Some standard content:
National Standard of the People's Republic of China
Benzene
Theme content and scope of application
Aniline
Amine
GB2961
90
Replacing GB2961-82
This standard specifies the technical conditions, test methods, inspection rules and requirements for marking, packaging, storage and transportation of aniline. This standard applies to aniline prepared by reduction of nitrobenzene. Aniline is mainly used as raw material for dye intermediates, pesticides, medicines, rubber additives and other organic synthesis.
Molecular formula CH-N
NH2
Structural formula
Relative molecular mass 9
93.13 (according to the 1987 international atomic weight)
2 quotes Standard
GB601
GB603
GB6283
GB9722
Chemical reagents
Preparation of standard solutions for titration analysis (volume analysis) Chemical reagents :
Preparation of preparations and products used in test methods Determination of moisture content of chemical products Karl Fischer method (general method) General principles of chemical reagent gas chromatography
GB190
Dangerous goods packaging Logo
3 Technical requirements
Aniline should comply with the requirements of Table 1:
Table 1
Indicator name
Appearance
Sweat freezing point, C
Aniline content (on a dry basis), % (m/m) nitrobenzene content, % (m/m)
Moisture.% (m/m)
Test method
4
Superior product
Reference
Standard
First-class product
Qualified product
Colorless to light yellow transparent wave body, the forehead color is allowed to become darker during storage 6.2
99.6
0.002
0.1
-6. 4
99.5|| tt||0.010
0.3
—6.6
99.3
0.015
0.5
The reagents and water used in this standard are not When other requirements are indicated, they refer to analytically pure reagents and distilled water that comply with current national standards or water of the same purity approved by the State Bureau of Technical Supervision on December 30, 1990 and implemented on January 01, 1992
485
. | |tt |
4.1 Appearance
Observe visually.
4.2 Determination of freezing point of dry products
4.2.1 Instrument
a.
b.
Freezing point tester (Figure 1);||tt ||The outer diameter of the crystallized tube is about 25mm, the length is about 150mm; the inner diameter of the outer tube is about 28mm, the length is about 120mm, and the wall thickness is about 2mm; c.
d. The thermometer has a graduation value of 0.1℃, a temperature range of -15~+10℃, a calibrated mercury glass thermometer with a length of about 350mm; e.
Made of stainless steel wire or glass rod with a diameter of about 2mm, with a length of more than 150mm , there is a horizontal ring with a diameter of about 20mm at the lower end of the stirrer
;
f. Cooler
600mL beaker or other suitable container.
Figure丨Freezing point tester
1—Thermometer: 2—Stirrer; 3—Crystallizer tube; 4—Outer tube; 5—Cooling bath 4.2.2 Reagents and materials
Drying Agent: 4A or 5A spherical molecular sieve. After activation at 550°C for 2 hours, place it in a desiccator for later use. Coolant: ice and industrial salt. Mix crushed ice and industrial salt appropriately when using. 4.2.3 Measurement steps
In the fume hood, take about 30mL of aniline sample and put it into a clean and dry ground-mouth bottle, add 10 molecular sieves, close the bottle cap, and shake it thoroughly every 15 minutes. The drying time About 1 hour, pour the supernatant liquid into a clean and dry crystallization tube. The depth of the sample is about 75mm. Insert the cold thermometer and stirrer vertically into the sample and keep the end of the mercury bulb of the thermometer about 15mm from the bottom of the crystallization tube. Place it in In the cooling bath, stir the sample up and down with a stirrer at a stirring speed of approximately once per second. When the temperature of the sample drops to -5°C, put the crystallization tube into the outer tube pre-immersed in the cooling bath and continue stirring to gradually drop the temperature. When crystallization appears in the sample, stop stirring immediately and the temperature begins to rise. The temperature 486 | |tt||GB 2961-- 90
The temperature rises to the highest point and maintains it for a certain period of time. This temperature is the freezing point of aniline. If a total immersion thermometer is used, the freezing point is calibrated according to formula (1): t = t + 0.000 16 h·(t — t2) wu: t
The freezing point of aniline,;
t, ----Observed freezing point, C;
·The temperature of the air around the middle of the mercury sphere outside the plug (measured with an auxiliary thermometer), C; ----The height of the mercury column outside the plug (expressed by the thermometer scale); 0.00016-
The expansion coefficient of mercury in glass.
4.2.4 Allowable difference
The difference between two parallel measurement values ??shall not be greater than 0.1C, and the arithmetic mean shall be used as the analysis result. The result should be rounded to two decimal places. 4.3 Determination of aniline content
4.3.1 Principle
Aniline undergoes a quantitative diazotization reaction with sodium nitrite under acidic conditions. The reaction formula is as follows: NH2 +NaNO2+2HCI —||tt| |>-N =NCI+NaC1+2H20
The reaction end point is determined with potassium iodide starch test paper. The reaction formula is as follows: 2KI+ 2HNO2 +2HC1 ---12 + 2KC1+ 2NO+ 2H20. The iodine generated by 2H20 turns the starch blue. bZxz.net
4.3.2 Reagents and solutions
a Hydrochloric acid (GB 622);
b. Potassium bromide solution: 100g/L solution;
c, sodium nitrite standard solution: c(NaNOz)=0.5 mol/L. 4.3.3 Measurement steps
Weigh 10~~12g aniline sample (weigh accurately to 0.001g) and place it in a 500mL volumetric flask filled with 150mL water. Add 25mL hydrochloric acid, dilute with water to the mark and shake well. Use a pipette to take 50 mL of the above solution into a 400 mL beaker, add 100 mL water, 10 mL hydrochloric acid and 10 mL potassium bromide solution, and titrate with sodium nitrite standard solution at 10 to 15°C while stirring continuously. During titration, the tip of the burette should be inserted under the liquid surface. When the end point is approaching, raise the buret so that it is away from the liquid surface, and continue to titrate drop by drop until the potassium iodide starch test paper turns slightly blue. After 5 minutes, the same test method still appears slightly blue, that is, as the end point. A blank test was performed at the same time. The aniline content is calculated according to formula (2):
X1 i(V- V) × 0. 093 13 × 10050
m500
× (100 - W)||tt| |Wuzhong: Volume of sodium nitrite standard solution consumed, mL; '
Volume of sodium nitrite standard solution consumed in blank test, mL; m
Mass of aniline sample, 8; || tt||W——moisture content measured by 4.5;
0.09313
NaNO2) = 1.000mol/L) equivalent, the mass base of aniline expressed in grams
4.3.4 Allowable difference
The difference between two parallel determinations should not be greater than 0.2%, in arithmetic. The average value is taken as the analysis result. The result should be kept to two decimal places. 487
4.4 Determination of nitrobenzene content
4.4.1 Instruments and reagents
4.4.1.1 Instruments||tt| |GB 2961-90
Polarograph: The continuously adjustable range of the scanning amplitude is not less than 2.5V, and the sensitivity is not less than 2.5μA/mV. 4.4.1.2 Reagent
Hydrochloric acid (GB622);||tt ||#,
Nitrobenzene (HG 3-963));
b.
Stupid amine: does not contain nitrobenzene.
c.|| tt||4.4.2 Preparation of standard solution and drawing of standard curve 4.4.2.1 Preparation of standard solution
Weigh 0.05g nitrobenzene (weigh to the nearest 0.0002g) and 99.95g aniline (weigh to the nearest 0.01g) and mix Uniformly, this is solution A. Use a pipette to take 6 mL of solution A into a 100 mL volumetric flask, dilute it with aniline to the mark, and mix evenly. The nitrobenzene content of this standard solution is 0.003%.
Use a pipette to take 20mL of solution A into a 100mL volumetric flask, dilute it with aniline to the mark, and mix evenly. The nitrobenzene content of this standard solution is 0.01%.
4.4.2.2 Drawing of standard curve
Use a pipette to take 10 mL of the standard solution into a 25 mL clean beaker, add 2.5 mL of hydrochloric acid to each, stir evenly with a glass dropper, and cool to room temperature. Then record the polarograms on the polarograph between -0.2~~-0.6V, and accurately measure the polarographic wave height of each standard solution. Draw a standard curve with the content of the standard solution as the abscissa and the corresponding polarographic wave height as the ordinate. 4.4.3 Measurement steps
Use a pipette to take 10mL of aniline sample into a 25mL clean beaker, add 2.5mL of hydrochloric acid, stir evenly with a glass rod, cool to room temperature, and then use the same conditions as the standard curve. , record the polarogram on the polarograph, accurately measure the polarographic wave height of the sample, and find the nitrobenzene content corresponding to the wave height on the standard curve, which is the nitrobenzene content in the aniline sample. 4.4.4 The allowable difference
is that the relative error of two parallel measurement values ??does not exceed 10%, and the arithmetic mean is used as the analysis result. 4.5 Determination of moisture
4.5.1 Karl Fischer method
4.5.1.1 Instrument
Trace moisture analyzer: A trace moisture measuring device that complies with the regulations of GB6283 and is equipped with a 5mL microburette; a.
b.
Micro-based syringe: 10μL.
4.5.1.2 Reagent
a.
b.
d.
c.
Sulfuric acid (GB625): chemically pure;
Iodine (GB675);
Methanol (GB683);
Pyridine (GB 689);
Anhydrous sodium acetate (GB694);
None Aqueous sodium sulfite (HG3-1078): chemically pure; f.
j.
anhydrous sodium iodide;
h. Sulfur dioxide: Sulfur dioxide in cylinders or prepared by decomposing sodium sulfite with concentrated sulfuric acid. 4.5.1.3 Preparation of Karl Ferris reagent
Put 85g of iodine into a dry 1L stoppered brown bottle, add 670mL of methanol, cap the bottle stopper, shake until all iodine is dissolved, then add 270mL of pyridine and mix well. According to the device shown in Figure 2, continuously introduce about 65g of sulfur dioxide gas into this solution (a slight excess is not a problem). When passing sulfur dioxide, use an ice water bath to cool it so that the temperature of the solution does not exceed 20°C. Reagents should be placed in a dark place for at least 24 hours before use. 188
4.5.1.4 Preparation of Karl Fischer modified reagent GB 2961--90
Put 63g iodine into a dry 1L stoppered brown bottle, add 600mL methanol and 25g anhydrous sodium iodide (Bake at 120°C for 2 hours) and 85g anhydrous sodium acetate (bake at 120°C for 2 hours), cap the bottle, and shake until all iodine and others are dissolved (liquid A). Pour sulfur dioxide into methanol cooled with an ice-water bath so that each liter of methanol contains 256 sulfur dioxide (liquid B). Add 90mL of liquid B (containing 23g of sulfur dioxide) or directly pass about 23g of sulfur dioxide gas into liquid A, then dilute it with methanol to 1L, and keep it in the dark for later use.
Figure 2 Karl Fischer reagent (improved reagent) preparation device 1--Sulfur dioxide gas generator; 2-Concentrated sulfuric acid filter bottle; 3-Separator; 4-Absorption of solutions containing iodine, methanol, etc. Bottle: 5 ice water bath 4.5.1.5 Calibration of titer of Karl Fischer reagent (or modified reagent) Use a microsyringe to absorb 5 μL of water, weigh its mass (accurate to 0.0002g), repeat twice, and use the arithmetic average as the The mass of 5uL water.
Add 20mL methanol into the reaction bottle, cap the bottle stopper, start the electromagnetic stirrer, and use Karl Fischer reagent (or improved reagent) to titrate the water barrier in methanol. The pointer of the ammeter will deflect greatly and keep it for about 1 minute. It becomes a blank titration end point and the volume of reagent consumed is not recorded. Use a microsyringe to inject 5 μL of water into the reaction bottle, and titrate with Karl Fischer reagent (or modified reagent) until the ammeter pointer stays at the same position as the blank titration and remains unchanged for about 1 minute as the end point, and record the volume of reagent consumed. The titer of the reagent is calculated according to formula (3):
2
Wuzhong:
The titer of a Karl Fischer reagent (or improved reagent), mg/mL; ms Mass of water, mg;
}: -...-The volume of Karl Fischer reagent (or modified reagent) consumed during titration, mL. Note: The titer should be calibrated every day.
4.5.1.6 Measurement steps
3
489
GB 2961-90
Add 20mL methanol to the reaction bottle, cap the bottle stopper, and start Using an electromagnetic stirrer, use Karl Fischer reagent (or improved reagent) to titrate the water in methanol until the pointer of the ammeter deflects greatly and remains unchanged for about 1 minute (the volume of reagent consumed is not included), then use a pipette to take a 5mL aniline sample. Add to the reaction bottle, cap the bottle stopper, and titrate with Karl Fischer reagent (or modified reagent) until the ammeter pointer stays at the same position as the blank titration and remains unchanged for about 1 minute as the end point, and record the volume of the consumed reagent. The moisture in aniline is calculated according to formula (4):
W
In the formula: w
T
1.02
The moisture in aniline, %; || tt||TV
P × 1. 02×1 000 × 100
Titer of Karl Fischer reagent (or improved reagent), mg/mL; Karl Fischer consumed in titration Volume of reagent (or modified reagent), mL; volume of aniline sample, mL;
Density of aniline, g/mL.
Allowable difference
4. 5. 1. 7
The difference between two parallel measurement values ??does not exceed 0.02%, and the arithmetic mean is used as the analysis result. The result should be rounded to two decimal places. 4.5.2 Gas Chromatography
4.5.2.1 Instruments and Reagents
a.
b.
c.
Gas Chromatograph: Instrument Sensitivity and Stability should comply with the regulations of GB9722; detector: thermal conductivity detector;
chromatographic column: stainless steel column with diameter 3mm or 4mm and length 1m; d.
micro-stack syringe: 1μL; || tt||Stationary phase: GDX-1030.250.40mm (40~60 mesh)); e.
f.
Carrier gas: hydrogen.
4.5.2.2 Chromatographic column preparation and aging
(4)
Use a vacuum pump to pump and gently tap the column to fill the stationary phase into the column tube at 5.32×10\ Pa (approximately 400mmHg) is pumped down for about 5 minutes, and the filling should be even and tight.
Aging the packed chromatographic column by passing hydrogen gas at a column temperature of 200°C for 6 to 7 hours. 4.5.2.3 Chromatographic operating conditions
Select the best operating conditions according to different instruments. Taking the SP2304A chromatograph as an example, the operating conditions are as follows: column temperature: 180°C (actual measurement);
Vaporization temperature: 250C;
Column pressure: 3.92×10*Pa; ||tt| |Carrier gas flow rate: 5256mL/min;
Bridge flow: 190mA (can be increased or decreased appropriately);
Injection base: 1μL;
Fixed base method: external standard method.
4.5.2.4 Preparation of standard sample moisture
In a clean and dry small glass bottle, use aniline as the base solution and add water (water is injected with a micro-syringe) and use the gravimetric method to accurately prepare the standard with the required concentration. Take the sample, mix it thoroughly, cover it tightly with a rubber stopper, and seal it with paraffin. After leaving it for 3 hours, inject the sample on the chromatograph at the same time as the bottom solution, and accurately measure the peak height of the water in the bottom solution and the peak height of the water in the standard sample. The moisture in the standard sample is calculated according to formula (5):
C,
490
C+hs
hs - ho
(5)| | tt | , mm;
nThe peak height of bottom liquid water, mm.
GB 2961--90
The moisture content of aniline bottom liquid is required to be less than 0.1%; the shelf life of the standard sample is half a month. 4.5.2.5 Measurement steps
After starting the instrument and stabilizing the conditions, use a syringe to inject 1L aniline sample, and at the same time, inject a standard sample with a moisture content close to that of the test sample, and accurately measure the moisture content of the sample and standard sample. Peak height. The moisture in aniline is calculated according to formula (6):
w
where. W...-Moisture in aniline, %
C - Moisture in standard sample, %;
hl - Peak height of water in aniline sample, mm; - Peak height of standard water ,mm.
4.5.2.6 Allowable difference
C,· h
(6)
The relative error of two parallel measurement values ??is not greater than 15%, and the arithmetic mean is used as the Analyze the results. The result should be rounded to two decimal places. 4.5.3 The arbitration method shall be the Karl Fischer method. 5 Inspection Rules
5.1 Aniline should be inspected by the quality inspection department of the manufacturer. The manufacturer should ensure that all aniline shipped meets the requirements of this standard. Each batch of aniline shipped from the factory should be accompanied by a quality certificate in a certain format. 5.2 The user has the right to inspect and accept the aniline received in accordance with the provisions of this standard. 5.3 Take the uniform products for each inspection as a batch. 5.4 Stupid amine shall be sampled from 10% of the total number of barrels of each batch of products, and the sampling of small batches of products shall not be less than 5 barrels. For sampling, use a glass tube with a diameter of about 10mm and a length of about 1m to take out samples from the upper, middle and lower parts of the barrel; when transporting aniline by tanker, take out samples from the upper, middle and lower parts (the upper part is 1/10 liquid layer away from the liquid level) , the lower part is 1/10 liquid layer away from the bottom) take out equal amounts of samples and mix them. The total volume of samples taken shall not be less than 500mL. 5.5 Carefully mix the collected samples and put them into two clean and dry fine-mouth ground-mouth bottles. Label the bottles to indicate: manufacturer name, product name, batch number and sampling date. One bottle will be inspected by the inspection department. Keep one bottle for three months for future reference. 5.6 If one indicator of the inspection result does not meet the requirements of this standard, re-test should be carried out by taking twice the amount of aniline from the packaging container. Even if only one indicator of the retest result does not meet the requirements of this standard, the entire batch of products cannot be accepted. . 5.7 When the supply and demand parties have objections to product quality, they can be resolved through negotiation between the two parties. 6 Marking, packaging, transportation, storage
6.1 The surface of the aniline packaging container should be marked with non-fading paint on the surface of the manufacturer, product name, trademark, production date, batch number and net weight, and in accordance with the provisions of GB190, mark "toxic" "sign." 6.2 Aniline is packed in iron drums or shipped in tank trucks. When packed in iron drums, the thickness of the iron sheet shall not be less than 1.25mm, and the net weight of each drum shall be 200kg. 6.3 Keep away from fire sources during transportation and storage. It should be placed in a cool and dry place to prevent exposure to sunlight and rain; it should be handled with care when handling. 6.4 Aniline is toxic. When using and handling, you must use labor protection equipment. Do not come into contact with the skin or be inhaled into the body. Pay strict attention to safety. 491
Additional notes:
GB2961-90
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is not under the jurisdiction of the Shenyang Chemical Industry Research Institute of the Ministry of Chemical Industry. This standard is drafted by the Nanjing Chemical Plant of the Ministry of Chemical Industry. The main drafter of this standard is Liang Zhishun.
This standard refers to the Soviet national standard rOCT313-77 (84) "Industrial Aniline". 4.92
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