CN113861033A - Process for preparing 1-nitronaphthalene by continuous low-temperature nitration - Google Patents
Process for preparing 1-nitronaphthalene by continuous low-temperature nitration Download PDFInfo
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- 238000006396 nitration reaction Methods 0.000 title claims abstract description 112
- RJKGJBPXVHTNJL-UHFFFAOYSA-N 1-nitronaphthalene Chemical compound C1=CC=C2C([N+](=O)[O-])=CC=CC2=C1 RJKGJBPXVHTNJL-UHFFFAOYSA-N 0.000 title claims abstract description 24
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 19
- 238000005406 washing Methods 0.000 claims abstract description 58
- 239000002253 acid Substances 0.000 claims abstract description 56
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 41
- 239000002699 waste material Substances 0.000 claims abstract description 32
- 238000000034 method Methods 0.000 claims abstract description 26
- 238000000605 extraction Methods 0.000 claims abstract description 16
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 57
- 229910017604 nitric acid Inorganic materials 0.000 claims description 48
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 42
- 238000006243 chemical reaction Methods 0.000 claims description 33
- -1 hydrogen nitrate ions Chemical class 0.000 claims description 30
- 239000002351 wastewater Substances 0.000 claims description 21
- IQUPABOKLQSFBK-UHFFFAOYSA-N 2-nitrophenol Chemical compound OC1=CC=CC=C1[N+]([O-])=O IQUPABOKLQSFBK-UHFFFAOYSA-N 0.000 claims description 19
- UFWIBTONFRDIAS-UHFFFAOYSA-N Naphthalene Chemical compound C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 claims description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 18
- 150000001875 compounds Chemical class 0.000 claims description 17
- 239000000126 substance Substances 0.000 claims description 15
- 230000008569 process Effects 0.000 claims description 13
- 230000003472 neutralizing effect Effects 0.000 claims description 12
- 238000007254 oxidation reaction Methods 0.000 claims description 11
- SCYULBFZEHDVBN-UHFFFAOYSA-N 1,1-Dichloroethane Chemical compound CC(Cl)Cl SCYULBFZEHDVBN-UHFFFAOYSA-N 0.000 claims description 10
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 7
- 230000000802 nitrating effect Effects 0.000 claims description 7
- 229910002651 NO3 Inorganic materials 0.000 claims description 6
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 6
- 230000002378 acidificating effect Effects 0.000 claims description 6
- 150000001768 cations Chemical class 0.000 claims description 6
- 229910052739 hydrogen Inorganic materials 0.000 claims description 6
- 239000001257 hydrogen Substances 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 6
- LQNUZADURLCDLV-UHFFFAOYSA-N nitrobenzene Chemical compound [O-][N+](=O)C1=CC=CC=C1 LQNUZADURLCDLV-UHFFFAOYSA-N 0.000 claims description 6
- 150000004767 nitrides Chemical class 0.000 claims description 4
- 239000003153 chemical reaction reagent Substances 0.000 claims description 3
- 238000000354 decomposition reaction Methods 0.000 claims description 3
- 230000007246 mechanism Effects 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 3
- 239000002904 solvent Substances 0.000 claims description 3
- 230000009286 beneficial effect Effects 0.000 abstract description 3
- ZJYJZEAJZXVAMF-UHFFFAOYSA-N 2-nitronaphthalene Chemical compound C1=CC=CC2=CC([N+](=O)[O-])=CC=C21 ZJYJZEAJZXVAMF-UHFFFAOYSA-N 0.000 description 8
- 230000008859 change Effects 0.000 description 7
- 230000003647 oxidation Effects 0.000 description 7
- 238000007086 side reaction Methods 0.000 description 6
- 230000036632 reaction speed Effects 0.000 description 5
- 239000000047 product Substances 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000376 reactant Substances 0.000 description 3
- SCFXRRMXMMHURF-UHFFFAOYSA-N 2-nitrophenol;sodium Chemical compound [Na].OC1=CC=CC=C1[N+]([O-])=O SCFXRRMXMMHURF-UHFFFAOYSA-N 0.000 description 2
- RXQNKKRGJJRMKD-UHFFFAOYSA-N 5-bromo-2-methylaniline Chemical compound CC1=CC=C(Br)C=C1N RXQNKKRGJJRMKD-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000012074 organic phase Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
- 239000012190 activator Substances 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 150000001491 aromatic compounds Chemical class 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 238000012824 chemical production Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 239000012024 dehydrating agents Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000005060 rubber Substances 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 235000017550 sodium carbonate Nutrition 0.000 description 1
- 235000010344 sodium nitrate Nutrition 0.000 description 1
- 239000004317 sodium nitrate Substances 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- AXKBOWBNOCUNJL-UHFFFAOYSA-M sodium;2-nitrophenolate Chemical compound [Na+].[O-]C1=CC=CC=C1[N+]([O-])=O AXKBOWBNOCUNJL-UHFFFAOYSA-M 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000010189 synthetic method Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C201/00—Preparation of esters of nitric or nitrous acid or of compounds containing nitro or nitroso groups bound to a carbon skeleton
- C07C201/06—Preparation of nitro compounds
- C07C201/08—Preparation of nitro compounds by substitution of hydrogen atoms by nitro groups
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C201/00—Preparation of esters of nitric or nitrous acid or of compounds containing nitro or nitroso groups bound to a carbon skeleton
- C07C201/06—Preparation of nitro compounds
- C07C201/16—Separation; Purification; Stabilisation; Use of additives
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- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a process for preparing 1-nitronaphthalene by continuous low-temperature nitration, which mainly comprises the procedures of nitration, prewashing, neutralization and washing, wherein a nitration device is formed by connecting three nitration kettles, a waste acid extraction kettle, two prewashing kettles, two neutralization kettles and two washing kettles in series, the three nitration kettles comprise a 1# nitration kettle, a 2# nitration kettle and a 3# nitration kettle, the two prewashing kettles comprise a 1# prewashing kettle and a 2# prewashing kettle, the two neutralization kettles comprise a 1# neutralization kettle and a 2# neutralization kettle, and the two washing kettles comprise a 1# washing kettle and a 2# washing kettle. The invention has stable technological parameters, improves and stabilizes the yield and the quality of products, is beneficial to safe production and is easy to realize automatic control.
Description
Technical Field
The invention relates to the technical field of chemical production, in particular to a process for preparing 1-nitronaphthalene by continuous low-temperature nitration.
Background
The aromatic hydrocarbon nitration is a classical organic synthesis reaction, the preparation of the 1-nitronaphthalene can be realized through the nitration reaction of naphthalene, and the 1-nitronaphthalene is an important intermediate for synthesizing medicines, dyes, pesticides, rubber antioxidants and the like and has important and wide application in the chemical industry.
The traditional synthetic method for 1-nitronaphthalene is characterized in that naphthalene is used as a raw material and is prepared by nitration of mixed acid consisting of concentrated nitric acid and concentrated sulfuric acid, meanwhile, 2-nitronaphthalene as a byproduct is obtained, and the synthesis of 1-nitronaphthalene can be divided into an intermittent nitration method and a continuous nitration method according to the production process, and compared with the intermittent nitration method, the continuous nitration method has the advantages that: firstly, the technological parameters such as reaction temperature, feeding amount, reactant concentration and the like are stable and do not change along with the change of time, so that the reaction can be carried out under favorable conditions, and the yield and the quality of products are favorably improved and stabilized; secondly, the process condition change is small, the operation is convenient for workers, the safety production is facilitated, and the automatic control is easy to realize; in contrast, the continuous countercurrent nitration method is more convenient to use the results of automatic control and safety science, and fundamentally eliminates the main factors (unstable factors such as reaction temperature, feeding amount, reactant concentration and the like) of accident formation; if the production enterprises can not meet the requirements temporarily, two or more relative safety measures can be adopted to form an optimal safety combination system, so that the maximum safety production possibility is obtained, and at present, a solvent-free nitration method is adopted for domestic continuous nitration, but 2-nitronaphthalene is produced as a byproduct.
Therefore, the process for preparing the 1-nitronaphthalene by continuous low-temperature nitration is provided for solving the problems.
Disclosure of Invention
The invention aims to solve the problems of unstable process parameters and large process condition change in the prior art, and provides a process for preparing 1-nitronaphthalene by continuous low-temperature nitration.
In order to achieve the purpose, the invention adopts the following technical scheme:
the process for preparing 1-nitronaphthalene by continuous low-temperature nitration mainly comprises the procedures of nitration, prewashing, neutralization and washing, wherein a nitration device is formed by connecting three nitration kettles, a waste acid extraction kettle, two prewashing kettles, two neutralization kettles and two washing kettles in series, three nitration kettles comprise a 1# nitration kettle, a 2# nitration kettle and a 3# nitration kettle, two prewashing kettles comprise a 1# prewashing kettle and a 2# prewashing kettle, two neutralization kettles comprise a 1# neutralization kettle and a 2# neutralization kettle, and two washing kettles comprise a 1# washing kettle and a 2# washing kettle, and the specific steps are as follows:
step 1: nitration
Naphthalene and dichloroethane are respectively added into 95 percent and 5 percent of the total amount of the naphthalene and the dichloroethane from a 1# nitration kettle and an extraction kettle, sulfuric acid and nitric acid are all added from the 1# nitration kettle, nitrified liquid sequentially flows into a 2# nitration kettle and a 3# nitration kettle to carry out three-kettle series kettle type continuous nitration reaction, the nitrified liquid in the 3# nitration kettle is continuously separated to obtain waste acid and acidic nitrate, part of the lower waste acid is recycled to the 1# nitration kettle for adjusting the nitration modulus, the rest waste acid enters a waste acid extraction kettle, the upper acidic nitrate enters the 1# nitration kettle after extraction and separation, the lower waste acid is concentrated, and the concentrated acid is recycled;
step 2: pre-washing
Acid nitrated substance flows into a No. 1 prewashing kettle from a No. 3 nitrating kettle, prewashing water is added from the No. 2 prewashing kettle, the two prewashing kettles are connected in series, the nitrated substance and prewashing wastewater flow in a countercurrent manner, the prewashing wastewater flows into the No. 1 prewashing kettle one by one and then flows into an extraction kettle, nitric acid and sulfuric acid in the acid wastewater are recovered, and the acid nitrating flows into the No. 2 prewashing kettle;
and step 3: neutralization
Acid nitrated compound flows into a No. 1 neutralizing kettle from a No. 2 prewashing kettle, soda solution and washing wastewater are added from the No. 2 neutralizing kettle, the two neutralizing kettles are connected in series, the nitrated compound and the wastewater carry out a neutralization reaction in a counter-current manner, the wastewater flows into the No. 1 neutralizing kettle one by one and flows out of the No. 1 neutralizing kettle, and the nitrated compound flows out of the No. 2 neutralizing kettle;
and 4, step 4: washing machine
The nitrified substance flows into a No. 1 washing kettle from a No. 2 neutralization kettle, washing water is added from the No. 2 washing kettle, the two washing kettles are connected in series, the nitrified substance and the washing water flow in a countercurrent manner to be fully washed, wastewater flows into the No. 1 washing kettle one by one and flows into the No. 2 neutralization kettle from the No. 1 washing kettle, and the nitrified substance qualified for washing flows into a nitronaphthalene transfer tank from the No. 2 washing kettle.
Preferably, the dichloroethane is a solvent, and the mixed acid of the nitric acid and the sulfuric acid is a nitrating reagent.
Preferably, the nitration reaction mechanism: firstly, reacting nitric acid with sulfuric acid to generate hydrogen nitrate ions and negative hydrogen sulfate radicals; decomposition of hydrogen nitrate ions to water and NO2 +A nitroxyl cation; NO2 +Reacting the nitroxyl cation with nitrobenzene to generate a cation complex; then decomposing the cation complex to obtain a nitride and hydrogen ions; the hydrogen ions are combined with hydrogen sulfate radicals to form sulfuric acid; reaction formula is
In the process of simultaneous nitration, the reaction formula is that dinitration is carried out to generate dinitrate compounds and side oxidation reaction is carried out to generate nitrophenol
Compared with the prior art, the invention has the beneficial effects that:
1. the technological parameters such as reaction temperature, feeding amount, reactant concentration and the like are stable and do not change along with the change of time, so that the reaction can be carried out under favorable conditions, and the yield and the quality of the product are favorably improved and stabilized;
2. the process condition change is small, the operation is convenient for workers, the safe production is facilitated, and the automatic control is easy to realize.
The invention has stable technological parameters, improves and stabilizes the yield and the quality of products, is beneficial to safe production and is easy to realize automatic control.
Drawings
FIG. 1 is a flow chart of the process for preparing 1-nitronaphthalene by continuous low-temperature nitration provided by the invention.
Detailed Description
The technical solutions in the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.
In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
Referring to fig. 1, the process for preparing 1-nitronaphthalene by continuous low-temperature nitration mainly comprises the procedures of nitration, prewashing, neutralization and washing, the nitration device is formed by connecting three nitration kettles, a waste acid extraction kettle, two prewashing kettles, two neutralization kettles and two washing kettles in series, the three nitration kettles comprise a 1# nitration kettle, a 2# nitration kettle and a 3# nitration kettle, the two prewashing kettles comprise a 1# prewashing kettle and a 2# prewashing kettle, the two neutralization kettles comprise a 1# neutralization kettle and a 2# neutralization kettle, the two washing kettles comprise a 1# washing kettle and a 2# washing kettle, and the specific steps are as follows:
step 1: nitration
Naphthalene and dichloroethane are respectively added into 95 percent and 5 percent of the total amount of the naphthalene and the dichloroethane from a 1# nitration kettle and an extraction kettle, sulfuric acid and nitric acid are all added from the 1# nitration kettle, nitrified liquid sequentially flows into a 2# nitration kettle and a 3# nitration kettle to carry out three-kettle series kettle type continuous nitration reaction, the nitrified liquid in the 3# nitration kettle is continuously separated to obtain waste acid and acidic nitrate, part of the lower waste acid is recycled to the 1# nitration kettle for adjusting the nitration modulus, the rest waste acid enters a waste acid extraction kettle, the upper acidic nitrate enters the 1# nitration kettle after extraction and separation, the lower waste acid is concentrated, and the concentrated acid is recycled;
step 2: pre-washing
Acid nitrated substance flows into a No. 1 prewashing kettle from a No. 3 nitrating kettle, prewashing water is added from the No. 2 prewashing kettle, the two prewashing kettles are connected in series, the nitrated substance and prewashing wastewater flow in a countercurrent manner, the prewashing wastewater flows into the No. 1 prewashing kettle one by one and then flows into an extraction kettle, nitric acid and sulfuric acid in the acid wastewater are recovered, the acid nitrated substance flows into the No. 2 prewashing kettle, and the prewashing has the functions of washing acid and water-soluble impurities in the nitrated substance with water and reducing the consumption of soda in the neutralization process;
and step 3: neutralization
Acid nitrated compound flows into a 1# neutralization kettle from a 2# prewashing kettle, soda solution and washing wastewater are added from the 2# neutralization kettle, the two neutralization kettles are connected in series, the nitrated compound and the wastewater perform a neutralization reaction in a countercurrent way, the wastewater flows into the 1# neutralization kettle one by one and flows out of the 1# neutralization kettle, and the nitrated compound flows out of the 2# neutralization kettle, wherein the purpose of neutralization is to neutralize acid, more mainly, nitrophenol and soda are reacted to generate nitrophenol sodium salt, and then the nitrophenol sodium salt is dissolved in water and separated from the nitrated compound;
and 4, step 4: washing machine
The method comprises the following steps that a nitrated compound flows into a No. 1 washing kettle from a No. 2 neutralization kettle, washing water is added from the No. 2 washing kettle, the two washing kettles are connected in series, the nitrated compound and the washing water flow in a countercurrent mode to be fully washed, wastewater flows into the No. 1 washing kettle one by one and flows into a No. 2 neutralization kettle from the No. 1 washing kettle, the nitrated compound which is qualified in washing flows into a nitronaphthalene transfer tank from the No. 2 washing kettle, and the purpose of washing after neutralization is to wash out impurities such as sodium carbonate, sodium sulfate, sodium nitrate, sodium nitrophenolate and the like which are remained in the nitrated compound.
In the invention, dichloroethane is used as a solvent, mixed acid of nitric acid and sulfuric acid is used as a nitration reagent, and the nitration reaction mechanism is as follows: firstly, reacting nitric acid with sulfuric acid to generate hydrogen nitrate ions and negative hydrogen sulfate radicals; decomposition of hydrogen nitrate ions to water and NO2 +A nitroxyl cation; NO2 +Reacting the nitroxyl cation with nitrobenzene to generate a cation complex; then decomposing the cation complex to obtain a nitride and hydrogen ions; the hydrogen ions are combined with hydrogen sulfate radicals to form sulfuric acid; reaction formula is
In the process of simultaneous nitration, the reaction formula is that dinitration is carried out to generate dinitrate compounds and side oxidation reaction is carried out to generate nitrophenol
In the invention, the influence of the effective concentration (phi value) of the sulfuric acid on the reaction is as follows:
changing the effective concentration of sulfuric acid (phi value) under the condition of keeping other conditions unchanged, and examining the influence of the effective concentration of sulfuric acid (phi value) on nitration reaction, the results are shown in Table 1
TABLE 1 influence of the effective concentration of sulfuric acid (. phi.) on the nitration reaction
Note: phi is the mass fraction of sulfuric acid in the waste acid/(mass fraction of sulfuric acid in the waste acid + mass fraction of water in the waste acid).
As can be seen from the above table, in the mixed acid, sulfuric acid acts as an activator, which dissociates nitric acid into NO2 +And NO2 +Is the strongest activating nitrating agent; meanwhile, as a strong dehydrating agent, the sulfuric acid can be combined with water generated by nitration reaction to form a hydrate of the sulfuric acid, so that the nitric acid is not diluted by water, even does not contain water, the nitric acid is prevented from acid ionization, and the utilization rate of the nitric acid is improved. Within a certain range, the phi is increased, the conversion rate and the yield are both increased and tend to be stable, and the yield begins to decrease when the phi is continuously increased, because the phi is increased, the dinitration side reaction is caused, but the reaction of the oxidation kettle is reduced, the generation amount of nitrophenol is reduced, and the effective concentration of sulfuric acid (phi) has little influence on the generation ratio of the isomer 2-nitronaphthalene. Therefore, the effective concentration of the sulfuric acid (phi) is properly controlled between 57.5 percent and 58.5 percent by comprehensive consideration.
In the present invention, the effect of modulus on the reaction:
under the condition that other conditions are unchanged, the modulus is changed, the influence of the modulus on the nitration reaction is investigated, and the results are shown in Table 2
TABLE 2 influence of modulus on nitration reactions
| Serial number | Modulus of elasticity | Conversion rate% | Yield% | 1-nitronaphthalene% | 2-nitronaphthalene% | Nitrophenol% |
| 1 | 0.5 | 94.6 | 95.5 | 96.58 | 2.58 | 0.1275 |
| 2 | 1.0 | 96.2 | 97.8 | 96.47 | 2.62 | 0.1123 |
| 3 | 1.5 | 98.5 | 98.4 | 96.55 | 2.53 | 0.1056 |
| 4 | 2.0 | 99.9 | 98.4 | 96.69 | 2.64 | 0.0842 |
| 5 | 2.5 | 100 | 98.2 | 96.70 | 2.68 | 0.0786 |
| 6 | 3.0 | 100 | 98.3 | 96.67 | 2.57 | 0.0781 |
| 7 | 3.5 | 100 | 98.1 | 96.59 | 2.62 | 0.0785 |
| 8 | 4.0 | 99.8 | 97.6 | 96.62 | 2.65 | 0.0863 |
| 9 | 4.5 | 99.7 | 97.4 | 96.63 | 2.59 | 0.0946 |
As can be seen from the above table, in the course of nitration reaction, the modulus increases, the reaction rate increases, and the oxidation side reaction decreases. The difference of the distribution coefficients of the nitric acid in the waste acid and the organic phase is large, so that the nitric acid is used for nitration in the waste acid and oxidation in the nitride, the waste acid in the nitration kettle is increased, and the organic phase is reduced. Within a certain range, the modulus is increased, the conversion rate and the yield are both increased, the oxidation side reaction is reduced, the generated amount of nitrophenol is reduced, but the modulus is too large, the conversion rate and the yield are both correspondingly reduced, the oxidation side reaction is increased, the generated amount of nitrophenol is increased, and the equipment productivity is reduced. The data in Table 2 show that the suitable modulus of the nitration reaction is 2.5-3.5.
In the present invention, the effect of the reaction temperature on the reaction:
under the condition that other conditions are not changed, the reaction temperature is changed, the influence of the reaction temperature on the nitration reaction is examined, and the results are shown in Table 3
TABLE 3 influence of the reaction temperature on the nitration reaction
| Serial number | Temperature/. degree.C | Conversion rate/% | Yield/% | 1-nitronaphthalene/%) | 2-nitronaphthalene/%) | Nitrophenol/%) |
| 1 | 0 | 98.2 | 96.4 | 96.75 | 2.38 | 0.0784 |
| 2 | 5 | 98.4 | 97.1 | 96.72 | 2.40 | 0.0796 |
| 3 | 10 | 99.8 | 97.9 | 96.65 | 2.58 | 0.0878 |
| 4 | 15 | 100 | 98.4 | 96.69 | 2.64 | 0.0895 |
| 5 | 20 | 100 | 98.2 | 96.62 | 2.68 | 0.0898 |
| 6 | 25 | 100 | 97.6 | 96.46 | 2.93 | 0.0945 |
| 7 | 30 | 100 | 96.8 | 96.31 | 3.26 | 0.1035 |
| 8 | 35 | 100 | 95.5 | 95.64 | 3.85 | 0.1140 |
| 9 | 40 | 100 | 94.7 | 94.37 | 4.26 | 0.1269 |
The nitration reaction is a strong exothermic reaction, the reaction speed is accelerated due to the temperature rise, the temperature is further increased due to the speed, a dinitro compound is generated, the content can reach 2.5-3.5% by mass, and meanwhile, the combustion and explosion are easily caused by high temperature, so the temperature needs to be controlled in the nitration process. When the nitration reaction speed is increased by 10 ℃, the reaction speed is increased by 2.2 times, the oxidation side reaction is increased by 4 times, the generation amount of nitrophenol is correspondingly increased, and the generation amount of 2-nitronaphthalene is obviously increased. The data in Table 3 show that the suitable temperature for the nitration reaction is controlled to be 15-20 ℃.
In the invention, the influence of the nitric acid content in the waste acid on the reaction is as follows:
under the condition that other conditions are not changed, the content of nitric acid in the waste acid is changed, the influence of the content of nitric acid in the waste acid on the nitration reaction is examined, and the result is shown in Table 4
TABLE 4 influence of nitric acid content in the spent acid on the nitration reaction
| Serial number | Content of nitric acid/%) | Conversion rate/% | Yield/% | 1-nitronaphthalene/%) | 2-nitronaphthalene/%) | Nitrophenol/%) |
| 1 | 1.15 | 99.5 | 96.1 | 96.42 | 2.61 | 0.1523 |
| 2 | 1.25 | 99.8 | 97.3 | 96.51 | 2.66 | 0.1442 |
| 3 | 1.35 | 100 | 98.6 | 96.51 | 2.73 | 0.1305 |
| 4 | 1.45 | 100 | 98.0 | 96.58 | 2.61 | 0.980 |
| 5 | 1.55 | 100 | 98.5 | 96.74 | 2.58 | 0.862 |
| 6 | 1.65 | 100 | 98.2 | 96.69 | 2.59 | 0.861 |
| 7 | 1.75 | 100 | 98.7 | 96.62 | 2.64 | 0.857 |
| 8 | 1.85 | 100 | 98.2 | 96.72 | 2.63 | 0.858 |
| 9 | 1.95 | 100 | 98.1 | 96.65 | 2.61 | 0.849 |
The content of nitric acid is increased, the nitration reaction is facilitated, and the side oxidation reaction is inhibited. According to the reaction principle, the content of nitric acid in the waste acid is increased, the concentration of nitroxyl cation is increased, the oxidation side reaction speed is reduced, the nitration reaction speed is increased, if the content of nitric acid in the waste acid is increased, the nitric acid which is lost along with the waste acid is increased, and the consumption of nitric acid is increased.
In the present invention, the effect of nitric acid ratio on the reaction:
under the condition that other conditions are not changed, the nitric acid ratio is changed, the influence of the nitric acid ratio on the nitration reaction is investigated, and the results are shown in Table 5
TABLE 5 influence of nitric acid ratio on nitration reactions
| Serial number | Nitric acid ratio | Conversion rate/% | Yield/% | 1-nitronaphthalene/%) | 2-nitronaphthalene/%) | Nitrophenol/%) |
| 1 | 0.90 | 78.5 | 83.2 | 96.35 | 2.41 | 0.1424 |
| 2 | 0.95 | 99.8 | 97.3 | 96.47 | 2.53 | 0.1352 |
| 3 | 1.00 | 100 | 98.2 | 96.59 | 2.81 | 0.1084 |
| 4 | 1.05 | 100 | 98.4 | 96.48 | 2.69 | 0.8532 |
| 5 | 1.10 | 100 | 98.5 | 96.68 | 2.49 | 0.7528 |
| 6 | 1.15 | 100 | 98.2 | 96.61 | 2.62 | 0.9450 |
| 7 | 1.20 | 100 | 98.0 | 96.65 | 2.59 | 0.1165 |
| 8 | 1.25 | 100 | 97.8 | 96.60 | 2.77 | 0.1336 |
| 9 | 1.30 | 100 | 97.5 | 96.48 | 2.59 | 0.1542 |
When the nitric acid is less than the theoretical amount in the nitration process of the aromatic compound, the amount of nitrophenol is large, but when the nitric acid is more than the theoretical amount, the amount of nitrophenol generated is increased. When nitric acid is less than the theoretical amount, nitrophenol is increased due to the presence of nitrosylsulfuric acid in the latter part of the reaction. While nitrophenol is generated, nitrosyl ions are generated in an equal molar quantity, and when the generated nitrosyl ions are quickly combined into nitrosyl sulfuric acid, the nitrophenol is generated. However, when the amount of nitric acid exceeds a certain amount, the amount of nitrophenol increases. In this case, the nitrophenol is formed as a product of the autonitration of excess nitroxyl cation. The data in Table 5 show that the ratio of nitric acid suitable for the nitration reaction is 1.05-1.10: 1.
In summary, naphthalene, sulfuric acid, nitric acid and dichloroethane are used as raw materials to carry out low-temperature continuous nitration to produce 1-nitronaphthalene, and the suitable process conditions are as follows: the effective concentration (phi value) of the sulfuric acid is 57.5 to 58.5 percent; the modulus is 2.5-3.5; the reaction temperature is 15-20 ℃, and the nitric acid content in the waste acid is 1.55-1.65%; the nitric acid ratio is 1.05-1.10: 1.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (3)
1. The process for preparing 1-nitronaphthalene by continuous low-temperature nitration is characterized by mainly comprising the procedures of nitration, prewashing, neutralization and washing, wherein a nitration device is formed by connecting three nitration kettles, a waste acid extraction kettle, two prewashing kettles, two neutralization kettles and two washing kettles in series, three nitration kettles comprise a 1# nitration kettle, a 2# nitration kettle and a 3# nitration kettle, two prewashing kettles comprise a 1# prewashing kettle and a 2# prewashing kettle, two neutralization kettles comprise a 1# neutralization kettle and a 2# neutralization kettle, and two washing kettles comprise a 1# washing kettle and a 2# washing kettle, and the specific steps are as follows:
step 1: nitration
Naphthalene and dichloroethane are respectively added into 95 percent and 5 percent of the total amount of the naphthalene and the dichloroethane from a 1# nitration kettle and an extraction kettle, sulfuric acid and nitric acid are all added from the 1# nitration kettle, nitrified liquid sequentially flows into a 2# nitration kettle and a 3# nitration kettle to carry out three-kettle series kettle type continuous nitration reaction, the nitrified liquid in the 3# nitration kettle is continuously separated to obtain waste acid and acidic nitrate, part of the lower waste acid is recycled to the 1# nitration kettle for adjusting the nitration modulus, the rest waste acid enters a waste acid extraction kettle, the upper acidic nitrate enters the 1# nitration kettle after extraction and separation, the lower waste acid is concentrated, and the concentrated acid is recycled;
step 2: pre-washing
Acid nitrated substance flows into a No. 1 prewashing kettle from a No. 3 nitrating kettle, prewashing water is added from the No. 2 prewashing kettle, the two prewashing kettles are connected in series, the nitrated substance and prewashing wastewater flow in a countercurrent manner, the prewashing wastewater flows into the No. 1 prewashing kettle one by one and then flows into an extraction kettle, nitric acid and sulfuric acid in the acid wastewater are recovered, and the acid nitrating flows into the No. 2 prewashing kettle;
and step 3: neutralization
Acid nitrated compound flows into a No. 1 neutralizing kettle from a No. 2 prewashing kettle, soda solution and washing wastewater are added from the No. 2 neutralizing kettle, the two neutralizing kettles are connected in series, the nitrated compound and the wastewater carry out a neutralization reaction in a counter-current manner, the wastewater flows into the No. 1 neutralizing kettle one by one and flows out of the No. 1 neutralizing kettle, and the nitrated compound flows out of the No. 2 neutralizing kettle;
and 4, step 4: washing machine
The nitrified substance flows into a No. 1 washing kettle from a No. 2 neutralization kettle, washing water is added from the No. 2 washing kettle, the two washing kettles are connected in series, the nitrified substance and the washing water flow in a countercurrent manner to be fully washed, wastewater flows into the No. 1 washing kettle one by one and flows into the No. 2 neutralization kettle from the No. 1 washing kettle, and the nitrified substance qualified for washing flows into a nitronaphthalene transfer tank from the No. 2 washing kettle.
2. The process for preparing 1-nitronaphthalene by continuous low-temperature nitration according to claim 1, wherein dichloroethane is used as a solvent, and the mixed acid of nitric acid and sulfuric acid is used as a nitration reagent.
3. The process for preparing 1-nitronaphthalene by continuous low-temperature nitration according to claim 1, wherein the nitration reaction mechanism is as follows: firstly, reacting nitric acid with sulfuric acid to generate hydrogen nitrate ions and negative hydrogen sulfate radicals; decomposition of hydrogen nitrate ions to water and NO2 +A nitroxyl cation; NO2 +Reacting the nitroxyl cation with nitrobenzene to generate a cation complex; then decomposing the cation complex to obtain a nitride and hydrogen ions; the hydrogen ions are combined with hydrogen sulfate radicals to form sulfuric acid; reaction formula is
In the process of simultaneous nitration, the reaction formula is that dinitration is carried out to generate dinitrate compounds and side oxidation reaction is carried out to generate nitrophenol
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