A method for manufacturing a bio-based spandex precursor

Abstract

The application belongs to the technical field of polymer materials, and particularly relates to a preparation method of a bio-based spandex using lactone. In the application, a series of lactones are directly synthesized from dihydric alcohol and dibasic acid through a molecular structure design and a preparation process optimization by using a suitable diluent in a 'polycondensation-directing depolymerization' method. After the addition of an ionic liquid in a depolymerization reaction system, the depolymerization reaction rate is fast, and the byproduct is less. The conversion from cheap and easily available dihydric alcohol and dibasic acid to a series of lactone monomers is realized. The limitation of only commercially available cyclic monomers such as propiolactone and caprolactone is broken. The cyclic monomer system and the polyester material category are expanded. The application has important significance for promoting the upgrading of the green degradable polyester industry and widening the application scenarios of high-end functional materials.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a method for preparing bio-based spandex using lactone. Technical Background

[0002] Spandex is a type of highly elastic fiber with polyurethane as its main structure, widely used in clothing, sportswear fabrics, medical textiles, and high-end functional textiles. Currently, industrialized spandex is mainly based on polyether-type polyurethane, with its soft segments typically derived from petroleum-based polyether polyols. While this type of spandex possesses good elastic recovery properties and processing stability, its raw materials are highly dependent on fossil resources, and it still falls short in terms of renewability, low carbon footprint, chlorine resistance, and green recycling, making it difficult to meet the demands of the elastic fiber industry for bio-based, high-performance, and sustainable development.

[0003] Bio-based polyester spandex uses polyester polyols derived from renewable biomass as the source of its soft segment structure. Its molecular chain contains ester bonds, which endow the material with good sustainability, chlorine resistance, and structural controllability, making it an important direction for developing green, low-carbon, and high-performance spandex. The performance of polyester spandex is highly dependent on the structure of the polyester soft segment. Bio-based lactones, as cyclic monomers that can be obtained by converting bio-based glycols, bio-based hydroxy acids, bio-based diacids, or their derivatives, can be used to prepare bio-based polyester polyols with well-defined structures, controllable molecular weights, and tunable properties through ring-opening polymerization. By controlling the ring size, carbon chain length, side group structure, and ester bond density of the bio-based lactone monomer, the flexibility, crystallization behavior, hydrophilicity / phobicity, and terminal hydroxyl reactivity of the polyester soft segment can be further adjusted, thereby affecting the elastic recovery, strength, elongation at break, chlorine resistance, and spinning stability of bio-based spandex.

[0004] However, the types of lactone monomers currently available for bio-based spandex are still relatively limited, with commonly used monomers mainly concentrated in a few conventional structures such as lactide and ε-caprolactone. Some of these monomers still rely on petroleum-based routes or have insufficient bio-based sources, limiting the scope for structural control and making it difficult to meet the requirements of bio-based polyester spandex for fine design of soft segment structures. Polyester polyols prepared from existing conventional lactone monomers often suffer from problems such as limited bio-based content, difficulty in balancing flexibility and strength, uncontrollable crystallization behavior, and insufficient hydrolysis or chlorine resistance, thus restricting the application expansion of bio-based spandex in fields such as chlorine-resistant swimwear, sportswear, medical care, and high-end functional textiles.

[0005] Currently, novel bio-based lactone monomers can be generated from bifunctional raw materials such as bio-based glycols, bio-based hydroxy acids, and bio-based diesters through transesterification or condensation reactions to produce low-molecular-weight linear prepolymers. However, in the above processes, the linear oligomers obtained by pre-condensation of bio-based bifunctional raw materials typically have high viscosity, leading to poor melt flowability, low mass and heat transfer efficiency, and restricted chain segment movement during high-temperature processes, thus hindering the orderly control of chain segments. Furthermore, high-viscosity systems are prone to localized overheating, material carbonization, monomer thermal decomposition, and intermolecular side reactions, affecting the yield, purity, and structural stability of the target bio-based polyester polyol. For bio-based spandex, the quality of the polyester polyol directly affects the terminal hydroxyl content, color, and the stability of spandex polymerization and spinning.

[0006] Therefore, there is an urgent need to develop a universal, efficient, green, and scalable synthesis process for preparing lactone monomers for bio-based spandex. Based on renewable raw materials such as bio-based glycols, bio-based hydroxy acids, bio-based diacids, and their derivatives, this process would reduce the viscosity of the prepolymer system, improve the mass and heat transfer efficiency during the depolymerization and cyclization process, increase the yield and purity of the target bio-based lactone monomer, and form lactone monomers for controllable ring-opening polymerization. This would reduce the uncontrollable factors brought about by traditional polycondensation reactions, thereby expanding the library of bio-based polyester spandex soft segment monomers and enhancing the bio-based content, performance regulation space, and green and low-carbon properties of spandex materials. Summary of the Invention

[0007] The problem this invention aims to solve is a large-scale method for directly synthesizing lactones from diols and diacids. It provides a lactone synthesis method that uses diols and diacids as raw materials, and through different combinations, can synthesize a series of lactones, filling a gap in the variety of cyclic monomer systems.

[0008] To solve the above-mentioned technical problems, the technical solution adopted in this invention is to prepare lactones through a process design of "condensation-directional depolymerization".

[0009] This invention provides a class of lactones, as shown in formula (I):

[0010]

[0011] Where n is 1-14 and m is 3-14.

[0012] The specific preparation method of the lactone of formula (I) prepared by the present invention is as follows: a diol and a diacid undergo a polycondensation reaction under the action of a catalyst to obtain a polyester, a diluent is added to depolymerize, and then recrystallization is carried out to obtain the product.

[0013] The reaction equation is as follows:

[0014]

[0015] Where n is 1-14, m is 3-14, and x is the degree of polymerization.

[0016] The polycondensation reaction is preferably carried out under bulk conditions:

[0017] The molar ratio of the diol to the diacid is 1.0-2.0:1, preferably 1.4:1.

[0018] The catalyst may be stannous chloride, stannous octoate, stannous oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate, stannous chloride, stannous oxalate, stannous bromide, stannous acetate, butyltin oxide hydroxide, tetraalkyltin, sodium stannate, tetraethyl stannate, tetrabutyl stannate, titanium dioxide, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, tetratert-butyl titanate, tetraphenyl titanate, tetracyclohexyl titanate, tetrabenzyl titanate, etc. Hexyloxy titanium, tetra(2-ethylhexyloxy) titanium, tetraoctyloxy titanium, glycolate titanium, ethylene glycol titanium, titanium oxalate, potassium titanium oxalate, lithium oxalate titanium oxy, oxyacetylacetone titanium, tetraacetylacetone titanium, diisopropanol acetylacetone titanium, ammonium dilactic acid titanium hydroxide, ethyl acetoacetate diisopropanol titanium, triethanolamine isopropanol titanium, polyhydroxystearate titanium, lactate titanium, triethanolamine titanium, tetrabutyl titanate dimer, titanium-magnesium composite catalyst, silica-titanium dioxide composite. Antimony trioxide, antimony glycolate, antimony acetate, antimony pentoxide, sodium antimonate, potassium antimonate, germanium dioxide, germanium tetroxide, germanium hydroxide, germanium oxalate, tetraethoxygermanium, tetra-n-butoxygermanium, zirconium oxide, sodium zirconate, tetrabutyl zirconate, tetraethyl zirconate, tetrapropyl zirconate, tetraisopropyl zirconate, aluminum oxide, aluminum alkoxide, aluminum isopropoxide, aluminum trichloride, sodium aluminate, silicon dioxide, tetraethyl silicate, tetrabutyl silicate, silicotungstic acid, silicotungstate, tungsten trioxide, paratungsten Any one of the following: acid, metatungstic acid, tungstic acid, phosphotungstic acid, phosphotungstate, cobalt formate, cobalt acetate, cobalt stearate, cobalt oxalate, cobalt carbonate, cobalt bromide, cobalt oxide, cobalt hydroxide, magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium dimethoxide, magnesium acetate, magnesium chloride, calcium oxide, calcium hydroxide, calcium carbonate, calcium acetate, calcium dimethoxide, zinc oxide, zinc acetate, zinc acetylacetonate, alkyl zinc, dialkyl zinc, zinc dimethoxide, diethyl zinc, and zinc chloride, preferably stannous chloride.

[0019] The total amount of catalyst added is 1-20% of the total mass of the raw materials, preferably 2%.

[0020] The polycondensation reaction temperature is 60-340 °C, preferably 180-230 °C.

[0021] The polycondensation reaction is characterized in that the reaction is carried out under a vacuum of 0.001 MPa to 0.1 MPa, preferably 0.098 MPa.

[0022] The polycondensation reaction time is 3-12 h, preferably 4-6 h.

[0023] The depolymerization reaction temperature is 200-300 °C.

[0024] The depolymerization reaction is characterized in that the reaction occurs at a temperature of 1 × 10⁻⁶. -3 MPa to 1×10 -7 The test is performed under a vacuum of MPa, preferably 1×10 MPa. -6 MPa.

[0025] The depolymerization reaction time is 8-24 h, preferably 12 h.

[0026] The diluent may be 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-decyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-dodecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-tetradecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-hexadecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-propyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-butyl-2,3-Dimethylimidazolium bis(fluorosulfonyl)imide salt, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-octyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, 1-octyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide salt, 1-butyl-3-methylimidazolium bis(fluorosulfonyl)imide salt, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-butyl 1-Butyl-3-methylimidazolium trifluoroacetate, 1-Butyl-3-methylimidazolium methanesulfonate, 1-Butyl-3-methylimidazolium p-toluenesulfonate, 1-Butyl-3-methylimidazolium dicyandiamide, 1-Butyl-3-methylimidazolium thiocyanate, 1-Butyl-3-methylimidazolium dicyandiamide, 1-Propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-Pentyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-Heptyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-Nonyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-Undecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-Tetanedecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-Pentadedecyl-3-methylimidazolium Imidazole bis(trifluoromethanesulfonyl)imide salt, 1-benzyl-3-methylimazole bis(trifluoromethanesulfonyl)imide salt, 1-hydroxyethyl-3-methylimazole bis(trifluoromethanesulfonyl)imide salt, 1-methoxyethyl-3-methylimazole bis(trifluoromethanesulfonyl)imide salt, 1-ethoxyethyl-3-methylimazole bis(trifluoromethanesulfonyl)imide salt, N-butyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-hexyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-octyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, tetrabutylammonium chloride, tetrabutylammonium acetate, tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate, tetrabutylammonium bis(trifluoromethanesulfonyl)imide salt, tetrabutylammonium hydroxide, tributylmethylammonium chloride The following are listed: tributylmethylammonium acetate, tributylmethylammonium tetrafluoroborate, tributylmethylammonium bis(trifluoromethanesulfonyl)imide salt, benzyltributylammonium chloride, benzyltributylammonium acetate, tetraethylammonium chloride, tetraethylammonium acetate, tetraethylammonium tetrafluoroborate, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium tetrafluoroborate, tetrabutylphosphonium hexafluorophosphate, tetrabutylphosphonium bis(trifluoromethanesulfonyl)imide salt, tributylmethylphosphonium chloride, tributylmethylphosphonium acetate, tributylmethylphosphonium tetrafluoroborate, tributylethylphosphonium acetate, trihexyltetradecylphosphonium chloride, choline acetate, choline formate, choline propionate, choline butyrate, choline chloride, choline hydroxide, and betaine hydrochloride.

[0027] Beneficial effects

[0028] (1) Lactones with the structure of formula (I) have not been reported before. They are bio-based, green, and environmentally friendly products with the dual benefits of saving petroleum resources and protecting the environment. They are of great significance to promoting the sustainable development of the polyester industry.

[0029] (2) The raw materials used in this invention are biologically derived diols and dicarboxylic acids, which have the advantages of being inexpensive, readily available, green and non-toxic. A cyclic lactone with the structure of formula (I) can be obtained through simple polycondensation and depolymerization reactions, and can be produced on a large scale using existing chemical equipment.

[0030] (3) After adding ionic liquid to the depolymerization reaction system, the depolymerization reaction rate is fast and there are few by-products. The diluent contains no highly toxic raw materials or highly corrosive waste. Attached Figure Description

[0031] The embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein...

[0032] Figure 1 Example 1 (I) of implementation: lactone E24 1 H NMR image

[0033] Figure 2 Example 2 (I) Implementation of lactone E34 1 H NMR image

[0034] Figure 3 Example 3 (I) Implementation of lactone E35 1 H NMR image

[0035] Figure 4 Example 4 (I) of implementation: lactone E45 1 H NMR image

[0036] Figure 5 Example 5 (I) of implementation: lactone E46 1 H NMR image

[0037] Figure 6 Example 6 (I) of implementation: lactone E54 1 H NMR image

[0038] Figure 7 Example 7 (I) of implementation: lactone E56 1 H NMR image

[0039] Figure 8 Example 8 (I) of implementation: lactone E57 1 H NMR image

[0040] Figure 9 Example 9 (I) of implementation: lactone E59 1 H NMR image

[0041] Figure 10 Example 10 (I) Implementation of lactone E510 1 H NMR image

[0042] Figure 11 Example 11 (I) of implementation: lactone E66 1 H NMR image

[0043] Figure 12 Example 12 (I) Implementation of lactone E84 1 H NMR image Detailed Implementation

[0044] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are as follows:

[0045] Unless otherwise specified, all items are available through commercial channels.

[0046] The 1H NMR spectra involved in the examples were measured using a Bruker Ascend TM-400 NMR spectrometer, and the deuterated reagent used was deuterated chloroform (CDCl3).

[0047] Example 1

[0048] (I) Preparation of lactone E24: Ethylene glycol (33.91 g, 0.546 mol, 1.4 eq) and succinic acid (46.08 g, 0.39 mol, 1 eq) totaling 80 g were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120°C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 200 °C. The reaction was carried out for 4 h to obtain the condensation product. 1-Ethyl-3-methylimidazolium acetate (30 g) was added, and the mixture was then distilled under reduced pressure at 270 °C for 12 h to obtain the crude product. The crude product was then recrystallized with ethanol to obtain lactone E24.

[0049] Example 2

[0050] (I) Preparation of lactone E34: 80 g of 1,3-propanediol (37.94 g, 0.498 mol, 1.4 eq) and succinic acid (42.06 g, 0.356 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 220 °C. The reaction was carried out for 4 h to obtain the condensation product. 30 g of 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain the crude product. The crude product was then recrystallized from ethanol to obtain lactone E34.

[0051] Example 3

[0052] (I) Preparation of lactone E35: 80 g of 1,3-propanediol (35.71 g, 0.469 mol, 1.4 eq) and glutaric acid (42.28 g, 0.335 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 220 °C. The reaction was carried out for 4 h to obtain the condensation product. 30 g of 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain the crude product. The crude product was then recrystallized from ethanol to obtain lactone E35.

[0053] Example 4

[0054] (I) Preparation of lactone E45: 80 g of 1,4-butanediol (39.07 g, 0.433 mol, 1.4 eq) and glutaric acid (40.92 g, 0.309 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 230 °C. The reaction was carried out for 4 h to obtain the condensation product. 1-decyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt (30 g) was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain the crude product. The crude product was then recrystallized from ethanol to obtain lactone E45.

[0055] Example 5

[0056] (I) Preparation of lactone E46: 80 g of 1,4-butanediol (37.06 g, 0.411 mol, 1.4 eq) and adipic acid (42.93 g, 0.293 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 230 °C. The reaction was carried out for 4 h to obtain the condensation product. 30 g of 1-dodecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain the crude product. The crude product was then recrystallized from ethanol to obtain lactone E46.

[0057] Example 6

[0058] (I) Preparation of lactone E54: 80 g of 1,5-pentanediol (44.2 g, 0.424 mol, 1.4 eq) and succinic acid (35.79 g, 0.303 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 250 °C. The reaction was carried out for 4 h to obtain the condensation product. 30 g of 1-tetradecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain the crude product. The crude product was then recrystallized from ethanol to obtain lactone E54.

[0059] Example 7

[0060] (I) Preparation of lactone E56: 80 g of 1,5-pentanediol (39.95 g, 0.383 mol, 1.4 eq) and adipic acid (40.04 g, 0.274 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 250 °C. The reaction was carried out for 4 h to obtain the condensation product. 30 g of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain the crude product. The crude product was then recrystallized from ethanol to obtain lactone E56.

[0061] Example 8

[0062] (I) Preparation of lactone E57: 80 g of 1,5-pentanediol (38.12 g, 0.366 mol, 1.4 eq) and pimelic acid (41.84 g, 0.261 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 250 °C. The reaction was carried out for 4 h to obtain the condensation product. 30 g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain the crude product. The crude product was then recrystallized from ethanol to obtain lactone E57.

[0063] Example 9

[0064] (I) Preparation of lactone E59: 80 g of 1,5-pentanediol (34.92 g, 0.335 mol, 1.4 eq) and azelaic acid (45.07 g, 0.239 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 250 °C. The reaction was carried out for 4 h to obtain the condensation product. 1-Butyl-3-methylimidazolium tetrafluoroborate (30 g) was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain the crude product. The crude product was then recrystallized from ethanol to obtain lactone E59.

[0065] Example 10

[0066] (I) Preparation of lactone E510: 80 g of 1,5-pentanediol (33.51 g, 0.321 mol, 1.4 eq) and sebacic acid (46.48 g, 0.229 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 250 °C. The reaction was carried out for 4 h to obtain the condensation product. 1-Ethyl-3-methylimidazolium tetrafluoroborate (30 g) was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain the crude product. The crude product was then recrystallized from ethanol to obtain lactone E510.

[0067] Example 11

[0068] (I) Preparation of lactone E66: 80 g of 1,6-hexanediol (42.47 g, 0.359 mol, 1.4 eq) and adipic acid (37.52 g, 0.256 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 250 °C. The reaction was carried out for 4 h to obtain a condensation product. 1-Butyl-3-methylimidazolium hexafluorophosphate (30 g) was added, and the mixture was then distilled under reduced pressure at 270 °C for 12 h to obtain the crude product. The crude product was then recrystallized from ethanol to obtain lactone E66.

[0069] Example 12

[0070] (I) Preparation of lactone E84: 80 g of 1,8-octanediol (50.73 g, 0.346 mol, 1.4 eq) and succinic acid (29.26 g, 0.247 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 250 °C. The reaction was carried out for 4 h to obtain the condensation product. 30 g of 1-ethoxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain the crude product. The crude product was then recrystallized from ethanol to obtain lactone E84.

Claims

1. A method for preparing lactone for bio-based spandex: lactone is prepared by a process design of "condensation-directional depolymerization".

2. A lactone, characterized in that... It has a structure as shown in equation (I): Where n is 1-14 and m is 3-14.

3. The specific preparation method of the lactone according to formula (I) in claim 2 is as follows: a diol and a diacid undergo a polycondensation reaction under the action of a catalyst to obtain a polyester, a diluent is added for depolymerization, and then recrystallization is carried out to obtain the product. The reaction equation is as follows: in, n is 1-14, m is 3-14, and x is the degree of polymerization.

4. The polycondensation reaction as described in claim 3 preferably occurs under bulk conditions. The molar ratio of the diol to the diacid is 1.2-1.6:1, preferably 1.4:

1.

5. The catalyst as described in claim 3 may be stannous chloride, stannous octoate, stannous oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate, stannous chloride, stannous oxalate, stannous bromide, stannous acetate, butyltin oxide hydroxide, tetraalkyltin, sodium stannate, tetraethyl stannate, tetrabutyl stannate, titanium dioxide, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, tetratert-butyl titanate, tetraphenyl titanate, or tetracyclohexyl titanate. Tetrabenzyl titanate, tetrahexyloxy titanium, tetra(2-ethylhexyloxy) titanium, tetraoctyloxy titanium, titanium glycolate, titanium glycolate, titanium oxalate, titanium potassium oxalate, lithium oxalate titanium oxide, titanium oxyacetylacetone, titanium tetraacetylacetone, titanium diisopropanol acetylacetone, ammonium dilactic acid dihydrogen phosphate, ethyl diacetoacetate diisopropanol titanium, titanium triethanolamine isopropanol, titanium polyhydroxystearate, titanium lactate, titanium triethanolamine, titanium tetrabutyl titanate dimer, titanium magnesium composite catalyst, silicon dioxide. Titanium dioxide complex, antimony trioxide, antimony glycolate, antimony acetate, antimony pentoxide, sodium antimonate, potassium antimonate, germanium dioxide, germanium tetroxide, germanium hydroxide, germanium oxalate, tetraethoxy germanium, tetran-n-butoxy germanium, zirconium oxide, sodium zirconate, tetrabutyl zirconate, tetraethyl zirconate, tetrapropyl zirconate, tetraisopropyl zirconate, aluminum oxide, aluminum alkoxide, aluminum isopropoxide, aluminum trichloride, sodium aluminate, silicon dioxide, tetraethyl silicate, tetrabutyl silicate, silicotungstic acid, silicotungstate. Any one of tungsten trioxide, paratungstic acid, metatungstic acid, tungstic acid, phosphotungstic acid, phosphotungstate, cobalt formate, cobalt acetate, cobalt stearate, cobalt oxalate, cobalt carbonate, cobalt bromide, cobalt oxide, cobalt hydroxide, magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium dimethyl ether, magnesium acetate, magnesium chloride, calcium oxide, calcium hydroxide, calcium carbonate, calcium acetate, calcium dimethyl ether, zinc oxide, zinc acetate, zinc acetylacetonate, alkyl zinc, dialkyl zinc, zinc dimethyl ether, diethyl zinc, and zinc chloride.

6. The total amount of catalyst added as described in claim 3 is 1-20% of the total mass of the raw materials, preferably 2%.

7. The polycondensation reaction temperature as described in claim 3 is 60-340 °C, preferably 180-230 °C. The reaction is carried out under a vacuum of 0.001 MPa to 0.1 MPa, preferably 0.098 MPa. The reaction time is 3-12 h, preferably 4-6 h.

8. The depolymerization reaction temperature as described in claim 3 is 200-300 °C. The reaction occurs at a temperature of 1 × 10⁻⁶ °C. -3 MPa to 1×10 -7 The test is performed under a vacuum of MPa, preferably 1×10 MPa. -6 MPa. The reaction time is 8-24 h, preferably 12 h.

9. The diluent as described in claim 3 may be 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-decyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-dodecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-tetradecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-hexadecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-propyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-butyl-2,3-Dimethylimidazolium bis(fluorosulfonyl)imide salt, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-octyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, 1-octyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide salt, 1-butyl-3-methylimidazolium bis(fluorosulfonyl)imide salt, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-butyl 1-Butyl-3-methylimidazolium trifluoroacetate, 1-Butyl-3-methylimidazolium methanesulfonate, 1-Butyl-3-methylimidazolium p-toluenesulfonate, 1-Butyl-3-methylimidazolium dicyandiamide, 1-Butyl-3-methylimidazolium thiocyanate, 1-Butyl-3-methylimidazolium dicyandiamide, 1-Propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-Pentyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-Heptyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-Nonyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-Undecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-Tetanedecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-Pentadedecyl-3-methylimidazolium Imidazole bis(trifluoromethanesulfonyl)imide salt, 1-benzyl-3-methylimazole bis(trifluoromethanesulfonyl)imide salt, 1-hydroxyethyl-3-methylimazole bis(trifluoromethanesulfonyl)imide salt, 1-methoxyethyl-3-methylimazole bis(trifluoromethanesulfonyl)imide salt, 1-ethoxyethyl-3-methylimazole bis(trifluoromethanesulfonyl)imide salt, N-butyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-hexyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-octyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, tetrabutylammonium chloride, tetrabutylammonium acetate, tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate, tetrabutylammonium bis(trifluoromethanesulfonyl)imide salt, tetrabutylammonium hydroxide, tributylmethylammonium chloride The following are listed: tributylmethylammonium acetate, tributylmethylammonium tetrafluoroborate, tributylmethylammonium bis(trifluoromethanesulfonyl)imide salt, benzyltributylammonium chloride, benzyltributylammonium acetate, tetraethylammonium chloride, tetraethylammonium acetate, tetraethylammonium tetrafluoroborate, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium tetrafluoroborate, tetrabutylphosphonium hexafluorophosphate, tetrabutylphosphonium bis(trifluoromethanesulfonyl)imide salt, tributylmethylphosphonium chloride, tributylmethylphosphonium acetate, tributylmethylphosphonium tetrafluoroborate, tributylethylphosphonium acetate, trihexyltetradecylphosphonium chloride, choline acetate, choline formate, choline propionate, choline butyrate, choline chloride, choline hydroxide, and betaine hydrochloride.

Images