Preparation method of 5-bromo-4, 4, 5, 5-tetrafluoro-1-pentanol

Abstract

The invention relates to a preparation method of 5-bromo-4, 4, 5, 5-tetrafluoro-1-pentanol, and belongs to the technical field of organic chemistry. The preparation method comprises the following steps: under a protective atmosphere, mixing 1, 2-dibromotetrafluoroethane and ethyl allyl ether in tetrahydrofuran, and adding a free radical initiator for reaction; after the reaction is finished, a product is collected, and the 5-bromo-4, 4, 5, 5-tetrafluoro-1-pentanol is obtained. The intermediate subjected to free radical addition is directly reduced and dehalogenated to obtain the product, so that the reaction steps are shortened, the reaction yield is improved, the use amount of the initiator is less, the initiator is easier to treat and easier to carry out amplification transfer, the operation is simpler and more convenient, and the industrial value is higher. And after the initiator and the reducing agent are replaced and optimized by the technology provided by the invention, the operation is simple, and the waste output is greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of organic chemistry, and in particular to a method for preparing 5-bromo-4,4,5,5-tetrafluoro-1-pentanol. Background Art

[0002] Photoresists are light-sensitive films that transfer images to a substrate. They form both negative and positive images. The photoresist is applied to a substrate to form a photoresist layer, which is then exposed to an excitation energy source, such as ultraviolet light, through a patterned photomask to form a latent image in the photoresist layer. The photomask has areas that are opaque to the excitation radiation and areas that are transparent, defining the image that is desired to be transferred to the underlying substrate. The latent image pattern in the resist layer is developed to produce a relief image.

[0003] 5-Bromo-4,4,5,5-tetrafluoro-1-pentanol is a fluorinated fatty alcohol and an important intermediate for the synthesis of photoresists and photoacid generators. Its structural formula is shown below:

[0004]

[0005] JP2022051549 reported that a target product was obtained by reacting allyl alcohol and tetrafluorodibromide through free radical addition, oxidative dehalogenation, and reduction. In the oxidative dehalogenation step, there is a byproduct in which the hydroxyl group is oxidized by the halogen and is not removed, resulting in low product yield and purity. The reaction process is as follows:

[0006]

[0007] It can be seen that the amount of free radical initiator used in the prior art is large, the free radical initiation reaction is not easy to control, the conversion rate and yield are unstable during multi-batch production, which makes it difficult to estimate the output in the later stage. In addition, the prior art has too many unit operations in the R&D and production process, and produces a lot of wastewater and solid waste in the production process. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a method for preparing 5-bromo-4,4,5,5-tetrafluoro-1-pentanol. In THF solvent, 1,2-dibromotetrafluoroethane and ethyl allyl ether are reacted using Cp2TiCl2 / Fe, Cp2TiCl2 / Zn as free radical initiators to generate 5-bromo-4,4,5,5-tetrafluoro-1-pentanol. Directly reducing and dehalogenating the intermediate of free radical addition to obtain the product shortens the reaction steps and improves the reaction yield. The amount of initiator used is less and easier to handle, and it is easier to carry out amplification and transfer, which is simpler to operate and has more industrial value. After replacing and optimizing the initiator and reducing agent through the technology of the present invention, the operation is simple and the waste output is greatly reduced.

[0009] The present invention is achieved through the following technical solutions:

[0010] The object of the present invention is to provide a method for preparing 5-bromo-4,4,5,5-tetrafluoro-1-pentanol, comprising the following steps:

[0011] (1) Under a protective atmosphere, 1,2-dibromotetrafluoroethane and ethyl allyl ether are mixed in tetrahydrofuran, and a free radical initiator is added to react;

[0012] (2) After the reaction is completed, the product is collected to obtain the 5-bromo-4,4,5,5-tetrafluoro-1-pentanol;

[0013] In step (1), the free radical initiator is a mixture of Cp2TiCl2 and metal powder.

[0014] In one embodiment of the present invention, in step (1), the metal powder is iron powder.

[0015] In one embodiment of the present invention, the molar ratio of Cp2TiCl2 to iron powder is 1:10 to 1:30.

[0016] In one embodiment of the present invention, in step (1), the molar ratio of the 1,2-dibromotetrafluoroethane to the Cp2TiCl2 in the free radical initiator is 1:0.02-0.03.

[0017] In one embodiment of the present invention, in step (1), the molar ratio of the 1,2-dibromotetrafluoroethane to the ethyl allyl ether is 1:1-10.

[0018] In one embodiment of the present invention, in step (1), the reaction temperature is 55°C to 65°C.

[0019] In one embodiment of the present invention, the reaction temperature is 58°C to 60°C.

[0020] In one embodiment of the present invention, in step (1), the reaction time is 30 min-4 h.

[0021] In one embodiment of the present invention, in step (1), the mass ratio of 1,2-dibromotetrafluoroethane to tetrahydrofuran is 1:1-50.

[0022] In one embodiment of the present invention, after collecting the product, the process further comprises the step of purifying 5-bromo-4,4,5,5-tetrafluoro-1-pentanol by distillation under reduced pressure.

[0023] In some specific embodiments of the present invention, the scheme comprises the following steps:

[0024] Under nitrogen protection, tetrahydrofuran, 1,2-dibromotetrafluoroethane, ethyl allyl ether, iron powder or zinc powder are added, and the external temperature is heated to 60°C. There is strong reflux in the reactor. When the temperature of the reaction liquid is monitored and slowly rises to 60°C, it is maintained for 30 minutes. The reaction is completed, the reaction liquid is cooled, and 5-bromo-4,4,5,5-tetrafluoro-1-pentanol is obtained by filtration. The crude product solution is concentrated and distilled for purification;

[0025] The above technical solution of the present invention has the following advantages compared with the prior art:

[0026] The invention provides a method for preparing 5-bromo-4,4,5,5-tetrafluoro-1-pentanol. The method adopts industrial raw materials 1,2-dibromotetrafluoroethane and ethyl allyl ether as starting raw materials and uses a relatively safe solvent for reaction to prepare 5-bromo-4,4,5,5-tetrafluoro-1-pentanol. A higher reaction yield and a higher product purity are achieved. The process flow is simple to operate and there are no harsh reaction conditions, so the method is more likely to be used in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0028] Figure 1 It is the H NMR spectrum of the product prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0030] The present invention provides a method for preparing 5-bromo-4,4,5,5-tetrafluoro-1-pentanol. Initiators used in the first step of the reaction include benzoyl peroxide, tert-butyl hydroperoxide, cyclohexanone peroxide, sodium dithionite, azobisisobutyronitrile, cuprous chloride and hydrazine hydrate. It is found that when Cp2TiCl2 / Fe is used to initiate the reaction, all intermediates can be generated, and when other initiators are used, a certain proportion of isomers will be generated.

[0031]

[0032] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods, and the materials, reagents, etc. used are all available from commercial sources unless otherwise specified.

[0033] The CAS numbers of the reagents used in the present invention are shown in the table below:

[0034] Table 1

[0035] Reagent Name CAS 1,2-Dibromotetrafluoroethane 124-73-2 Ethyl Allyl Ether 109-92-2 Titanocene dichloride 1271-19-8 Tetrahydrofuran 109-99-9

[0036] Example 1

[0037] This embodiment provides a method for preparing 5-bromo-4,4,5,5-tetrafluoro-1-pentanol, and the specific method is as follows:

[0038] Under nitrogen protection, 24L of tetrahydrofuran, 6kg of 1,2-dibromotetrafluoroethane, 2.33kg of ethyl allyl ether, 115g of dichlorotantalum, and 388g of iron powder were added to a 50L reactor. The external temperature was raised to 60°C, and a strong reflux reaction was carried out until the internal temperature of the reaction solution reached 58-60°C. The reaction was continued for 30 minutes under insulation. No raw material was left by GC monitoring (the chromatographic column used was DB-1; this detection was a central control detection, and its main purpose was to detect the progress of the reaction). The reaction solution was cooled, filtered through diatomaceous earth, and a crude product of 5-bromo-4,4,5,5-tetrafluoro-1-pentanol was obtained. 3312g of 5-bromo-4,4,5,5-tetrafluoro-1-pentanol was obtained by reduced pressure distillation. The total yield was 60%, and the GC purity was 99.5%.

[0039] The obtained product was characterized by NMR. Figure 1 shown.

[0040] NMR data: 1 H NMR (400MHz, Chloroform-d) δ3.74 (t, J = 6.2 Hz, 2H), 2.22 (tt, J = 18.0, 8.6 Hz, 2H), 1.87 (dq, J = 12.3, 6.3 Hz, 2H).

[0041] Comparative Example 1

[0042] This comparative example provides a method for preparing 5-bromo-4,4,5,5-tetrafluoro-1-pentanol, which is similar to Example 1, except that the added initiator is 115 g of dichlorotantalum and 388 g of zinc powder.

[0043] The total yield was 30% and the GC purity was 98%.

[0044] Comparative Example 2

[0045] This comparative example provides a method for preparing 5-bromo-4,4,5,5-tetrafluoro-1-pentanol, which is similar to Example 1, except that the initiators used are cuprous chloride and hydrazine hydrate.

[0046] The total yield was 19% and the GC purity was 98%.

[0047] Comparative Example 3

[0048] This comparative example provides a method for preparing 5-bromo-4,4,5,5-tetrafluoro-1-pentanol, which is similar to Example 1, except that the initiator used is azobisisobutyronitrile.

[0049] The total yield obtained was 13% and the GC purity was 97%.

[0050] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A method for preparing 5-bromo-4,4,5,5-tetrafluoro-1-pentanol, characterized in that: The following steps are involved: (1) Under a protective atmosphere, 1,2-dibromotetrafluoroethane and ethyl allyl ether are mixed in tetrahydrofuran, and a free radical initiator is added to react; (2) After the reaction is completed, the product is collected to obtain the 5-bromo-4,4,5,5-tetrafluoro-1-pentanol; In step (1), the free radical initiator is a mixture of Cp2TiCl2 and metal powder.

2. The preparation method according to claim 1, characterized in that: In step (1), the metal powder is iron powder.

3. The synthesis method according to claim 2, characterized in that The molar ratio of Cp2TiCl2 to iron powder is 1:10 to 1:

30.

4. The synthesis method according to claim 1, characterized in that In step (1), the molar ratio of the 1,2-dibromotetrafluoroethane to the Cp2TiCl2 in the free radical initiator is 1:0.02-0.

03.

5. The synthesis method according to claim 1, characterized in that In step (1), the molar ratio of the 1,2-dibromotetrafluoroethane to the ethyl allyl ether is 1:1-10.

6. The synthesis method according to claim 1, characterized in that In step (1), the reaction temperature is 55°C to 65°C.

7. The synthesis method according to claim 6, characterized in that The reaction temperature is 58°C to 60°C.

8. The synthesis method according to claim 1, characterized in that In step (1), the reaction time is 30 min-4 h.

9. The synthesis method according to claim 1, characterized in that In step (1), the mass ratio of 1,2-dibromotetrafluoroethane to tetrahydrofuran is 1:1-50.

10. The synthesis method according to claim 1, characterized in that After the product is collected, the method further comprises the step of purifying 5-bromo-4,4,5,5-tetrafluoro-1-pentanol by distillation under reduced pressure.

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