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Chemical Industry Standard of the People's Republic of China
HG2025—91
p-Nitrotoluene
Published on June 27, 1991
Ministry of Chemical Industry of the People's Republic of China
Implemented on March 1, 1992
Chemical Industry Standard of the People's Republic of China
p-Nitrotoluene
Subject Content and Scope of Application
HG2025—91
This standard specifies the technical requirements, test methods, inspection rules, and marking, packaging, storage and transportation requirements for p-nitrotoluene. This standard applies to p-nitrotoluene obtained by separation and crystallization of mixed nitrotoluene after nitration of toluene. p-Nitrotoluene is mainly used as a dye intermediate.
Structural formula:
Empirical formula: C,HNO2
Relative molecular mass: 137.14 (according to the international relative atomic mass in 1987)2
Cited standards
GB190 Dangerous goods packaging mark
GB9722 Chemical reagents - General rules for gas chromatography 3 Technical requirements
Para-nitrotoluene shall comply with the requirements of Table 1.
Indicator name
Freezing point (thousand samples), ℃
p-Nitrotoluene content, %(m/m)
o-Nitrotoluene content, %(m/m)
Impurity content
Moisture, %(m/m)
m-Nitrotoluene content, %(m/m)
Low-boiling-point substance content, %(m/m)
High-boiling-point substance content, %(m/m)
Note: Moisture, low-boiling-point substance and high-boiling-point substance are type inspection items. Test method
Approved by the Ministry of Chemical Industry of the People's Republic of China on 1991-06-27>
Superior grade
Light yellow solid
First grade
Qualified grade
Light yellow to light brown solid
Implemented on 1992-03-01
4.1 Determination of appearance
Determination shall be made by visual method.
4.2 Determination of freezing point (dry product)
4.2.1 Apparatus
Freezing point tester (Figure 1);
Product tube: outer diameter about 25mm, length about 150mm; outer sleeve: inner diameter about 28mm, length about 120mm; HG2025--91
Thermometer: a short-rod partial immersion or full immersion thermometer with a graduation value of 0.1℃ and calibrated, about 300mm long, temperature range 45～60℃.
4.2.2 Desiccant
4A or 5A spherical molecular sieve, roasted at 550℃ for 3h, placed in a desiccator for use. Figure 1 Freezing point determination apparatus
1—Thermometer, 2—Sample tube, 3—Shell
4.2.3 Determination steps
Weigh 50g of p-nitrotoluene sample and 20g of 4A or 5A molecular sieve into a 250mL wide-mouth bottle with a ground-mouth stopper, cover the bottle stopper tightly and place it in a constant temperature box at 80℃ to melt. Shake the sample bottle several times during the melting process. After the sample is melted, continue to keep warm for 10 minutes, take it out, and pour the molten material into the preheated crystallization tube with an outer sleeve. The sample height is about 60mm. Use a thermometer to stir at a speed of about 2 times per second to avoid the thermometer hitting the wall. At the same time, carefully observe the gradually cooling p-nitrotoluene sample. When the first crystallization is found (that is, the liquid begins to become turbid), continue stirring until the crystallization is uniform (at this time, the thermometer should be vertical to the sample, and keep the bottom of the mercury ball about 15mm away from the bottom of the crystallization tube). When the temperature rises to the highest point and stays at this temperature for a period of time without rising, this temperature is the freezing point of p-nitrotoluene. If a full immersion thermometer is used, the freezing point t is corrected according to formula (1): t-ti+At..
At=0.00016h(ti-t2)
wherein t is the observed freezing point, °C;
t2 is the ambient air temperature at the middle of the mercury column outside the Great Wall (measured by an auxiliary thermometer, the mercury ball of the auxiliary thermometer should be located in the middle of the mercury column outside the Great Wall), °C;
h is the height of the mercury column outside the Great Wall (expressed in thermometer scale); 0.00016 is the expansion coefficient of mercury in glass. 2
HG2025-91
The difference between the two measurement results should not be greater than 0.1 °C, and the arithmetic mean is taken as the freezing point of the sample. 4.3 Determination of p-nitrotoluene, o-nitrotoluene, m-nitrotoluene, low-boiling substances and high-boiling substances 4.3.1 Instruments
Gas chromatograph: should comply with the provisions of GB9722-88; Detector: hydrogen flame ionization detector; Recorder: full scale 10mV, response time 1s or data processor with this function; Chromatographic column: one stainless steel spiral column with diameter (g) 4mm, length (L) 2m and one stainless steel spiral column with diameter (g) 4mm, length (L) 0.5m; Micro syringe: 10uL.
4.3.2 Preparation of chromatographic column
4.3.2.1 Filler
Stationary liquid: polyethylene glycol adipate (PEGA); Carrier: 101 white carrier 180~250μm (60~80 mesh); Liquid phase loading: 3/100.
4.3.2.2 Stationary liquid coating
Weigh 0.42g of stationary liquid (PEGA) into a 250mL beaker, add chloroform reagent equivalent to 14g of support volume, dissolve the stationary liquid under infrared lamp, slowly pour 14g of dried support into the beaker, place the beaker in a desiccator, keep it at a vacuum of about 7.99×10'Pa for 5-10min, take it out and place it in a fume hood, slowly evaporate the solvent to dryness under infrared lamp (pat the beaker frequently) to make it evenly coated. 4.3.2.3 Filling method
Plug the detector end of the chromatographic column with a copper mesh, connect it to a vacuum pump, and connect the other end to a funnel. Slowly pour the stationary phase under a vacuum of about 7.99×10°Pa, and tap the chromatographic column until the stationary phase is no longer drawn into the column. Remove the chromatographic column and take out the copper mesh, add some stationary phase, plug the two ends of the chromatographic column with glass wool, and prepare for aging.
4.3.2.4 Chromatographic column aging
Put the filled chromatographic column into the chromatographic column box, pass nitrogen (flow rate is 5-20mL/min) and age it at 145℃ for 8h. 4.3.3 Chromatographic instrument operating conditions
Select the chromatographic operating conditions according to different instruments. Taking SP2305E gas chromatograph as an example, the operating conditions are as follows: 4.3.3.1 Chromatographic operating conditions for p-nitrotoluene, o-nitrotoluene, m-nitrotoluene and low-boiling substances: Column box temperature: 1052℃ (indicated on the meter); Detector temperature: 200~220℃;
Vaporization chamber temperature: 280~300℃;
Carrier gas (N2) flow rate: 30mL/min;
Gas gas (H2) flow rate: 30mL/min;
Air flow rate: 300~400mL/min;
Amplifier sensitivity: 2×1;
Injection volume: 0.4uL.
4.3.3.2 Chromatographic operating conditions for high boiling substances
Column box temperature: 140±2℃ (indicated by the meter); injection volume: luL;
Other chromatographic operating conditions are the same as those in 4.3.3.1.
4.3.4 Preparation of standard solution and determination of relative correction factor 4.3.4.1 Reagents
Toluene (GB684)
Nitrobenzene (HG3-963);
O-nitrotoluene: chemically pure;
M-nitrotoluene: chemically pure;
P-nitrotoluene: refined product;
f.2,4-dinitrotoluene: chemically pure;
gChloroform (GB682).
HG2025-91
4.3.4.2 Preparation of calibration solutions of o-nitrotoluene, m-nitrotoluene and p-nitrotoluene Weigh about 0.07 g (accurate to 0.0002 g) of m-nitrotoluene (4.3.4.1d) and o-nitrotoluene (4.3.4.1e) respectively into two 25 mL volumetric flasks, and dilute to the mark with chloroform (4.3.4.1g). Weigh 6 portions of 0.5000 g of p-nitrotoluene (4.3.4.1e) (accurate to 0.0002 g), and place them in 6 numbered 10 mL volumetric flasks, and mix the above solutions according to Table 2 to obtain calibration mixed solutions No. 1, No. 2, No. 3, No. 4, No. 5, and No. 6. Preparation table of calibration mixed solution
Volume flask number
Amount of solution added, mL
Single standard solution
m-nitrotoluene
o-nitrotoluene
Total volume after dilution with chloroform, mL
Note: p-nitrotoluene should be a pure product obtained through multiple distillations, or p-nitrotoluene after the impurity component content is accurately quantified using the external standard method, and its impurities are calculated into the standard solution.
4.3.4.3 Determination of relative correction factor
After the instrument's operating conditions are stable, take 0.4uL of calibration mixed solution No. 1, 2, 3, 4, 5, and 6 respectively, and inject them into the chromatograph's vaporization chamber. After the peak is completely discharged, accurately measure the peak height of each component. The relative correction factor f of each component is calculated according to formula (2): m.ho
wherein: m is the mass of a certain component, g;
h; the peak height of a certain component, mm;
mo is the mass of p-nitrotoluene, g;
ho is the peak height of p-nitrotoluene, mm.
Note: The relative correction factor of each component is recalibrated once a week, and the validity period of the standard solution is 1 month. 4.3.4.4 Preparation of low-boiling standard solution
Use a microsyringe to draw 10uL of toluene (4.3.4.1a) and nitrobenzene (4.3.4.1b) respectively, and then add them to a 10mL volumetric flask, dilute to the mark with pure o-nitrotoluene, and then calculate the percentage of toluene and nitrobenzene in the standard solution according to the mass of toluene and nitrobenzene.
4.3.4.5 Preparation of high-boiling standard solution
Weigh about 0.5g (accurate to 0.0002g) of 2,4-dinitrotoluene (4.3.4.1f), put it in a 25mL volumetric flask, and dilute to the mark with o-nitrotoluene (4.3.4.1c).
Take 0.2, 0.5, and 1.0 mL of the above solution into three 10 mL volumetric flasks, and dilute to the mark with o-nitrotoluene (4.3.4.1c). Then calculate the percentage of 2,4-dinitrotoluene in the standard solution according to the mass of 2,4-dinitrotoluene. 4.3.5 Determination steps
4.3.5.1 Determination of p-nitrotoluene, o-nitrotoluene, and m-nitrotoluene content Weigh 0.5 g of p-nitrotoluene sample (accurate to 0.1 g) into a 10 mL volumetric flask, dissolve it with chloroform (4.3.4.1 g), dilute to the mark, and shake well. After the operating conditions of the chromatograph are stable, draw 0.4 uL of the sample solution and inject it into the vaporization chamber of the chromatograph. After the peaks are completely emitted, accurately measure the peak height of each component (see Figure 2 for the chromatogram). 4
The percentage content X of each component is calculated according to formula (3): HG2025-91
×(100-X1-X2X)
Wherein: \Signal attenuation of a certain component;
fRelative correction factor of a certain component;
h;-Peak height of a certain component, mm;
Xi——water content, %;
X2—low boiling matter content, %;
X8—high boiling matter content, %;
The difference between two parallel determination results of p-nitrotoluene content shall not be greater than 0.2%. The difference between two parallel determination results of o-nitrotoluene and m-nitrotoluene content shall not be greater than 0.07% respectively. 6
Figure 2 Spectrum of p-nitrotoluene
1 Solvent: 2 o-nitrotoluene: 3 m-nitrotoluene: 4 p-nitrotoluene 4.3.5.2 Determination of low boiling point content
After the chromatographic conditions of 4.3.3.1 are stable, draw 0.4uL of low boiling point standard solution and inject it into the gasification chamber of the chromatograph. After the peak is completely discharged, accurately measure the peak height of each low boiling point component. Then use a preheated micro syringe to draw 0.4uL of melted p-nitrotoluene sample and quickly inject it into the gasification chamber of the chromatograph. After the peak is completely discharged, accurately measure the peak height of each low boiling point component. Use the external standard method for quantification (see Figure 3 for the chromatogram). The percentage of low boiling point content: Area 2 is calculated according to formula (4): C.·h
Where: C. - Content of a low boiling point component in the standard solution, %; h; Peak height of a low boiling point component in the sample, mm; h Peak height of a low boiling point component in the standard solution, mm. (4)
HG2025--91
Figure 3 Spectrum of low-boiling substances in p-nitrotoluene
1 Toluene; 2 Nitrobenzene; 3 Ortho-nitrotoluene; 4 Meta-nitrotoluene; 5 p-nitrotoluene 4.3.5.3 Determination of high-boiling substances
Weigh about 0.5g of p-nitrotoluene sample (accurate to 0.0002g) in a 10mL volumetric flask, dissolve it with chloroform (GB682) and dilute to the scale. Calculate the percentage concentration Cp of the sample. The determination of high-boiling substances is carried out on another 0.5m short column. After the operating conditions of the instrument are stable, take 1uL of the standard solution with the same dinitro content as the sample and inject it into the gasification chamber of the chromatograph. After the peak is completely discharged, accurately measure the peak height. Then take 1uL of the p-nitrotoluene sample solution and inject it into the gasification chamber of the chromatograph. After the peak is completely discharged, accurately measure the peak height. Quantitative analysis by external standard method (chromatogram shown in Figure 4). High boiling point percentage X: calculated according to formula (5): C,·ho
Wherein: C—the content of 2,4-dinitrotoluene in the standard sample, %; ho——the peak height of 2,4-dinitrotoluene in the sample, mm; h,——the peak height of 2,4-dinitrotoluene in the standard sample, mm; p-nitrotoluene sample concentration in chloroform, %. Cp
Figure 4 Spectrum of dinitro in nitrotoluene
1—nitrotoluene; 2—2,4-dinitrotoluene 6
4.4 Determination of water content
4.4.1 InstrumentbzxZ.net
HG2025--91
KF-1 micro-water analyzer (equipped with 5mL micro-burette); micro-syringe: 10uL.
4.4.2 Reagents
Methanol (GB683);
Pyridine (GB689);
Iodine (GB675);
Anhydrous sodium sulfite (HG3-1078): chemically pure; d.
Sulfuric acid (GB625): chemically pure;
Anhydrous sodium acetate (GB694);
Anhydrous sodium iodide: dry the sodium iodide at 120℃ and store it in a sealed bottle; g.
Sulfur dioxide: sulfur dioxide in a cylinder or obtained by decomposing sodium sulfite with concentrated sulfuric acid. 4.4.3 Preparation and calibration of Karl Fischer reagent (or improved reagent) 4.4.3.1 Preparation of Karl Fischer reagent
Put 85g iodine (4.4.2c) in a dry, 1L, stoppered brown narrow-necked bottle, add 670mL methanol (4.4.2a), plug the bottle, and shake until the iodine is completely dissolved. Then add 270mL pyridine (4.4.26) and shake until the mixture is hooked. According to the connection in Figure 5, pass about 65g sulfur dioxide gas into the solution (a little excess sulfur dioxide will not be a problem). When passing sulfur dioxide, cool it in an ice-water bath to ensure that the solution temperature does not exceed 20℃. Place the solution in a dark place for at least 24h before use. 4.4.3.2 Preparation of Karl Fischer modified reagent Place 63g iodine (4.4.2c) in a dry, 1L brown narrow-necked bottle with a stopper, add 600mL methanol (4.4.2a), then add 25g anhydrous sodium iodide and 85g anhydrous sodium acetate (4.4.2f), plug the bottle, and shake until the iodine and other ingredients are completely dissolved (liquid A). According to Figure 5, pass sulfur dioxide into a stoppered bottle containing no less than 90mL methanol and cooled in an ice-water bath to make the sulfur dioxide concentration c(SO2) = 4mol/L (256g/L) (liquid B). Add 90mL of liquid B (containing 23g sulfur dioxide), or directly pass dry sulfur dioxide gas into liquid A, and then dilute with methanol to 1L and mix. Place in a dark place for later use.
Figure 5 Karl Fischer reagent preparation device
1-sulfur dioxide gas generator, 2-concentrated sulfuric acid filter, 3-separator: 4-absorption bottle containing iodine pyridine solution, 5-ice bath 4.4.3.3 Calibration of the titer of Karl Fischer reagent (or improved reagent) Use 10uL, micro syringe to absorb 5uL of water, weigh its mass (accurate to 0.0002g), repeat 2 times, and take the arithmetic mean as the mass of 5uL water.
Put 25mL of chloroform-methanol (3+1) mixed solvent in the reactor, cover the bottle stopper, connect the power supply, start the electromagnetic stirrer, and use Karl Fischer reagent (or improved reagent) to titrate the water in the solvent until the ammeter pointer produces a large deflection and remains unchanged for 1min as the end point (do not record the volume of the reagent consumed).
HG2025—91
Use a 10uL microsyringe to inject 5uL of water into the reactor, cover the bottle stopper, and continue to titrate with Karl Fischer reagent (or improved reagent) until the ammeter pointer stays at the same position as the blank titration, and keep unchanged for 1min as the end point. The titer T of Karl Fischer reagent (or improved reagent) is calculated according to formula (6): Tm
Where: mi—the mass of water, mg;
V—the volume of Karl Fischer reagent (or improved reagent) consumed in titration, mL. Note: The titer T should be calibrated every day.
4.4.4 Determination steps
: (6)
Put 25mL of chloroform-methanol (3+1) mixed solvent in a reactor, cover the bottle stopper, connect the power supply, start the electromagnetic stirrer, and titrate the water in the solvent with Karl Fischer reagent (or improved reagent) until the ammeter pointer has a large deflection and remains unchanged for 1 minute (the volume of the reagent consumed is not counted), then add 2-5 (accurate to 0.1g) of p-nitrotoluene sample to the reactor, cover the bottle stopper, wait until the sample is completely dissolved, and titrate with Karl Fischer reagent (or improved reagent) until the ammeter pointer stays at the same position as the blank titration and remains unchanged for 1 minute as the end point. The percentage of water X is calculated according to formula (7):
5×100
Wherein, V is the volume of Karl Fischer reagent (or improved reagent) consumed when titrating the sample, mL; T is the titer of Karl Fischer reagent (or improved reagent), mg/mL; m2 is the mass of the sample, g.
The difference between the results of two parallel determinations shall not exceed 0.03%, and the arithmetic mean shall be taken as the determination result. Note: Karl Fischer reagent is used for arbitration analysis. 5 Inspection rules
5.1 Para-nitrotoluene shall be inspected by the technical inspection department of the manufacturer. The manufacturer shall ensure that all para-nitrotoluene shipped out of the factory meets the requirements of this standard. Each batch of para-nitrobenzene shipped out of the factory shall be accompanied by a quality certificate in a certain format. 5.2 The user has the right to verify the received para-nitrotoluene in accordance with the provisions of this standard to verify whether it meets the requirements of this standard.
5.3 Each package of para-nitrotoluene products is considered a batch. 5.4 Sampling method: 10% of the barrels are selected from each batch of products for sampling. The sampling of small batches of products shall not be less than 5 barrels. When sampling, first heat the packaging barrel with steam until all the para-nitrotoluene is melted, then open the packaging barrel, and insert a glass tube with a diameter of 13mm and a length of 1m with a thinner end into the barrel to sample from top to bottom. The total amount of sampling shall not be less than 250g. 5.5 Put the sample into a porcelain mortar and mix it carefully. After cooling, grind the para-nitrotoluene sample and put it in a clean and dry ground-mouth bottle, and seal it with paraffin. Stick a label on the bottle, indicating: manufacturer name, product name, batch number and sampling date, and send it to the inspection department for inspection. 5.6 If one of the indicators in the inspection results does not meet the requirements of this standard, a para-nitrotoluene sample should be selected from twice the amount of packaging for re-inspection. If even one indicator of the re-inspection result does not meet the requirements of this standard, the entire batch of para-nitrotoluene cannot be accepted. 5.7 When the supply and demand parties have disputes over product quality and need arbitration, the arbitration institution can be determined by agreement between the two parties. During arbitration, arbitration analysis should be conducted in accordance with the sampling method and inspection method specified in this standard. 6 Packaging, marking, storage and transportation
6.1 Para-nitrotoluene is packaged in iron drums. The net weight of each drum is 100 or 200 kg. 6.2 Each batch of packaged products should be accompanied by a quality certificate. The certificate includes: manufacturer name, product name, batch number, production date, net weight, proof that the product quality meets the requirements of this standard and the number of this standard. 8
HG202591
6.3 The packaging container should be painted with a firm mark, which includes: manufacturer name, registered trademark, product name, production date, batch number, net weight, and the "toxic substance" mark should be marked according to the provisions of GB190. 6.4 The product should be stored in a cool and ventilated place, away from sunlight. It should not be close to fire during transportation and storage, and should be handled with care. 6.5 Para-nitrotoluene is toxic. Do not allow it to come into contact with the skin or be inhaled during handling. Wear labor protection equipment and pay strict attention to safety. Additional notes:
This standard was proposed by the Science and Technology Department of the Ministry of Chemical Industry of the People's Republic of China. This standard is under the technical jurisdiction of the Shenyang Chemical Research Institute of the Ministry of Chemical Industry. This standard was drafted by the Jilin Dye Factory of the Jilin Chemical Industry Company of the Ministry of Chemical Industry. The main drafters of this standard are Li Shulan, Zhang Huiren, and Lin Jun. This standard refers to the Japanese Industrial Standard JISK4108-81 "Nitrobenzene". From the date of implementation of this standard, the former Ministry of Chemical Industry Standard HG2-373-80 "Para-Nitrotoluene" will be invalid. 9
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