JP7257869B2 - Citronellol-based anionic surfactant and method for producing citronellol-based anionic surfactant - Google Patents

Description

The present invention relates to a citronellol-based anionic surfactant and a method for producing a citronellol-based anionic surfactant. In particular, the present invention relates to the generation of a new type of ester-based branched anionic surfactants containing a citronellyl moiety as the hydrophobic tail, using sodium sulfoacetate as the hydrophilic head group. This type of surfactant is the first of its class and may replace the commercially produced lauryl sulfonacetate (SLSA) surfactant.

Anionic surfactants find use in myriad application areas and are important ingredients in several industrial and consumer formulations. Today, these surfactants are used in personal care and household products such as detergents and cleaners, dishwashing liquids, industrial detergents, paints and coatings, and rubber and polymer additives.

Ester-based anionic surfactants:
Linear alkyl sulfoacetates (C6-C14), especially lauryl sulfoacetate (SLSA), are used in several application areas and are important ingredients in several consumer formulations. These linear ester anionic surfactants are used in cleaning formulations (see Patent Documents 1 and 2), detergents (see Patent Documents 3 and 4), shampoo formulations (see Patent Document 5), and hair care formulations (Patent Documents 6 and 7). See), transdermal topical preparations (see Patent Documents 8 and 9), oral care compositions (see Patent Documents 11 and 12), cosmetic preparations (see Patent Documents 13 and 14), pharmaceutical compositions (see Patent Document 15), etc. .

Ger. Offen. (1991), DE 4007638 A1 19910912 Repub. Korean Kongkae Taeho Kongbo (2018), KR 2018094238 A 20180823 U.S. Pat. Appl. Publ. (2017), US 20170044471 A1 20170216 Faming Zhuanli Shenqing (2017), CN 107446717 A 20171208 Repub. Korea (2018), KR 1891083 B1 20180823 U.S. (2000), US 6139828 A 20001031 U.S. Pat. Appl. Publ. (2008), US 20080222820 A1 20080918 U.S. Pat. Appl. Publ. (2013), US 20130337031 A1 20131219 U.S. Pat. Appl. Publ. (2011), US 20110028460 A1 20110203 PCT Int. Appl. (2015), WO 2015061910 A1 20150507 PCT Int. Appl. (2015), WO 2015008824 A1 20150122 Jpn. Kokai Tokkyo Koho (2013), JP 2013100259 A 20130523 PCT Int. Appl. (2015), WO 2015079026 A1 20150604 Fr. Demande (2015), FR 3013968 A1 20150605 PCT Int. Appl. (2018), WO 2018075071 A1 20180426

Currently, there are no commercially available anionic surfactants composed of naturally occurring plant-based acyclic monoterpenoid moieties as hydrophobic tails.

Demand for anionic surfactants is expected to increase in the coming years, thus requiring the development of a new generation of anionic surfactants with a substantial fraction of reproducible structural motifs that can be synthesized by sustainable approaches. .

Thus, a new type of branched anionic surfactant, namely citronellyl sulfoacetate sodium (SCSA) containing an acyclic monoterpenoid citronellyl moiety, can find applications in several industrial and consumer formulations. Developed from citronellol.

The present invention relates to a new type of renewable citronellol-based anionic surfactant, citronellyl sulfacetate sodium (SCSA), developed by a sustainable approach. A new surfactant molecule contains an ester functional group that is easily degraded in the environment after use and was developed by a green approach through an energy-saving and cost-effective methodology.

In order to achieve the above objects, the citronellol-based anionic surfactant of the present invention comprises the following chemical formula (1).

In order to achieve the above objects, the method for producing a citronellol-based anionic surfactant of the present invention includes the following two steps.
Step 1: Esterification of citronellol and chloroacetic acid to give citronellyl chloroacetate.
Step 2: Sulfation of the citronellyl chloroacetate produced in step 1 to obtain the citronellol-based anionic surfactant, citronellyl sulfoacetate sodium (SCSA).

In order to achieve the above objects, another method for producing a citronellol-based anionic surfactant of the present invention includes the following two steps.
Step 1: Esterification of citronellol and bromoacetic acid to give citronellyl bromoacetate.
Step 2: Sodium citronellyl sulfoacetate (SCSA) is sulfited from the citronellyl bromoacetate produced in step 1 to obtain a citronellol-based anionic surfactant, sodium citronellyl sulfonate.

In order to achieve the above objects, another method for producing a citronellol-based anionic surfactant of the present invention includes the following two steps.
Step 1: Acylation of citronellol with 2-chloroacetyl chloride gives the chloroacetate of citronellyl.
Step 2: Sulfation of the citronellyl chloroacetate produced in step 1 to obtain the citronellol-based anionic surfactant, citronellyl sulfoacetate sodium (SCSA).

In order to achieve the above objects, another method for the citronellol-based anionic surfactant of the present invention includes the following two steps.
Step 1: Acylation of citronellol with 2-bromoacetyl chloride to give citronellyl bromoacetate.
Step 2: Sodium citronellyl sulfoacetate (SCSA) is sulfited from the citronellyl bromoacetate produced in step 1 to obtain a citronellol-based anionic surfactant, sodium citronellyl sulfonate.

In order to achieve the above objects, another method for producing a citronellol-based anionic surfactant of the present invention includes the following two steps.
Step 1: Acylation of citronellol with 2-bromoacetyl bromide to give citronellyl bromoacetate.
Step 2: Sodium citronellyl sulfoacetate (SCSA) is sulfited from the citronellyl bromoacetate produced in step 1 to obtain a citronellol-based anionic surfactant, sodium citronellyl sulfonate.

Figure showing the ^1H NMR spectrum of citronellyl chloroacetate recorded in _CDCl3 . Figure showing the ^13C NMR spectrum of citronellyl chloroacetate recorded in _CDCl3 . Diagram showing the ^1H NMR spectrum of citronellyl bromoacetate recorded in _CDCl3 . Diagram showing the ^13C NMR spectrum of citronellyl bromoacetate recorded in _CDCl3 . Figure showing the ¹ H NMR spectrum of SCSA recorded in D ₂ O, a citronellol-based anionic surfactant. ^13C NMR spectrum of SCSA recorded with a citronellol-based anionic surfactant, a mixture of 500 μl D ₂ O+100 μl CD ₃ OD. The δ49.15 ppm signal is referenced to the CD ₃ OD signal. Figure showing log-log C plot of SCSA in water at 25°C and surface tension Concentration plot and conductivity of SCSA in water at 25°C

<Characteristics of the present invention>
The citronellol-based anionic surfactants of the present invention were synthesized by a sustainable approach using a renewable raw material - citronellol, which is suitable for plants such as lemongrass and many flowers such as roses in good proportions. occur in nature.
The environmentally diluted citronellol-based anionic surfactants of the present invention comprise a sodium sulfonate headgroup linked via an ester functionality covalently bonded to a native citronellol branched hydrophobic tail.
The citronellol-based anionic surfactants of the present invention are produced in good yields through minimal chemical waste production and a green approach.
The citronellol-based anionic surfactants of the present invention demonstrate the ability to self-aggregate in aqueous solutions, and the surfactant properties of the new surfactants were investigated by surface tension and conductivity methods.
The citronellol-based anionic surfactants of the present invention undergo slow, self-controlled hydrolysis in aqueous systems releasing a characteristic sweet odor. This sweet scent comes from hydrolyzed citronellol – a volatile oil used to synthesize these molecules with unique olfactory properties.
The citronellol-based anionic surfactants of the present invention are biodegradable in nature due to their self-hydrolyzing ability.

<Synthetic process for the production of citronellol-based anionic surfactants>
Citronellol-based anionic surfactants can be synthesized in a two-step synthetic process according to the following method:

<Method 1>
Esterification of citronellol and chloroacetic acid was carried out with citronellyl chloroacetic acid chloroacetate followed by sulfitization of citronellyl chloroacetic acid with sodium sulfite (Formula 2) to form a citronellol-based anionic surfactant i.e. citronellyl sulfoacetate. Obtain sodium (SCSA).

(Synthetic process of method 1)
Step 1: Esterification of citronellol and chloroacetic acid to give citronellyl chloroacetate:
Citronellol (31.25 g, 200 mmol) is reacted with chloroacetic acid (20.78 g, 220 mmol) under solvent-free conditions at 85° C. for 15 hours (effective temperature is between 75 and 90° C.) and cooling the reaction mixture. , transferred to a differentiation funnel and washed with 100 ml deionized water. A water wash removes excess chloroactic acid. The lower aqueous layer is discarded and the upper oily layer is washed with 100 ml methanol water (4:1 or 80 ml methanol + 20 ml deionized water) mixture to remove traces of organic impurities formed by the reaction. This time, the lower oily layer after separation was dried on a rotary evaporator at 85° C. under 10 mbar-vacuum to remove traces of aqueous methanol present in the oil. This oil contains citronellyl chloroacetate and is purified by distillation. Initial unreacted citronellol is present along with traces of other organic impurities and distills at 125-127° C. under reduced pressure (10 mbar). The temperature is increased to 135-145°C to obtain a pure fraction of citronellyl chloroacetate as a colorless liquid with an isolated yield of 72-75%. The amount that remains above the yellowish liquid in the distillation vessel is a small amount of organic impurities and is discarded.

Step 2: Sulfitation of citronellyl chloroacetate and sodium sulfite to obtain a citronellol-based anionic surfactant i.e. citronellyl sodium sulfoacetate (SCSA):
In a round bottom flask fitted with an addition funnel and reflux condenser, citronellyl chloroacetate (9.28 g, 40 mmol) is dissolved in 10 ml of ethanol and transferred to the addition funnel attached to the round bottom flask. An aqueous solution of sodium sulfite is prepared in a beaker by dissolving sodium sulfite (6.04 g, 48 mmol) in 40 ml deionized water. This aqueous solution of sodium sulfite is prepared separately, transferred to a round bottom flask and stirred at room temperature. The ethanolic solution of citronellyl chloroacetate is slowly added to the round bottom flask containing the aqueous solution of sodium sulfite stirred at room temperature for 10 minutes. Then, after adding an aqueous solution of sodium sulfite, the temperature of the reaction is increased to 95° C. and the reaction is stirred for an additional 4 hours. After the reaction was complete, the round bottom flask was removed from the oil bath and allowed to cool. 150 ml of ethanol is then added to the reaction mixture and the solution is filtered to remove inorganic salts. Ethanol water solvent is removed using a rotary evaporator at 55° C. and 300 mbar pressure. The temperature of the rotary water bath after removing the water ethanol solvent is increased to 80° C. and the pressure is reduced to 10 mbar to completely dry the contents in the rotary flask. Allow the rotary flask to cool and add 80 ml of hexane. The hexane dissolves any traces of organic implite present in the reaction mixture. The solids content is allowed to settle and the hexane is decanted to leave a white paste like material. Another 60 ml of hexane is added and removed in the same manner as above. The paste is dried on a rotary evaporator, dissolved in 150 ml warm ethyl acetate at 45° C. and then filtered. The solid separated on the filter paper is washed with an additional 50 ml of warm ethyl acetate. The collected filtrate (ethyl acetate) is removed by a rotary evaporator under reduced pressure to give pure citronellol-based anionic surfactant, SCSA, with an isolated yield of 75-78%. The hot rotary flask containing the product must be cooled as the pasty mass will convert to a solid when cooled at room temperature.

<Method 2>
Esterification of citronellyl and bromoacetic acid yielded citronellyl bromoacetate followed by sulfitization of citronellyl bromoacetate with sodium sulfite (Formula 3) to yield a citronellol-based anionic surfactant i.e. citronellyl sulfoacetate sodium. (SCSA).

(Synthetic process of method 2)
Step 1: Esterification of citronellol and bromoacetic acid to give citronellyl bromoacetic acid:
Citronellol (31.25 g, 200 mmol) is reacted under solvent-free conditions at 85° C. for 15 hours with brotroacetic acid (30.59 g, 220 mmoles) (effective temperature is between 75 and 90° C.). Transferred to a funnel and washed with 100 ml deionized water. A water wash removes excess bromate. The lower aqueous layer is discarded and the upper oily layer is washed with 100 ml methanol water (4:1 or 80 ml methanol + 20 ml deionized water) mixture to remove traces of organic impurities formed by the reaction. This time, the lower oily layer after separation was dried on a rotary evaporator at 85° C. under 10 mbar-vacuum to remove traces of aqueous methanol present in the oil. This oil contains citronellyl bromoacetate and is then purified by distillation. Initial unreacted citronellol is present along with traces of other organic impurities and distills at 125-135° C. under reduced pressure (10 mbar). The temperature is increased to 145-148°C to obtain a pure fraction of citronellyl bromoacetate as a colorless liquid with an isolated yield of 70-74%. The amount that remains above the yellowish liquid in the distillation vessel is a small amount of organic impurities and is discarded.

Step 2: To obtain the sulfite salt of citronellyl bromoacetate and sodium sulfite a citronellol-based anionic surfactant i.e. citronellyl sulfoacetate sodium (SCSA):
In a round bottom flask fitted with a dropping funnel and reflux condenser, citronellyl bromoacetate (11.09 g, 40 mmol) is decomposed with 10 ml of ethanol and transferred to the dropping funnel attached to the round bottom flask. An aqueous solution of sodium sulfite is prepared in a beaker by dissolving sodium sulfite (6.04 g, 48 mmoles) in 40 ml deionized water. This aqueous solution of sodium sulfite is prepared separately, transferred to a round bottom flask and stirred at room temperature. The ethanolic solution of citronellyl bromoacetate is slowly added to a round bottom flask containing a stirred aqueous solution of sodium sulfite at 0-5° C. over 10 minutes. Then, after adding an aqueous solution of sodium sulfite, the temperature of the reaction is increased to 45-50° C. and the reaction is stirred for an additional hour. After the reaction was complete, the round bottom flask was removed from the oil bath and allowed to cool. 150 ml of ethanol is then added to the reaction mixture and the solution is filtered to remove inorganic salts. Ethanol water solvent is removed using a rotary evaporator at 55° C. and 300 mbar pressure. The temperature of the rotary water bath after removing the water ethanol solvent is increased to 80° C. and the pressure is reduced to 10 mbar to completely dry the contents in the rotary flask. Allow the rotary flask to cool and add 80 ml of hexane. The hexane dissolves any traces of organic implite present in the reaction mixture. The solids content is allowed to settle and the hexane is decanted to leave a white paste like material. Another 60 ml of hexane is added and removed in the same manner as above. The paste is dried on a rotary evaporator, dissolved in 150 ml warm ethyl acetate at 45° C. and then filtered. The solid separated on the filter paper is washed with an additional 50 ml of warm ethyl acetate. The collected filtrate (ethyl acetate) is removed by a rotary evaporator under reduced pressure to give a pure citronellol-based anionic surfactant, SCSA, with an isolated yield of 73-75%. The hot rotary flask containing the product must be cooled as the pasty mass will convert to a solid when cooled at room temperature.

<Method 3>
Acylation of citronellol with 2-chloroacetyl chloride to give citronellyl chloroacetate followed by sulfitization of citronellyl chloroacetate with sodium sulfite (Formula 4) to give the citronellol-based anionic surfactant i.e. citronellyl Obtain sodium sulfoacetate (SCSA).

(Synthetic process of method 3)
Step 1: Acylation of citronellol with 2-chloroacetyl chloride to give citronellyl chloroacetate:
Add 70 ml chloroform dissolved in citronellol (31.25 g, 200 mmol) and add to a stirred solution of aqueous potassium carbonate (41.46 g, 300 mmol dissolved in 100 ml water). The temperature of the reaction mixture drops to 0-5°C. Chloroform dissolved in 2-chloroacetyl chloride (33.87 g, 300 mmol) is slowly added to the above reaction mixture maintained at 0-5° C. with the aid of an addition funnel over a period of 1 hour. After complete addition of 2-chloroacetyl chloride to the reaction mixture, the reaction is further stirred at 25° C. or room temperature for 15 hours. The reaction mixture is then transferred to a separatory funnel, washing the separated lower chloroform layer containing the product with 100 ml of deionized water. The chloroform layer containing the product is separated and the stripped solvent chloroform is removed using a rotary evaporator. The citronellyl chloroacetate obtained as an oil after removing the chloroform was washed with 100 ml methanol water (4:1 or 80 ml methanol+20 ml deionized water). This time, the lower oily layer after separation was dried on a rotary evaporator at 85° C. under 10 mbar-vacuum to remove traces of aqueous methanol present in the oil. This oil contains citronellyl chloroacetate and is purified by distillation. Initial unreacted citronellol is present along with traces of other organic impurities and distills at 125-127° C. under reduced pressure (10 mbar). The temperature is increased to 135-145°C to obtain a pure fraction of citronellyl chloroacetate as a colorless liquid with an isolated yield of 70-75%.

Step 2: Sulfitation of citronellyl chloroacetate and sodium sulfite to obtain a citronellol-based anionic surfactant i.e. citronellyl sodium sulfoacetate (SCSA):
This method is the same as described in Method 1 Step 2.

<Method 4>
Acylation of citronellol with 2-bromoacetyl chloride of citronellyl followed by sulfite of citronellyl bromoacetate with sodium sulfite (Formula 5) yields a citronellol-based anionic surfactant, citronellyl sodium sulfoacetate (SCSA).

(Synthetic process of method 4)
Step 1: Acylation of citronellol with 2-bromoacetyl chloride to give citronellyl bromoacetate:
Citronellol (31.25 g, 200 mmol) is dissolved in 100 ml chloroform and added to aqueous potassium carbonate solution (41.46 g, 300 mmol dissolved in 100 ml water). The temperature of the reaction mixture drops to 0-5°C. Chloroform dissolved in 2-bromoacetyl chloride (47.22 g, 300 mmol) is slowly added to the above reaction mixture maintained at 0-5° C. with the aid of an addition funnel over a period of 1 hour. After complete addition of 2-bromoacetyl chloride to the reaction mixture, the reaction is stirred for an additional 15 hours at 25° C. or room temperature. The reaction mixture is then transferred to a separatory funnel, washing the separated lower chloroform layer containing the product with 100 ml of deionized water. The chloroform layer containing the product is separated and the stripped solvent chloroform is removed using a rotary evaporator. The citronellyl bromoacetate obtained as an oil after removing the chloroform is then washed with 100 ml methanol water (4:1 or 80 ml methanol+20 ml deionized water). This time, the lower oily layer after separation was dried on a rotary evaporator at 85° C. under 10 mbar-vacuum to remove traces of aqueous methanol present in the oil. This oil contains citronellyl bromoacetate and is then purified by distillation. Initial unreacted citronellol is present along with traces of other organic impurities and distills at 125-135° C. under reduced pressure (10 mbar). The temperature is increased to 145-148°C to obtain a pure fraction of citronellyl bromoacetate as a colorless liquid with an isolated yield of 70-75%.

Step 2: To obtain citronellyl bromoacetate sulfite and sodium sulfite citronellol-based anionic surfactant i.e. citronellyl sulfoacetate sodium (SCSA):
This method is the same as described in step 2 of Method 2.

<Method 5>
Acylation of citronellol with 2-bromoacetyl bromide to give citronellyl bromoacetate followed by sulfite of citronellyl bromoacetate with sodium sulfite (Scheme 6) yields citronellol-based anionic surfactants. The agent namely citronellyl sulfoacetate sodium (SCSA) is obtained.

(Synthetic process of method 5)
Step 1: Acylation of citronellol with 2-bromoacetyl bromide to give citronellyl bromoacetate:
Citronellol (31.25 g, 200 mmol) is dissolved in 100 ml chloroform and added to aqueous potassium carbonate solution (41.46 g, 300 mmol dissolved in 100 ml water). The temperature of the reaction mixture drops to 0-5°C. 50 ml chloroform dissolved in 2-bromoacetyl bromide (54.81 g, 260 mmol) is slowly added over a period of 1 hour to the above reaction mixture maintained at 0-5° C. with the aid of an addition funnel. After complete addition of 2-bromoacetyl bromide to the reaction mixture, the reaction is further stirred at 25° C. or room temperature for 15 hours. The reaction mixture is then transferred to a separatory funnel, washing the separated lower chloroform layer containing the product with 100 ml of deionized water. The chloroform layer containing the product is separated and the stripped solvent chloroform is removed using a rotary evaporator. The citronellyl bromoacetate obtained as an oil after removing the chloroform is then washed with 100 ml methanol water (4:1 or 80 ml methanol+20 ml deionized water). This time, the lower oily layer after separation was dried on a rotary evaporator at 85° C. under 10 mbar-vacuum to remove traces of aqueous methanol present in the oil. This oil contains citronellyl bromoacetate and is then purified by distillation. Initial unreacted citronellol is present along with traces of other organic impurities and distills at 125-135° C. under reduced pressure (10 mbar). The temperature is increased to 145-148°C to obtain a pure fraction of citronellyl bromoacetate as a colorless liquid with an isolated yield of 75-77%.

Step 2: To obtain citronellyl bromoacetate sulfite and sodium sulfite citronellol-based anionic surfactant i.e. citronellyl sulfoacetate sodium (SCSA):
This method is the same as described in step 2 of Method 2.

<Characterization by NMR>
(Spectral NMR data of citronellyl chloroacetate)
The distilled chloroacetate is characterized by ¹ H NMR and ¹³ C NMR spectroscopy. Figure 1 shows the ¹ H NMR spectrum and Figure 2 shows the ¹³ C NMR spectrum of chloroacetate recorded in _CDCl3 .

500 MHz ¹ H NMR (CDCl ₃ ) δ ppm (see Figure 1):
0.92-0.93(3H,-CH- _CH3 ), 1.19(1H,-CH- _CH3 ), 1.35(1H, _{-OCOCH2 - CHaHb-} ), 1.48(1H, _{-OCOCH2 -} CHaH _b -), 1.56(1H, _-CH2 - _CHaHb- ), 1.60(3H,=C- _CH3 ), 1.68(3H,=C- _CH3 ), _1.71 (1H, _-CH2- CH _aHb- ), 1.98 (2H,=CH- _CH2 ), 4.06 (2H, -OCO _{- CH2Cl-} ), 4.18-4.25 (2H, -COO- _CH2- ), 5.08(1H,=CH -C-).

75 MHz ¹³ C NMR (CDCl3) δ ppm (see Figure 2):
17.78, 19.48, 25.46, 25.84, 29.45, 35.35, 37.02, 64.92, 124.55, 131.55, 167.49.

(Spectral NMR data of citronellyl bromoacetate)
Distilled citronellyl bromoacetate is also characterized by ¹ H NMR and ¹³ C NMR spectroscopy. Figure 3 shows the ¹ H NMR spectrum and Figure 4 shows the ¹³ C NMR spectrum of citronellyl bromoacetate recorded in _CDCl3 .

500 MHz ¹ H NMR(CDCl ₃ ) δ ppm (see Figure 3):
0.91-0.93(3H,-CH- _CH3 ), 1.20(1H,-CH- _CH3 ), 1.34(1H, _{-OCOCH2 - CHaHb-} ), 1.47(1H, _{-OCOCH2 -} CHaH _b -), 1.60-1.68(8H, _-CH2- CHaHb-, =C- _CH3 , =C- _{CH3 , -CH2 - CHaHb-} ), 1.99 (2H, ₌ CH- CH2 _, ), 3.83 (2H, -OCO- _CH2Cl- ), 4.19-4.23 (2H, -COO- _CH2 ), 5.08 (1H, =CH-C-).

75 MHz ¹³ C NMR (CDCl ₃ ) δ ppm (see Figure 4):
17.77, 19.46, 25.45, 25.83, 26.06, 29.39, 35.30, 36.99, 64.92, 124.55, 131.47, 167.37.

(Spectral NMR data for a citronel-based anionic surfactant i.e. SCSA)
Citronellol anionic surfactants or SCSAs are characterized by ¹ H NMR spectroscopy. FIG. 5 shows ^{the 1} H NMR spectrum of SCSA recorded in D ₂ O and FIG. 6 shows ^{the 13} C NMR spectrum of SCSA recorded in a mixture of 500 μl D ₂ O +100 μl CD ₃ OD. The δ49.15 ppm signal is referenced to the CD ₃ OD signal.

500 MHz ¹ H NMR (D2O) δ ppm (see Figure 5):
0.99(3H, _-CH - _CH3 ), 1.25(1H,-CH- _CH3 ), 1.42( _1H , _-OCOCH2 ,-CHaHb-), 1.43(1H, _{-OCOCH2 - CHaHb} -), 1.55(1H, _{-CH2 - CHaHb-} ), 1.65(3H,= _CH3 ), 1.71(3H,=C- _CH3- ), 1.78(1H, _{-CH2 -} CHaH _b -), 2.08 (2H, =CH- _CH2 ), 3.99 (2H, -OCO- _CH2 - _SO3Na- ), 4.29 (2H, -COO- _CH2- ), 5.18 (1H, =CH- C-).

75 MHz ¹³ C NMR (500 μl D2O+100 μl CD3OD) δppm (see Figure 6):
18.29, 19.93, 26.34, 26.38, 30.43, 36.00, 38.09, 56.59, 65.64, 125.90, 131.84, 167.94.

<Surfactant properties of citronellol-based anionic surfactants>
Citronellol-based anionic surfactants, or SCSAs, typically behave as surfactant molecules because they can lower the surface tension of water when dissolved in them. SCSA surface-active molecules initially diffuse to the interface and reduce the surface tension of water. The migration process of SCSA molecules to the air-water interface corresponds to a gradual decrease in the surface tension value of water. However, unlike common surfactant molecules, SCSA behaves slightly differently as it continues to decrease slightly even when the observed surface tension value is slightly above its CMC value.

This behavior may be attributed to the dual nature of SCSA surfactants, which behave not only as typical surfactants, but also as typical anionic electrolytes. Figure 7 shows a plot of SCSA surface tension versus concentration. Breakpoints in the graph correspond to surfactant CMC values. SCSA was able to form micelles at a concentration of 18.03 mM and reduce the surface tension of water (γcmc) to 32.6 mN.m ^-1 . As noted above, SCSA surfactants behave slightly differently when increasing the concentration of SCSA in water above its CMC value, as the surface tension gradually decreases above the CMC value. This phenomenon can be seen in the SCSA surfactant tension plot (Figure 7). The CMC value of SCSA was also investigated by the conductivity method (Fig. 8).

Conductivity experiments further confirmed the ability of SCSA to form micelles in aqueous solutions. The calculated CMC values determined by the two different techniques are slightly different (Table 1).
Table 1: Surface properties of citronellol-based surfactant SCSA at 25°C.

<Commercial Use of Citronellol-Based Anionic Surfactants>
Citronellol-based anionic surfactants are potential alternatives to commercial lauryl sulfoacetate (SLSA) surfactants, e.g. , industrial product detergents, household detergents), skin surface lipids, oils, fat dispersants, peeling agents, etc.

Claims (6)

Citronellol-based anionic surfactants include the following chemical formula (1).

A method for producing a citronellol-based anionic surfactant, comprising the following two steps.
Step 1: Esterification of citronellol and chloroacetic acid to give citronellyl chloroacetate.
Step 2: Sulfate the sodium sulfite produced in Step 1 to obtain a citronellol-based anionic surfactant, sodium citronellyl sulfoacetate (SCSA). A method for producing a citronellol-based anionic surfactant, comprising the following two steps.
Step 1: Esterification of citronellol and bromoacetic acid to give citronellyl bromoacetate.
Step 2: Sodium citronellyl sulfoacetate (SCSA) is sulfited from the citronellyl bromoacetate produced in step 1 to obtain a citronellol-based anionic surfactant, sodium citronellyl sulfonate. A method for producing a citronellol-based anionic surfactant, comprising the following two steps.
Step 1: Acylation of citronellol with 2-chloroacetyl chloride gives the chloroacetate of citronellyl.
Step 2: Sulfation of the citronellyl chloroacetate produced in step 1 to obtain the citronellol-based anionic surfactant, citronellyl sulfoacetate sodium (SCSA). A method for producing a citronellol-based anionic surfactant, comprising the following two steps.
Step 1: Acylation of citronellol with 2-bromoacetyl chloride to give citronellyl bromoacetate.
Step 2: Sodium citronellyl sulfoacetate (SCSA) is sulfited from the citronellyl bromoacetate produced in step 1 to obtain a citronellol-based anionic surfactant, sodium citronellyl sulfonate. A method for producing a citronellol-based anionic surfactant, comprising the following two steps.
Step 1: Acylation of citronellol with 2-bromoacetyl bromide to give citronellyl bromoacetate.
Step 2: Sodium citronellyl sulfoacetate (SCSA) is sulfited from the citronellyl bromoacetate produced in step 1 to obtain a citronellol-based anionic surfactant, sodium citronellyl sulfonate.

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