual ils possessing ether or polyether containing alkyl ester side chains . a large range of these types of ils , possessing different properties have been made through the final synthetic anion exchange step from halide to different salts lintf 2 , nabf 4 , kpf 6 , nan ( cn ) 2 and naoctoso 3 . it will be appreciated that other related salts may be used to introduce the desired anions , for example , alkali metal salts comprising na , k , li and the appropriate anion may be used . typically , the first step ( i ) is the preparation of the alkylating agent obtained by reaction between the bromoacetyl bromide and different alcohols , amines or thiols . the reaction involving bromoacetyl bromide and alcohols was performed under a nitrogen atmosphere at − 78 ° c . for 3 hours . after purification by distillation the corresponding bromoester in a yield ranging from 62 - 83 % was obtained ( table 1 ). this reaction has been performed successfully on a broad range of scales from 10 mmol to 0 . 5 mol based on a 1 to 1 . 4 equivalence of bromoacetyl bromide with the different alcohols . from 2 - methoxyethyl to 2 -( butoxyethoxy )- ethyl , all the bromoesters were purified by distillation . the higher molecular mass bromo ester derivatives were easily prepared in pure form on a large scale without the need for purification by column chromatography . typically , the first step ( i ) is the preparation of the alkylating agent obtained by reaction between the bromo acetyl bromide and different alcohols , amines or thiols . the reaction involving bromo acetyl bromide and alcohols was performed in the absence of solvent and promoted by neutral alumina . the reaction required typically 1 hour to reach completion , cooling with an ice bath during addition , then warming to rt without any requirement of an inert atmosphere , according to the procedure of yadav ( 20 ). after purification by absorption of the crude reaction mixture onto excess solid nahco 3 and standing overnight , the solid was washed with toluene , filtered and the filtrate evaporated to give the corresponding bromoester in a yield typically around 88 % ( table 1 ). this reaction has been performed successfully on a broad range of scales using at least 2 equivalents of bromo acetyl bromide with the different alcohols . the bromides prepared by this method are pure enough to carry through to the subsequent imidazole alkylation without the need for purification by column chromatography . to a stirred solution of dcm , diethylene glycol mono ethyl ether ( 21 . 0 ml , 150 mmol ), and triethylamine ( 34 . 7 ml , 250 mmol ) under a nitrogen atmosphere at − 78 ° c . was added dropwise bromo acetyl bromide ( 17 . 2 ml , 200 mmol ). after stirring at − 78 ° c . for 3 h , the reaction mixture was allowed to warm up to − 20 ° c . and quenched by addition of water ( 50 ml ). the organic phase was washed with distilled water ( 3 × 50 ml ), saturated ammonium chloride ( 3 × 50 ml ), saturated sodium bicarbonate ( 3 × 50 ml ) and brine ( 2 × 50 ml ). the organic phase was then dried over magnesium sulfate , filtered and solvents removed via rotary evaporation to yield a crude product in 87 % yield . this crude product was distilled ( bp 105 - 115 ° c .) to give a colourless liquid at rt in 71 % yield . to diethylene glycol mono ethyl ether ( 21 . 0 ml , 150 mmol ), and neutral alumina [ e . g . aldrich type wn - 3 ] ( 17 g , 167 mmol ) cooled with an ice - bath was added bromo acetyl bromide ( 44 ml , 500 mmol ). the ice bath was removed and after 1 h standing at rt , the reaction mixture was poured onto solid nahco 3 in a glass filter funnel , with a cotton wool plug ( effervescence ). after standing overnight , the solid was washed with toluene until 200 ml of filtrate had been collected . the volatiles were removed via rotary evaporation to yield a crude product in 88 % yield . this crude product was sufficiently pure to carry through to the next step . 1 h 6 ppm 4 . 34 ( t , j = 4 . 4 hz , 2h ), 3 . 88 ( s , 2h ), 3 . 74 ( t , j = 4 . 8 hz , 2h ), 3 . 66 ( t , j = 4 . 0 hz , 2h ), 3 . 60 ( t , j = 4 . 0 hz , 2h ), 3 . 53 ( q , j = 6 . 8 hz , 2h ), 1 . 22 ( t , j = 7 . 0 hz , 3h ) table 1 shows the alcohols converted to the bromo ester alkylating agents with isolated yields after distillation . the second step ( ii ) is the preparation of the bromide salt . this reaction takes place between the 1 - methylimidazole and the previously prepared family of bromo esters ( table 1 ) under a nitrogen atmosphere in diethyl ether solution at − 15 ° c . for 3 hours then 18 hours at room temperature . the product precipitates and after washing and evaporation of the resulting solvent , the family of bromide salts was obtained in very good yield , between 82 - 98 % ( table 2 ). most of the bromide salts are solids at room temperature , but with a low melting point ( mp & lt ; 100 ° c ., current limit for definition as ionic liquids ) with some examples melting close to room temperature ( table 2 ). hence all the ester , ether ester or polyether ester imidazolium bromide salts prepared can be classified as ionic liquids . the final synthetic step ( iii ) is an anion exchange . this exchange is important as it results in changes to the bulk solvent proprieties of the corresponding ionic liquid . the following salts were used salts lintf 2 , nabf 4 , kpf 6 , nan ( cn ) 2 , naoctoso 3 . in most cases , anion exchange results in a melting point decrease compared to the bromide salt analogue , especially when ntf 2 − is used as counter anion . ntf 2 − and n ( cn ) 2 − derivatives also have low viscosities , low viscosity being a key parameter for solvent applications . hydrophobic ionic liquids can be made by using ntf 2 − or pf 6 − counter anions . increasing biodegradability is achieved by using octoso 3 − as the counter anion . ntf 2 ils : the reaction between lintf 2 and the bromide salt was realized in water at room temperature for 4 to 18 hours . after that time the corresponding hydrophobic ionic liquids precipitated . after different washing the product was obtained with good yield ( table 2 , column 3 ). all the resulting liquids are liquid at room temperature . a flask was charged with 3 - methyl - 1 -( ethoxyethoxycarbonylmethyl ) imidazolium bromide ( 2 . 98 g , 10 . 0 mmol ) and distilled water ( 10 ml ). lintf 2 ( 4 . 59 g , 16 . 0 mmol ) in distilled water ( 3 ml ) was added in one portion and the suspension was stirred vigorously for 4 h at rt . the top aqueous layer was removed and the il was washed with distilled water ( 3 × 10 ml ). the solvent was then removed on the rotary evaporator and under high vacuum for 8 h to give a liquid at rt in 90 % yield ( 4 . 42 g , 8 . 97 mmol ). 1 h δ ppm 8 . 82 ( s , 1h ), 7 . 39 ( t , j = 1 . 8 hz , 1h ), 7 . 34 ( t , j = 1 . 8 hz , 1h ), 5 . 06 ( s , 2h ), 4 . 38 ( t , j = 4 . 6 hz , 2h ), 3 . 97 ( s , 3h ), 3 . 68 ( t , j = 4 . 6 hz , 2h ), 3 . 56 ( q , j = 7 . 2 hz , 2h ), 1 . 22 ( t , j = 7 . 0 hz , 3h ) 13 c δ ppm 165 . 76 , 137 . 63 , 123 . 80 , 123 . 25 , 67 . 62 , 66 . 67 , 65 . 97 , 49 . 92 , 36 . 56 , 15 . 01 pf 6 ils : the exchange with kpf 6 was first completed using the same method as the ntf 2 ils , but the yield was poor , even with extended reaction times . optimisation of the reaction conditions required refluxing in acetone for 4 days . the yield obtained was very good , up to 90 % in most cases ( table 2 column 5 ). only two of those ionic liquids were solid but with a melting point less than 100 ° c . a flask was charged with 3 - methyl - 1 -( methoxyethoxyethoxycarbonylmethyl ) imidazolium bromide ( 3 . 51 g , 11 . 0 mmol ) and acetone ( 10 ml ). kpf 6 ( 3 . 31 g , 18 . 0 mmol ) in acetone ( 5 ml ) was added in one portion and the suspension was stirred vigorously for 4 days under reflux . the fine white precipitate was then filtered and washed with acetone ( 2 × 5 ml ). the solvent was removed from the product on the rotary evaporator . the product was then dried under high vacuum for 4 h to give a viscous liquid at rt in 91 % yield ( 3 . 87 g , 9 . 97 mmol ). 1 h δ ppm 8 . 60 ( s , 1h ), 7 . 52 - 7 . 50 ( m , 2h ), 5 . 13 ( s , 2h ), 4 . 44 ( t , j = 4 . 6 hz , 2h ), 4 . 00 ( s , 3h ), 3 . 81 ( t , j = 4 . 6 hz , 2h ), 3 . 71 - 3 . 67 ( m , 2h ), 3 . 61 ( s , 2h ) 13 c δ ppm 165 . 98 , 136 . 76 , 123 . 33 , 123 . 17 , 71 . 16 , 69 . 69 , 67 . 85 , 65 . 23 , 57 . 54 , 49 . 44 , 35 . 84 bf 4 ils : the anion exchange was realized with nabf 4 using the same new conditions as those used for the synthesis of the ionic liquid with pf 6 as anion . all the yields were excellent and up to 92 % yield was obtained . a dry flask was charged with 3 - methyl - 1 -( propoxyethoxyethoxycarbonylmethyl ) imidazolium bromide ( 2 . 94 g , 8 . 38 mmol ) and acetone ( 10 ml ) under a nitrogen atmosphere . nabf 4 ( 1 . 11 g , 10 . 1 mmol ) was added in one portion and the suspension was stirred vigorously for 4 days under reflux . the fine white precipitate was filtered quickly in air and washed with dry acetone ( 2 × 3 ml ). the filtrate and washings were combined , solvent removed by rotary evaporation and then under high vacuum to give a slight viscous oil at rt in 93 % yield ( 2 . 88 g , 8 . 21 mmol ). 1 h δ ppm 8 . 95 ( s , 1h ), 7 . 45 ( t , j = 1 . 8 hz , 1h ), 7 . 37 ( t , j = 1 . 8 hz , 1h ), 5 . 12 ( s , 2h ), 4 . 38 ( t , j = 4 . 6 hz , 2h ), 3 . 97 ( s , 3h ), 3 . 75 ( t , j = 4 . 8 hz , 2h ), 3 . 67 ( t , j = 3 . 2 hz , 2h ), 3 . 60 ( t , j = 3 . 2 hz , 2h ), 3 . 44 ( t , j = 10 . 8 hz , 2h ), 1 . 59 - 1 . 55 ( m , 2h ), 0 . 92 ( t , j = 7 . 6 hz , 3h ) 13 c δ ppm 166 . 23 , 137 . 96 , 123 . 79 , 123 . 13 , 73 . 06 , 70 . 54 , 69 . 89 , 68 . 54 , 65 . 66 , 49 . 85 , 36 . 52 , 22 . 75 , 10 . 49 n ( cn ) 2 ils : for the exchange with nan ( cn ) 2 , different conditions were used . the acetone was substituted by acetonitrile and reflux was found not to be necessary . after 4 days the solution was filtered and washed to remove the precipitated nabr salt . good yields were obtained with the majority of the bromide salts used . a dry flask was charged with 3 - methyl - 1 -( butoxycarbonylmethyl ) imidazolium bromide ( 2 . 52 g , 11 . 00 mmol ) and acetonitrile ( 10 ml ) under a nitrogen atmosphere . nan ( cn ) 2 ( 1 . 42 g , 16 . 00 mmol ) was added in one portion and the suspension was stirred vigorously for 4 days at rt . the fine white precipitate was filtered quickly in air and washed with dry acetonitrile ( 2 × 1 ml ). the filtrate and washings were combined , solvent removed by rotary evaporation and then under high vacuum to give a yellow oil at rt in 87 % yield ( 2 . 50 g , 9 . 51 mmol ). 1 h δ ppm 9 . 82 ( s , 1h ), 7 . 56 ( t , j = 1 . 8 hz , 1h ), 7 . 46 ( t , j = 1 . 8 hz , 1h ), 5 . 32 ( s , 2h ), 4 . 15 ( t , j = 6 . 8 hz , 2h ), 4 . 02 ( s , 3h ), 1 . 61 - 1 . 58 ( m , 2h ), 1 . 33 - 1 . 27 ( m , 2h ), 0 . 87 ( t , j = 7 . 4 hz , 3h ) 13 c δ ppm 164 . 10 , 136 . 12 , 121 . 89 , 121 . 18 , 64 . 85 , 48 . 22 , 34 . 87 , 28 . 31 , 16 . 96 , 11 . 67 octoso 3 ils : with na octoso 3 , the reaction conditions were extensively optimised . according to the literature , the bromide salt and na octoso 3 were stirred in water for 2 h at 60 ° c . the water was then slowly removed under vacuum . the precipitate was dissolved in dcm and washed with a small amount of distilled water . after evaporation of the solvent , the product was obtained in good yields up to 82 %. however , the yield can decrease rapidly if caution is not taken during the washing . this is explained by the fact that the ionic liquid is extremely soluble in water and it is easy to lose compound during work - up . it is noted that 3 out of 13 of these octoso 3 ionic liquids are solid at room temperature although their melting points are still lower than 100 ° c . to a solution of 3 - methyl - 1 -( propoxyethoxycarbonylmethyl ) imidazolium bromide ( 3 . 32 g , 12 . 0 mmol ) in distilled water ( 20 ml ) was added in one portion sodium octyl sulfate ( 2 . 09 g , 9 . 00 mmol ) and stirred at 60 ° c . for 2 h . the water was then slowly removed under vacuum . the precipitate was dissolved in dcm ( 10 ml ) and washed with distilled water ( 2 × 5 ml ). the product remaining was dried on the rotary evaporator and then under high vacuum for 8 h to yield a dark yellow grease at rt in 85 % yield ( 3 . 33 g , 7 . 64 mmol ). 1 h δ ppm 9 . 45 ( s , 1h ), 7 . 48 ( t , j = 1 . 6 hz , 1h ), 7 . 41 ( t , j = 1 . 6 hz , 1h ), 5 . 25 ( 5 , 2h ), 4 . 36 ( t , j = 4 . 8 hz , 2h ), 4 . 01 ( s , 3h ), 3 . 67 ( t , j = 4 . 6 hz , 2h ), 3 . 43 ( t , j = 6 . 8 hz , 2h ), 1 . 63 - 1 . 58 ( m , 2h ), 0 . 92 - 0 . 86 ( m , 3h ) 13 c δ ppm 166 . 45 , 138 . 89 , 123 . 71 , 123 . 06 , 73 . 04 , 67 , 92 , 67 . 89 , 65 . 67 , 49 . 91 , 36 . 58 , 31 . 83 , 29 . 50 , 29 . 36 , 29 . 26 , 25 . 87 , 22 . 73 , 22 . 66 , 14 . 13 , 10 . 47 to a stirred solution of dcm , bis ( 2 - methoxyethyl ) amine ( 40 . 0 g , 44 . 0 ml , 300 mmol ), and triethylamine ( 69 . 25 ml , 500 mmol ), under a nitrogen atmosphere at − 78 ° c . was added drop wise bromo acetyl bromide ( 34 . 8 ml , 400 mmol ). after stirring at − 78 ° c . for 5 h , the reaction mixture was allowed to warm up to − 20 ° c . and then quenched by addition of water ( 60 ml ). the organic phase was washed with distilled water ( 3 × 30 ml ), saturated ammonium chloride ( 3 × 30 ml ), saturated sodium bicarbonate ( 3 × 30 ml ) and brine ( 2 × 30 ml ). the organic phase was then dried over magnesium sulfate , filtered and solvents removed via rotary evaporation to yield a crude product in 82 % yield ( 62 . 3 g , 245 mmol ). the crude product was then distilled under high vacuum at 170 ° c . to give pale yellow crystals in 49 % yield ( 35 . 57 g , 140 mmol ). pure product can also be recrystallised from the crude material with diethyl ether . 1 h δ ppm 4 . 02 ( s , 2h ), 3 . 66 ( t , j = 5 . 2 hz , 2h ), 3 . 55 ( br , 3h ), 3 . 53 ( t , j = 5 . 0 hz , 3h ), 3 . 33 ( s , 6h ) 13 c δ ppm 167 . 79 , 70 . 74 , 70 . 27 , 59 . 13 , 58 . 94 , 50 . 12 , 46 . 90 , 27 . 20 to a stirred solution of 1 - methylimidazole ( 45 . 0 mmol , 3 . 69 g , 3 . 58 ml , d : 1 . 030 ) in diethyl ether ( 100 ml ) at − 15 ° c . under a nitrogen atmosphere was added 2 - bromo - n , n - bis ( 2 - methoxyethyl ) acetamide ( 50 . 0 mmol , 13 . 28 g ) in diethyl ether . the reaction mixture was stirred vigorously at − 15 ° c . for 2 h , then at rt overnight . the ether top phase was decanted and the product washed with ether ( 3 × 10 ml ), the solvent removed on the rotary evaporator and dried under high vacuum for 8 h to give a white powder at rt in 91 % yield ( 13 . 7 g , 40 . 8 mmol ). 1 h δ ppm 9 . 91 ( s , 1h ), 7 . 44 ( t , j = 1 . 8 hz , 1h ), 7 . 42 ( t , j = 1 . 8 hz , 1h ), 5 . 66 ( s , 2h ), 4 . 07 ( s , 3h ), 3 . 70 ( t , j = 4 . 8 hz , 2h ), 3 . 57 - 3 . 55 ( m , 4h ), 3 . 50 - 0 . 47 ( m , 2h ), 3 . 36 ( s , 3h ), 3 . 31 ( s , 3h ) 13 c δ ppm 165 . 46 , 138 . 30 , 124 . 14 , 122 . 31 , 70 . 51 , 70 . 05 , 59 . 25 , 58 . 92 , 50 . 63 , 48 . 82 , 46 . 83 , 36 . 75 to a stirred solution of ( 3 - methyl - 1 -[ bis - 1 - methoxyethyl ] carbamylmethyl ) imidazolium bromide in distilled water ( 20 ml ) was added in one portion sodium octyl sulfate ( 4 . 0 mmol , 0 . 93 g ). the mixture was left stirring for 4 h , then the water was evaporated on the rotary evaporator . the remaining product was dissolved in dcm ( 10 ml ) and washed with water ( 2 × 2 ml ). the product was then dried on the rotary evaporator and under high vacuum for 8 h to give a viscous oil at rt in 92 % yield ( 1 . 36 g , 2 . 75 mmol ) 1 h δ ppm 9 . 34 ( s , 1h ), 7 . 25 ( t , j = 1 . 6 hz , 1h ), 7 . 20 ( t , j = 1 . 6 hz , 1h ), 5 . 30 ( s , 2h ) 3 . 91 ( s , 3h ), 3 . 60 ( t , j = 4 . 8 hz , 2h ), 3 . 51 - 3 . 43 ( m , 6h ), 3 . 30 ( s , 3h ), 3 . 26 ( s , 3h ) 13 c δ ppm 165 . 64 , 139 . 03 , 124 . 03 , 122 . 17 , 70 . 54 , 70 . 03 , 67 . 91 , 59 . 17 , 58 . 91 , 50 . 43 , 48 . 62 , 46 . 77 , 36 . 47 , 31 . 83 , 29 . 51 , 29 . 36 , 29 . 27 , 25 . 87 , 22 . 67 , 14 . 13 physical properties of ils prepared and their suitability as biodegradable solvents table 2 shows that all the solvents prepared can be characterized as ils as their melting points are below 100 ° c . closer examination of the table leads to the observation that nearly all are liquid at room temperature . this is an important property for these materials . the breadth of il type , from short chain to long chain substituted imidazolium compounds , suggests great scope for the usefulness of the il compounds . the biodegradability of the test compounds was evaluated using the “ closed bottle ” test ( oecd 301 d ). ( 12 ) in this method , the chemical being evaluated is added to an aerobic aqueous medium inoculated with wastewater microorganisms and the depletion of dissolved molecular oxygen is measured for a defined period of time and reported as a percentage of the theoretical maximum . compounds which reach a biodegradation level higher than 60 % are referred to as “ readily biodegradable ”. sodium n - dodecyl sulfate ( sds ) was used as reference substance . solutions containing 2 mg l − 1 of the test ionic liquids and the reference chemical as sole sources of organic carbon were prepared , separately , in previously aerated mineral medium . the solutions were then inoculated with secondary effluent collected from an activated sludge treatment plant and each well - mixed solution was carefully dispensed into a series of biochemical oxygen demand ( bod ) bottles so that all the bottles were completely full . a control with inoculum , but without test chemicals was run parallel for the determination of oxygen blanks . duplicate bottles of each series were analysed immediately for dissolved oxygen and the remaining bottles were incubated at 20 ° c .± 1 ° c . in the dark . bottles of all series were withdrawn in duplicate for dissolved oxygen analysis over the 28 day incubation period . the biodegradation after n days was expressed as the ratio of the bod to the chemical oxygen demand ( cod ) both of them expressed as mg o 2 per mg compound . the chemical oxygen demand was determined by the dichromate reflux method . ( 13 , 21 ) for the calculation of the biochemical oxygen demand the determined oxygen depletions were divided by the concentration of ionic liquid . to evaluate the biodegradability of the test ionic liquids , the “ co 2 headspace ” test ( iso 14593 ) ( 14 ) was also applied . this method allows the evaluation of the ultimate aerobic biodegradability of an organic compound in aqueous medium at a given concentration of microorganisms by analysis of inorganic carbon . the test ionic liquid , as the sole source of carbon and energy , was added at a concentration of 40 mg l − 1 to a mineral salt medium . these solutions were inoculated with activated sludge collected from an activated sludge treatment plant , washed and aerated prior to use and incubated in sealed vessels with a headspace of air . biodegradation ( mineralization to carbon dioxide ) was determined by measuring the net increase in total organic carbon ( toc ) levels over time . the octylsulfate anion based achiral ils gave the best biodegradation test results . ils : kg34 ( 3 - methyl - 1 -( butoxycarbonylmethyl ) imidazolium octylsulfate ); kg36 : ( 3 - methyl - 1 -( methoxyethoxycarbonylmethyl ) imidazolium octylsulfate ); kg38 : ( 3 - methyl - 1 -( propoxyethoxycarbonylmethyl ) imidazolium octylsulfate ); kg40 : ( 3 - methyl - 1 -( methoxyethoxyethoxycarbonylmethyl ) imidazolium octylsulfate ). kg42 : ( 3 - methyl - 1 -( propoxyethoxyethoxycarbonylmethyl ) imidazolium octylsulfate ) kg44 : ( 2 , 3 - dimethyl - 1 -( butoxyethoxycarbonylmethyl ) imidazolium octylsulfate kg35 : ( 3 - methyl - 1 -( pentoxycarbonylmethyl ) imidazolium octylsulfate ); kg37 : ( 3 - methyl - 1 -( ethoxyethoxycarbonylmethyl ) imidazolium octylsulfate ); kg39 : ( 3 - methyl - 1 -( butoxyethoxycarbonylmethyl ) imidazolium octylsulfate ); kg41 : ( 3 - methyl - 1 -( ethoxyethoxyethoxycarbonylmethyl ) imidazolium octylsulfate ). kg43 : ( 3 - methyl - 1 -( butoxyethoxyethoxycarbonylmethyl ) imidazolium octylsulfate ) and kg45 : ( 2 , 3 - dimethyl - 1 -( methoxyethoxyethoxycarbonylmethyl ) imidazolium octylsulfate . kg35 , 38 , 39 , 42 , 43 , 44 passed the co 2 - headspace test ( at least 60 % over 28 days duration ) and clearly are “ readily biodegradable ” according to this test ( see tables 3 and 4 ). kg34 , 36 , 37 , 40 , 41 , 45 all show significant biodegradation properties ( between 55 - 59 % in co 2 - headspace test ) and a significant improvement on the negligible biodegradation result obtained for bmimbf 4 and bmimpf 6 . ( 9 ) seven strains of bacteria were used in the assessment of the antimicrobial activity of the ils claimed : 4 gram negative and three gram positive as shown below . the minimum inhibitory concentrations were measured for those ils which showed activity . a wide concentration range was tested ( 0 - 20000 μg / ml ). the concentrations screened for antibacterial activity are generally from 2 μg / ml to 1000 μg / ml ( table 6 ). potent antibacterial compounds will have mic values at the lower end of this range , compounds which have mic values at the higher end of the range , show antibacterial activity but at levels not significant for antibacterial drug development . the concentration range screened for the ils containing ethers was up to 20000 μg / ml . at these high concentrations a lack of antibacterial activity is a significant result . il examples containing a hydrocarbon side chain , or an ester with a long hydrocarbon chain have proven potent antibacterial properties ( table 7 and references 9 , 12 ). in general , the toxicities of the ionic liquids of the present invention are found to be some orders of magnitude lower than those of conventional solvents such as acetone and methanol . as previously mentioned , a common problem with the toxicity of ionic liquids is associated with the presence of an extended hydrocarbon chain . the length of the side chains was found to influence the dialkylimidazolium ionic liquids toxicity , with longer chain length provide to be more toxic . bodor et al . ( 9 ) have showed that the long chain ester derivatives of methyl imidazole ( shown as compound 6 in fig3 ) show effective antimicrobial activity at ppm concentrations . compound 6 , fig3 ( 9 ) appears similar to the family of ionic liquids of the present invention , except the fact that a different side of the chain is linked to the ester , and the inclusion of ether functional groups . table 6 shows that all the ionic liquids prepared show significantly lower toxicity than derivatives without ester and ether or polyether functional groups ( fig4 ). kg 405 , 422 , 423 and 407 show that the presence of oxygen atoms in the side chain of amide derivatives leads also to low toxicity ils , when compared to ils with hydrocarbon sidechains of similar size . ( eg kg407 vs potent antibacterial dodecyl substituted imidazolium salts ). kg 403 , 404 , 420 , 421 were used as reference compounds , containing a substituted amide group without extended linear alkyl chains . these results have significant implications for the usefulness of the ils , as the toxicity is exceptional low for ils . kg50 ( 3 - methyl - 1 -( 2 -[ 2 - ethoxy ] ethoxycarbonylmethyl ) imidazolium ntf 2 ), kg51 ( 3 - methyl - 1 -( 2 -[ 2 - propoxy ] ethoxycarbonylmethyl ) imidazolium ntf 2 ), kg52 ( 3 - methyl - 1 -( 2 -[ 2 - butoxy ] ethoxycarbonylmethyl ) imidazolium ntf 2 ), kg53 ( 3 - methyl - 1 -( 2 -[ 2 - methoxyethoxy ] ethoxycarbonylmethyl ) imidazolium ntf 2 ), kg54 ( 3 - methyl - 1 -( 2 -[ 2 - ethoxyethoxy ] ethoxycarbonylmethyl ) imidazolium ntf 2 ), kg55 ( 3 - methyl - 1 -( 2 -[ 2 - propoxyethoxy ] ethoxycarbonylmethyl ) imidazolium ntf 2 ), kg56 ( 3 - methyl - 1 -( 2 -[ 2 - butoxyethoxy ] ethoxycarbonylmethyl ) imidazolium ntf 2 ), kg58 ( 2 , 3 - dimethyl - 1 -( 2 -[ 2 - butoxy ] ethoxycarbonylmethyl ) imidazolium ntf 2 ), kg59 ( 2 , 3 - dimethyl - 1 -( 2 -[ 2 - methoxyethoxy ] ethoxycarbonylmethyl ) imidazolium ntf 2 ). kg62 ( 3 - methyl - 1 -( 2 -[ 2 - methoxy ] ethoxycarbonylmethyl ) imidazolium bf 4 ), kg63 ( 3 - methyl - 1 -( 2 -[ 2 - ethoxy ] ethoxycarbonylmethyl ) imidazolium bf 4 ), kg64 ( 3 - methyl - 1 -( 2 -[ 2 - propoxy ] ethoxycarbonylmethyl ) imidazolium bf 4 ), kg65 ( 3 - methyl - 1 -( 2 -[ 2 - butoxy ] ethoxycarbonylmethyl ) imidazolium bf 4 ), kg66 ( 3 - methyl - 1 -( 2 -[ 2 - methoxyethoxy ] ethoxycarbonylmethyl ) imidazolium bf 4 ), kg67 ( 3 - methyl - 1 -( 2 -[ 2 - ethoxyethoxy ] ethoxycarbonylmethyl ) imidazolium bf 4 ), kg68 ( 3 - methyl - 1 -( 2 -[ 2 - propoxyethoxy ] ethoxycarbonylmethyl ) imidazolium bf 4 ), kg69 ( 3 - methyl - 1 -( 2 -[ 2 - butoxyethoxy ] ethoxycarbonylmethyl ) imidazolium bf 4 ), kg71 ( 2 , 3 - dimethyl - 1 -( 2 -[ 2 - butoxy ] ethoxycarbonylmethyl ) imidazolium bf 4 ), kg72 ( 2 , 3 - dimethyl - 1 -( 2 -[ 2 - methoxyethoxy ] ethoxycarbonylmethyl ) imidazolium bf 4 ). kg75 ( 3 - methyl - 1 -( 2 -[ 2 - methoxy ] ethoxycarbonylmethyl ) imidazolium n ( cn 2 ), kg76 ( 3 - methyl - 1 -( 2 -[ 2 - ethoxy ] ethoxycarbonylmethyl ) imidazolium n ( cn ) 2 ), kg77 ( 3 - methyl - 1 -( 2 -[ 2 - propoxy ] ethoxycarbonylmethyl ) imidazolium n ( cn ) 2 ), kg78 ( 3 - methyl - 1 -( 2 -[ 2 - butoxy ] ethoxycarbonylmethyl ) imidazolium n ( cn ) 2 ), kg79 ( 3 - methyl - 1 -( 2 -[ 2 - methoxyethoxy ] ethoxycarbonylmethyl ) imidazolium n ( cn ) 2 ), kg80 ( 3 - methyl - 1 -( 2 -[ 2 - ethoxyethoxy ] ethoxycarbonylmethyl ) imidazolium n ( cn ) 2 ), kg81 ( 3 - methyl - 1 -( 2 -[ 2 - propoxyethoxy ] ethoxycarbonylmethyl ) imidazolium n ( cn ) 2 ), kg82 ( 3 - methyl - 1 -( 2 -[ 2 - butoxyethoxy ] ethoxycarbonylmethyl ) imidazolium n ( cn ) 2 ), kg84 ( 2 , 3 - dimethyl - 1 -( 2 -[ 2 - butoxy ] ethoxycarbonylmethyl ) imidazolium n ( cn ) 2 ), kg85 ( 2 , 3 - dimethyl - 1 -( 2 -[ 2 - methoxyethoxy ] ethoxycarbonylmethyl ) imidazolium n ( cn ) 2 ). kg421 ( 2 , 3 - dimethyl - 1 -( pyrrolidinylcarbonylmethyl ) imidazolium bromide ), kg403 ( 3 - methyl - 1 -( pyrrolidinylcarbonylmethyl ) imidazolium octylsulfate , kg404 ( 2 , 3 - dimethyl - 1 -( pyrrolidinylcarbonylmethyl ) imidazolium octylsulfate , kg405 ( 3 - methyl - 1 -[ bis - 1 - methoxyethyl ] carbamylmethyl ) imidazolium octylsulfate ), kg407 ( 3 - methyl - 1 -[ bis - 1 - methoxyethyl ] carbamylmethyl ) imidazolium bromide ), kg422 ( 3 - methyl - 1 -[ 1 - methoxyethyl ] carbamylmethyl ) imidazolium bromide ) and kg423 ( 3 - methyl - 1 -[ 1 - methoxypropyl ] carbamylmethyl ) imidazolium bromide ), a test reference study with 1 - methyl - 3 - decyloxy - carbonyl methylimidazole bromide salt kg20 , known to be toxic due to the long alkyl chain , has been completed to provide reference data . this experiment compares , for the same side chain length , the impact of the presence of the oxygen ( e . g . kg15 ) on toxicity . as expected kg20 was toxic to all the different bacteria screened ( see table 7 ), and in some cases even at low concentrations ( table 7 . e . coli , enterococcus sp . and s . aureus ). a comparison of the result of the table 7 to those from table 6 , ( kg15 ), indicates that the presence of the oxygen in the side chain is crucial to suppress the toxicity . the incorporation of the ether or polyether sidechain into the structure of the ionic liquid reduces the toxicity of the ionic liquid compared to alkyl derivatives . the viscosities of the ionic liquids claimed are observed to be significantly lower than the alkyl derivatives known . the combination of the ester in the side chain with ether or polyether sidechain leads to imidazolium ionic liquids with considerably greater propensity to biodegrade . when the octylsulfate counterion is present then the greatest degree of biodegradation is observed . the following example demonstrates the utility of non - toxic ionic liquids in cellulose dissolution , especially in cases where further biological processes ( e . g . enzymatic transformations ) may be required to be performed on the dissolved cellulose and a biologically benign medium is preferred . il kg81 ( 0 . 84 g ) was heated to 150 ° c ., in a small beaker , stirring with a small teflon - coated magnetic bead and cellulose powder ( avicel ® ph - 101 , fluka ), 5 mg , was added in one portion . after stirring for 30 minutes the cellulose was observed to have dissolved in the ionic liquid . thus the dissolution of cellulose at a level of at least 0 . 6 % by mass can occur using kg81 at a temperature of 150 ° c ., for 30 minutes . the dissolution may occur even with a less favourable dca ( dicyanoamide ) counter - anion . other groups have demonstrated cellulose dissolution for related polyether ils ( 19 )], but the ils of the invention have the added advantage over previously reported il cellulose dissolution since their low microbial toxicity and bio - compatibility are favourable for facilitating further biocatalytic or enzymatic reactions on the dissolved cellulose . selective hydrogenation of trans - cinnamaldehyde and hydrogenolysis - free hydrogenation of benzyl cinnamate in non - toxic ils the following example demonstrates the utility of ionic liquids in hydrogenation reactions , for example , in hydrogenation reactions involving α , β - unsaturated aldehydes and in particular an α , β - unsaturated carbonyl , such as trans - cinnamaldehyde , benzyl cinnamate or allyl cinnamate , where control of selectivity is required . thus , the ionic liquids of the present invention may be used to selectively hydrogenate trans - cinnamaldehyde to hydrocinnamaldehyde using a commercially available palladium catalyst in a non - toxic solvent environment . the selective hydrogenation extends to benzyl cinnamate , where the ester is protected from hydrogenolysis under similar conditions . due to its highly conjugated system , the hydrogenation of the α , β - unsaturated aldehyde , trans cinnamaldehyde , usually leads to the reduction of the olefin moiety but also the carbonyl group , yielding the alcohol , 3 - phenylpropanol ( fig6 ). the selective formation of hydrocinnamaldehyde is of both academic interest and of interest to the fine chemical industry ( 22 ). using the pentyl derivative ( kg48 ) of the imidazolium ils of the invention , selectivities generally ranged from 90 to 100 %. the most impressive results obtained were achieved using the dimethyl derivative ( kg59 ) of the ils , where 100 % conversion and selectivity were reached at 24 h upon the 1 st recycle ( table 8 ). although slight variations in conversion and selectivity occurred during the recycling procedure , almost the same reaction efficiency can be seen upon the fourth recycle ( conversion 97 %, selectivity 100 %). ( table 8 ) when the il side chain length is increased , or contains an oxygen atom , the result obtained does not vary significantly ; the conversion remains consistent at 100 % and the selectivity still does not decrease below 90 %. thus , the method is shown to be still applicable when an oxygen atom is present in the side chain of the il ( table 9 ). upon increasing the number of oxygen atoms in the il side chain from one to two , the selectivity is only slightly negatively affected . there is however a significant drop in conversion by the 3 rd recycle ( to 64 %) ( table 10 ). in order to compare the reactions in commercially available solvents , including a commercially available il , trans cinnamaldehyde was hydrogenated using [ bmim ][ ntf 2 ], [ bmim ][ octoso 3 ] or toluene . the results obtained ( table 11 ), show selectivity in these commercially available ils is merely comparable to a volatile organic solvent ( toluene ). demonstrating the further versatility of this process , the aldehyde trans -( 4 - hydroxy - 3 - methoxy ) cinnamaldehyde was reduced to the corresponding 4 - hydroxy - 3 - methoxy - dihydrocinnamaldehyde derivative ( 1 , 4 - reduction ) in 100 % conversion and with 90 % selectivity over the undesired product of over - reduction to the alcohol ( both 1 , 2 and 1 , 4 - reduction ). this compares favourably with reduction in bmimntf 2 , a conventional ionic liquid in which only 74 % selectivity is achieved ( table 12 ). the effect of catalyst loading , as well as the solvent effect was investigated during hydrogenations of benzyl cinnamate using a number of ils of the invention , along with a number of commercially available solvents ( table 13 ). the least amount of catalyst effective in inducing 100 % conversion was 0 . 005 g . using half this value , only 32 % conversion was achieved after 24 h with il ( kg51 ). the octylsulfate ils (( kg35 ) and ( kg38 ) gave promising results in terms of selectivity ; however this was only achieved when conversion was low for il ( kg35 ), but with optimal conversion for il ( kg38 ). the most compelling results from this data set are obtained using ils ( kg51 ) and ( kg38 ). using 0 . 005 g catalyst , after 24 h , 100 % conversion and selectivity were obtained . more surprising is the fact that the selectivity was retained up to 48 h , thus suggesting that hydrogenolysis of this compound in this il system only occurs with the unsaturated ester . more evidence of this fact is observed when the non - hydrogenolysed reduced product ( 12 ) is further subjected to hydrogenation conditions using an increased amount of catalyst . no hydrogenolysis is observed ( table 14 ). the significance of this result is based on the fact that il ( kg51 ) completely prevents hydrogenolysis of the benzyl ester . after the fourth recycle , the selectivity remains constant , but the conversion decreases slightly to 91 % upon recycle 7 . only upon recycle 8 is a significant drop in conversion observed ( 81 %). varying catalytic amounts were tested for the hydrogenation of benzyl cinnamate using il ( kg38 ) ( table 16 ). as can be seen from the results displayed in table 16 , the increasing amount of catalyst favours hydrogenolysis , optimum conditions being observed with 0 . 005 g catalyst . the effect of cation chain length and the number of oxygens in the side chain was investigated to determine whether , it was only the cation from ils ( kg51 ) and ( kg38 ) that gave the best selectivity ( table 17 ). it is evident from the results obtained that any difference in the length of the side chain or the number of oxygen atoms in the chain negatively affects the selectivity of the reaction . this reaction is therefore sensitive to any changes in il composition concerning the il cation . based on the conditions from the result obtained using il ( kg51 ) and ( kg38 ) and 0 . 005 g catalyst , this system was used to test other compounds comprising hydrogenolysable functionalities . the hydrogenation of allyl cinnamate can lead to the reduction either of the olefinic bonds , or even hydrogenolysis of the allyl functionality may be observed ( fig8 ). using both ils , although no hydrogenolysis was observed in either the corresponding bmim ils nor the common organic solvent , ethyl acetate , 84 % selectivity was reached using il ( kg51 ) ( table 18 ). 10 % pd / c ( 5 . 0 mg unless otherwise stated ) was weighed into a dry 2 - neck round bottom flask . the pre - dried il ( 2 . 0 ml ) was then added to the flask , followed by the desired substrate ( 4 mmol ) and 3 n 2 / vacuum cycles were performed . 0 . 0012 mol % catalyst was used . the reaction mixture was allowed to stir for 10 minutes or until reaching the desired reaction temperature , or until all the substrate had dissolved in the il . hydrogen was then introduced to the reaction via a balloon , and the progress of the reaction was monitored by 1 h nmr at 24 and 48 hour intervals . quantitative analysis of the reaction products was carried out by measuring the integration ratio of the peaks from the crude nmr spectrum . these values were then often verified by purification of the product by column chromatography and thus the calculation of isolated yields . upon termination of the reaction , the products were extracted using hexane ( 10 × 3 ml ). the mass recovery after extraction from the il was always & gt ; 98 %. in the case of reactions carried out in octylsulfate ils , the product was either distilled from the il using high vacuum or a brief column was prepared to separate product from il . these procedures generally led to a lower mass recovery (& gt ; 80 %), due to product being lost on the column or lost during the distillation procedure . all reactions carried out in the ntf 2 ils were carried out at 55 ° c . and 65 ° c . in the octylsulfate ils . following extraction of the products from the il , the il ( containing the catalyst ) was dried and analysed by 1 h nmr . following confirmation that the il was substrate / product - free and had not degraded , fresh substrate was then added to the system and the reactions recommenced as described . the use of il kg51 as a solvent in the selective reduction of trans - cinnamaldehyde to hydrocinnamaldehyde in the presence of hydrogen gas and palladium supported on carbon as a catalyst . kg51 , is preferred because of the presence of ether oxygens in the side - chain , which increase biodegradability and decrease toxicity . at the same time , the selectivity of the reduction is much higher than with conventional ils such as 1 - butyl - 3 - methylimidazolium octylsulfate ( bmim octoso 3 ) ( table 11 and fig1 ). also the use of il kg51 as a solvent for the selective hydrogenation of the carbon - carbon double bond conjugated to the carbonyl group in benzyl cinnamate without cleaving the benzyl ester using hydrogen gas and palladium supported on carbon as a catalyst . the use of conventional ils such as 1 - butyl - 3 - methylimidazolium ntf 2 ( bmimntf 2 ) or 1 - butyl - 3 - methylimidazolium octylsulfate ( bmim octoso 3 ) typically leads to hydrogenolysis of the benzyl ester , as well as hydrogenation of the carbon - carbon double bond conjugated to the carbonyl group ( table 13 and fig1 ). 1 . 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