SYNTHESIS AND CHARACTERIZATION OF PYRIDINIUM BASED IONIC LIQUID AND ITS APPLICATION TO IMPROVE LIPASE STABILITY IN METHANOL-WATER SOLUTION

• Main Author: Hendra Cipta, Oktavianus
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/37747
• Institution: Institut Teknologi Bandung

Ion ic liq uids a re materials tha t consist of cations and anions whi ch m elt at temperatures below I 00 oc. Ioni c liqui ds have non-volatile properties, non­ flammable, have low toxicity and their chemical and physica l pro perties can be changed b y repl aci ng the cation or an i on. Ionic liquids can be used in va rious applications, such as anticonosion material s, vitamin base materia ls and en zymatic react i on media. One enzyme that has various functions a nd is often used i s li pase. Li pase (EC 3. 1 .1. 3) is a group of h ydrolase enzymes that can catal yze va rious kinds of reactions, such as transesterification, am inol ysi s, acidol ysi s, esterificati on , t ransesteri fication and hydrolysis. Factors that influence the acti vi ty of lipase are t he reacti on en v i ronment or react i on medium of the lipase itself. Lipase which has high activity in water sol vents in gen eral will experience a significant decrease in activi ty while in non-water sol vents. In thi s st udy, ioni c liquids that ha ve been successfull y synthesi zed are N-butylpyridinium bromide, N -hexylpyridinium bromide and N-octylpyridinium bromide. The i onic liquid synthesized was characteri zed using a nucl ear magnetic resonance (NMR) spectrophotometer and the si gnal was obta in ed at a chem ical shift of 4.9 ppm indicating that i onic liquids had been fanned. The ionic liquid that have been synthesi zed will undergo ion exchange reacti on (metathesis) to exchange the anion parts. The ionic liquid synthesized was reacted w i th NaBFsa lt to produce ionic liquid N-butyl pyridinium tetrafluoroborate, N -hexyl pyridinium tetrafluoroborate and N-oct ylpyridinium tetrafluoroborate. Ionic li qu ids resulting from ion exchange were cha racterized using NMR spectrophotometer and found the sa me chemi ca l shift pattern for the three ionic li qu ids, chem i cal shifts of 9.50 ppm to 8.99 ppm for butylpyridinium, 9.51 ppm to 9.01 ppm for N­ hexyl pyridinium and 9.48 ppm to 9.00 ppm for N-oct ylpyridin ium. Th is i s due to the higher electronegat i vity of the Br• i on compared to the electronegat i vit y of BF4-, so that the chemica l shi ft cha n ges to the right i f the a nion of ioni c li quid cha nges fi:om 8( to BF -. This metathesis reaction can ca use changes in th e physical properti es of ionic liquids, N-butylpyridinium bromide which ini t i a ll y have solids fom1s tums into liquid when the anio n is replaced. Ionic liquids that ha ve been syn thesi zed are then used as reaction medium of lipase. The reacti on carri ed out in thi s study was hydrolysis reaction with 4-n itrophenyl acetate, 4- nitrophenyl octanoate and 4-nitrophen yl palmitate as a substrate. The use of ionic liquid as a react ion med i um of lipase has spccitic properties to the substrate. N­ hexylp yridinium tetrafloroborate can increase lipase act i vit y b y 4.79° o w hen used as a react ion medium for the 4-nitrophcnyl acetate hydrol ysi s reaction, w hile other ioni c li qu ids tend to reduce th e act i vit y of lipase. N-butylpyridinium t etral1oroborate and N-hexylpiridinium tctra tloro bo ratc can increase hydrol ysis acti v ity of lipase for 4-nitrophen y l octanoatc by 2.29° o a nd 2.16° o. N­ h exylpyriclinium bromide ca n increase th e acti v i t y of lipase to h ydrol yze a -1- ­ nitro phenyl pa lmitate by 5.54° o. Ioni c I i quids used as reaction med ium also have differen t effects on the opti mum cond itions of the reaction. The optimum lipase temperature for hydrol yz ing -1--nitrophen yl octanoa te a nd 4-nitrophcnyl palmi ta te 'i Ubst ratcs decreased lhllll 50 C a tier adding ion ic I iq u id to the rcactitm medium. Ionic liquids can also increase l ipase hyd rol ysi s acti\ it y wh i le i n methanol -water so h•ents. In the reacti o n of -1- -n i trofcn y l octanoate h ydrol ysis with methanol -water '-'1 h nt il'•li c liqu i d c,'n inL re:tse ,tcti\ i t; b; . I ::_n,