Dodecanol (2)

4 Test method

The reagents and water used in this standard are analytical reagents and distilled water or water of equivalent purity when no other requirements are indicated

The standard solutions, preparations and products used in this standard shall be implemented in accordance with the provisions of GB601 and GB603 unless other requirements are indicated

4.

Measure according to GB3143 standard

4.

Measure according to GB6365 standard

4.

4.

The excess alkali neutralizes the acid in the sample and undergoes a saponification reaction with the esters in the sample.

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4.

4.

Preparation of aldehyde-free ethanol: 5g aluminum flakes were refluxed in 1000mL neutral anhydrous ethanol for 1h, and then distilled immediately

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4.

4.

4.
3.
3.
1 Water bath or electric heating plate
.

4.
3.
4 Analysis steps

Weigh 10g of the sample (accurate to 0.
0002g), place it in a conical flask with a grinding mouth, use a pipette to pipette 50.
0mL potassium hydroxide ethanol solution, install the reflux condenser, put it in the water bath, the temperature of the water bath is not low Heat at 95°C and reflux for 1 hour.
Wash the wall of the condenser with 10mL neutral absolute ethanol solution, remove the conical flask, add 2-3 drops of phenolphthalein indicator solution, and titrate with hydrochloric acid standard titration solution until the red color disappears as the end point
.
At the same time do a blank test
.

4.
3.
5 Calculation of analysis results

The saponification value X ₁ (mgKOH/g) is calculated according to formula (1):

Where: V ₀ -the volume of the hydrochloric acid standard titration solution used in the blank test, mL;

V ₁ —The volume of the hydrochloric acid standard titration solution consumed by the titration sample, mL;

c— Concentration of hydrochloric acid standard titration solution, mol/L;

0.
0561— The mass of potassium hydroxide expressed in grams is equivalent to 1.
00mL hydrochloric acid standard titration solution [c(HCl)=1.
000mol/L] ;

m—the mass of the sample, g
.

Take the arithmetic average of two parallel determinations as the result
.

4.
3.
6 Allowance

The difference between the two parallel determinations should not be greater than 0.
4mg KOH/g
.

4.
4 Determination of iodine value

4.
4.
1 Principle of the method

Under specified conditions, how many grams of iodine are consumed by a 100g sample is a measure of the degree of material unsaturation
.

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4.
2 Reagents and solutions

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4.
2.
1 Carbon tetrachloride or chloroform ;

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4.
2.
2 Glacial acetic acid ;

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2.
3 Potassium iodide solution: 150g/L;

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4.
2.
4 Chlorinated iodo-glacial acetic acid solution (Webster's solution): 16.
2g/L
.
Was dissolved 16.
2g of iodine monochloride in 11 glacial acetic acid formed in
.
Or weigh 13g of iodine and dissolve it in 1L of glacial acetic acid, and pass in dry chlorine until the solution turns from brown to red
.
Before and after the chlorine gas is introduced, it is calibrated according to the blank measurement
.
The volume of sodium thiosulfate standard titration solution (4.
4.
2.
5) consumed by the latter should be twice that of the former, otherwise it needs to be adjusted
.

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4.
2.
5 Sodium thiosulfate standard titration solution: c(Na ₂ S ₂ O ₃ )=0.
1mol/L;

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4.
2.
6 Starch indicator solution: 10g/L
.

4.
4.
3 Analysis steps

Weigh 5g (accurate to 0.
0002g) sample in an iodine flask, add 25mL of carbon tetrachloride or chloroform to dissolve, accurately pipette 25.
0mL of Webster's solution, cover the bottle stopper, and seal the bottle with potassium iodide solution , Shake it slowly, and place it in a dark place at room temperature for 1 hour
.
After taking it out, add 25mL potassium iodide solution and 50mL water.
When titrated with sodium thiosulfate standard titration solution to light yellow, add about 1mL starch indicator solution and continue titration until the blue color disappears as the end point
.
At the same time do a blank test
.

4.
4.
4 Calculation of analysis results

Iodine value X ₂ (gI ₂ /100g) is calculated according to formula (2):

Where: V ₀ -blank consumption sodium thiosulfate standard titration solution volume, mL;

V ₂ —The volume of sodium thiosulfate standard titration solution consumed by the titration sample, mL;

c ₂ —The concentration of sodium thiosulfate standard titration solution, mol/L;

0.
1269 —The mass of iodine expressed in grams is equivalent to 1.
00mL sodium thiosulfate standard titration solution (c(Na ₂ S ₂ O ₃ )=1.
000mol/L);

m—the mass of the sample, g
.

Take the arithmetic average of two parallel determinations as the result
.

4.
4.
5 Allowance

The difference between the two parallel determination values ​​shall not be greater than 0.
2gI2/100g
.

Related link: Dodecanol (1)