CN112645899A - Green and clean process for continuously synthesizing 2-mercaptobenzothiazole - Google Patents
Green and clean process for continuously synthesizing 2-mercaptobenzothiazole Download PDFInfo
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- CN112645899A CN112645899A CN202011565340.0A CN202011565340A CN112645899A CN 112645899 A CN112645899 A CN 112645899A CN 202011565340 A CN202011565340 A CN 202011565340A CN 112645899 A CN112645899 A CN 112645899A
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D277/00—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings
- C07D277/60—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings condensed with carbocyclic rings or ring systems
- C07D277/62—Benzothiazoles
- C07D277/68—Benzothiazoles with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached in position 2
- C07D277/70—Sulfur atoms
- C07D277/72—2-Mercaptobenzothiazole
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Abstract
The invention belongs to the field of chemistry and chemical engineering, and relates to a green and clean process for continuously synthesizing 2-mercaptobenzothiazole. The process is realized by adopting a continuous reaction system, wherein the continuous reaction system comprises a preheating device, a multistage reaction kettle and a gas-liquid separation tank which are connected in series. The benzothiazole sulfur-dissolving solution is heated by a preheating device through a metering pump, then reacts in a multistage series reaction kettle, finally leaves from the top of the reaction kettle, enters a gas-liquid separation tank, and is separated into tail gas and a liquid 2-mercaptobenzothiazole crude product through phase separation. The benzothiazole sulfur-dissolving solution is a mixed solution obtained by dissolving sulfur in benzothiazole; the number of stages of the reaction kettle is 3-6. According to the invention, the benzothiazole sulfur solution is used as a single feed, the ratio of two raw materials in the solution is stable, the two raw materials are uniformly mixed, the requirement of continuous reaction on the stable conveying of the raw materials is reduced, the requirement of rapid mixing of the materials in the reaction kettle on the stirring strength is reduced, and the production safety risk and the equipment cost are reduced.
Description
Technical Field
The invention belongs to the field of chemistry and chemical engineering, and particularly relates to a green and clean process for continuously synthesizing 2-mercaptobenzothiazole.
Background
The accelerator 2-Mercaptobenzothiazole (MBT) is an important variety in thiazole vulcanization accelerators and is also the high-efficiency accelerator invented at the earliest. The rubber product has the excellent performances of flat vulcanization curve, easy dispersion, no pollution, high tensile strength, high hardness and the like in the aspect of promoting rubber vulcanization. Furthermore, the rubber accelerator can be used as a matrix of a plurality of rubber vulcanizing agents, thiazoles and sulfenamides, and synthetic accelerators MZ, DM, CBS, NS, DZ, TBSI, DIBS and the like can not separate from accelerator MBT. Meanwhile, the accelerator MBT is also widely applied to the fields of flotation agents, metal corrosion inhibitors, chemical plasticizers and the like.
The synthesis method of the 2-mercaptobenzothiazole mainly comprises the following steps: sodium nitrite method, o-nitrochlorobenzene method, aniline method and benzothiazole method. Compared with other methods, the benzothiazole method has low raw material cost and low production safety risk. For example, the Chinese patent application with the publication number of CN106397353A discloses a preparation method of 2-mercaptobenzothiazole, which is characterized in that benzothiazole and sulfur are placed in a reaction kettle, and the following reactions are carried out under the conditions of 200 ℃ and more than 0.3 MPa:
however, the existing technical equipment for synthesizing 2-mercaptobenzothiazole mainly adopts an intermittent high-pressure reaction kettle, and the equipment repeatedly fills materials and raises and lowers temperature in the using process, so that the production efficiency is low and the energy consumption is high. In addition, the concentrations of the materials in the same kettle at different time are different, the concentrations of the benzothiazole and the sulfur are the highest at the beginning, the concentrations of the benzothiazole and the sulfur are gradually reduced along with the progress of the reaction, and the concentration of the 2-mercaptobenzothiazole is gradually increased. In the process, materials cannot be fully mixed by stirring, and the heat exchange of a jacket of the reaction kettle is not timely, so that the radial temperature difference exists, the batch difference of the batch reaction can be caused, and the stability of the product quality is poor. And the use of an intermittent high-pressure reaction kettle also has the defects of high labor intensity, poor operating environment and the like. Therefore, the realization of continuous stable production has great industrial value.
Disclosure of Invention
The invention aims to solve the problems of low production efficiency, high energy consumption and poor stability of product quality in the prior art of producing 2-mercaptobenzothiazole by adopting an intermittent high-pressure reaction kettle, and provides a green and clean process for continuously synthesizing 2-mercaptobenzothiazole.
In order to achieve the purpose, the invention adopts the following technical scheme:
a green and clean process for continuously synthesizing 2-mercaptobenzothiazole is realized by adopting a continuous reaction system, wherein the continuous reaction system comprises a preheating device, a multistage reaction kettle and a gas-liquid separation tank which are connected in series. The preheating device, the multistage reaction kettle connected in series and the gas-liquid separation tank are respectively used for completing the preheating, reaction and phase separation processes of the benzothiazole sulfur solution.
The benzothiazole sulfur-dissolving solution is heated by a preheating device through a metering pump, then reacts in a multistage series reaction kettle, finally leaves from the top of the reaction kettle, enters a gas-liquid separation tank, and is separated into tail gas and a liquid 2-mercaptobenzothiazole crude product through phase separation. The benzothiazole sulfur-dissolving solution is a mixed solution obtained by dissolving sulfur in benzothiazole; the number of stages of the reaction kettle is 3-6, and the benzothiazole sulfur solution enters from the bottom of the reaction kettle and overflows from the top when entering the reaction kettle.
In a further scheme, the feeding temperature of the benzothiazole sulfur solution entering the preheating device is 60-100 ℃, and the molar ratio of benzothiazole to sulfur in the benzothiazole sulfur solution is 1: 1.06-4.22.
In a further aspect, the preheating device is a heat exchanger.
In a further scheme, the preheating temperature range of the benzothiazole sulfur solution is 150-240 ℃.
In a further scheme, the multistage series reaction kettle is formed by serially connecting stirring reaction kettles, the stirring reaction kettles are provided with heat exchange pipelines or jacket heat exchange, and a heating system outside the kettles is one or two of far infrared heating and oil bath heating.
In a further scheme, the reaction temperature in the multistage series reaction kettle is 170-260 ℃, the reaction temperature of each reaction kettle of the multistage series reaction kettle is the same or different, the reaction pressure is 0-5 MPa, and the reaction materials stay in the multistage series reaction kettle for 1-5 hours.
In a further scheme, the temperature in the gas-liquid separation tank is controlled to be 160-230 ℃, and the pressure is 0-5 MPa. The tail gas is treated by alkali absorption to prepare sodium hydrosulfide or by a Claus furnace to recover sulfur. The produced liquid can be purified by an acid-base method or a solvent method.
The invention has the beneficial effects that:
1. the benzothiazole sulfur solution is used as the raw material, the two raw materials in the solution are stable in proportion and uniform in mixing, the raw material feeding can be realized by adopting a common metering pump, and the requirement on equipment is low.
In addition, the invention realizes single feeding of the reaction kettle, reduces the requirement of continuous reaction on stable raw material conveying, and avoids the product quality problem caused by metering fluctuation when two materials are fed.
2. The invention adopts multistage series reaction kettles to realize continuous production, the yield of the product 2-mercaptobenzothiazole is higher than 95 percent, the resin content is lower than 1 percent, and the product is stable.
Drawings
FIG. 1: the invention relates to a reaction system for continuously synthesizing 2-mercaptobenzothiazole.
In the figure: 1-a preheating device, 2-a multistage reaction kettle, a 201 reaction kettle and 3-a gas-liquid separation tank which are connected in series.
Detailed Description
The following examples are intended to illustrate the invention, but are not intended to limit the scope of the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. The test methods in the following examples are conventional methods unless otherwise specified.
The green and clean process for continuously synthesizing 2-mercaptobenzothiazole in the following examples is realized by adopting a continuous reaction system as shown in fig. 1, wherein the continuous reaction system comprises a preheating device 1, a multistage reaction kettle 2 and a gas-liquid separation tank 3 which are connected in series. The preheating device 1, the multistage series reaction kettle 2 and the gas-liquid separation tank 3 are respectively used for completing the preheating, reaction and phase separation processes of the benzothiazole sulfur solution. The preheating device 1 described in the following examples is a heat exchanger.
The procedure for the continuous synthesis of 2-mercaptobenzothiazole is as follows: a metering pump is adopted to continuously and stably convey a benzothiazole sulfur-dissolving solution as a reaction raw material to a heat exchanger for preheating, the reaction process is completed in a multistage series reaction kettle 2, the reaction temperature of each reaction kettle 201 of the multistage series reaction kettle 2 is the same or different, crude 2-mercaptobenzothiazole is obtained after phase separation in a gas-liquid separation tank 3, and the purity of the crude product is measured through liquid chromatography. The crude product is refined through the processes of alkali dissolution, filtration, extraction, neutralization, filtration, drying and the like, the yield is measured through weighing, and the melting point is measured through a melting point instrument.
The benzothiazole sulfur solution is prepared from benzothiazole and sulfur according to a molar ratio of 1: 1.06-4.22, and specifically comprises the following components: heating benzothiazole to 50-100 ℃, adding solid sulfur or liquid sulfur, stirring uniformly, and dissolving to form a uniform solution.
Example 1
The benzothiazole sulfur solution is prepared from benzothiazole and sulfur according to the molar ratio of 1: 1.06.
Preheating benzothiazole sulfur solution to 150 ℃ through a heat exchanger by a metering pump at 60 ℃, and then entering a 5-stage reaction kettle for reaction, wherein the temperature of each reaction kettle in the 5-stage reaction kettle is 170 ℃, 210 ℃, 240 ℃, 230 ℃ and 210 ℃ in sequence, the reaction pressure is 1MPa, and the retention time is 5 hours in total. After the reaction product is subjected to gas-liquid separation of hydrogen sulfide (the temperature of a gas-liquid separation tank is 200 ℃, and the pressure is 0.4MPa), a high-pressure product with the purity of 2-mercaptobenzothiazole of 95.5 percent is obtained, wherein the resin content is 0.92 percent, and a finished product of 2-mercaptobenzothiazole is obtained by alkali dissolution, filtration and drying, and the initial melting point of the finished product of 2-mercaptobenzothiazole is 176.0 ℃.
Example 2
The benzothiazole sulfur solution is prepared from benzothiazole and sulfur according to the molar ratio of 1: 2.20.
Preheating benzothiazole sulfur solution to 220 ℃ through a heat exchanger by a metering pump at 90 ℃, and then entering a 3-stage reaction kettle for reaction, wherein the temperature of each reaction kettle in the 3-stage reaction kettle is 230 ℃, 250 ℃ and 220 ℃ in sequence, the reaction pressure is 3MPa, and the retention time is 1h in total. After the reaction product is subjected to gas-liquid separation of hydrogen sulfide (the temperature of a gas-liquid separation tank is 190 ℃ and the pressure is 2MPa), a high-pressure product with the purity of 2-mercaptobenzothiazole of 97.5 percent is obtained, wherein the resin content is 0.43 percent, and a finished product of 2-mercaptobenzothiazole is obtained by alkali dissolution, filtration and drying, and the initial melting point of the finished product of 2-mercaptobenzothiazole is 177.5 ℃.
Example 3
The benzothiazole sulfur solution is prepared from benzothiazole and sulfur according to the molar ratio of 1: 4.22.
Preheating benzothiazole sulfur solution to 240 ℃ through a heat exchanger by a metering pump at 80 ℃, and then entering a 3-stage reaction kettle for reaction, wherein the temperature of each reaction kettle in the 3-stage reaction kettle is 240 ℃, 260 ℃ and 210 ℃ in sequence, the reaction pressure is 4MPa, and the retention time is 2 hours in total. After the reaction product is subjected to gas-liquid separation of hydrogen sulfide (the temperature of a gas-liquid separation tank is 200 ℃, and the pressure is 3MPa), a high-pressure product with the purity of 2-mercaptobenzothiazole of 96 percent is obtained, wherein the resin content is 0.77 percent, and a finished product of 2-mercaptobenzothiazole is obtained by alkali dissolution, filtration and drying, and the initial melting point of the finished product of 2-mercaptobenzothiazole is 174.0 ℃.
Example 4
The benzothiazole sulfur solution is prepared from benzothiazole and sulfur according to the molar ratio of 1: 3.00.
Preheating benzothiazole sulfur solution to 170 ℃ through a heat exchanger by a metering pump at 70 ℃, and then entering a 6-stage reaction kettle for reaction, wherein the temperature of each reaction kettle in the 6-stage reaction kettle is 170 ℃, 190 ℃, 200 ℃, 210 ℃, 200 ℃ and 180 ℃ in sequence, the reaction pressure is 2MPa, and the retention time is 5 hours. After the hydrogen sulfide is subjected to gas-liquid separation (the temperature of a gas-liquid separation tank is 170 ℃, and the pressure is 1MPa), a high-pressure product with the purity of the 2-mercaptobenzothiazole of 97 percent is obtained, wherein the resin content is 0.55 percent, and the initial melting point of the finished product, namely the 2-mercaptobenzothiazole is 177.0 ℃ after the alkali dissolution, filtration and drying.
Example 5
The benzothiazole sulfur solution is prepared from benzothiazole and sulfur according to the molar ratio of 1: 1.06.
Preheating benzothiazole sulfur solution to 190 ℃ through a heat exchanger by a metering pump at 100 ℃, and then entering a 4-stage reaction kettle for reaction, wherein the temperature of each reaction kettle in the 4-stage reaction kettle is 200 ℃, 230 ℃, 240 ℃ and 210 ℃ in sequence, the reaction pressure is 0.3MPa, and the retention time is 3 hours. After the reaction product is subjected to gas-liquid separation of hydrogen sulfide (the temperature of a gas-liquid separation tank is 200 ℃, and the pressure is 0.1MPa), a high-pressure product with the purity of 2-mercaptobenzothiazole of 95.2 percent is obtained, wherein the resin content is 0.97 percent, and a finished product of 2-mercaptobenzothiazole is obtained by alkali dissolution, filtration and drying, and the initial melting point of the finished product of 2-mercaptobenzothiazole is 175.0 ℃.
Example 6
The benzothiazole sulfur solution is prepared from benzothiazole and sulfur according to the molar ratio of 1: 1.06.
Preheating benzothiazole sulfur solution to 220 ℃ through a heat exchanger by a metering pump at 100 ℃, and then feeding the preheated solution into a 3-stage reaction kettle, wherein the temperature of each reaction kettle in the 3-stage reaction kettle is 240 ℃, 260 ℃ and 250 ℃ in sequence, the reaction pressure is 3MPa, and the retention time is 2 hours. After the reaction product is subjected to gas-liquid separation of hydrogen sulfide (the temperature of a gas-liquid separation tank is 230 ℃, and the pressure is 2MPa), a high-pressure product with the purity of 2-mercaptobenzothiazole of 96 percent is obtained, wherein the resin content is 0.82 percent, and a finished product of 2-mercaptobenzothiazole is obtained by alkali dissolution, filtration and drying, and the initial melting point of the finished product of 2-mercaptobenzothiazole is 176.5 ℃.
Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention. The present invention is capable of other embodiments, and various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention.
Claims (7)
1. A green and clean process for continuously synthesizing 2-mercaptobenzothiazole is characterized in that the process is realized by adopting a continuous reaction system, and the continuous reaction system comprises a preheating device (1), a multistage reaction kettle (2) and a gas-liquid separation tank (3) which are connected in series;
the benzothiazole sulfur-dissolving solution is heated by a preheating device (1) through a metering pump, then reacts in a multistage series reaction kettle (2), finally leaves from the top of the reaction kettle (201), enters a gas-liquid separation tank (3), and the reaction product is separated into tail gas and a liquid 2-mercaptobenzothiazole crude product through phase separation;
the benzothiazole sulfur-dissolving solution is a mixed solution obtained by dissolving sulfur in benzothiazole; the number of stages of the reaction kettle is 3-6.
2. The green and clean process for continuously synthesizing 2-mercaptobenzothiazole according to claim 1, wherein the feeding temperature of the benzothiazole sulfur solution into a preheating device is 60-100 ℃, and the molar ratio of benzothiazole to sulfur in the benzothiazole sulfur solution is 1: 1.06-4.22.
3. The green and clean process for continuously synthesizing 2-mercaptobenzothiazole according to claim 1, wherein the preheating device is a heat exchanger.
4. The green and clean process for continuously synthesizing 2-mercaptobenzothiazole according to claim 1, wherein the preheating temperature of the benzothiazole solution is in the range of 150 ℃ to 240 ℃.
5. The green and clean process for continuously synthesizing 2-mercaptobenzothiazole according to claim 1, wherein the multistage serially connected reaction kettles are serially connected by using stirred reaction kettles, the stirred reaction kettles are provided with heat exchange pipes or jackets for heat exchange, and the heating system outside the kettles is one or both of far infrared heating and oil bath heating.
6. The green and clean process for continuously synthesizing 2-mercaptobenzothiazole according to claim 1, wherein the reaction temperature in the multistage series reaction kettles is 170 ℃ to 260 ℃, the reaction temperature of each reaction kettle of the multistage series reaction kettles is the same or different, the reaction pressure is 0MPa to 5MPa, and the reaction time of the reaction materials in the multistage series reaction kettles is 1 to 5 hours.
7. The green and clean process for continuously synthesizing 2-mercaptobenzothiazole according to claim 1, wherein the temperature in the gas-liquid separation tank is controlled to be 160-230 ℃ and the pressure in the gas-liquid separation tank is 0-5 MPa.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3975394A (en) * | 1974-11-14 | 1976-08-17 | American Cyanamid Company | Process for 2-mercaptobenzothiazole |
| CN106397353A (en) * | 2016-07-22 | 2017-02-15 | 蔚林新材料科技股份有限公司 | A preparing method of a rubber vulcanization accelerator 2-mercaptobenzothiazole |
| CN106432133A (en) * | 2016-09-30 | 2017-02-22 | 王显权 | Preparation method of 2-mercaptobenzothiazole |
| CN107629024A (en) * | 2017-10-13 | 2018-01-26 | 山东尚舜化工有限公司 | A kind of continuous synthesizer of rubber vulcanization accelerator M and its production technology |
| CN109810074A (en) * | 2019-02-19 | 2019-05-28 | 蔚林新材料科技股份有限公司 | A kind of reaction unit of continuous synthesis 2-mercaptobenzothiazole |
-
2020
- 2020-12-25 CN CN202011565340.0A patent/CN112645899A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3975394A (en) * | 1974-11-14 | 1976-08-17 | American Cyanamid Company | Process for 2-mercaptobenzothiazole |
| CN106397353A (en) * | 2016-07-22 | 2017-02-15 | 蔚林新材料科技股份有限公司 | A preparing method of a rubber vulcanization accelerator 2-mercaptobenzothiazole |
| CN106432133A (en) * | 2016-09-30 | 2017-02-22 | 王显权 | Preparation method of 2-mercaptobenzothiazole |
| CN107629024A (en) * | 2017-10-13 | 2018-01-26 | 山东尚舜化工有限公司 | A kind of continuous synthesizer of rubber vulcanization accelerator M and its production technology |
| CN109810074A (en) * | 2019-02-19 | 2019-05-28 | 蔚林新材料科技股份有限公司 | A kind of reaction unit of continuous synthesis 2-mercaptobenzothiazole |
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