1. FIELD OF THE INVENTION

The present invention, in general, relates to novel compounds and a process for the preparation of the same. The present invention, in particular, relates to a novel amido-amine and a glycerol based cationic surfactant, a process for their preparation and use of these novel amido amine based compounds.

2. DESCRIPTION OF THE RELATED ART

Cationic surfactants contain positively charged hydrophilic group (head group) and hydrocarbon as a hydrophobic group (tail group). These are basically quaternary ammonium salts of long chain tertiary amines as disclosed in Detergency of Specialty Surfactants, Shoaib Arif and Floyd E. Friedli, Surfactant Science series Vol.98 p. 71 Marcel Dekker, Inc. (2001 ).

Prior art patents US20080207933 and US6964940 disclose amido-amine based cationic surfactants with quaternary centers and a process of preparation of the surfactant. However the surfactants disclosed suffer from several disadvantages such as poor biodegradability, higher krafft point and lower solubility and hence these are not stable and not applicable at a wide range of temperatures.. This, for instance, would pose problems in agricultural applications, wherein the formulations are to be used at a wide range of temperatures in different regions of the world.

Further the eco-toxicological profile is one of the most important features of surfactants, as regulations are becoming more restrictive.

Thus there is a need to provide a surfactant having lower krafft point, better solubility, better biodegradability and which is practically applicable over a wide range of temperatures. Also there is a need to provide the simple route for the synthesis of surfactant using the reagents which are readily available and cost effective.

SUMMARY OF THE INVENTION

The present invention relates to novel amido-amine compounds of the general Formula I

Formula I

Wherein, n represents alkyl chain having from 8 to 30 carbon atoms; m represents alkyl chain having from 1 to 6 carbon atoms; R1 represents alkyl chain having from 1 to 10 carbon atoms; and X is selected from halides.

The applicant has surprisingly found that the compound based on amido-amine and glycerol have several advantages such as better biodegradability, lower krafft point, better solubility and these can be used at wide range of temperature and suitable to use and transport in the colder regions.

The present invention further relates to a process for the preparation of novel amido-amine compounds of Formula I

Formula I

Wherein , n represents alkyl chain having from 8 to 30 carbon atoms; m represents alkyl chain having from 1 to 6 carbon atoms; R1 represents alkyl chain having from 1 to 10 carbon atoms; and X is selected from F, Br, I and CI. The applicant has found the simple and cost effective process for the synthesis of these compounds using 3- chloro-glycerol which is a byproduct of several chemical processes and so is cheap and readily available thus giving us an alternative for the synthesis of a novel eco-friendly cationic surfactant.

The method involves: i) reacting glycerol with hydrochloric acid in the presence of acetic acid to obtain monohalo glycerol; and ii) reacting the compound of formula II with the monohalo glycerol of step i to obtain the compound of formula I.

Formula II

The present invention also provides a composition comprising the novel amido-amine compounds of Formula I dispersed in water.

The present invention also relates to the use of novel amido-amine compounds of Formula I as a surfactant.

The present invention still further provides an antimicrobial composition comprising the novel amido-amine compound of Formula I as antimicrobial agent.

BRIEF DESCRIPTION OF DRAWINGS

For a more complete understanding of the invention, reference should now be made to the embodiments illustrated in greater detail in the accompanying drawings and described below by way of embodiments of the invention. It should be understood, of course, that the invention is not necessarily limited to the particular embodiments illustrated herein.

FIGURE 1 is a graph illustrating critical micellar concentration (CMC) measurement obtained by plotting surface tension and conductivity Vs concentration of aqueous solutions of N-(3-dodecanamidopropyl)-2,3- dihydroxy-N,N-dimethylpropan-1 -ammonium chloride.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to novel amido-amine compounds of the general Formula I

Formula I Wherein , n represents alkyi chain having from 8 to 30 carbon atoms; m represents alkyi chain having from 1 to 6 carbon atoms; R1 represents alkyi chain having from 1 to 10 carbon atoms; and X is selected from F, Br, I and CI. According to an embodiment of the invention, n represents alkyl chain having 8 to 30 carbon atoms. According to another embodiment of the invention, m represents alkyl chain having 1 to 6 carbon atoms. According to yet another embodiment, R1 represents alkyl chain having 1 to 10 carbon atoms.

According to a still further embodiment, the invention specifically relates, but is not limited to the following compounds of Formula I:

1 N-(3-octaamidoethyl)-2,3-dihydroxy-N,N-dimethylpropan-1-ammo nium chloride

2 N-(3-octaamidopropyl)-2,3-dihydroxy-N,N-dimethylpropan-1 -ammonium chloride

3 N-(3-decaamidopropyl)-2,3-dihydroxy-N,N-dimethylpropan-1-amm onium chloride

4 N-(3-dodecanamidopropyl)-2,3-dihydroxy-N,N-dimethylpropan-1 -ammonium chloride

5 N-(3-tetradecanamidopropyl)-2,3-dihydroxy-N,N-dimethylpropan -1-ammonium chloride

6 N-(3-octadodecanamidopropyl)-2,3-dihydroxy-N,N-dimethylpropa n-1 -ammonium chloride

7 N-(3-hexaamidohexyl)-2,3-dihydroxy-N,N-dimethylpropan-1 -ammonium chloride

8 N-(3-octaamidohexyl)-2,3-dihydroxy-N,N-dimethylpropan-1 -ammonium chloride

9 N-(3-decaamidohexyl)-2,3-dihydroxy-N,N-dimethylpropan-1-ammo nium chloride

10 N-(3-dodecanamidohexyl)-2,3-dihydroxy-N,N-dimethylpropan-1 -ammonium chloride

11[N-(3-octadecanamidohexyl)-2,3-dihydroxy-N,N-dimethylpr opan-1 -ammonium chloride

12 [N-(3-octadecanamidohexyl)-2,3-dihydroxy-N,N-dimethylpropan- 1 -ammonium chloride

According to yet another embodiment, the invention relates to a process for the preparation of novel amido- amine compounds of Formula I

Formula I Wherein n represents alkyl chain having from 8 to 30 carbon atoms; m represents alkyl chain having from 1 to 6 carbon atoms; R1 represents alkyl chain having from 1 to 10 carbon atoms; and X is selected from F, Br, I and CI. The method involves:

i) reacting glycerol with halogen acid in presence of acetic acid to obtain monohalo glycerol; and ii) reacting compound of formula II with the monohalo glycerol of step i to obtain compound of formula I.

A general method of the present invention is represented by the following representative scheme.

Formula I

According to an embodiment, the first step of the process for the preparation of the novel amido-amine compounds of Formula I, involves reacting glycerol with halogen acid in presence of an organic solvent to obtain monohalo glycerol. The organic solvent is selected from any conventionally used alliphatic and aromatic hydrocarbons such as benzene, toluene, xylene, acetonitrile and isopropanol. According to another embodiment, the organic solvent preferably used is isopropanol. This reaction is carried out at the temperature of around 105-110°C. However, those skilled in the art will appreciate that it is possible to utilize other solvents known in the art without departing from the scope of the invention.

According to an embodiment, the second step of reacting the compound of formula II with the monohalo glycerol of step i to obtain the compound of formula I is also carried out in the presence of a solvent. The solvent is an organic solvent such as acetone, ethanol, acetonitrile, isopropanol and chloroform. This reaction is carried out for 10-12 hrs. However, those skilled in the art will appreciate that it is possible to utilize other solvents known in the art without departing from the scope of the invention.

According to an embodiment, the step 2 of the process is carried out in absence of any solvent.

According to a preferred embodiment, the process for the preparation of the novel amido-amine compounds of Formula I, is carried out in an inert atmosphere.

According to an embodiment, the halogen acid can be selected from at least one of hydrochloric acid, hyrobromic acid, hydrofluoric acid, hydroiodic acid.

According to another embodiment, the invention relates to an aqueous composition comprising the novel amido-amine compounds of Formula I in water or water miscible solvent.

According to an embodiment, the water miscible solvent can be selected from any of the conventionally used solvents such as lower ketones such as acetone, lower esters such as methyl acetate, ethyl acetate, lower alcohols such as methanol and ethanol. However, those skilled in the art will appreciate that it is possible to utilize other water miscible solvents known in the art without departing from the scope of the invention. According to another embodiment, the aqueous composition can optionally include additives selected from any of the conventionally used additives such as thickening agent, anti-foaming agent, viscocity modifying agent, flavoring agent, perfumes, sterilizing or disinfecting agent, and pH modifying agents.

According to yet another embodiment, the invention relates to the use of the novel amido-amine compounds of Formula I, as surfactants.

According to yet another embodiment, the invention relates to the use of the novel amido-amine compounds of Formula I, as an antimicrobial agent.

These novel amido-amine compounds have excellent surface activity and are useful as emulsifiers, solubilizing agents, dispersing agents, foaming agents and dispersing agents. They can be used in compositions for fabric conditioning, detergent compositions,, as adjuvants for various types of compounds, including but not limited to, agriculturally active compounds and pharmaceutically active compounds, dermatological composition, cosmetic composition, concrete admixtures, inks and dyes, paints, leather chemicals, and in petroleum industries.

The following examples will serve to illustrate the invention, but should not be construed to limit the invention. All parts, percentages, ratios and the like in these examples and in the remainder of the specification and claims are in mole/mole percentages unless otherwise indicated.

Examples: The following examples are intended to illustrate but not to limit the present invention. Without further elaboration it is belived that one skilled in the art can, based on the description herein, utilize the present invention to its fullest extent. The aspects of the invention are now explained with the non-limiting examples below. Example 1 : [N-(3-dodecanamidopropyl)-2,3-dihydroxy-N,N-dimethylpropan-1 -ammonium chloride.]

The reaction was carried by mixing dodecanoic acid (3-dimethyl amino-propyl)-amide (17.5mmol, 5g) and 3- chloro glycerol (17.5mmol, 1.95g) in isopropanol. The mixture was refluxed for 12 hours. The product was separated from isopropanol by vaccum evaporation of isopropanol and recrystallized from diethyl ether several times. The yield of the amido amine compound obtained is 70 %.

The spectroscopy study of the novel amido amine compound of example 1 showed following results. NMR spectroscopy: 1 HNMR was carried out at 500MHz using D20 as solvent. In the NMR spectroscopy following peaks were observed and are measured as 5ppm: 0.814: t, 3H; 1.226: m, 18H; 1.529: m, 2H; 2.195: t, 2H; 3.157: s, 6H; 3.224: t, 2H; 3.414: d, 2H; 3.539: m, 1 H, 4.702: m, 4H.

For most of the surfactants, peak corresponding to NH and OH did not appear probably due to efficient relaxation by the attached nitrogen and oxygen respectively.

Fourier transfer IR spectroscopy (FTIR): In FTIR spectroscopy following peaks were observed. 3333.73 (O- H, Streching) which is obtained because of hydroxyl group present in the glycerol part of the surfactant, 1641 (Amide I band), 1546 (Amide II band) are due to the presence of amide linkage in the surfactant.

Mass Spectroscopy (MS) (positive): theoretical: 357.55; observed: 358.20 this positive peak represents only cationic section of the surfactant excluding counter anion.

Example 2: [N-(3-dodecanamidopropyl)-2,3-dihydroxy-N,N-dimethylpropan-1 -ammonium chloride.]

The reaction was carried by mixing dodecanoic acid (3-dimethyl amino-propyl)-amide (17.5mmol, 5g) and 3- chloro glycerol (17.5mmol, 1.95g) in absence of a solvent and recrystallized from diethyl ether several times. The yield of the amido amine compound obtained is 70 %.

The spectroscopy study of the novel amido amine compound of example 2 showed following results.

NMR spectroscopy: 1 HNMR was carried out at 500MHz using D20 as solvent. In the NMR spectroscopy following peaks were observed and are measured as 6ppm: 0.814: t, 3H; 1.226: m, 18H; 1.529: m, 2H; 2.195: t, 2H; 3.157: s, 6H; 3.224: t, 2H; 3.414: d, 2H; 3.539: m, 1 H, 4.702: m, 4H. For most of the surfactants, peak corresponding to NH and OH did not appear probably due to efficient relaxation by the attached nitrogen and oxygen respectively.

Fourier transfer IR spectroscopy (FTIR): In FTIR spectroscopy following peaks were observed 3333.73 (O-H, Streching), 1641(Amide I band), 1546 (Amide II band). Mass Spectroscopy (MS) (positive): theoretical: 357.55; observed: 358.20

Example 3: [N-(3-dodecanamidopropyl)-2,3-dihydroxy-N,N-dimethylpropan-1 -ammonium chloride.]

The reaction was carried by mixing dodecanoic acid (3-dimethyl amino-propyl)-amide (17.5mmol, 5g) and 3- chloro glycerol (17.5mmol, 1.95g) in ethanol. The mixture was refluxed for 12 hours. The product was separated from ethanol by vaccum evaporation of ethanol and recrystallized from diethyl ether several times. The yield of the amido amine compound obtained is 70 %.

The spectroscopy study of the novel amido amine compound of example 3 showed following results. NMR spectroscopy: 1 HNMR was carried out at 500MHz using D20 as solvent. In the NMR spectroscopy following peaks were observed and are measured as 5ppm: 0.814: t, 3H; 1.226: m, 18H; 1.529: m, 2H; 2.195: t, 2H; 3.157: s, 6H; 3.224: t, 2H; 3.414: d, 2H; 3.539: m, 1 H, 4702: m, 4H. For most of the surfactants, peak corresponding to NH and OH did not appear probably due to efficient relaxation by the attached nitrogen and oxygen respectively.

Fourier transfer IR spectroscopy (FTIR): In FTIR spectroscopy following peaks were observed 3333.73 (O-H, Streching), 1641 (Amide I band), 1546 (Amide II band).

Surface activity study:

For testing surface activity of novel cationic surfactant, the equilibrium surface tension of aqueous solution of the N-(3-dodecanamidopropyl)-2,3-dihydroxy-N,N-dimethylpropan-1- ammonium chloride surfactant was obtained using Wilhelmy plate method on Kruss K11 Tensiometer. The instrument was calibrated against distilled water. All the measurements were carried out at 298 ± 2 K. The conductivity was measured using LABTRONICS (LT 23) conductivity meter having cell constant of 0.830 cm-1.

The critical micellar concentration (CMC) of synthesized novel surfactant was investigated by the surface tension method and the conductivity method. The surface tension and conductivity of the surfactant solution was measured for a range of concentrations from premicellar to postmicellar regions. The graph of surface tension and conductivity Vs concentration of the surfactant solution is plotted to obtain surface tension isotherm as shown in Fig. 1. Premicellar region can be defined as a region where surface tension values decreases with the increase in the concentration. Postmicellar region can be defined as a region where surface tension values remains constant after reaching a minimum value with increasing concentration. Thus, the concentration at which the surface tension value ceases to decrease and attains constancy with increasing concentration can be termed as the 'CMC.

Aqueous solutions of the surfactant were prepared and placed in ice-water mixture for 12 hours to study the precipitation behaviour. The temperature was raised slowly till the surfactant crystals melted and a clear solution was obtained. This temperature was noted as the Krafft temperature (KT). The maximum surface excess concentration (rmax) value can be obtained using the Szyszkowski equation: π = γο-γ = nRT Tmax ln(1 +KC)

Where, π is surface pressure,

γο is surface tension of solvent (water),

Y is surface tension of solution at concentration C,

n is the prefactor,

K is the adsorption coefficient,

rmax is the maximum surface excess concentration,

R is the universal gas constant and

T is the temperature.

Szyszkowski equation is a correlation that relates the surface tension of surfactant solution with the bulk phase concentration.

Using the Tmax value obtained, we can determine the area per molecule or head group area of surfactant Amin. The parameters derived from the surface tension isotherm and Szyszkowski equation for N-(3- dodecanamidopropyl)-2,3-dihydroxy-N,N-dimethylpropan-1 -ammonium chloride surfactant are listed in the Table below:

Table 1 : The parameters derived from the surface tension isotherm and Szyszkowski equation

a CMC measured by conductivity method i) CMC, the critical micelle concentration;

ii) rmax, the maximum surface concentration (mol/m ² )

iii) Amin the minimum surface area per molecule (A2);

iv) C20, the efficiency of surface tension reduction i.e. the surfactant required to produce a decrease in surface tension of 20 mN/m;

v) ycmc, i.e. the effectiveness of the surface tension reduction and

vi) CMC/C20, which compares micellization and adsorption phenomena. It was observed that N-(3-dodecanamidopropyl)-2,3-dihydroxy-N,N-dimethylpropan-1 -ammonium chloride surfactant shows good surface active properties, with low CMC and C ₂₀ values. The compound also exhibits Krafft temperature below 0 °C and hence it can be utilized in low temperature environment.

Antimicrobial Activity study:

The antimicrobial activity of N-(3-dodecanamidopropyl)-2,3-dihydroxy-N,N-dimethylpropan-1- ammonium chloride was determined as the minimum inhibitory concentration (MIC) values.

MIC is defined as the lowest concentration of antimicrobial agent that inhibits the development of visible microorganism growth after 24 hrs of incubation at 310 ± 1 K.

The antimicrobial activity of N-(3-dodecanamidopropyl)-2,3-dihydroxy-N,N-dimethylpropan-1- ammonium chloride was determined by Kirby-Bauer disk-diffusion method in nutrient agar. The antimicrobial activity of the test compounds was assayed against Bacillus subtilis, Staphylococcus aureus (Gram Positive) and Escherichia coli, Salmonella typhi (Gram Negative). The MIC values obtained from the experiments are represented in Table No.2.

Table 2: Minimum Inhibitory Concentration (MIC) in ppm of surfactant

While the invention has been described with reference to specific embodiments, it will be appreciated that numerous variations, modifications and embodiments are possible, and accordingly all such variations, modifications and embodiments are to be regarded as deemed within the scope and spirit of the invention.