Preparation and application of polymer-loaded volatile composite perfume

Abstract

The invention discloses preparation and application of a polymer-loaded volatile compound perfume. Volatile perfume is prepared into polyacrylate and polymethacrylate type monomers, then a binary copolymer is synthesized through free radical copolymerization, the alcohol solubility and water solubility of the binary copolymer are improved by introducing hydrophilic oligomeric glycol type monomers, and the composite perfume polymer with good solubility is obtained. The thermal stability of the polymer is tested through TGA-DSC, and the release effect of the target perfume is investigated through slow and rapid pyrolysis. Results show that the thermal stability can be effectively improved by loading the composite perfume on the polymer, and controllable synchronous release of the composite perfume is realized in the heating process.

Description

Technical Field

[0001] The invention discloses the preparation and application of a polymer-loaded volatile composite fragrance, and belongs to the field of polymers. Background Art

[0002] Flavors and fragrances provide consumers with pleasant olfactory and flavor experiences and are important additives in industrial production. However, some small organic molecule fragrances are highly volatile, and their aroma dissipates during storage or transportation, resulting in a loss of sensory impact. Furthermore, different fragrances have varying volatility, and the proportion of fragrance components in a product changes continuously with natural evaporation. Therefore, the development of a series of fragrance-loaded polymers that can release complex aromas across a consistent temperature range is of great research interest. Summary of the Invention

[0003] In response to the problems existing in the prior art, the present invention provides a preparation method and application of a polymer-loaded volatile composite fragrance. The present invention designs four fragrance small molecules containing citronellol, anise alcohol, 1-phenylethanol and MCP to undergo esterification reaction with acryloyl chloride and methacryloyl chloride respectively to prepare vinyl monomers, and then free radical copolymerizes two different fragrance precursors to prepare a series of loaded mixed fragrance polymers. According to the commonly used formula in industrial production, three fragrance combinations are selected, namely citronellol and anise alcohol, 1-phenylethanol and MCP, and citronellol and MCP. In actual production, hydrophilic chains are introduced into the polymer, which effectively improves the solubility of the polymer in polar solvents such as water or ethanol. In the present invention, the polymer carrier releases fragrances with different release temperatures in the same temperature range, preliminarily achieving the goal of improving the thermal stability of the fragrance molecules and realizing the release of composite fragrances.

[0004] The preparation method of the polymer-supported volatile composite fragrance of the present invention comprises the following steps:

[0005] Step 1: First, volatile fragrances are subjected to an esterification reaction with acryloyl chloride or methacryloyl chloride to prepare a vinyl monomer. The preparation process is illustrated as follows:

[0006] To a 50 mL round-bottom flask, citronellol (420 mg, 2 mmol), triethylamine (1.4 mL, 10 mmol), and anhydrous THF (10 mL) were added dropwise. Acryloyl chloride (0.8 mL, 10 mmol) in anhydrous THF (5 mL) was added dropwise to the mixture under ice-cooling conditions, and the reaction was continued by stirring at room temperature for 2 hours. The precipitate was removed by filtration, and the filtrate was diluted with ethyl acetate (20 mL), washed sequentially with deionized water (10 mL), saturated sodium bicarbonate aqueous solution (10 mL), and saturated brine (10 mL), dried over anhydrous sodium sulfate, filtered, and concentrated to obtain the crude product. Purification by flash column chromatography (SiO2, hexane / ethyl acetate, 100:1) afforded the product as a yellow oil (89%).

[0007] Step 2: In a solvent system, any two of the vinyl monomers obtained in step 1 are used as polymerization monomers, with the molar ratio of the two monomers being 1:1, to obtain a binary copolymer through a free radical copolymerization reaction; or, any two of the vinyl monomers obtained in step 1 and a hydrophilic monomer are used as comonomers, with the molar ratio of the two vinyl monomers to the hydrophilic monomer being 1:1:0.5, to obtain a ternary copolymer through a free radical copolymerization reaction.

[0008] In step 1, the volatile fragrance is selected from citronellol, anise alcohol, 1-phenylethanol or methylcyclopentenolone (MCP), and the structure is shown below:

[0009]

[0010] In step 1, the structure of the vinyl monomer is as follows:

[0011]

[0012] In step 2, the free radical copolymerization reaction is carried out in the presence of an initiator, wherein the initiator is AIBN, the reaction temperature is 70-80° C., and the reaction time is 20-24 h.

[0013] In step 2, the hydrophilic monomer is triethylene glycol monomethyl ether acrylate.

[0014] In step 2, the structure of the binary copolymer obtained is as follows:

[0015]

[0016] In step 2, the structure of the terpolymer obtained is as follows:

[0017]

[0018] Among the above copolymers, P1-P6 are acrylic acid ester copolymers, and P7-P12 are methacrylic acid ester copolymers.

[0019] The invention relates to the application of the polymer-loaded volatile composite flavoring in the preparation of cigarettes.

[0020] The polymer-loaded volatile composite flavoring is used as a tobacco latent flavor compound during the preparation process of cigarettes.

[0021] 10 mg of the polymer-loaded volatile composite flavor was dissolved in 100 mL of ethanol and then applied to cigarettes.

[0022] The present invention prepares volatile fragrances represented by citronellol, anise alcohol, 1-phenylethanol, and methylcyclopentenolone into polyacrylate and polymethacrylate monomers. This is then copolymerized into a binary copolymer through free radicals. The alcohol and water solubility of the copolymer is enhanced by introducing a hydrophilic oligoethylene glycol-containing monomer, resulting in a highly soluble composite fragrance polymer. The thermal stability of the polymer was tested by TGA-DSC, and the release of the target fragrance was investigated by slow and rapid pyrolysis. The results demonstrate that polymer-loaded composite fragrances can effectively enhance thermal stability and achieve controlled, synchronized release of the composite fragrance during heating. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 For M1, M2, M5 and P1, P4 1 HNMR spectrum comparison. Figure 1 It can be seen that the signals corresponding to the P1 and P4 monomer units are significantly broadened, and the vinyl signal peak disappears, indicating that the vinyl group in the monomer has been successfully polymerized.

[0024] Figure 2 For M3, M4, M5 and P2, P5 1 HNMR spectrum comparison. Figure 2 It can be seen that the signals corresponding to the P2 and P5 monomer units are significantly broadened, and the vinyl signal peak disappears, indicating that the vinyl group in the monomer has been successfully polymerized.

[0025] Figure 3 For M1, M4, M5 and P3, P6 1 HNMR spectrum comparison. Figure 3 It can be seen that the signals corresponding to the P3 and P6 monomer units are significantly broadened, and the vinyl signal peak disappears, indicating that the vinyl group in the monomer has been successfully polymerized.

[0026] Figure 4 For M6, M7, M10 and P7, P10 1 HNMR spectrum comparison. Figure 4 It can be seen from the figure that the signals corresponding to the P7 and P10 monomer units are significantly broadened, and the vinyl signal peak disappears, indicating that the vinyl group in the monomer has been successfully polymerized.

[0027] Figure 5 For M8, M9, M10 and P8, P11 1 HNMR spectrum comparison. Figure 5 It can be seen that the signals corresponding to the P8 and P11 monomer units are significantly broadened, and the vinyl signal peak disappears, indicating that the vinyl group in the monomer has been successfully polymerized.

[0028] Figure 6 For M6, M9, M10 and P9, P12 1 HNMR spectrum comparison. Figure 6 It can be seen that the signals corresponding to the P9 and P12 monomer units are significantly broadened, and the vinyl signal peak disappears, indicating that the vinyl group in the monomer has been successfully polymerized.

[0029] Figure 7 SEC chromatogram of P1-P12 (ag) of copolymer. Figure 7 As can be seen from the SEC chromatograms of the polymers, they all show a single peak distribution. The number average molecular weight (M n ) and molecular weight distribution index (M w / M n ) are 5.43 kDa and 1.69, P2 are 5.50 kDa and 1.59, P3 are 5.21 kDa and 1.59, P4 are 5.98 kDa and 1.71, P5 are 6.26 kDa and 1.62, P6 are 5.85 kDa and 1.60, P7 are 9.24 kDa and 1.84, P8 are 5.61 kDa and 1.43, P9 are 4.67 kDa and 1.67, P10 are 8.02 kDa and 2.34, P11 are 9.52 kDa and 2.46, and P12 are 6.96 kDa and 2.19.

[0030] Figure 8 FT-IR spectra of (a) citronellol, anise alcohol, M1, M2, P1 and P4, (b) 1-phenylethanol, MCP, M3, M4, P2 and P5, (c) citronellol, MCP, M1, M4, P3 and P6, (d) citronellol, anise alcohol, M6, M7, P7 and P10, (e) 1-phenylethanol, MCP, M8, M9, P8 and P11, (f) citronellol, MCP, M6, M9, P9 and P12. Figure 8 As can be seen in the figure, the disappearance of OH stretching vibration and the appearance of C=O stretching vibration in the monomer and polymer confirm the successful reaction between hydroxyl group and acyl chloride to form ester bond.

[0031] Figure 9TG-DSC of (a) P1, (b) P2, (c) P3, (d) P4, (e) P5, and (f) P6 in a dynamic N2 atmosphere. Figure 9 It can be seen that the decomposition temperature is steadily increased in the polyacrylate series P1-P6.

[0032] Figure 10 TG-DSC of (a) P7, (b) P8, (c) P9, (d) P10, (e) P11, and (f) P12 in a dynamic N2 atmosphere. Figure 10 As can be seen, relatively low decomposition temperatures are observed in the polymethacrylate series.

[0033] Figure 11 The relationship between the relative intensity of the MS signals of (a) citronellol, anise alcohol, P1, (b) 1-phenylethanol, MCP, P2, (c) citronellol, MCP, P3, (d) citronellol, anise alcohol, P4, (e) 1-phenylethanol, MCP, P5, (f) citronellol, MCP, P6 and temperature. Figure 11 It can be seen that the release temperature of the four fragrances increased significantly for the acrylate-based copolymers (P1-P6).

[0034] Figure 12 The relationship between the relative intensity of MS signals of (a) citronellol, anise alcohol, P7, (b) 1-phenylethanol, MCP, P8, (c) citronellol, MCP, P9, (d) citronellol, anise alcohol, P10, (e) 1-phenylethanol, MCP, P11, (f) citronellol, MCP, P12 and temperature. Figure 12 It can be seen that for methacrylate-based polymers (P7-P12), the steric hindrance effect of the methacrylate main chain has a significant influence on the release behavior of the side chain fragrance groups.

[0035] Figure 13 The SPI-MS temperature curve of P1-P12(al) and the first derivative curve of TG mass loss are shown in Figure 2. Figure 13 As can be seen from the graph, the release temperature of the target fragrance's volatile components falls within the primary thermal weight loss phase of the TG curve, indicating that fragrance release is synchronized with polymer weight loss. For the terpolymer system, the additional mass loss between 230 and 280°C is attributed to the thermal decomposition of the polyethylene glycol (PEG) segments.

[0036] Figure 14 Four fragrances (citronellol, anise alcohol, 1-phenylethanol and MCP) were grafted onto polyacrylate and polymethacrylate backbones to prepare polymer-supported composite latent fragrance compounds. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further analyzed and explained below through specific embodiments.

[0038] Example 1: Preparation of vinyl monomer

[0039]

[0040] To a 50 mL round-bottom flask, citronellol (420 mg, 2 mmol), triethylamine (1.4 mL, 10 mmol), and anhydrous THF (10 mL) were added dropwise. Acryloyl chloride (0.8 mL, 10 mmol) in anhydrous THF (5 mL) was added dropwise to the mixture under ice-cooling conditions, and the reaction was continued by stirring at room temperature for 2 hours. The precipitate was removed by filtration, and the filtrate was diluted with ethyl acetate (20 mL), washed sequentially with deionized water (10 mL), saturated aqueous sodium bicarbonate solution (10 mL), and saturated brine (10 mL), dried over anhydrous sodium sulfate, filtered, and concentrated to obtain the crude product. Purification by flash column chromatography (SiO2, hexane / ethyl acetate, 100:1) afforded the product as a yellow oil (89%).

[0041] The preparation of other vinyl monomers can refer to the above process, replacing the corresponding raw materials. The structures of the obtained vinyl monomers are shown below:

[0042]

[0043] Example 2: Preparation of polymer-supported fragrances P1-P12

[0044] The preparation of binary copolymer takes P1 as an example:

[0045] 210 mg (1 mmol) of citronellol acrylate, 192 mg (1 mmol) of anisyl acrylate, and 1.6 mg (0.01 mmol) of initiator AIBN were weighed into a Shrek tube and dissolved in 2 mL of DMF in a glove box. The mixture was heated in an oil bath at 75°C for 24 h. The polymer solution was added dropwise to 8 mL of methanol to produce a white precipitate. The polymer precipitate was centrifuged and the supernatant was discarded. The polymer precipitate was dissolved in 1 mL of THF and added dropwise to 8 mL of methanol. The precipitation and centrifugation were repeated three times, and the supernatant was discarded. Polymer P1 was obtained after drying.

[0046] The reaction route is as follows:

[0047]

[0048] The preparation of other binary copolymers can refer to the above process, replacing the corresponding monomer raw materials. The structure of the obtained binary copolymer is shown below:

[0049]

[0050] The preparation of terpolymer takes P4 as an example:

[0051] 210 mg (1 mmol) of citronellol acrylate, 192 mg (1 mmol) of anisyl acrylate, 109 mg (0.5 mmol) of triethylene glycol monomethyl ether acrylate, and 1.6 mg (0.01 mmol) of initiator AIBN were weighed and added to a Shrek tube. The mixture was dissolved in 2 mL of DMF in a glove box and heated in an oil bath at 75°C for 24 h. The polymer solution after the reaction was added dropwise to 8 mL of deionized water to produce a white precipitate. The polymer precipitate was centrifuged and the supernatant was discarded. The polymer precipitate was then dissolved in 1 mL of DCM and added dropwise to 8 mL of n-hexane. After precipitation and centrifugation, the supernatant was discarded. This was repeated three times and dried to obtain polymer P4.

[0052] The reaction route is as follows:

[0053]

[0054] The preparation of other terpolymers can refer to the above process, replacing the corresponding monomer raw materials. The structure of the obtained terpolymer is shown below:

[0055]

[0056] Among the above copolymers, P1-P6 are acrylic acid ester copolymers, and P7-P12 are methacrylic acid ester copolymers.

[0057] Table 1. SEC data and polymerization yields of samples P1-P12

[0058]

[0059]

[0060] Table 2. Relative contents of alcohol flavors and their corresponding dehydrated olefins in volatile gases during pyrolysis of twelve polymers

[0061]

[0062] Analysis of polymer pyrolysis product release: Analysis of the volatile components of six terpolymers containing OEG structural units revealed that a signal of 2-(2-(2-methoxyethoxy)ethoxy)ethanol (m / z = 164) was detected in P10, P11, and P12, but the relative intensity was low. No other thermal decomposition products of the OEG structural unit were detected. In contrast, no signal at mass 164 was observed in P4, P5, and P6, suggesting that the OEG in the polyacrylate backbone may have greater thermal stability due to reduced steric hindrance. P2: Upon pyrolysis at 600°C, citronellol (9.21%) and citronellene (28.81%) were primarily released, indicating that the ester bond breaks down to form an alcohol through hydrogen abstraction or an alkene through β-hydrogen elimination. At 900°C, the relative proportions of citronellol and citronellene were similar, but the released amounts decreased to 7.23% and 17.87%, respectively. Anisyl alcohol was not detected at either temperature, likely due to the high reactivity of the benzylic carbon. P4: Citronellol release increased to 18.70% at 600°C and 14.09% at 900°C; however, citronellene release decreased to 7.01% and 5.77% at 600°C and 900°C, respectively, indicating that the addition of OEG chains inhibited the β-hydrogen elimination process. Furthermore, the degradation product of the OEG building block, 2-(2(2-methoxyethoxy)ethoxy)ethanol, was detected (6.7% at 600°C and 7.0% at 900°C). P3: MCP and styrene were efficiently released, but the target fragrance, 1-phenylethanol, was not detected. The formation of styrene was attributed to the degradation of the 1-phenylethanol building block via β-hydrogen elimination at high temperatures. The pyrolysis yields of MCP and styrene were 46.55% and 51.50% at 600°C, respectively, and stabilized at 45.24% and 51.42% at 900°C, respectively. In terpolymer P5, the additional contribution of OEG fragmentation products slightly reduced the yields of MCP and styrene to 37.88% and 46.98% at 600°C, and further to 37.13% and 48.93% at 900°C. Signals for 2-(2-(2-methoxyethoxy)ethoxy)ethanol (12.57% and 9.38%) were observed at 600°C and 900°C, respectively. Furthermore, its dehydration product, (2-(2-methoxyethoxy)ethoxy)ethylene, was detected at 900°C. Due to its strong dehydration tendency, 1-phenylethanol was completely converted to the corresponding olefin and was therefore not detected under all conditions. P3: The main pyrolysis products were citronellol, citronellene, and MCP. At 600°C, the released yields were 17.92%, 12.19%, and 52.10%, respectively. At 900°C, citronellol slightly increased to 18.57%, citronellene decreased to 10.10%, and MCP decreased to 44.47%. In the terpolymer P6, the OEG chain had little effect on the release of citronellol, citronellene, and MCP, and only a small amount of 2-(2-(2-methoxyethoxy)ethoxy)ethanol was detected (5.6% at 600°C and 11.6% at 900°C).The content of the main pyrolytically released components in the P7-P12 series was generally lower than that in the polyacrylate series. This difference is mainly due to the lower polymerization ceiling temperature of polymethacrylate (approximately 220°C) than that of polyacrylate (due to steric hindrance of the methyl group). Therefore, a large amount of monomer was observed in the volatiles of polymethacrylate-based polymers, which is attributed to the degradation of the polymer backbone. In contrast, the release of monomers in the polyacrylate series was minimal or undetectable. These results indicate that the thermal stability of the polymer backbone plays a key role in the effective release of pendant fragrances.

Claims

1. A method for preparing a polymer-supported volatile composite fragrance, characterized in that The steps include: Step 1: First, a volatile fragrance is subjected to an esterification reaction with acryloyl chloride or methacryloyl chloride to prepare a vinyl monomer; Step 2: In a solvent system, using any two of the vinyl monomers obtained in step 1 as polymerization monomers, a binary copolymer is obtained through a free radical copolymerization reaction; or, using any two of the vinyl monomers obtained in step 1 and a hydrophilic monomer as comonomers, a ternary copolymer is obtained through a free radical copolymerization reaction.

2. The preparation method according to claim 1, wherein: In step 1, the volatile fragrance is selected from citronellol, anise alcohol, 1-phenylethanol or methylcyclopentenolone.

3. The preparation method according to claim 1, wherein: In step 1, the vinyl monomer is selected from the compound shown in the following structure:

4. The preparation method according to claim 1, wherein: When any two of the vinyl monomers obtained in step 1 are used as polymerization monomers, the molar ratio of the two monomers is 1:

1.

5. The preparation method according to claim 1, wherein: When any two of the vinyl monomers obtained in step 1 and a hydrophilic monomer are used as comonomers, the molar ratio of the two vinyl monomers to the hydrophilic monomer is 1:1:0.

5.

6. The preparation method according to claim 5, characterized in that: In step 2, the hydrophilic monomer is triethylene glycol monomethyl ether acrylate.

7. The preparation method according to claim 1, wherein: In step 2, the free radical copolymerization reaction is carried out in the presence of an initiator, wherein the initiator is AIBN, the reaction temperature is 70-80° C., and the reaction time is 20-24 h.

8. Use of the polymer-supported volatile composite flavoring prepared by the preparation method according to any one of claims 1 to 7 in the preparation of cigarettes.

9. The use according to claim 8, characterized in that: The polymer-loaded volatile composite flavoring is used as a tobacco latent flavor compound during the preparation process of cigarettes.

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