Synthesis of Glycerol-Based Pyridinium Surfactants and Appraisal of

Jan 8, 2009 - Sukhprit Singh,*,† Avinash Bhadani,† Hardeep Kataria,‡ Gurcharan Kaur,‡ and Raman Kamboj†. Department of Chemistry and Departm...
0 downloads 0 Views 401KB Size
Download PDF
Ind. Eng. Chem. Res. 2009, 48, 1673–1677

1673

RESEARCH NOTES Synthesis of Glycerol-Based Pyridinium Surfactants and Appraisal of Their Properties Sukhprit Singh,*,† Avinash Bhadani,† Hardeep Kataria,‡ Gurcharan Kaur,‡ and Raman Kamboj† Department of Chemistry and Department of Biotechnology, Guru Nanak DeV UniVersity, Amritsar 143005, India

β-Bromo glycerol monoethers, when heated with pyridine at 100 °C for 10 h, gave a new glycerol-based pyridinium cationic surfactant, 1-(1-(2,3-dihydroxypropoxy)alkane-2-yl)pyridinium bromide (6a-10a)/1-(2(2,3-dihydroxypropoxy)alkyl)pyridinium bromide (6b-10b) in a yield of 60%-70%. The surface properties and biocompatibility of these cationic surfactants has been determined and compared to tetradecyl trimethyl ammonium bromide (10) and cetyl pyridinium bromide (11). Introduction Cationic surfactants are an important class of surfactants that has found countless applications in various industries. Pyridinium surfactants particularly are important ingredients of several cosmetic products.1-3 They are often utilized as corrosion inhibitors,4,5 as well as being used in emulsion polymerization,6,7 the flotation of minerals,8 and textile processing.9 Biological applications of these surface-active agents include their antimicrobial activity,10-13 as well as their use as drug14,15 and gene delivery agents.16,17 Several cationic surfactants are also used in DNA extraction methods.18-20 The overall production of cationic surfactant amounts to 350 000-500 000 tonnes per annum.21 One major challenge that industry faces in the 21st century is to get the desired molecule not only in cost-effective manner but also via environmentally friendly means. Furthermore, environmental aspects, such as the biodegradability of the surfactants, must be further improved, so that the surfactants can be easily degraded in the environment. Cationic surfactants due to their biocide activity and emulsification properties are resistant, to some extent, to biological agents and undergo slow biodegradation.22 Recently, the overproduction of glycerol has become a cause of concern. Glycerol is an important byproduct of biodiesel manufacturing; it is produced by transesterfication during the production of biodiesel fuel. Approximately 10 kg of glycerol is produced for every 100 kg of oil taken for the production of biodiesel. With the total production of biodiesel amounting to thousands of tons, a huge amount of glycerol is also produced as a byproduct.23 It has been estimated that, by the year 2010, the overall production of glycerol will reach 1.2 million tons. Also, if glycerol can be utilized to make value-added products, the cost of B100-type biodiesel can be reduced from $0.63US to $0.35US.24 This enormous amount of glycerol can only be utilized if new value-added products are developed that have a huge demand in various industries and can replace existing products. Despite its green origin and overproduction, the scientific community had not been able to fully explore the potential usefulness of this naturally occurring molecule for * To whom correspondence should be addressed. Mobile Tel.: +919855557324. Fax: +911832258820. E-mail address: suk_preet@ yahoo.com. † Department of Chemistry. ‡ Department of Biotechnology.

the manufacture of value-added products. Thus, the utilization of glycerol for the production of surfactants will examine the loss of energy and resources that is due to the overproduction of glycerol. Recently, we have reported the synthesis of a chromatographically inseparable isomeric mixture of β-bromo glycerol monoethers,25 using simple cohalogenation protocol. These β-bromo glycerol monoethers, which include 3-(2-bromoalkyloxy)propane-1,2-diol/3-(1-bromoalkane-2-yloxy)propane-1,2diol (1b-4b), were heated to 100 °C for 10 h with pyridine to give the respective pyridinium bromidess1-(1-(2,3-dihydroxypropoxy)alkane-2-yl)pyridinium bromide (6a-10a)/1-(2-(2,3dihydroxypropoxy)alkyl)pyridinium bromide (6b-10b) in 60%-70% yield (see Scheme 1). These new surfactants exhibit better surface properties, as well as biological properties, when compared with commercially available cationic surfactants tetradecyl trimethyl ammonium bromide (10) and cetyl pyridinium bromide (11). Results and Discussion The CHNO elemental analysis of the new cationic surfactants revealed an almost accurate composition of carbon, hydrogen, nitrogen, and oxygen present in the salts 6-9a(b). The carbon content for 6a(b), 7a(b), 8a(b), and 9a(b) was determined to be 57.62%, 59.27%, 60.83%, and 62.23%, respectively, which lies extremely close to those calculated values. Similarly, the nitrgoen content was determined to be 3.41%, 3.20%, 2.98%, and 2.79% for 6a(b), 7a(b), 8a(b), and 9a(b), respectively. The oxygen and hydrogen contents also lie very close to those calculated values. The characterization of synthesized surfactants was further done using mass spectroscopy. The parent ion peaks of 6a(b) were observed at 338 cm-1 (100% intensity), 339.2 cm-1 (26%), and 340.2 cm-1 (2%) for a surfactant with a molecular formula of C20H36NO3+ and a calculated molecular weight of 339.2. Similarly, the parent ion peaks that had 100% intensity for 6a(b), 7a(b), and 9a(b) were observed at 366.3, 394.4, and 422.4 cm-1, respectively, which matched the calculated value. The infrared (IR) spectra of the products gave a broad peak at 3388-3427 cm-1 for the -OH group. The C-O stretching were observed at 1047-1048 cm-1 and 1110-1112 cm-1. Two multiplets were observed at a chemical shift of δ 4.74-4.79 and 5.14-5.18 for -O-CH2-CH-N+C5H5, and

10.1021/ie801737m CCC: $40.75  2009 American Chemical Society Published on Web 01/08/2009

1674 Ind. Eng. Chem. Res., Vol. 48, No. 3, 2009 Scheme 1

Table 1. Haemolytic Activity, Cytotoxicity, and Surface Tension Assessment of Cationic Surfactants 6a(b), 7a(b), 8a(b), 9a(b), 10, and 11 isomer hemolysis CMC surface ratio, cytotoxicity, PBS concentrationb tension, compound a:ba IC50 [µM] [µM] (mM) γcmc (mN/m) 6a(b) 7a(b) 8a(b) 9a(b) 10 11

46:54 50:50 50:50 56:44

35.99 19.07 11.85 8.43 5.78 2.30

250 100 80 60 40 40

3.13 2.58 0.81 0.51 3.84 0.90c

Figure 1. Plot of surface tension versus surfactant concentration for compounds 6-9a(b).

37.7 39.5 43.5 44.9 38.1

a Ratio of isomers determined by integration value of chemical shift at δ 4.74-4.79 and 5.14-5.18 by 1H NMR. b Obtained using a du Nouy ring tensiometer. c Data taken from ref 30.

C5H5N+CH2, respectively, in the 1H NMR spectra of 6a(b) to 9a(b), suggests the presence of two positional isomers. The integration ratio of the two signals, which denotes two protons each, is helpful in establishing the amount of each isomer present. The ring protons of pyridine were observed at δ 8.13-8.19, 8.58, and 9.33 ppm. The 13C NMR spectroscopy further helped to establish the structure of these compounds. The sp3 carbons for terminal methyl were observed at δ 14.05-14.11 ppm, whereas the sp3 carbons for CH2 were observed in the range of δ 22.60-31.91 ppm. However, the sp3 carbons directly linked to a heteroatom, such as oxygen and nitrogen, was observed at δ 63.97-64.01 ppm. The CH-O carbon was observed at δ 78.21-78.33. The CH-N carbon was observed at δ 78.55-78.64. The assignment of chemical shifts to various protons and carbons has been done on the basis of distortionless enhanced polarization transfer (DEPT), two-dimensional heteronuclear chemical shift correlation (2D HETCORE), and two-dimensional correlation spectroscopy (2D COSY) experiments. (Graphical results are provided as Supporting Information.) Thus, the structure of these new glycerol-based pyridinium surfactants has been established via several spectroscopic techniques, as well as using elemental analysis. The surface activity of cationic surfactants was evaluated by measuring the surface tension. The values of the critical micellar concentration (CMC) and the surface tension attained at the cmc of compounds 6a(b), 7a(b), 8a(b), and 9a(b) are given in Table 1, and plots of the surface tension versus the surfactant concentration of each compound are provided in Figure 1. The presence of two hydroxyl groups imparts polarity, and there exists the possibility of significant hydrogen bonding in the aqueous system, because such types of bonding favor aggregation of surfactant monomers to form micelles.26 However, a general trend is followed as the cmc decreases with increasing chain length.27 Low toxicity of a molecule is a prerequisite for biomedical applications such as gene and drug delivery and also environmental aspects such as biodegradability. Thus, the cytotoxicity of these pyridinium surfactants was assessed on C6 glioma cells.

Figure 2. MTT assay for cytotoxicity; the compounds were tested for cytotoxicity in C6 glioma cell line in the range of 1-100 µM. Data are represented as phase contrast photographs of compound 6a/b (scale ) 200×).

Interestingly, the results of these new molecules explicate a direct relationship between the alkyl chain length of the compounds and their cytotoxicity. 1-(1-(2,3-Dihydroxypropoxy)dodecan-2-yl) pyridinium bromide/1-(2-(2,3-dihydroxypropoxy)dodecyl) pyridinium bromide (6a(b)) was determined to be the least toxic, having an IC50 value of 35.99 µM, whereas 1-(1(2,3-dihydroxypropoxy)octadecan-2-yl) pyridinium bromide/1(2-(2,3-dihydroxypropoxy)octadecyl) pyridinium bromide (9a (b)) was determined to be the most toxic among the series of pyridinium cationics synthesized and reported in the present study, having an IC50 value of 8.43 µM. Furthermore, evaluation of the hemolytic activity of these compounds correlates the trend of increasing toxicity with increasing alkyl chain length, as evident by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay results (see Table 1 and Figure 2). Again, the most toxic of all the surfactants synthesized was 9a(b), which caused the rupture of red blood cells at a surfactant concentration of 60 µM. The presence of two hydroxyl group imparts polarity and is responsible for the increase in the hydrophilic character of the molecule, which correspondingly reduces its toxicity. Keeping the hydrophilic part constant and subsequently increasing the alkyl chain length causes an increase in toxicity. All the new compounds synthesized were less toxic than the commercially available cationic surfactants tetradecyl trimethyl ammonium bromide (10) and cetyl pyridinium bromide (11). DNA binding capability of the synthesized molecules was evaluated through simple agarose gel electrophoresis. This binding capability of the new surfactants to DNA increases as the alkyl chain length increases and has better DNA binding capability than tetradecyl trimethyl ammonium bromide (10) and cetyl pyridinium bromide (11). This important property can be exploited for DNA extraction methods as well as for gene delivery. It was observed that all surfactants were able to bind

Ind. Eng. Chem. Res., Vol. 48, No. 3, 2009 1675

Figure 3. Gel electrophoresis of pDNA (120 ng per lane). Lane 1 has only plasmid DNA. Lanes 2, 5, 8, 11, 14, and 17 represent 6a(b), 7a(b), 8a(b), 9a(b), 10, and 11, respectively, present in a concentration of 100 µM. Lanes 3, 6, 9, 12, 15, and 18 represent 6a(b), 7a(b), 8a(b), 9a(b), 10, and 11, respectively, present in a concentration of 1 mM. Lanes 4, 7, 10, 13, 16, and 19 represent 6a(b), 7a(b), 8a(b), 9a(b), 10, and 11, respectively, present in a concentration of 10 mM. (Note: 10 µL of surfactant solution is added in each well.)

plasmid DNA (pUC18). All the molecules synthesized were able to bind plasmid DNA at a surfactant concentration of 10 mM. However, it was observed that the binding capability increases as the alkyl chain length increases, as compounds 6a(b) and 7a(b) were unable to bind plasmid DNA at surfactant concentrations of 100 µM and 1 mM, while compound 8a(b) was able to bind at a surfactant concentration of 1 mM but no binding was observed at a surfactant concentration of 100 µM. Compound 9a(b) was able to bind at surfactant concentrations of 100 µM as well as 1 mM. (See Figure 3.) It was also observed that the presence of the glycerol moiety in the surfactant molecule increases its DNA binding capability, because all the molecules synthesized were able to bind DNA at a surfactant concentration level of 10 mM but none of the two reference molecules were able to bind DNA at same surfactant concentration, although slight retardation was observed in case of cetyl pyridinium bromide (11). The findings of the study suggest that new glycerol-based pyridinium surfactants have better surface properties as well as biological compatibility. They have better DNA binding capability, and, hence, they can find application in various industries and can replace the standard cationic surfactants that are available commercially. The production of these new surfactants in commercial quantity will save energy and resources, which has become a concern because of the overproduction of glycerol. Experimental Section Compounds 1-4a(b) were synthesized using a previously reported procedure.25 Pyridine and glycerol was purchased from Qualigens Fine Chemicals (Mumbai, India). 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and ethidium bromide (EtBr) was purchased from Sigma (St. Louis, MO, USA). Agarose and Tris buffer was purchased from Sisco Research Laboratory PVT, Ltd. (Mumbai, India). Plasmid DNA (pUC 18) was purchased from Bangalore GeNei (Bangalore, India). Instrumentation Infrared (IR) spectra were recorded as a thin neat film on a Fourier transform infrared (FT-IR) instrument (Model 8400s,

Shimadzu, Kyoto, Japan). Mass spectra were recorded on Waters Q-Tof Micromass equipment at the Sophisticated Analytical Instrumentation Facility (SAIF) at Panjab University, in Chandigarh, India. 1H and 13C NMR were recorded on a FT-NMR 300 MHz system (Model AL-300, JEOL, Tokyo, Japan) and a FT NMR 400 MHz system (Model AVANCE II, Bruker, Basel, Switzerland), at the SAIF at Panjab University, in a solution of CDCl3, using tetramethylsilane (TMS) as an internal standard. Surface tension was determined using a Du Nouy tensiometer with a platinum ring (CSC Scientific Company, Fairfax, VA, USA). General Procedures Synthesis. The following compounds were placed in a roundbottom flask and warmed to 50 °C: 3-(2-bromododecyloxy)propane-1,2-diol (1a)/3-(1-bromododecan-2-yloxy)propane-1,2-diol (1b), 6.79 g (20 mmol); 3-(2-bromotetradecyloxy)propane-1,2diol (2a)/3-(1-bromotetradecan-2-yloxy)propane-1,2-diol (2b), 7.34 g (20 mmol); 3-(2-bromohexadecyloxy)propane-1,2-diol (3a)/3-(1-bromohexadecan-2-yloxy)propane-1,2-diol (3b), 7.9 g (20 mmol); 3-(2-bromooctadecyloxy)propane-1,2-diol (4a)/3(1-bromohexadecan-2-yloxy)propane-1,2-diol (4b), 8.48 g (20 mmol). Pyridine (5) (1.89 g (24 mmol)) was then added, and the mixture was stirred at 100 °C for 10 h. The reaction mixture was allowed to cool to 25 °C. The crude reaction mixture (solid) was suspended in 40 mL of diethyl ether and stirred for 15 min at temperatures between 0 °C and -5 °C. The suspended material was filtered to remove excess pyridine and unreacted reactant. The step was repeated with diethyl ether and acetone at temperatures between 0 °C and -5 °C to obtain product (6-9a(b)) that was white to off white in color. The product was vacuum-dried at 35 °C in a rotary flash evaporator. Cytotoxicity and Hemolytic Assessments. The MTT-based cytotoxicity test28 was used to evaluate all four glycerol-based pyridinium surfactants, and the test was performed on C6 glioma (cancerous brain cell line). Cells were seeded in 96-well flatbottom microplates at a density of (2.5-3.0) × 104 per mL, 100 µL per well, and were allowed to grow for 24 h. The compounds, which were dissolved in double-distilled water,

1676 Ind. Eng. Chem. Res., Vol. 48, No. 3, 2009

were sterilized using a 0.22 µm Millipore filter and were added to culture media over a concentration range of 0.1-100 µM. The cytotoxicity of the compounds was assessed after 24 h of exposure. Assessment was made using a plate reader (Muliskan PLUS, Labsystem). The statistical analysis was performed using the Sigma Stat 3.5.1 and Sigma Plot 11.0 programs. Hemolytic activity28 of the compounds was assessed on human red blood cells (2% in PBS). The concentration range of the compounds was 1 µM to 1 mM. Human red blood cells were kept in incubation for 2 h, and the amount of hemoglobin released was determined using a plate reader (Muliskan PLUS, Labsystem) at 540 nm. The cytotoxicity and hemolysis experiments were performed twice in triplicate. Surface Tension Determination. The critical micelle concentration (CMC) and surface tension attained at the CMC was determined using a du Nouy tensiometer (CSC Scientific Company) with a platinum-iridium ring at 25 ( 0.1 °C. The tensiometer was calibrated using triple-distilled water. Agarose Gel Electrophoresis. DNA binding capability was determined through agarose gel electrophoresis.29 In this study, 120 ng of DNA was loaded into 1% agarose gel that contained 0.5 µg/mL ethidium bromide (EtBr), along with loading buffer glycerol. Compounds 6-9a(b) were evaluated to determine the binding efficiency. Electrophoresis was conducted at 100 V in a TBE buffer for 30 min. The DNA band was visualized under an ultraviolet (UV) transilluminator. Spectral Results. 1-(1-(2,3-Dihydroxypropoxy)dodecan2yl)pyridinium bromide (6a)/1-(2-(2,3-dihydroxypropoxy)dodecyl)pyridinium bromide (6b). (5.25 g, 62.72%) as a off white solid. Mp 73.3 °C (phase transition), 109.8 °C. m/z TOF MS ES+: calcd 338.2 (for C20H36NO3+), found 338.2 (100%), 339.2 (26%), 340.2 (2%). IR (cm-1) 3427, 3388, 2923, 2854, 1636, 1488, 1110, 1048; 1H NMR (CDCl3) δ ppm 0.87(t, J ) 6.3 Hz, 6H, 2× CH3), 1.25(br s, 30H, CH2 chain), 1.39(br s, 4H, C5H5N+CH-CH2, -CHO-CH2-), 1.55(br s, 2H, β to C5H5N+CH-), 2.31(br s, 3H, 3× -OH), 3.42-3.67(m, 8H, 2× -CHaHbOH, 2× CH-CHaHb-O-), 3.73(m, 2H, 2× -CHOH), 3.91(br s, 3H, -OH, C5H5N+CH2-CHO-, C5H5N+CH-), 4.69-4.75(q, 2H, -O-CH2-CH-N+C5H5), 5.12-5.16(m, 2H, C5H5N+CH2), 8.12-8.20(q, 4H, 2× H-3,5), 8.57(t, J ) 7.8 Hz, 2H, 2× H-4), 9.27(t, 4H, 2× H-2,6). 13C NMR (normal/DEPT135) (CDCl3) δ ppm 14.09(+ve, terminal CH3), 22.64-31.88(ve, chain CH2), 63.30, 63.67(-ve, C3 (-CH2-OH)), 64.01(-ve, 2× C, -O-CH2-CH-N+C5H5, C5H5N+CH2), 70.72, 71.61(+ve, C2 -CHOH), 71.09, 72.12(-ve, C1 -CH2O), 78.26, 78.60(+ve, C5H5N+CH2-CHO-, C5H5N+CH-), 128.02(2× C-3,5 of N+C5H5), 145.63(2× C-4 of N+C5H5), 145.96(2× C-2,6 of N+C5H5). CHNO Found: C, 57.62; H, 8.61; N, 3.41; O, 11.56. C20H36BrNO3 requires C, 57.41; H, 8.67; N, 3.35; O, 11.47%. 1-(1-(2,3-Dihydroxypropoxy)tetradecan-2yl)pyridinium bromide (7a)/1-(2-(2,3-dihydroxypropoxy)tetradecyl)pyridinium bromide (7b). (5.43 g, 60.87%) as a white solid. Mp 96.6 °C (phase transition) 143 °C. m/z TOF MS ES+: calcd 366.3 (for C22H40NO3+), found 366.3 (100%), 367.3 (27%), 368.3 (4%). IR (cm-1) 3415, 3350, 2923, 2852, 1635, 1488, 1112, 1049. 1H NMR (CDCl3) δ ppm 0.87(t, J ) 6.0 Hz, 6H, 2× CH3), 1.25(br s, 38H, CH2 chain), 1.39(4H, C5H5N+CH-CH2, -CHO-CH2-), 1.56(br s, 2H, β to C5H5N+CH-), 3.39-3.67(m, 8H, 2× -CHaHbOH, 2× CH-CHaHb-O-), 3.72(m, 2H, 2× -CHOH), 3.90(br s, 2H, C5H5N+CH2-CHO-, C5H5N+CH-),4.17(br s, 2H, 2× -OH), 4.25(br s, 2H, 2× -OH), 4.71-4.75(q, 2H, -O-CH2-CH-N+C5H5), 5.13-5.16(m, 2H, C5H5N+CH2), 8.11-8.17(q, 4H, 2× H-3,5), 8.57(t, J ) 7.5 Hz, 2H, 2× H-4), 9.29(d, 4H, 2× H-2,6). 13C NMR (normal/DEPT-135) (CDCl3)

δ ppm 14.16(+ve, terminal CH3), 22.65-31.88(-ve, chain CH2), 63.30, 63.66(-ve, C3 (-CH2-OH)), 64.02(-ve, 2× C, -O-CH2-CH-N+C5H5, C5H5N+CH2), 70.71, 71.62(+ve, C2 -CHOH), 71.65, 72.12(-ve, C1 -CH2O), 78.26, 78.63 (+ve, C5H5N+CH2-CHO-, C5H5N+CH-), 128.04 (2× C-3,5 of N+C5H5), 145.64 (2× C-4 of N+C5H5), 146.03 (2× C-2,6 of N+C5H5). CHNO Found: C, 59.27; H, 8.99; N, 3.20; O, 10.82. C22H40BrNO3 requires C, 59.18; H, 9.03; N, 3.14; O, 10.75%. 1-(1-(2,3-Dihydroxypropoxy)hexadecan-2yl)pyridinium bromide (8a)/1-(2-(2,3-dihydroxypropoxy)hexadecyl)pyridinium bromide (8b). (6.52 g, 68.92%) as a white solid. Mp - broad phase transition at ambient temperature; determination of the onset of this transition was not possible. m/z TOF MS ES+: calcd 394.5 (for C24H44NO3+), found 394.4 (100%), 395.4 (31%), 396.4 (4%). IR (cm-1) 3413, 3390, 2923, 2852, 1636, 1467, 1110, 1047. 1H NMR (CDCl3) δ ppm 0.87(t, J ) 6.4 Hz, 6H, 2× CH3), 1.29(br s, 46H, CH2 chain), 1.39(br.s, 7H, 3× -OH, C5H5N+CH-CH2, -CHO-CH2-), 1.58(m, 2H, β to C5H5N+CH-), 3.38-3.66(m, 8H, 2× -CHaHbOH, 2× CH-CHaHb-O-), 3.73(m, 2H, 2× -CHOH), 3.88(br s, 3H, -OH, C5H5N+CH2-CHO-, C5H5N+CH-), 4.74-4.79(q, 2H, -O-CH2-CH-N+C5H5), 5.14-5.18(m, 2H, C5H5N+CH2), 8.13-8.19(q, 4H, 2× H-3,5), 8.58(t, J ) 7.6 Hz, 2H, 2× H-4), 9.33(t, 4H, 2× H-2,6). 13C NMR (normal/DEPT-135) (CDCl3) δ ppm 14.11(+ve, terminal CH3), 22.67-31.91(-ve, chain CH2), 63.33, 63.69(-ve, C3 (-CH2-OH), 63.99(-ve, 2× C, -O-CH2-CH-N+C5H5, C5H5N+CH2), 70.80, 71.63(+ve, C2 -CHOH), 71.11, 72.12(-ve, C1 -CH2O), 78.33, 78.64(+ve, C5H5N+CH2-CHO-, C5H5N+CH-), 128.04(2× C-3,5 of N+C5H5), 145.64(2× C-4 of N+C5H5), 146.03 (2× C-2,6 of N+C5H5). CHNO Found: C, 60.83; H, 9.41; N, 2.98; O, 10.07. C24H44BrNO3 requires C, 60.75; H, 9.35; N, 2.95; O, 10.12%. 1-(1-(2,3-Dihydroxypropoxy)octadecan-2yl)pyridinium bromide (9a)/1-(2-(2,3-dihydroxypropoxy)octadecyl)pyridinium bromide (9b). (6.66 g, 66.2%) as a white solid. Mp 98.2 °C (phase transition). m/z TOF MS ES+: calcd 422.4 (for C26H48NO3+), found 422.4 (100%), 423.4 (41%), 424.4 (9%). IR (cm-1) 3407, 3388, 2920, 2850, 1635, 1465, 1110, 1048. 1H NMR (CDCl3) δ ppm 0.87(t, J ) 6.0 Hz, 6H, 2× CH3), 1.25(br s, 54H, CH2 chain), 1.39(br s, 4H, C5H5N+CH-CH2), 1.66(br s, 6H, 4× -OH, β to C5H5N+CH-), 3.40-3.70(m, 8H, 2× -CHaHbOH, 2× CH-CHaHb-O-), 3.76(m, 2H, 2× -CHOH), 3.93(br s, 2H, C5H5N+CH2-CHO-, C5H5N+CH-), 4.73(m, 2H, -O-CH2-CH-N+C5H5), 5.18-5.20(m, 2H, C5H5N+CH2), 8.08-8.15(q, 4H, 2× H-3,5), 8.51(t, J ) 7.5 Hz, 2H, 2× H-4), 9.32(d, 4H, 2× H-2,6). 13C NMR (normal/DEPT-135) (CDCl3) δ ppm 14.05(+ve, terminal CH3), 22.60-31.84(-ve, chain CH2), 63.25, 63.61(-ve, C3 (-CH2-OH), 63.97(-ve, 2× C, -O-CH2-CH-N+C5H5, C5H5N+CH2), 70.67, 71.56(+ve, C2 -CHOH), 71.03, 72.06(-ve, C1 -CH2O), 78.21, 78.55(+ve, C5H5N+CH2-CHO-, C5H5N+CH-), 127.91(2× C-3,5 of N+C5H5), 145.57(2× C-4 of N+C5H5), 145.89(2× C-2,6 of N+C5H5). CHNO Found: C, 62.23; H, 9.59; N, 2.85; O, 9.61. C26H48BrNO3 requires C, 62.14; H, 9.63; N, 2.79; O, 9.55%). Conclusion In the present study, we have synthesized new glycerol-based pyridinium surfactants in ca. 60%-70% isolated yield and evaluated their properties. It has been determined that the new glycerol-based pyridinium surfactants exhibit better surface properties, better DNA binding capability, and lower toxicity, compared to commercially available cationic surfactants (cetyl pyridinium bromide and tetradecyl trimethyl ammonium bro-

Ind. Eng. Chem. Res., Vol. 48, No. 3, 2009 1677

mide). Thus, these new surfactants have the potential to replace commercially available surfactants in a wide range of applications. Acknowledgment The authors are thankful to the Council of Scientific & Industrial Research (CSIR) India, for providing the research grant for this work, and the Sophisticated Analytical Instrumentation Facility (SAIF) at Panjab University (Chandigarh, India), for the 13C DEPT, 2D COSY, HETCORE, and mass spectra analyses of the compounds. Supporting Information Available: 1H and 13C NMR spectra, 13C DEPT, 2D COSY, 2D HETCORE for 8a(b), and mass spectroscopic analysis of all the surfactants studied in this research. (PDF) This material is available free of charge via the Internet at http://pubs.acs.org. Literature Cited (1) Bartuska, W. R.; Silverman, P. Henna hair coloring and/or conditioning compositions,U.S. Patent 4,183,366, January 15, 1980. (2) Hatanaka, K.; Hirayama, T. Liquid cleansing cosmetics containing carboxyl group-containing acidic polymers and nitrogen heterocyclic cationic surfactants,Japanese Patent JP 2005187338, July 14, 2005. (3) Kenji, N.; Nakamura, K. Antimicrobial and deodorant cosmetic brush and method of producing the same,U.S. Patent 6,604,531, August 12, 2003. (4) Free, M. L. Understanding the effect of surfactant aggregation on corrosion inhibition of mild steel in acidic medium. Corros. Sci. 2002, 44, 2865–2870. (5) Shah, S. S.; Fahey, W. F.; Oude, B. A. Corrosion inhibitors, for distribution of petroleum and petroleum products, consisting of a pyridinium compound and a quaternary ammonium salt,U.S. Patent 5,336,441, August 9, 1994. (6) Chigwada, G.; Wang, D.; Wilkie, C. A. Polystyrene nanocomposites based on quinolinium and pyridinium surfactants. Polym. Degrad. Stab. 2006, 91, 848–855. (7) Zaragoza-Contreras, E. A.; Rodriguez-Gonzalez, R. J.; NavoarroRodriguez, D. Emulsion polymerization of styrene using a new series of rigid rodlike cationic surfactants. Macromol. Chem. Phys. 1999, 200, 828– 833. (8) Koopal, L. K.; Goloub, T.; Keizer, A.; De Marianna, P. The effect of cationic surfactants on wetting colloid stability and flotation of silica. Colloids Surf. A 1999, 151, 15–25. (9) Prince, A. K.; Sukonick, B. Polyfluoroisoalkoxyalkyl pyridinium salts,U.S. Patent 3,674,798, July 4, 1972. (10) Viscardi, G.; Quagliotto, P.; Barolo, C.; Savarino, P.; Barni, E.; Fisicaro, E. Synthesis and Surface and Antimicrobial Properties of Novel Cationic Surfactants. J. Org. Chem. 2000, 65, 8197–8203. (11) Pernak, J.; Branicka, M. The properties of 1-alkoxymethyl-3hydroxypyridinium and 1-alkoxymethyl-3-dimethylaminopyridinium chlorides. J. Surfactants Deterg. 2003, 6, 119–123. (12) Haider, J.; Kondaiah, P.; Bhattacharya, S. Synthesis and Antibacterial Properties of Novel Hydrolyzable Cationic Amphiphiles. Incorporation

of Multiple Head Groups Leads to Impressive Antibacterial Activity. J. Med. Chem. 2005, 48, 3823–3831. (13) Zhao, T.; Sun, G. Synthesis and characterization of antimicrobial cationic surfactants: aminopyridinium salts. J. Surfactants Deterg. 2006, 9, 325–330. (14) Karande, P.; Mitragotri, S. High Throughput Screening of Transdermal Formulations. Pharm. Res. 2002, 19, 665–660. (15) Pop, E. Targeting penicillins to the central nervous system: chemical delivery systems and redox analogs. AdV. Drug DeliVery ReV. 1994, 14, 211–226. (16) Ilies, M. A.; Seitz, W. A.; Ghiviriga, I.; Johnson, B. H.; Miller, A.; Thompson, E. B.; Balaban, A. T. Pyridinium cationic lipids in gene delivery: a structure-activity correlation study. J. Med. Chem. 2004, 47, 3744–3754. (17) van der Woude, I.; Wagenaar, A.; Meekel, A. A. P.; ter Beest, M. B. A.; Rutters, M. H. J.; Engberts, J. B. F. N.; Hoekstra, D. Novel pyridinium surfactants for efficient, nontoxic in Vitro gene delivery. Proc. Natl. Acad. Sci., U.S.A. 1997, 94, 1160–1165. (18) Goto, M.; Momota, A.; Ono, T. DNA extraction by cationic reverse micelles. J. Chem. Eng. Jpn. 2004, 37 (5), 662–668. (19) Rai, H.; Ohtsuka, S.; Nishiyama, M.; Senoo, K. Optimizing beadbeating DNA extraction protocol from environmental samples with use of surfactant and heat treatment,PCT Int. Appl. WO 2005073377, August 11, 2005. (20) Suzuki, M.; Ishida, Y.; Komatsubara, S.; Kamakami, F.; Kamamura, Y. Extraction method for plant DNA,Japanese Patent JP 11169170, June 29, 1999. (21) Gunstone, F. D.; Padley, F. B. Lipid Technologies and Application; Marcel Dekker: New York, 1997. (22) Karsa, D. R.; Porter, M. R. Biodegradability of Surfactants; Blackie Academic & Professional Publishers: London, 1995. (23) Pagliaro, M.; Rossi, M. The Future of Glycerol: New Uses of a Versatile Raw Material; RSC Green Chemistry Series; Royal Society for Chemistry: Cambridge, U.K., 2008. (24) Zhou, C.-H.; Beltramini, J. N.; Fan, Y.-X.; Lu, G. Q. Chemoselective catalytic conversion of glycerol as a biorenewable source to value commodity chemicals. Chem. Soc. ReV. 2008, 37, 527–549. (25) Singh, S.; Bhadani, A.; Kamboj, R. Synthesis of β-Bromoglycerol monoethers from R-olefins. Ind. Eng. Chem. Res. 2008, 47, 8090–8094. (26) Bakshi, M. S. Cetylpyridinium chloride-tetradecylammonium bromide mixed micelles in ethylene glycol-water and diethylene glycol-water mitures. J. Chem. Soc., Faraday Trans. 1997, 93 (22), 4004–4008. (27) Madaan, P.; Tyagi, V. K. Quaternary Pyridinium Salts: A Review. J. Oleo Sci. 2008, 57 (4), 197–215. (28) Vyas, S. M.; Tura´nek, J.; Kno¨tigova´, P.; Kanˆa´, A.; Kvardova´, V.; Koganti, V.; Rankin, S. E.; Knutsonc, B. L.; Lehmler, H.-J. Synthesis and biocompatibility evaluation of partially fluorinated pyridinium bromides. New J. Chem. 2006, 30, 944–951. (29) Zhao, X.; Zhang, Z.; Pan, F.; Waigh, T. A.; Lu, J. R. Plasmid DNA complexation with phosphorylcholine diblock copolymers and its effect on cell transfection. Langmuir 2008, 24, 6681–6888. (30) Paria, S.; Yuet, P. K. Effects of Chain Length and Electrolyte on Adsorption of n-Alkyl Pyridinium Bromide Surfactants at Sand-Water Interfaces. Ind. Eng. Chem. Res. 2006, 45, 712–718.

ReceiVed for reView November 14, 2008 ReVised manuscript receiVed December 23, 2008 Accepted December 28, 2008 IE801737M