A method for synthesizing 2,4-pentadien-1-ol and 1,4-pentadien-3-ol from C5 sugar alcohols

Abstract

This invention belongs to the field of fine chemical synthesis and relates to a method for synthesizing 2,4-pentadien-1-ol and 1,4-pentadien-3-ol from C5 sugar alcohols. The C5 sugar alcohol is mixed with an orthoformate compound and a first acidic catalyst, and then subjected to an esterification reaction to obtain a first mixture. The first mixture is pumped into a conventional distillation reactor containing an organic solvent for deoxygenation and dehydration reactions to obtain 2,4-pentadien-1-ol and 1,4-pentadien-3-ol. This invention provides a novel method for the efficient synthesis of 1,4-pentadien-3-ol and 2,4-pentadien-1-ol from biomass raw materials. This reaction method is simple and efficient, and the reactants used are green, safe, and environmentally friendly. The reactive distillation apparatus used can continuously prepare 1,4-pentadien-3-ol and 2,4-pentadien-1-ol, with yields reaching 30.0% and 51.4%, respectively.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical synthesis and relates to a method for synthesizing 2,4-pentadien-1-ol and 1,4-pentadien-3-ol from C5 sugar alcohols. Background Technology

[0002] Pentadienols mainly include 1,4-pentadien-3-ol and 2,4-pentadien-1-ol. Among them, 1,4-pentadien-3-ol is an important organic synthesis platform compound, serving as a key structural unit in the synthesis of natural products and complex bioactive molecules (J. Am. Chem. Soc. 2002, 124, 20, 5650–5651; Angew. Chem. Int. Ed. 2018, 57, 15587–15591), and is also used in the synthesis of perfumes and flavorings. Furthermore, studies have found that 1,4-pentadien-3-ol exhibits potential biomedical value, possessing antibacterial, antioxidant, antitumor, and cancer cell growth-inhibiting effects. 2,4-Pentadien-1-ol is an enol compound with a special structure. Due to the presence of polymerizable conjugated double bonds and hydroxyl groups, it has become a novel polymerizable monomer with important applications in the field of functional polymer materials (Die Angewandte Makromolekulare Chemie 1978, 67, 137-149; J Biomed Mater Res 1974, 8, 155–161). It is also an important organic synthesis intermediate with significant applications in drug molecule synthesis.

[0003] Currently, the preparation of 1,4-pentadien-3-ol mainly employs organic synthesis (Organic Letters, 2012, 14(18), 4730-4733), using magnesium powder, ethylene bromide, and highly toxic acrolein as raw materials. These materials undergo a coupling reaction under the catalysis of iodine to obtain 1,4-pentadien-3-ol (67% yield). This method uses highly toxic acrolein, generates a large amount of magnesium-containing waste after the reaction, and the reaction is batch-based, making it difficult to achieve continuous, large-scale preparation of 1,4-pentadien-3-ol. Therefore, there is an urgent need to develop a green, safe, and environmentally friendly method for preparing 1,4-pentadien-3-ol.

[0004] The Nicholas team reported a technical route for preparing 2,4-pentadien-1-ol from hemicellulose-derived xylitol (Organometallics, 2015, 34, 1985-1990). This method uses methyl rhenium trioxide (MeReO3) as a catalyst and dihydroindole as a reducing agent to selectively deoxygenate xylitol to 2,4-pentadien-1-ol with a yield of 56%. However, the methyl rhenium trioxide catalyst used in this method is expensive and difficult to separate from the reaction system, limiting its practicality. Furthermore, the reaction time is long (24 h), resulting in low efficiency, and the batch reaction mode makes it difficult to achieve continuous, large-scale preparation of 2,4-pentadien-1-ol. Therefore, there is an urgent need to develop a green, efficient, and continuous method for synthesizing pentadienol compounds. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a new method for synthesizing 2,4-pentadien-1-ol and 1,4-pentadien-3-ol from C5 sugar alcohols, addressing the shortcomings of the prior art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] This invention discloses a method for synthesizing 2,4-pentadien-1-ol and 1,4-pentadien-3-ol from C5 sugar alcohols, comprising the following steps:

[0008] (1) C5 sugar alcohol is mixed with orthoformate esters and a first acidic catalyst and then subjected to esterification in a conventional reactor to obtain a first mixture;

[0009] (2) The first mixture is pumped into a conventional distillation reaction apparatus containing organic solvent to carry out deoxygenation and dehydration reaction, thereby obtaining 2,4-pentadien-1-ol and 1,4-pentadien-3-ol.

[0010] In some embodiments, the C5 sugar alcohol is xylitol or arabinitol; the orthoformate ester is trimethyl orthoformate, triethyl orthoformate, tripropyl orthoformate, or triisopropyl orthoformate; the first acidic catalyst is any one or a combination of acetic acid, formic acid, chloroacetic acid, bromoacetic acid, iodoacetic acid, and methoxyacetic acid; and the organic solvent is any one or a combination of tetraethylene glycol dimethyl ether, N,N-dimethylpropenylurea, diethylene glycol dibutyl ether, and 18-crown ether-6.

[0011] In some embodiments, preferably, the C5 sugar alcohol is xylitol; the orthoformate ester compound is triethyl orthoformate; the first acidic catalyst is acetic acid, formic acid, or methoxyacetic acid, more preferably acetic acid; and the organic solvent is N,N-dimethylpropenylurea.

[0012] The amount of organic solvent used is not particularly limited, but shall not be less than 15% of the volume of the first mixture.

[0013] In some embodiments, in step (1), the molar amount of the orthoformate compound is 1 to 7 times the molar amount of the C5 sugar alcohol; the molar ratio of the C5 sugar alcohol to the first acidic catalyst is 5 to 40:1.

[0014] In some embodiments, preferably, in step (1), the molar amount of the orthoformate compound is 1 to 5 times the molar amount of the C5 sugar alcohol, more preferably 2 times; the molar ratio of the C5 sugar alcohol to the first acid catalyst is 5 to 15:1, more preferably 7 to 10:1, and even more preferably 9:1.

[0015] In some embodiments, in step (1), the esterification reaction is carried out at a temperature of 80–160°C for 1–10 h.

[0016] In some embodiments, preferably, in step (1), the esterification reaction is carried out at a temperature of 110–140°C, more preferably 120–140°C, and even more preferably 130°C, for a reaction time of 2–8 h, more preferably 3–6 h, and even more preferably 4 h.

[0017] In step (2), the flow rate of the first mixture pumped into the conventional distillation reaction apparatus is adjusted appropriately according to the volume of the first mixture and the size of the conventional distillation reaction apparatus.

[0018] In step (2), the conventional distillation reaction apparatus used in this embodiment of the invention is laboratory grade and small in size (volume of 20-100 mL), and the volume of the first mixture is small (25-30 mL). Preferably, the flow rate of the first mixture pumped into the conventional distillation reaction apparatus is 30-300 μL / min. More preferably, the flow rate of the first mixture pumped into the conventional distillation reaction apparatus is 100-250 μL / min. Even more preferably, it is 130-210 μL / min, and most preferably, it is 170 μL / min.

[0019] In some embodiments, in step (2), the deoxygenation and dehydration reaction is carried out at a temperature of 100–300°C.

[0020] In step (2), the deoxygenation and dehydration reaction has no special time limit, until no product is collected.

[0021] In some embodiments, preferably, in step (2), the deoxygenation and dehydration reaction is carried out at a reaction temperature of 160-260°C, more preferably 200-240°C, even more preferably 215-240°C, and most preferably 235°C.

[0022] or,

[0023] A method for synthesizing 2,4-pentadien-1-ol and 1,4-pentadien-3-ol from C5 sugar alcohols, comprising the following steps:

[0024] (1) C5 sugar alcohol is mixed with orthoformate esters and a first acidic catalyst and then subjected to esterification in a conventional reactor to obtain a first mixture;

[0025] (2) After mixing the first mixture with the second acidic catalyst, a second mixture is obtained; the second mixture is pumped into a conventional distillation reaction apparatus containing organic solvent to carry out deoxygenation and dehydration reaction, thereby obtaining 2,4-pentadien-1-ol and 1,4-pentadien-3-ol.

[0026] In some embodiments, the C5 sugar alcohol is xylitol or arabinitol; the orthoformate ester is trimethyl orthoformate, triethyl orthoformate, tripropyl orthoformate, or triisopropyl orthoformate; the first acidic catalyst is any one or a combination of acetic acid, formic acid, chloroacetic acid, bromoacetic acid, iodoacetic acid, and methoxyacetic acid; and the organic solvent is any one or a combination of tetraethylene glycol dimethyl ether, N,N-dimethylpropenylurea, diethylene glycol dibutyl ether, and 18-crown ether-6.

[0027] In some embodiments, preferably, the C5 sugar alcohol is xylitol; the orthoformate ester compound is triethyl orthoformate; the first acidic catalyst is acetic acid, formic acid, or methoxyacetic acid, more preferably acetic acid; and the organic solvent is N,N-dimethylpropenylurea.

[0028] The amount of organic solvent used is not particularly limited, but shall not be less than 15% of the volume of the second mixture.

[0029] In some embodiments, in step (1), the molar amount of the orthoformate compound is 1 to 7 times the molar amount of the C5 sugar alcohol; the molar ratio of the C5 sugar alcohol to the first acidic catalyst is 5 to 40:1.

[0030] In some embodiments, preferably, in step (1), the molar amount of the orthoformate compound is 1 to 5 times the molar amount of the C5 sugar alcohol, more preferably 2 times; the molar ratio of the C5 sugar alcohol to the first acid catalyst is 5 to 15:1, more preferably 7 to 10:1, and even more preferably 9:1.

[0031] In some embodiments, in step (1), the esterification reaction is carried out at a temperature of 80–160°C for 1–10 h.

[0032] In some embodiments, preferably, in step (1), the esterification reaction is carried out at a temperature of 110–140°C, more preferably 120–140°C, and even more preferably 130°C, for a reaction time of 2–8 h, more preferably 3–6 h, and even more preferably 4 h.

[0033] In some embodiments, in step (2), the second acidic catalyst is any one or a combination of several of acetic acid, formic acid, chloroacetic acid, bromoacetic acid, iodoacetic acid and methoxyacetic acid; the concentration of the second acidic catalyst in the second mixture is 0.1 to 3.0 mol / L.

[0034] In step (2), the flow rate of the second mixture pumped into the conventional distillation reaction apparatus is adjusted appropriately according to the volume of the second mixture and the size of the conventional distillation reaction apparatus.

[0035] In step (2), the conventional distillation reaction apparatus used in this embodiment of the invention is laboratory grade and small in size (volume of 20-100 mL), and the volume of the second mixture is small (25-30 mL). Preferably, the flow rate of the second mixture pumped into the conventional distillation reaction apparatus is 30-300 μL / min. More preferably, the flow rate of the second mixture pumped into the conventional distillation reaction apparatus is 100-250 μL / min. Even more preferably, it is 130-210 μL / min, and most preferably, it is 170 μL / min.

[0036] In some embodiments, preferably, in step (2), the second acidic catalyst is acetic acid; the concentration of the second acidic catalyst in the second mixture is 0.2 to 1.8 mol / L, more preferably 0.3 to 1.6 mol / L.

[0037] In some embodiments, the molar ratio of C5 sugar alcohol in step (1) to the second acidic catalyst in step (2) is 0.5 to 15:1.

[0038] In some embodiments, preferably, the molar ratio of C5 sugar alcohol in step (1) to the second acidic catalyst in step (2) is 1.0 to 8.0:1, more preferably 1.0 to 3.5:1, and even more preferably 1.2:1.

[0039] In some embodiments, in step (2), the deoxygenation and dehydration reaction is carried out at a temperature of 100–300°C.

[0040] In step (2), the deoxygenation and dehydration reaction has no special time limit, until no product is collected.

[0041] In some embodiments, preferably, in step (2), the deoxygenation and dehydration reaction is carried out at a reaction temperature of 160-260°C, more preferably 200-240°C, even more preferably 215-240°C, and most preferably 235°C.

[0042] The conventional distillation reaction apparatus used above includes a conventional reactor, condenser, and thermocouple, with temperature controlled by heating in a metal sand bath.

[0043] Beneficial effects:

[0044] This invention provides a novel method for the efficient synthesis of 1,4-pentadien-3-ol and 2,4-pentadien-1-ol from biomass raw materials. The method involves the esterification of C5 sugar alcohols with orthoformate compounds under an acidic catalyst, followed by deoxygenation and dehydration under another acidic catalyst to synthesize 1,4-pentadien-3-ol and 2,4-pentadien-1-ol. This reaction method is simple and efficient, using green, safe, and environmentally friendly reactants. The reactive distillation apparatus employed allows for the continuous preparation of 1,4-pentadien-3-ol and 2,4-pentadien-1-ol, achieving yields of 30.0% and 51.4%, respectively. Attached Figure Description

[0045] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0046] Figure 1 This is a diagram of a conventional distillation reaction apparatus used in an embodiment of the present invention.

[0047] Figure 2 Typical products of the deoxygenation and dehydration reaction of C5 sugar alcohols: 2,4-pentadien-1-ol and 1,4-pentadien-3-ol. 1 H-NMR spectrum.

[0048] Figure 3 The reaction equation is a reaction mediated by orthoformate esters to synthesize 2,4-pentadien-1-ol and 1,4-pentadien-3-ol from C5 sugar alcohols through dehydration and deoxygenation; wherein R is methyl, ethyl, propyl or isopropyl. Detailed Implementation

[0049] To further understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0050] Unless otherwise specified, all reagents involved in the embodiments of this invention are commercially available products and can be purchased through commercial channels.

[0051] The conventional distillation reaction apparatus used in the embodiments of the present invention is shown in the figure below. Figure 1 As shown, the deoxygenation and dehydration reaction is carried out in a three-necked flask. The reaction organic solvent is first added to the flask, one end of which is connected to a syringe on a syringe pump, the other end is inserted into a thermocouple, and a condenser is connected in the middle. The syringe is filled with the reaction solution of the esterification reaction (an acidic catalyst can be added). The deoxygenation and dehydration reaction is carried out by heating and distillation. The temperature is controlled by heating in a metal sand bath. After cooling, the vaporized product yields a mixture of 1,4-pentadien-3-ol and 2,4-pentadien-1-ol.

[0052] Typical C5 sugar alcohol deoxygenation and dehydration reaction products 2,4-pentadien-1-ol and 1,4-pentadien-3-ol in the embodiments of the present invention 1 H-NMR spectrum as shown Figure 2 As shown, the molar yield was calculated using mesitylene as an internal standard, and the characteristic peaks of each product used to calculate the yield are marked in the figure.

[0053] The reaction equations for the synthesis of 2,4-pentadien-1-ol and 1,4-pentadien-3-ol from C5 sugar alcohols mediated by orthoformate esters in this invention are as follows: Figure 3 As shown, R is methyl, ethyl, propyl or isopropyl.

[0054] Examples 1-4: Effect of deoxygenation and dehydration reaction temperature on the yields of 1,4-pentadien-3-ol and 2,4-pentadien-1-ol

[0055] (1) Esterification reaction: Xylitol (24g, 0.158mol, Mw=152.146), triethyl orthoformate (50g, 0.337mol, Mw=148.20) and acetic acid (1g, 0.017mol, Mw=60.052) were mixed in a reaction flask and stirred at 130℃ for 4h to obtain the first mixture.

[0056] (2) Deoxygenation and dehydration reaction: Take 28 mL of the first mixture obtained in step (1) (containing 0.06 mol xylitol) without adding acid and put it into a disposable syringe. Inject it into a three-necked flask containing 5 mL of N,N-dimethylpropenylurea at a flow rate of 170 μL / min using a syringe pump. Perform the deoxygenation and dehydration reaction by heating and distillation at different temperatures (205℃, 215℃, 225℃, 235℃). Collect the reaction product by condensation. After the reaction is completed, perform NMR analysis on the reaction solution. 1 H-NMR results, using mesitylene as an internal standard, yielded the molar yields of 1,4-pentadien-3-ol and 2,4-pentadien-1-ol, typical of...1 H-NMR spectrum as shown Figure 2 As shown in the figure. The experimental results are shown in Table 1.

[0057] Table 1. Effect of different deoxygenation and dehydration reaction temperatures on the yield of pentadienol

[0058] Reaction temperature (°C) Yield of 1,4-pentadien-3-ol (%) 2,4-Pentadien-1-ol yield (%) Example 1 205 16.5 9.4 Example 2 215 23.2 29.1 Example 3 225 25.4 42.9 Example 4 235 28.9 43.7

[0059] As shown in Table 1, as the deoxygenation and dehydration reaction temperature increases from 205℃ to 235℃, the yields of 1,4-pentadien-3-ol and 2,4-pentadien-1-ol gradually increase, with the yield of 2,4-pentadien-1-ol increasing more significantly. The optimal deoxygenation and dehydration reaction temperature is 235℃, with yields of 28.9% and 43.7% for 1,4-pentadien-3-ol and 2,4-pentadien-1-ol, respectively.

[0060] Examples 5-9: Effect of acid dosage on pentyrenol yield in deoxygenation and dehydration reactions

[0061] (1) The experimental method in this step is the same as that in step (1) of Example 1.

[0062] (2) The experimental method in this step is the same as that in step (2) of Example 1. The difference is that the first mixed solution is mixed with acetic acid to obtain the second mixed solution. The second mixed solution is pumped into the distillation reaction. The reaction temperature is 225℃. The amount of acetic acid used is 0mL, 0.5mL, 1.0mL, 1.5mL and 2.8mL respectively.

[0063] After the reaction was completed, the reaction solution was analyzed by NMR. 1 The molar yields of 2,4-pentadien-1-ol and 1,4-pentadien-3-ol were calculated using H-NMR results and mesitylene as an internal standard. The experimental results are shown in Table 2.

[0064] Table 2. Effect of different amounts of acetic acid on the yield of pentadienol in the deoxygenation and dehydration reaction.

[0065]

[0066] As shown in Table 2, with the increase of acetic acid dosage, the yield of 1,4-pentadien-3-ol initially increased and then remained constant, while the yield of 2,4-pentadien-1-ol increased slowly. The optimal amount of acetic acid for the deoxygenation and dehydration reaction was 2.8 mL, with yields of 30.0% and 51.4% for 1,4-pentadien-3-ol and 2,4-pentadien-1-ol, respectively.

[0067] Examples 10-13: Effects of different solvents on the yield of pentadienol in deoxygenation and dehydration reactions

[0068] (1) The experimental method in this step is the same as that in step (1) of Example 1.

[0069] (2) The experimental method in this step is the same as that in step (2) of Example 1. The difference is that the solvents used are N,N-dimethylpropenylurea, tetraethylene glycol dimethyl ether, diethylene glycol dibutyl ether, and 18-crown ether-6, the reaction temperature is 225℃, and the amount of acetic acid used is 2.8mL.

[0070] After the reaction was completed, the reaction solution was analyzed by NMR. 1 The molar yields of 2,4-pentadien-1-ol and 1,4-pentadien-3-ol were calculated using H-NMR results with mesitylene as an internal standard. The experimental results are shown in Table 3.

[0071] Table 3. Effects of different solvents on the yield of pentadienol in the deoxygenation and dehydration reaction.

[0072]

[0073]

[0074] As can be seen from Table 3, the optimal solvent for the deoxygenation and dehydration reaction is N,N-dimethylpropenylurea, and the yields of 1,4-pentadien-3-ol and 2,4-pentadien-1-ol are 30.0% and 51.4%, respectively.

[0075] Examples 14-18: Effects of different acids on the yield of pentadienol in deoxygenation and dehydration reactions

[0076] (1) The experimental method in this step is the same as that in step (1) of Example 1.

[0077] (2) The experimental method in this step is the same as that in step (2) of Example 1. The difference is that acetic acid, formic acid, methoxyacetic acid, chloroacetic acid and bromoacetic acid are added to the first mixed solution to obtain the second mixed solution. The second mixed solution is used for injection reaction. The amount of acid used is 17.5 mmol and the reaction temperature is 225℃.

[0078] After the reaction was completed, the reaction solution was analyzed by NMR. 1 The molar yields of 2,4-pentadien-1-ol and 1,4-pentadien-3-ol were calculated using 1,4-trimethylbenzene as an internal standard by ¹H-NMR results. The experimental results are shown in Table 4.

[0079] Table 4. Effects of different acids on the yield of pentadienol in the deoxygenation and dehydration reaction.

[0080]

[0081] As shown in Table 4, when using 17.5 mmol of different types of protic acids, acetic acid yielded the best pentadienol yield, with yields of 29.6% and 45.1% for 1,4-pentadien-3-ol and 2,4-pentadien-1-ol, respectively.

[0082] Examples 19-22: Effect of pumping the first mixture into the distillation reactor at different flow rates on the yield of pentadienol

[0083] (1) The experimental method in this step is the same as that in step (1) of Example 1.

[0084] (2) The experimental method in this step is the same as that in step (2) of Example 1. The difference is that the reaction temperature is 225℃ and the flow rates of the first mixture pumped into the distillation reactor are 64μL / min, 130μL / min, 170μL / min and 210μL / min, respectively.

[0085] After the reaction was completed, the reaction solution was analyzed by NMR. 1 The molar yields of 2,4-pentadien-1-ol and 1,4-pentadien-3-ol were calculated using H-NMR results with mesitylene as an internal standard. The experimental results are shown in Table 5.

[0086] Table 5. Effect of pumping the first mixture into the distillation reaction at different flow rates on the yield of pentadienol.

[0087]

[0088] As can be seen from Table 5, as the pumping speed of the first mixture into the distillation reaction device increases, the yield of 1,4-pentadien-3-ol first increases and then remains unchanged, while the yield of 2,4-pentadien-1-ol first increases and then decreases. The optimal pumping speed is 170 μL / min.

[0089] Examples 23-26: Effects of different orthoformate compounds on the yield of pentadienol

[0090] (1) The experimental method in this step is the same as that in step (1) of Example 1. The difference is that the orthoformate esters are triisopropyl orthoformate, tripropyl orthoformate, trimethyl orthoformate, and triethyl orthoformate.

[0091] (2) The experimental method in this step is the same as that in step (2) of Example 1, except that the amount of acetic acid used is 2.8 mL and the reaction temperature is 225 °C.

[0092] After the reaction was completed, the reaction solution was analyzed by NMR. 1 The molar yields of 2,4-pentadien-1-ol and 1,4-pentadien-3-ol were calculated using H-NMR results with mesitylene as an internal standard. The experimental results are shown in Table 6.

[0093] Table 6. Effects of different orthoformate compounds on the yield of pentadienol

[0094]

[0095] As shown in Table 6, orthoformate compounds with different structures have a significant impact on the yields of 1,4-pentadien-3-ol and 2,4-pentadien-1-ol, with triethyl orthoformate being the best choice.

[0096] Examples 27-28: Effect of C5 sugar alcohol type on pentaenol yield

[0097] (1) The experimental method in this step is the same as that in step (1) of Example 1. The difference is that the C5 sugar alcohols are arabinitol and xylitol.

[0098] (2) The experimental method in this step is the same as that in step (2) of Example 1, except that the amount of acetic acid used is 2.8 mL and the reaction temperature is 225 °C.

[0099] Table 7. Effect of C5 sugar alcohol type on pendienol yield

[0100]

[0101] As can be seen from Table 7, the yields of 1,4-pentadien-3-ol and 2,4-pentadien-1-ol obtained using xylitol are significantly higher than those of arabinitol, making xylitol the best choice among C5 sugar alcohols.

[0102] In summary, this application provides a novel method for synthesizing 1,4-pentadien-3-ol and 2,4-pentadien-1-ol. This method is simple and efficient, and the reactive distillation apparatus used can continuously prepare 1,4-pentadien-3-ol and 2,4-pentadien-1-ol with yields of 30.0% and 51.4%, respectively. Compared with the prior art, the reactants used in this invention are green, safe, environmentally friendly, and widely available.

[0103] This invention provides a method for synthesizing 2,4-pentadien-1-ol and 1,4-pentadien-3-ol from C5 sugar alcohols. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for synthesizing 2,4-pentadien-1-ol and 1,4-pentadien-3-ol from C5 sugar alcohols, characterized in that, Includes the following steps: (1) The C5 sugar alcohol is mixed with orthoformate compounds and a first acidic catalyst and then subjected to esterification in a conventional reactor to obtain a first mixture; (2) The first mixture is pumped into a conventional distillation reaction apparatus containing organic solvent to carry out deoxygenation and dehydration reaction, thereby obtaining 2,4-pentadien-1-ol and 1,4-pentadien-3-ol; The C5 sugar alcohol is xylitol or arabinitol; the orthoformate compound is trimethyl orthoformate, triethyl orthoformate, tripropyl orthoformate, or triisopropyl orthoformate. The organic solvent is any one or a combination of several of tetraethylene glycol dimethyl ether, N,N-dimethylpropenyl urea, diethylene glycol dibutyl ether, and 18-crown ether-6; In step (2), the first mixture is mixed with the second acidic catalyst to obtain the second mixture; the second mixture is pumped into a conventional distillation reaction apparatus containing organic solvent to carry out deoxygenation and dehydration reaction, thereby obtaining 2,4-pentadien-1-ol and 1,4-pentadien-3-ol. In step (2), the second acidic catalyst is any one or a combination of several of acetic acid, formic acid, chloroacetic acid, bromoacetic acid, iodoacetic acid and methoxyacetic acid; The molar ratio of C5 sugar alcohol in step (1) to the second acidic catalyst in step (2) is 0.5~15:1; In step (2), the deoxygenation and dehydration reaction is carried out at a temperature of 100~300℃; The flow rate of the first mixture pumped into the conventional distillation reaction apparatus is 30~300 mL / min; The first acidic catalyst is any one or a combination of several of acetic acid, formic acid, chloroacetic acid, bromoacetic acid, iodoacetic acid, and methoxyacetic acid.

2. The method according to claim 1, characterized in that, In step (1), the molar amount of the orthoformate compound is 1 to 7 times the molar amount of the C5 sugar alcohol; the molar ratio of the C5 sugar alcohol to the first acidic catalyst is 5 to 40:

1.

3. The method according to claim 1, characterized in that, In step (1), the esterification reaction is carried out at a temperature of 80~160℃ for 1~10 h.

4. The method according to claim 1, characterized in that, In step (2), the concentration of the second acidic catalyst in the second mixture is 0.1~3.0 mol / L.

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