Method for improving ortho-nitrochlorobenzene in chlorobenzene nitration process

Abstract

The invention provides a method for improving ortho-nitrochlorobenzene in a chlorobenzene nitration process. The method comprises the following steps: (1) mixing fuming nitric acid and sulfuric acid with the concentration of greater than 90% to obtain a nitrating agent; (2) synchronously inputting anhydrous chlorobenzene and a nitrating agent into a reactor containing sodium sulfite and a metal salt catalyst, and carrying out nitration reaction to obtain a nitrochlorobenzene crude product; and (3) separating the crude nitrochlorobenzene product to obtain an organic phase, and washing the organic phase to obtain nitrochlorobenzene with the ortho-contrast ratio greater than 1.4. According to the present invention, the high-concentration sulfuric acid and the fuming nitric acid are adopted as the efficient nitrating agent, and the synergistic effect of the metal salt catalyst and the sodium sulfite is combined, such that the high-selectivity nitration of the chlorobenzene is achieved, the yield and the purity of the ortho-nitrochlorobenzene are effectively improved, the ortho-contrast is improved, and the product quality is optimized.

Description

Technical Field

[0001] The invention relates to the technical field of aromatic hydrocarbon nitration, in particular to a method for increasing o-nitrochlorobenzene in the process of chlorobenzene nitration. Background Art

[0002] Nitrochlorobenzene is a Chinese medicine intermediate in many fine chemical products such as medicine, agriculture, and dyes. The production of nitrochlorobenzene mainly uses chlorobenzene as raw material, and uses a mixed acid of nitric acid and sulfuric acid as a nitrating agent for nitration. Due to the large radius of the chlorine atom and the short length of the C-Cl bond, the ortho-position steric hindrance is large, and the reaction activation energy is much higher than that of the para-position, which makes the output of p-nitrochlorobenzene in the nitration process of nitric acid or mixed acid much higher than that of o-nitrochlorobenzene.

[0003] In the actual industrial production and sales of nitrochlorobenzene, the market demand and price of para-nitrochlorobenzene and ortho-nitrochlorobenzene are unstable. In order to adapt to the market demand and price, some parameters are optimized on the basis of the existing process to increase the output of ortho-nitrochlorobenzene. Summary of the invention

[0004] 1. Technical issues to be solved

[0005] In view of the shortcomings of the prior art, the present invention provides a method for increasing o-nitrochlorobenzene in the nitration process of chlorobenzene, by adding sodium sulfite and optimizing the nitration conditions, the output of o-nitrochlorobenzene is increased on the basis of the original nitrochlorobenzene production process, thereby solving the problems raised in the above-mentioned background technology.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] According to a first aspect of the present invention, there is provided a method for increasing o-nitrochlorobenzene in a nitration process of chlorobenzene, comprising the following steps:

[0009] (1) mixing fuming nitric acid and sulfuric acid to obtain a nitrating agent, wherein the concentration of the sulfuric acid is greater than 90%;

[0010] (2) simultaneously introducing anhydrous chlorobenzene and a nitrating agent into a reactor containing sodium sulfite and a metal salt catalyst to carry out a nitration reaction to obtain a crude nitrochlorobenzene;

[0011] (3) Separating the crude nitrochlorobenzene to obtain an organic phase, and washing the organic phase to obtain nitrochlorobenzene with a para-ortho ratio of less than 1.4.

[0012] In the present invention, fuming nitric acid and sulfuric acid with a concentration greater than 90% are used as nitrating agents, and sulfuric acid is used as a dehydrating agent, so that the nitrating capacity of nitric acid can be improved, and the dilution of nitric acid by water generated by the reaction can be reduced, thereby improving the utilization rate of nitric acid; sodium sulfite plays a reducing role in the nitrification reaction, can reduce the generation of polynitro substances, and affect the regional selectivity of the digestion reaction; the metal salt catalyst and sodium sulfite are used in combination to increase the yield of o-nitrochlorobenzene.

[0013] Preferably, the amount of sodium sulfite added is 0.3-0.5 wt % of the anhydrous chlorobenzene.

[0014] Optionally, the amount of sodium sulfite added is any value among 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, 0.5wt% of the anhydrous chlorobenzene, or a range value between any two values.

[0015] Further preferably, the amount of sodium sulfite added is 0.3-0.4 wt % of the anhydrous chlorobenzene.

[0016] Preferably, the metal salt catalyst is selected from at least one of Yb(OSO2CF3)3, Lu(OSO2CF3)3, and Hf(OSO2CF3)3.

[0017] Preferably, the added amount of the metal salt catalyst is 8-10 wt % of the anhydrous chlorobenzene.

[0018] Optionally, the added amount of the metal salt catalyst is any value among 8wt%, 9wt%, 10wt% of the anhydrous chlorobenzene, or a range value between any two values.

[0019] Further preferably, the added amount of the metal salt catalyst is 10 to 12 wt % of the anhydrous chlorobenzene.

[0020] Preferably, the dehydration value of the nitrating agent is 2.5 to 3.5.

[0021] Optionally, the DVS of the nitrating agent is selected from any ratio among 2.5, 3.0, 3.5, or a range between any two values.

[0022] Further preferably, the DVS of the nitrating agent is 2.9 to 3.1

[0023] Preferably, the molar ratio of the anhydrous chlorobenzene to the nitrating agent is 1:1.1 to 1.3.

[0024] Preferably, the temperature of the nitration reaction is 80-100° C., and the time of the nitration reaction is 3-8 hours.

[0025] Optionally, the temperature of the nitration reaction is selected from any value of 80°C, 85°C, 90°C, 95°C, 100°C, or a range between any two values. Further preferably, the temperature of the nitration reaction is 85-95°C.

[0026] (III) Beneficial effects

[0027] The invention provides a method for increasing o-nitrochlorobenzene in the process of nitrification of chlorobenzene. High-concentration sulfuric acid and fuming nitric acid are used as efficient nitrating agents, and the synergistic effect of a metal salt catalyst and sodium sulfite is combined to achieve high-selective nitration of p-chlorobenzene, effectively increase the yield and purity of o-nitrochlorobenzene, and at the same time improve the o-to-to-to ratio, optimize the quality of the product, improve the original production process of producing p-nitrochlorobenzene, and flexibly respond to the market demand for p-nitrochlorobenzene and o-nitrochlorobenzene. DETAILED DESCRIPTION

[0028] In order to better illustrate the content of the present invention, a detailed description is given below in conjunction with specific embodiments.

[0029] Example 1

[0030] Step 1, fuming nitric acid and sulfuric acid with a concentration greater than 90% are mixed at a DVS of 2.5 to obtain sufficient nitrating agent;

[0031] Step 2, anhydrous chlorobenzene and a nitrating agent are simultaneously introduced into a reactor containing sodium sulfite and Hf(OSO2CF3)3 catalyst at a molar ratio of 1:1.1, and reacted at 80°C and normal pressure for 8 hours to obtain a crude nitrated chlorobenzene, wherein the amount of sodium sulfite added is 0.3wt% of the anhydrous chlorobenzene, and the amount of Hf(OSO2CF3)3 catalyst added is 10wt% of the anhydrous chlorobenzene;

[0032] Step 3: The crude nitrated chlorobenzene is placed to separate and remove acid, and the remaining organic phase is mixed with hot water, cooled, separated, dried, and crystallized to obtain nitrochlorobenzene. The ortho-to-tolerance ratio in nitrochlorobenzene is 1.55:1 as determined by gas chromatography.

[0033] Example 2

[0034] Step 1, fuming nitric acid and sulfuric acid with a concentration greater than 90% are mixed at a DVS of 3.0 to obtain a sufficient nitrating agent;

[0035] Step 2, anhydrous chlorobenzene and a nitrating agent are simultaneously introduced into a reactor containing sodium sulfite and Yb(OSO2CF3)3 catalyst at a molar ratio of 1:1.2, and reacted at 80°C and normal pressure for 8 hours to obtain a crude nitrated chlorobenzene, wherein the amount of sodium sulfite added is 0.3wt% of the anhydrous chlorobenzene, and the amount of Hf(OSO2CF3)3 catalyst added is 10wt% of the anhydrous chlorobenzene;

[0036] Step 3: The crude nitrated chlorobenzene is placed to stand for separation to remove acid, and the remaining organic phase is mixed with hot water, cooled, separated, dried, and crystallized to obtain nitrochlorobenzene. The ortho-to-pair ratio in nitrochlorobenzene is 1.53:1 as determined by gas chromatography.

[0037] Example 3

[0038] Step 1, mixing fuming nitric acid and sulfuric acid with a concentration greater than 90% at a DVS of 3.5 to obtain sufficient nitrating agent;

[0039] Step 2, anhydrous chlorobenzene and a nitrating agent are simultaneously introduced into a reactor containing sodium sulfite and Yb(OSO2CF3)3 catalyst at a molar ratio of 1:1.3, and reacted at 80°C and normal pressure for 8 hours to obtain a crude nitrated chlorobenzene, wherein the amount of sodium sulfite added is 0.3wt% of the anhydrous chlorobenzene, and the amount of Lu(OSO2CF3)3 catalyst added is 10wt% of the anhydrous chlorobenzene;

[0040] Step 3: The crude nitrated chlorobenzene is placed to separate and remove acid, and the remaining organic phase is mixed with hot water, cooled, separated, dried, and crystallized to obtain nitrochlorobenzene. The ortho-to-pair ratio in nitrochlorobenzene is 1.52:1 as determined by gas chromatography.

[0041] Example 4

[0042] The difference between this embodiment and embodiment 1 is that in step 2, the amount of sodium sulfite added is 0.35wt% of anhydrous chlorobenzene, and the ortho-to-negative ratio in nitrochlorobenzene detected by gas chromatography is 1.51:1.

[0043] Example 5

[0044] The difference between this embodiment and embodiment 1 is that in step 2, the amount of sodium sulfite added is 0.4 wt % of anhydrous chlorobenzene, and the ortho-to-negative ratio in nitrochlorobenzene detected by gas chromatography is 1.49:1.

[0045] Example 6

[0046] The difference between this embodiment and embodiment 1 is that in step 2, the amount of sodium sulfite added is 0.45wt% of anhydrous chlorobenzene, and the ortho-to-dioxin ratio in nitrochlorobenzene detected by gas chromatography is 1.49:1.

[0047] Example 7

[0048] The difference between this embodiment and embodiment 1 is that in step 2, the amount of sodium sulfite added is 0.5wt% of anhydrous chlorobenzene, and the ortho-to-negative ratio in nitrochlorobenzene detected by gas chromatography is 1.48:1.

[0049] Example 8

[0050] The difference between this embodiment and embodiment 1 is that in step 2, the amount of Hf(OSO2CF3)3 catalyst added is 11wt% of anhydrous chlorobenzene, and the ortho-to-negative ratio in nitrochlorobenzene detected by gas chromatography is 1.53:1.

[0051] Example 9

[0052] The difference between this embodiment and embodiment 1 is that in step 2, the amount of Hf(OSO2CF3)3 catalyst added is 12wt% of anhydrous chlorobenzene, and the ortho-to-negative ratio in nitrochlorobenzene detected by gas chromatography is 1.55:1.

[0053] Example 10

[0054] The difference between this embodiment and embodiment 1 is that in step 2, the amount of Hf(OSO2CF3)3 catalyst added is 5wt% of anhydrous chlorobenzene, and the ortho-to-negative ratio in nitrochlorobenzene detected by gas chromatography is 1.77:1.

[0055] Embodiment 11

[0056] The difference between this embodiment and embodiment 1 is that in step 2, the amount of Hf(OSO2CF3)3 catalyst added is 7wt% of anhydrous chlorobenzene, and the ortho-to-phosphorus ratio in nitrochlorobenzene detected by gas chromatography is 1.57:1.

[0057] Example 12

[0058] The difference between this embodiment and embodiment 1 is that in step 2, the amount of Hf(OSO2CF3)3 catalyst added is 9wt% of anhydrous chlorobenzene, and the ortho-to-negative ratio in nitrochlorobenzene detected by gas chromatography is 1.55:1.

[0059] Embodiment 13

[0060] The difference between this embodiment and embodiment 1 is that in step 2, the temperature of the nitration reaction is 85° C., and the ortho-to-ortho ratio in nitrochlorobenzene detected by gas chromatography is 1.49:1.

[0061] Embodiment 14

[0062] The difference between this embodiment and embodiment 1 is that in step 2, the temperature of the nitration reaction is 90° C., and the ortho-to-ortho ratio in nitrochlorobenzene detected by gas chromatography is 1.42:1.

[0063] Embodiment 15

[0064] The difference between this embodiment and embodiment 1 is that in step 2, the temperature of the nitration reaction is 100° C., and the ortho-to-tolerance ratio in nitrochlorobenzene detected by gas chromatography is 1.44:1.

[0065] Comparative Example 1

[0066] Step 1, fuming nitric acid and sulfuric acid with a concentration greater than 90% are mixed at a DVS of 3.0 to obtain a sufficient nitrating agent;

[0067] Step 2, anhydrous chlorobenzene and a nitrating agent are simultaneously introduced into a reactor containing a Yb(OSO2CF3)3 catalyst at a molar ratio of 1:1.2, and reacted at 80°C and normal pressure for 8 hours to obtain a crude nitrated chlorobenzene, wherein the amount of the Hf(OSO2CF3)3 catalyst added is 10wt% of the anhydrous chlorobenzene;

[0068] Step 3: The crude nitrated chlorobenzene is placed to stand for separation to remove acid, the remaining organic phase is mixed with hot water, cooled, separated, dried and crystallized to obtain nitrochlorobenzene, and the ortho-to-nitrochlorobenzene ratio is 1.40:1 as determined by gas chromatography.

[0069] Comparative Example 2

[0070] Step 1, mixing fuming nitric acid and sulfuric acid with a concentration greater than 90% at a DVS of 3.5 to obtain sufficient nitrating agent;

[0071] Step 2, anhydrous chlorobenzene and a nitrating agent are simultaneously introduced into a reactor containing sodium sulfite at a molar ratio of 1:1.2, and reacted at 80° C. and normal pressure for 8 hours to obtain a crude nitrated chlorobenzene, wherein the amount of sodium sulfite added is 0.3 wt% of the anhydrous chlorobenzene;

[0072] Step 3, the crude nitrated chlorobenzene is placed to separate and remove acid, the remaining organic phase is mixed with hot water, cooled, separated, dried and crystallized to obtain nitrochlorobenzene, and the ortho-to-nitrochlorobenzene ratio is 1.42:1 as determined by gas chromatography.

[0073] Comparative Example 3

[0074] The difference between this comparative example and Example 1 is that in step 2, the temperature of the nitration reaction is 70° C., and the reaction is not complete as detected by gas chromatography.

[0075] Comparative Example 4

[0076] The difference between this embodiment and embodiment 1 is that in step 2, the temperature of the nitration reaction is 75° C., and the reaction is not complete as detected by gas chromatography.

[0077] According to the above embodiments, the present invention can significantly improve the yield and purity of o-nitrochlorobenzene through the synergistic effect of the metal salt catalyst and sodium sulfite, and further improve the yield of o-nitrochlorobenzene on the original process of producing p-nitrochlorobenzene by optimizing the relevant parameters in the reaction process.

[0078] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for increasing o-nitrochlorobenzene in the nitration process of chlorobenzene, characterized in that: The following steps are involved: (1) mixing fuming nitric acid and sulfuric acid to obtain a nitrating agent, wherein the concentration of the sulfuric acid is greater than 90%; (2) simultaneously introducing anhydrous chlorobenzene and a nitrating agent into a reactor containing sodium sulfite and a metal salt catalyst to carry out a nitration reaction to obtain a crude nitrochlorobenzene; (3) Separating the crude nitrochlorobenzene to obtain an organic phase, and washing the organic phase to obtain nitrochlorobenzene with a para-ortho ratio of less than 1.

4.

2. The method for increasing o-nitrochlorobenzene in a chlorobenzene nitration process according to claim 1, characterized in that: The amount of sodium sulfite added is 0.3-0.5 wt % of the anhydrous chlorobenzene.

3. The method for increasing o-nitrochlorobenzene in a chlorobenzene nitration process according to claim 2, characterized in that: The amount of sodium sulfite added is 0.3-0.4 wt % of the anhydrous chlorobenzene.

4. The method for increasing o-nitrochlorobenzene in a chlorobenzene nitration process according to claim 1, characterized in that: The metal salt catalyst is selected from at least one of Yb(OSO2CF3)3, Lu(OSO2CF3)3, and Hf(OSO2CF3)3.

5. The method for increasing o-nitrochlorobenzene in a chlorobenzene nitration process according to claim 1, characterized in that: The added amount of the metal salt catalyst is 8-10 wt % of the anhydrous chlorobenzene.

6. The method for increasing o-nitrochlorobenzene in a chlorobenzene nitration process according to claim 1, characterized in that: The dehydration value of the nitrating agent is 2.5 to 3.

5.

7. The method for increasing o-nitrochlorobenzene in a chlorobenzene nitration process according to claim 1, characterized in that: The molar ratio of the anhydrous chlorobenzene to the nitrating agent is 1:1.1-1.

3.

8. The method for increasing o-nitrochlorobenzene in a chlorobenzene nitration process according to claim 1, characterized in that: The temperature of the nitration reaction is 80-100° C., and the time of the nitration reaction is 3-8 hours.