阅读说明：本技术 一种3-甲基-1,5-戊二醇的制备方法 (Preparation method of 3-methyl-1, 5-pentanediol ) 是由 庞计昌 朱小瑞 刘英俊 张红涛 沈元伟 安丽艳 张永振 于 2021-11-12 设计创作，主要内容包括：本发明提供一种3-甲基-1,5-戊二醇的制备方法,步骤包括：1)以异丁烯和甲醛为原料,在酸性催化剂和助剂的作用下进行缩合反应,生成3-亚甲基戊烷-1,5-二醇和3-甲基戊-2-烯-1,5-戊二醇；2)以3-亚甲基戊烷-1,5-二醇和3-甲基戊-2-烯-1,5-戊二醇为原料进行加氢反应,制得3-甲基-1,5-戊二醇。本发明异丁烯和甲醛缩合反应采用磺酸吡啶盐作为催化剂,磷酸盐作为助剂,能够显著提高产品收率。本发明具有工艺步骤短、收率高、成本低的优点,适合工业化放大。(The invention provides a preparation method of 3-methyl-1, 5-pentanediol, which comprises the following steps: 1) isobutene and formaldehyde are used as raw materials, condensation reaction is carried out under the action of an acid catalyst and an auxiliary agent, and 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-alkene-1, 5-pentanediol are generated; 2) 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-ene-1, 5-pentanediol are used as raw materials to carry out hydrogenation reaction to prepare the 3-methyl-1, 5-pentanediol. According to the invention, the condensation reaction of isobutene and formaldehyde adopts pyridinium sulfonate as a catalyst and phosphate as an auxiliary agent, so that the product yield can be obviously improved. The method has the advantages of short process steps, high yield and low cost, and is suitable for industrial amplification.)

1. A preparation method of 3-methyl-1, 5-pentanediol is characterized by comprising the following steps:

1) isobutene and formaldehyde are used as raw materials, condensation reaction is carried out under the action of an acid catalyst and an auxiliary agent, and 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-alkene-1, 5-pentanediol are generated;

2) 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-ene-1, 5-pentanediol are used as raw materials to carry out hydrogenation reaction to prepare the 3-methyl-1, 5-pentanediol.

2. The method according to claim 1, wherein the acidic catalyst in step 1) is selected from a pyridinium sulfonate compound, preferably any one or a combination of at least two of pyridinium propane sulfonate, pyridinium methanesulfonate, pyridinium 4-methylbenzenesulfonate and pyridinium p-toluenesulfonate, more preferably any one or a combination of at least two of pyridinium propane sulfonate, pyridinium methanesulfonate and pyridinium p-toluenesulfonate.

3. The preparation method according to claim 1 or 2, wherein the auxiliary agent in step 1) is selected from phosphate compounds, preferably any one or a combination of at least two of ferrous phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, diammonium hydrogen phosphate, disodium dihydrogen pyrophosphate, and sodium hexametaphosphate, more preferably any one or a combination of at least two of potassium dihydrogen phosphate, disodium dihydrogen pyrophosphate and sodium dihydrogen phosphate.

4. The preparation method according to any one of claims 1 to 3, wherein the molar ratio of the formaldehyde to the isobutene in step 1) is 0.5 to 5:1, preferably 1.5 to 2.5: 1.

5. The method according to any one of claims 1 to 4, wherein the amount of the acidic catalyst used in step 1) is 0.01 to 6%, preferably 0.05 to 3% of the total mass of the raw materials of formaldehyde and isobutylene.

6. The preparation method according to any one of claims 1 to 5, wherein the amount of the auxiliary agent is 0.01 to 3%, preferably 0.02 to 1% of the total mass of the raw materials of formaldehyde and isobutene.

7. The method according to any one of claims 1 to 6, wherein the condensation reaction in step 1) is carried out at a temperature of 150 to 350 ℃, preferably 200 to 280 ℃; the reaction pressure is 5-12 MPaG, preferably 6-10 MPaG; the reaction time is 5-35 min, preferably 10-20 min;

preferably, the condensation reaction is carried out in an acidic atmosphere, and the pH of a reaction system is 2-7, preferably 3-6.

8. The process according to any one of claims 1 to 7, wherein, after completion of the condensation reaction in the step 1), the condensation reaction mixture is rapidly cooled to obtain a mixture of isobutylene and 3-methylpentane-1, 5-diol and 3-methylpentane-2-ene-1, 5-pentanediol as the main components, unreacted isobutylene is recovered by flash evaporation, and then the mixture of 3-methylpentane-1, 5-diol and 3-methylpentane-2-ene-1, 5-pentanediol is separated by rectification.

9. The method according to any one of claims 1 to 8, wherein the hydrogenation in step 2) is carried out under catalytic conditions, and the hydrogenation catalyst is selected from preferably Raney nickel catalysts such as Nippon Raney metal technology RC-311, RC312 and RC 312. Palladium catalysts such as 1, 1-bis (di-t-butylphosphino) ferrocene dichloropalladium, tris (dibenzylideneacetone) dipalladium;

preferably, the dosage of the hydrogenation catalyst is 0.1-10%, preferably 0.5-2% of the total mass of the 3-methylene pentane-1, 5-diol and the 3-methyl pent-2-ene-1, 5-pentanediol.

10. The preparation method according to any one of claims 1 to 9, wherein hydrogen is continuously fed in the hydrogenation reaction process in the step 2), and the amount of hydrogen in the system is maintained to be 1 to 20%, preferably 5 to 10%, of the total molar amount of 3-methylene pentane-1, 5-diol and 3-methyl pent-2-ene-1, 5-pentanediol;

the hydrogenation reaction in the step 2), wherein the reaction pressure is normal pressure or pressurization, preferably pressurization, and more preferably 1-3 MPaG; the reaction temperature is 90-160 ℃, and preferably 100-130 ℃; the reaction time is 0.5-2 h, preferably 1-1.5 h.

Technical Field

The invention belongs to the field of fine chemical engineering, and particularly relates to a method for preparing 3-methyl-1, 5-pentanediol by using isobutene and formaldehyde as raw materials, firstly performing condensation reaction, and then hydrogenating.

Background

3-methyl-1, 5-pentanediol (MPD) is a polyol, widely used in polyester resins, alkyd resins for coatings, etc., and ester products synthesized therefrom are used in coatings, plastic plasticizers, etc.

In the traditional technology, side reactions are more and the product yield is low in the MPD synthesis process, for example, in the direct hydroformylation process of 3-methyl-3-alkene-1-butanol disclosed in US4663468, the reaction selectivity is only about 50%, and more byproducts are generated, wherein the byproducts include isovaleraldehyde, bis (4-methyl-tetrahydropyran-2-methyl) ether (main byproduct), 3-methyl-5- [ (4-methyl-2H-pyran-2-yl) oxy ] -valeraldehyde, 4-methyl-2- [ (3-methyl-3-butenyl) oxy ] -2H-pyran and the like.

CN101432255 provides a process for preparing 3-methyl-1, 5-pentanediol by hydrogenating 2-hydroxy-4-methyl tetrahydropyran in the presence of a hydrogenation catalyst, which has less sources of 2-hydroxy-4-methyl tetrahydropyran raw material, high cost and poor production economy.

US6072089(a) describes a method of obtaining a 1,5 pentanediol derivative by using a dibutene derivative and formaldehyde as raw materials, performing a condensation reaction under the action of an alkaline catalyst, and then performing hydrogenation, wherein the reaction time is long, and reaches 1-10 hours, the productivity is low, and the reactor volume is large, because the alkaline catalyst can initiate the disproportionation reaction of formaldehyde, the reaction time is long, the disproportionation of formaldehyde is increased, the selectivity is reduced, the subsequent alkaline catalyst needs to be removed by washing, the amount of wastewater is large, the three wastes treatment cost is high, and simultaneously, a solvent needs to be added to enable the reaction system to reach a homogeneous phase state, and the energy consumption of subsequent separation is increased. Most of raw materials such as 2-methyl-2-pentenal, diethyl dihexaenal and diethyl dibutenal need to be obtained through complex reaction, the cost is high, and the aldehyde compounds are unstable in an alkaline environment and are not suitable for industrial amplification.

Therefore, the existing process for synthesizing the 3-methyl-1, 5-pentanediol has many defects, and the technical difficulty of how to improve atom economy, improve product yield and reduce side reactions is urgent to make a breakthrough in the field.

Disclosure of Invention

In order to solve the above problems in the prior art, the present invention provides a method for preparing 3-methyl-1, 5-pentanediol, wherein isobutylene and formaldehyde are used as raw materials, and react under the action of an acidic catalyst and an auxiliary agent to generate 3-methylene pentane-1, 5-diol and 3-methyl-pent-2-ene-1, 5-pentanediol, and then the 3-methyl-1, 5-pentanediol is obtained by hydrogenation. The formula may be represented as follows:

has the advantages of short process steps, high yield and low cost, and is suitable for industrial amplification.

In order to achieve the purpose and achieve the technical effect, the invention adopts the following technical scheme:

the invention provides a preparation method of 3-methyl-1, 5-pentanediol, which comprises the following steps:

1) isobutene and formaldehyde are used as raw materials, condensation reaction is carried out under the action of an acid catalyst and an auxiliary agent, and 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-alkene-1, 5-pentanediol are generated;

2) 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-ene-1, 5-pentanediol are used as raw materials to carry out hydrogenation reaction to prepare the 3-methyl-1, 5-pentanediol.

In the present invention, the acidic catalyst in step 1) is selected from a pyridinium sulfonate compound, preferably any one or a combination of at least two of pyridinium propane sulfonate, pyridinium methanesulfonate, pyridinium 4-methylbenzenesulfonate, pyridinium p-toluenesulfonate, and the like, and more preferably any one or a combination of at least two of pyridinium propane sulfonate, pyridinium methanesulfonate, and pyridinium p-toluenesulfonate.

In the present invention, the auxiliary agent in step 1) is selected from phosphate compounds, preferably any one or a combination of at least two of ferrous phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, diammonium hydrogen phosphate, disodium dihydrogen pyrophosphate, sodium hexametaphosphate, and the like, and more preferably any one or a combination of at least two of potassium dihydrogen phosphate, disodium dihydrogen pyrophosphate, and sodium dihydrogen phosphate.

In the invention, the molar ratio of the formaldehyde to the isobutene in the step 1) is 0.5-5: 1, preferably 1.5-2.5: 1. The formaldehyde is a common commercially available raw material, and can be a methanol solution, such as a 15-50 wt% aqueous formaldehyde solution, and if not specifically stated, the formaldehyde raw material is calculated by pure formaldehyde contained therein.

In the invention, the dosage of the acidic catalyst in the step 1) accounts for 0.01-6%, preferably 0.05-3% of the total mass of the raw materials of formaldehyde and isobutene.

In the invention, the dosage of the auxiliary agent in the step 1) accounts for 0.01-3%, preferably 0.02-1% of the total mass of the raw materials of formaldehyde and isobutene.

In the invention, the condensation reaction in the step 1) has the reaction temperature of 150-350 ℃, preferably 200-280 ℃; the reaction pressure is 5-12 MPaG, preferably 6-10 MPaG; the reaction time is 5-35 min, preferably 10-20 min;

preferably, the condensation reaction is carried out in an acidic atmosphere, and the pH of a reaction system is 2-7, preferably 3-6.

In the invention, the condensation reaction in the step 1) is carried out in a batch mode, and after the condensation reaction is finished, the condensation reaction also comprises separation and refining post-treatment operation, and a person skilled in the art can select a proper treatment mode according to needs, such as flash evaporation, rectification and the like; in some specific examples of the present invention, the post-processing may specifically adopt the following method: rapidly cooling the condensation reaction mixture to obtain a mixture mainly containing isobutene, 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-alkene-1, 5-pentanediol, recovering unreacted isobutene by flash evaporation, and then rectifying and separating to obtain a mixture of 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-alkene-1, 5-pentanediol;

wherein, preferably, the cooling temperature is 100-180 ℃, preferably 120-150 ℃, and the pressure is 2-6 MPa, preferably 3-5 MPa; the flash pressure is 0.3-1 MPa, preferably 0.4-0.6 MPa; the rectification separation adopts a conventional rectification tower, the number of tower plates is 10-30, preferably 15-20, and the pressure at the top of the tower is 5-80 KPaG, preferably 10-30 KPaG.

In the invention, the condensation reaction in the step 1) has the conversion rate of more than 90 percent and the selectivity sum of the intermediate 3-methylpent-2-ene-1, 5-pentanediol and 3-methylenepentane-1, 5-diol of more than 99 percent;

after rectification, a mixture of 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-alkene-1, 5-pentanediol is obtained, and the purity is over 99.5 percent.

In the invention, the hydrogenation reaction in the step 2) is carried out under the condition of a catalyst, and the catalyst can use a common commercially available hydrogenation catalyst, preferably a Raney nickel catalyst such as Jiangsu Raney metal technology RC-311 and RC 312. Palladium catalysts such as 1, 1-bis (di-t-butylphosphino) ferrocene dichloropalladium, tris (dibenzylideneacetone) dipalladium and the like.

Preferably, the dosage of the hydrogenation catalyst is 0.1-10%, preferably 0.5-2% of the total mass of the 3-methylene pentane-1, 5-diol and the 3-methyl pent-2-ene-1, 5-pentanediol.

Preferably, hydrogen is continuously fed in the hydrogenation reaction process, and the amount of hydrogen in the system is maintained to be 1-20%, preferably 5-10% of the total molar amount of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-ene-1, 5-pentanediol.

In the invention, the hydrogenation reaction in the step 2) is carried out under the condition of no solvent; the reaction pressure is normal pressure or pressurization, preferably pressurization, and more preferably 1-3 MPaG; the reaction temperature is 90-160 ℃, and preferably 100-130 ℃; the reaction time is 0.5-2 h, preferably 1-1.5 h.

In the invention, in the hydrogenation reaction in the step 2), the conversion rate of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-ene-1, 5-pentanediol are both more than 98.5%, and the selectivity of the 3-methyl-1, 5-pentanediol is more than 99%.

By adopting the technical scheme, the invention has the following positive effects:

1. the method takes isobutene and formaldehyde as raw materials, the condensation reaction is carried out under the action of an acidic catalyst and an auxiliary agent to generate 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-alkene-1, 5-pentanediol, and then the 3-methyl-1, 5-pentanediol is obtained through hydrogenation.

2. According to the invention, pyridine sulfonate is used as a catalyst in the condensation reaction of isobutene and formaldehyde, and phosphate is used as an auxiliary agent, so that on one hand, the occurrence of side reactions of formaldehyde disproportionation and polymerization is inhibited through the synergistic effect of pyridine sulfonate and phosphate, on the other hand, the reaction rate and the reaction equilibrium constant can be improved, the forward proceeding of the reaction is promoted, the stability of a condensation product is improved, and the reaction of double bond hydration of the condensation product is reduced; the phosphate as the assistant can also improve the selectivity of the condensation product, reduce the proportion of isomers and facilitate the subsequent separation and purification.

3. The method is simple and convenient to operate, easy to amplify and good in application prospect.

Detailed Description

The present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples.

The main raw material information of the embodiment of the invention is as follows, and the other raw materials are common commercial raw materials unless otherwise specified:

chemical information in the examples of Table 1

Chemical product	Source	Specification of
			Formaldehyde (I)	Wanhua formaldehyde device	37～50％
Isobutene	Open torch gas Co Ltd	(High purity)
			Hydrogen gas	Open torch gas Co Ltd	(High purity)
Propane sulfonic acid pyridine salt	Aladdin reagent	98％
			Methanesulfonic acid pyridine salt	Lake south China Huateng	98％
Pyridinium 4-methylbenzenesulfonate	Nanjing chemical reagent	99％
			Ferrous phosphate	Orchidaceae (Middy stonecrop)	98％
Potassium dihydrogen phosphate	Shandong jin ao chemical Co Ltd	AR
			Disodium dihydrogen pyrophosphate	Jinanle bin chemical Co Ltd	AR
Sodium dihydrogen phosphate	Yao chemical Co Ltd of Shandong	AR
			Diammonium hydrogen phosphate	Chemical engineering of Kandis	AR
6-nitro-2, 5-diaminopyridine	Hubeixin Hongli chemical Co., Ltd	AR
			Pyridine quaternary ammonium salt	Nanjing Huazhou New materials Co., Ltd	AR
Pyridinium p-toluenesulfonate	Nanjing Milan chemical Co Ltd	AR
			Sodium nitrate	Merck	AR
Ferrous sulfate	Jining Lanxing chemical Co Ltd	AR

The gas chromatography test conditions of the present invention are as follows:

the instrument model is as follows: agilent GC 2010; a chromatographic column: agilent HP-5(30 m.times.0.25 mm.times.0.25 μm); column temperature: the initial temperature is 40 ℃, the temperature is increased to 100 ℃ at the speed of 5 ℃/min, the temperature is increased to 280 ℃ at the speed of 20 ℃/min, and the temperature is kept for 10 min; sample inlet temperature: 260 ℃; FID detector temperature: 240 ℃; the split ratio is 50: 1; sample introduction amount: 1.0. mu.L.

The invention determines the condensation product and the product structure by a nuclear magnetic resonance instrument, and concretely adopts BUKER NMR-300MHZ for analysis and qualification.

Example 1

1) Firstly, adding 180g (3.2mol) of isobutene into an autoclave, starting stirring, heating to 275 ℃, increasing the pressure to 9MPa, adding 1.2g of propane sulfonic acid pyridinium salt serving as a catalyst and 0.3g of ferrous phosphate serving as an auxiliary agent, then 900g of 50 wt% (14.9mol) formaldehyde aqueous solution is added, the PH of the system is 6.8 after the addition of the materials, the reaction is carried out for 20min at 275 ℃, cooling liquid is introduced for cooling after the reaction is finished, unreacted isobutene is recovered by flash evaporation, then rectifying and separating are carried out to obtain condensation products of 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-alkene-1, 5-pentanediol, wherein the conversion rate of formaldehyde is 95.6 percent, the selectivity of 3-methylene pentane-1, 5-diol is 93.2 percent, and the selectivity of 3-methyl pentane-2-alkene-1, 5-pentanediol is 6.1 percent.

NMR Hydrogen spectrum of 3-Methylenepentane-1, 5-diol:

¹H-NMR(CDCl₃)δ:2.15(4H),3.57(4H),3.65(2H),4.92(1H),5.11(1H)

NMR Hydrogen spectrum of 3-methylpent-2-ene-1, 5-pentanediol:

¹H-NMR(CDCl₃)δ:1.82(3H),2.15(2H),3.57(2H),3.65(2H),4.18(2H),5.39(1H)

2) taking 100g of the mixture of 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-ene-1, 5-pentanediol obtained by separation in the step 1), adding 0.8g of RC-311 serving as a hydrogenation catalyst and introducing hydrogen, keeping the hydrogen amount in the system to be 2.5 percent of the total molar amount of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-ene-1, 5-pentanediol in the reaction process, carrying out hydrogenation reaction for 1.8h at the temperature of 100 ℃ and under the pressure of 1MPaG to obtain the 3-methyl-1, 5-pentanediol, the hydrogenation conversion rates of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-ene-1, 5-pentanediol are respectively 99.82 percent and 98.8 percent, the selectivity of 3-methyl-1, 5-pentanediol was 99.2%.

The NMR hydrogen spectrum of the product 3-methyl-1, 5-pentanediol was as follows:

¹H-NMR(CDCl₃)δ:0.96(3H),1.43(4H),1.65(1H),3.50(4H),3.65(2H)

example 2

1) Firstly, adding 250g (4.5mol) of isobutene into an autoclave, starting stirring, heating to 185 ℃, increasing the pressure to 6MPa, adding 24g of catalyst pyridine methanesulfonate and 1.2g of auxiliary agent sodium dihydrogen phosphate, then 542.95g of 37 percent (6.7mol) formaldehyde aqueous solution is added, the PH of the material system is 4 after the addition, the reaction is carried out for 10min at 185 ℃, cooling liquid is introduced for cooling after the reaction is finished, the unreacted isobutene is recovered by flash evaporation, then rectifying and separating are carried out to obtain condensation products of 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-alkene-1, 5-pentanediol, the formaldehyde conversion rate is 95.2 percent, the selectivity of the 3-methylene pentane-1, 5-diol is 95.2 percent, and the selectivity of the 3-methyl pentane-2-alkene-1, 5-pentanediol is 4.6 percent.

2) Taking 100g of the mixture of 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-ene-1, 5-pentanediol obtained by separation in the step 1), adding 1.2g of RC-311 serving as a hydrogenation catalyst and introducing hydrogen, keeping the hydrogen amount in the system to be 18 percent of the total molar amount of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-ene-1, 5-pentanediol in the reaction process, carrying out hydrogenation reaction for 0.5h at the temperature of 150 ℃ and the pressure of 3MPaG to obtain the 3-methyl-1, 5-pentanediol, the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-ene-1, 5-pentanediol, wherein the hydrogenation conversion rates are respectively 99.98 percent and 99.25 percent, the selectivity of 3-methyl-1, 5-pentanediol was 99.3%.

Example 3

1) Firstly, 300g (5.3mol) of isobutene is added into an autoclave, stirring is started, the temperature is raised to 200 ℃, the pressure is raised to 10MPa, 20g of catalyst pyridinium p-toluenesulfonate and 13g of auxiliary agent disodium dihydrogen pyrophosphate are added, then 1004.4g of 40 percent (13.4mol) formaldehyde aqueous solution is added, the PH of the system is 3 after the addition of the materials, the reaction is carried out for 15min at 200 ℃, cooling liquid is introduced for cooling after the reaction is finished, unreacted isobutene is recovered by flash evaporation, then rectifying and separating to obtain condensation products of 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-ene-1, 5-pentanediol, wherein the formaldehyde conversion rate is 96.40%, the selectivity of 3-methylene pentane-1, 5-diol is 96.40%, and the selectivity of 3-methyl pentane-2-ene-1, 5-pentanediol is 3.4%.

2) Taking 100g of the mixture of 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-ene-1, 5-pentanediol obtained by separation in the step 1), adding 9.5g of 1, 1-bis (di-tert-butylphosphine) ferrocene palladium dichloride serving as a hydrogenation catalyst and introducing hydrogen, maintaining the hydrogen content in the system to be 10 percent of the total molar weight of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-ene-1, 5-pentanediol in the reaction process, and performing hydrogenation reaction for 1h at the temperature of 120 ℃ and the pressure of 2.5MPa to obtain the 3-methyl-1, 5-pentanediol, wherein the hydrogenation conversion rates of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-ene-1, 5-pentanediol are respectively 99.95 percent, 99.32 percent, and the selectivity of the 3-methyl-1, 5-pentanediol is 99.21 percent.

Example 4

1) Firstly, 400g (7.1mol) of isobutene is added into an autoclave, stirring is started, the temperature is raised to 340 ℃, the pressure is raised to 5MPa, 100g of propane sulfonic acid pyridinium salt serving as a catalyst and 3g of sodium dihydrogen phosphate serving as an auxiliary agent are added, then 4166.67g of 18 percent (25.0mol) formaldehyde aqueous solution is added, the PH of the system is 5 after the addition of the materials, the reaction is carried out for 6min at 340 ℃, cooling liquid is introduced for cooling after the reaction is finished, unreacted isobutene is recovered by flash evaporation, then rectifying and separating are carried out to obtain condensation products of 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-alkene-1, 5-pentanediol, the formaldehyde conversion rate is 97.3 percent, the selectivity of the 3-methylene pentane-1, 5-diol is 94.2 percent, and the selectivity of the 3-methyl pentane-2-alkene-1, 5-pentanediol is 5.3 percent.

2) Taking 100g of the mixture of 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-ene-1, 5-pentanediol obtained by separation in the step 1), adding 2g of 1, 1-bis (di-tert-butylphosphine) ferrocene palladium dichloride serving as a hydrogenation catalyst and introducing hydrogen, maintaining the hydrogen content in the system to be 5 percent of the total molar weight of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-ene-1, 5-pentanediol in the reaction process, and performing hydrogenation reaction for 1.5h at the temperature of 130 ℃ and the pressure of 1.5MPa to obtain the 3-methyl-1, 5-pentanediol, wherein the hydrogenation conversion rates of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-ene-1, 5-pentanediol are respectively 99.97 percent, 99.18% and the selectivity of 3-methyl-1, 5-pentanediol is 99.53%.

Example 5

1) Firstly, 350g (6.2mol) of isobutene is added into an autoclave, stirring is started, the temperature is raised to 240 ℃, the pressure is raised to 8MPa, 52g of catalyst 4-pyridine methyl benzene sulfonate and 25g of auxiliary agent diammonium hydrogen phosphate are added, then 525g of 25% formaldehyde aqueous solution (4.375mol) is added, the PH of the system is 2.3 after the addition of the materials, the reaction is carried out for 8min at 240 ℃, cooling liquid is introduced for cooling after the reaction is finished, unreacted isobutene is recovered by flash evaporation, then rectifying and separating are carried out to obtain condensation products of 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-alkene-1, 5-pentanediol, the formaldehyde conversion rate is 96.70 percent, the selectivity of the 3-methylene pentane-1, 5-diol is 95.8 percent, and the selectivity of the 3-methyl pentane-2-alkene-1, 5-pentanediol is 3.8 percent.

2) Taking 100g of the mixture of 3-methylene pentane-1, 5-diol and 3-methyl pentane-2-alkene-1, 5-pentanediol obtained by the separation in the step 1), adding 5g of RC-312 as a hydrogenation catalyst, introducing hydrogen, keeping the hydrogen amount in the system to be 20 percent of the total molar amount of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-alkene-1, 5-pentanediol in the reaction process, carrying out hydrogenation reaction for 1.2h at the temperature of 110 ℃ and the pressure of 2MPa to obtain the 3-methyl-1, 5-pentanediol, the hydrogenation conversion rates of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-alkene-1, 5-pentanediol are respectively 99.94 percent and 99.24 percent, the selectivity of 3-methyl-1, 5-pentanediol was 99.42%.

Comparative example 1

With reference to the process of example 1, except that no auxiliary agent, ferrous phosphate, was added, the other operations and parameters were unchanged:

1) the conversion rate of formaldehyde is 89.98 percent, the selectivity of 3-methylene pentane-1, 5-diol is 45.3 percent, and the selectivity of 3-methyl pentane-2-alkene-1, 5-pentanediol is 42.5 percent;

2) the hydrogenation conversion rates of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-ene-1, 5-pentanediol are respectively 98.23 percent and 92.45 percent, and the selectivity of the 3-methyl-1, 5-pentanediol is 96.26 percent.

Comparative example 2

With reference to the process of example 1, except that no catalyst pyridinium propanesulfonate was added, the other operations and parameters were unchanged:

1) the conversion rate of formaldehyde is 75.82 percent, the selectivity of 3-methylene pentane-1, 5-diol is 85.6 percent, and the selectivity of 3-methyl pentane-2-alkene-1, 5-pentanediol is 12.7 percent;

2) the hydrogenation conversion rates of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-ene-1, 5-pentanediol are respectively 98.32 percent and 96.65 percent, and the selectivity of the 3-methyl-1, 5-pentanediol is 97.85 percent.

Comparative example 3

With reference to the procedure of example 1, except that the catalyst pyridinium propanesulfonate was replaced with an equal mass of pyridinium quaternary amine, the other operations and parameters were unchanged:

1) the conversion rate of formaldehyde is 81.25 percent, the selectivity of 3-methylene pentane-1, 5-diol is 92.5 percent, and the selectivity of 3-methyl pentane-2-alkene-1, 5-pentanediol is 6.2 percent;

2) the hydrogenation conversion rates of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-ene-1, 5-pentanediol are respectively 98.98 percent and 97.68 percent, and the selectivity of the 3-methyl-1, 5-pentanediol is 98.32 percent.

Comparative example 4

The process of example 1 is referred to with the only difference that the catalyst pyridinium propanesulfonate is replaced by an equal mass of 6-nitro-2, 5-diaminopyridine with the other operations and parameters unchanged:

1) the conversion rate of formaldehyde is 79.65 percent, the selectivity of 3-methylene pentane-1, 5-diol is 91.8 percent, and the selectivity of 3-methyl pentane-2-alkene-1, 5-pentanediol is 6.5 percent;

2) the hydrogenation conversion rates of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-ene-1, 5-pentanediol are respectively 97.95 percent and 96.85 percent, and the selectivity of the 3-methyl-1, 5-pentanediol is 98.27 percent.

Comparative example 5

With reference to the process of example 1, except that the auxiliary agent ferrous phosphate was replaced by an equal mass of sodium nitrate, the other operations and parameters were not changed:

1) the conversion rate of formaldehyde is 90.23 percent, the selectivity of 3-methylene pentane-1, 5-diol is 82.68 percent, and the selectivity of 3-methyl pentane-2-alkene-1, 5-pentanediol is 15.98 percent;

2) the hydrogenation conversion rates of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-ene-1, 5-pentanediol are respectively 98.07 percent and 95.89 percent, and the selectivity of the 3-methyl-1, 5-pentanediol is 97.55 percent.

Comparative example 6

With reference to the process of example 1, except that the auxiliary agent ferrous phosphate was replaced by ferrous sulfate of equal mass, the other operations and parameters were not changed:

1) the conversion rate of formaldehyde is 91.12 percent, the selectivity of 3-methylene pentane-1, 5-diol is 81.92 percent, and the selectivity of 3-methyl pentane-2-alkene-1, 5-pentanediol is 16.23 percent;

2) the hydrogenation conversion rates of the 3-methylene pentane-1, 5-diol and the 3-methyl pentane-2-ene-1, 5-pentanediol are 98.12 percent and 96.12 percent respectively, and the selectivity of the 3-methyl-1, 5-pentanediol is 97.34 percent.