CN104950071A - Method for measuring coumarone hydroxyl value - Google Patents

Abstract

The invention discloses a method for measuring a coumarone hydroxyl value, which adopts acetic anhydride as an acylation reagent, selects tetrahydrofuran and N, N-dimethylformamide to be matched as a solvent, selects dimethylaminopyridine as a catalyst, and calculates the hydroxyl value content by carrying out a sample experiment and a blank experiment and according to experimental data. The method can accurately and rapidly measure the hydroxyl value of the coumarone resins, has good repeatability, RSD of 3.25 percent, high precision and standard recovery rate of 96-102 percent.

Description

A kind of assay method of coumarone hydroxyl value

Technical field

The present invention relates to the assay method of hydroxyl value in resin, more particularly, relate to a kind of assay method of coumarone hydroxyl value.

Background technology

Chinese patent 200810213797.8 discloses a kind of esterifying reagent for acid anhydrides method mensuration hydroxyl value and measures the method for hydroxyl value, wherein relate to the esterifying reagent that can be used for measuring polyvalent alcohol hydroxyl value.But, only esterifying reagent is discussed, does not relate to relevant suitable solvent and catalyzer.

Chinese patent 200710078494.5 discloses a kind of method utilizing ester carbonyl stretching vibration peak to measure hydroxyl value of polyester polyol, and what it adopted is infrared method, on-acylated method.

" plastics polyether glycol the 3rd part: the mensuration of hydroxyl value " of GB/T12008.3-2009 adopts phthalic anhydride method and near infrared spectroscopy to measure.Near infrared spectroscopy belongs to spectroscopic methodology, and phthalic anhydride method, during acidylate, need at (115 soil 2) DEG C backflow 30min, and acylating reagent is phthalic anhydride, solvent is then pyridine, has volatility, toxicity, and catalyzer is imidazoles.

In sum, at present, there is no the hydroxy value measuring that suitable method can be used for coumarone indene resin class.

Summary of the invention

For the above-mentioned shortcoming existed in prior art, the object of this invention is to provide a kind of assay method of coumarone hydroxyl value, by selecting suitable solvent and the catalyzer that all can dissolve coumarone sample, thus measuring its hydroxyl value quickly and accurately.

For achieving the above object, the present invention adopts following technical scheme:

The assay method of this coumarone hydroxyl value, comprises the following steps:

A. the acylating reagent of acetic anhydride and DMF mixed configuration is adopted;

B. the catalyzer to dimethylamino naphthyridine and DMF mixed configuration is adopted;

C. sample experiment is carried out: will take coumarone sample, IOH ' is for estimating hydroxyl value, be placed in beaker, and add the catalyzer of 20 ~ 30mL, add the tetrahydrofuran of 20 ~ 30mL, the acylating reagent of 10 ~ 15mL, stir 12 ~ 20min, add 3 ~ 5mL water again, stir 10 ~ 15min, then after the tetrahydrofuran adding 20 ~ 30mL, be titrated to terminal with the KOH/EtOH standard solution of 0.5mol/L;

D. carry out blank assay simultaneously;

E. experimentally data calculate hydroxyl value content, and computing formula is:

$\mathrm{IOH}=\frac{c(V_O-V_1)*56.11}{m}$

In formula, IOH is hydroxyl value content, mgKOH/g; C is the concentration of KOH/EtOH standard solution, mol/L; The volume of the KOH/EtOH standard solution that V0 consumes for blank assay, mL; The volume of the KOH/EtOH standard solution that V1 consumes for sample experiment, mL; M is sample mass, g.

Described acylating reagent is the DMF solution of acetic anhydride, and its percent by volume is 10 ~ 15v/v%.

Described catalyzer is the DMF solution to dimethylamino naphthyridine, and its concentration is 5 ~ 10g/L.

The final mixed volume of the tetrahydrofuran added in described sample experiment and DMF is than being 1:1 ~ 2.5.

In technique scheme; the assay method of coumarone hydroxyl value of the present invention adopts acetic anhydride to do acylating reagent, choose tetrahydrofuran and N; dinethylformamide matches as solvent, to choose dimethylamino naphthyridine be catalyzer, by carrying out sample experiment and blank assay and experimentally data calculate hydroxyl value content.Adopt the method can measure the hydroxyl value of coumarone indene resin class quickly and accurately, and repeatability is good, RSD reaches 3.25%, and precision is high, and recovery of standard addition is between 96 ~ 102%.

Embodiment

Technical scheme of the present invention is further illustrated below in conjunction with embodiment.

The basic ideas of the assay method of coumarone hydroxyl value of the present invention are as follows:

One. the selection of acylating reagent

When chemical analysis measures hydroxyl value, principle is all the various chemical reactions that reaction reagent and hydroxy functional group carry out.Be summed up following several method: acetic anhydride acylation method, phthalic acid anhydride acylation method, formylation method, bromination method, periodate oxidation method, coupling method, reactive hydrogen method etc.But mainly acetic anhydride acylation method, phthalic acid anhydride acylation method conventional in scientific research and actual production.

The reaction of acetic anhydride acylation method is very fast, but reagent is more volatile, and is subject to the interference of low-carbon (LC) aldehyde.Phthalic acid anhydride acylation method is not subject to the interference of aldehydes and phenolic compound, and reagent is not volatile, but acylation reaction speed is slower.Consider that experiment is carried out at normal temperatures; and it is shorter to react quick volatilizes, and in coumarone aldehydes and phenols content lower, the toxicity of acetic anhydride is lower than phthalic anhydride; phthalic anhydride very easily absorbs water and reduces acidylate ability, and the present invention adopts acetic anhydride as the raw material of acylating reagent.

Two, the selection of solvent

The solid shape of coumarone indene resin own, Powdered at different solvents [ethyl acetate, acetone, acetonitrile, toluene, N after porphyrize, dinethylformamide (DMF), tetrahydrofuran] in dissolubility also different, select suitable solvent can not only whole sample dissolution, ensure the accuracy of result, more can shorten the time of sample dissolution, shorten the running time.

The selection of table 1 solvent

Take 2g coumarone in beaker, add solvents different in 20mL table 1 respectively, find that namely coumarone dissolves in tetrahydrofuran neutrality, do not dissolve completely at acetonitrile, all slowly dissolve in all the other reagent.

Be hydrolyzed excessive acetic anhydride owing to needing in experimental principle to add water, so continue to add 3mL water, after discovery adds water there is the globule in ethyl acetate and toluene, and two-phase is not allowed, and this will cause acetic anhydride hydrolysis not exclusively to cause error.Occur muddy in remaining solvent, illustrate that coumarone is separated out.This can cause result error.

In view of coumarone dissolubility in tetrahydrofuran is best, continue to add 20mL tetrahydrofuran, find that the coumarone of separating out in acetone needs 3min to dissolve, and the coumarone of precipitation in DMF dissolves immediately.

Through experimental study, the present invention chooses tetrahydrofuran and DMF matches as solvent.

Three, the selection of catalyzer

The selection of catalyzer is very important, and it directly affects the length of minute and the accurate of measurement result.Measure the catalyzer of hydroxyl value for acetylation method to mainly contain: pyridine, perchloric acid, imidazoles, p-toluenesulfonic acid, to dimethylamino naphthyridine (DMPA).

Pyridine toxicity can to human body and environmental pollution.Perchloric acid, its catalytic capability is too strong, can make the ether bond rupture of poly alkyl alcohol ether product; Catalyzed by Imidazole ability is more weak, needs to add hot reflux half an hour in boiling water bath; P-toluenesulfonic acid reacts incomplete at low temperatures.Large quantity research shows, DMPA has superpower nucleophilic acidylate ability, and its catalytic capability is 1000 times of traditional catalyst pyridine.There is reaction conditions gentleness simultaneously and hold manageable advantage.And DMPA is solid powdery, suck infringement probability little, therefore, the present invention selects DMPA to be catalyzer.

Ensure that acidylate is complete in order to Reaction time shorten, by By consulting literatures, finally choosing dimethylamino naphthyridine is catalyzer.

Its principle is as follows:

With to dimethylamino naphthyridine for catalyzer, in tetrahydrofuran and DMF, acetic anhydride and hydroxyl generation acylation reaction generate acetic acid, and excessive acetic anhydride water is hydrolyzed.The titration of KOH/EtOH standard solution used again by the acetic acid (part is generated by acylated hydroxy, and another part is hydrolyzed by excessive acetic acid acid anhydride and generates) produced, and finally calculates and tries to achieve.

ROH+CH ₃CO-O-COCH ₃＝CH ₃COOH+CH ₃COOR

CH ₃CO-O-COCH ₃+H ₂O＝2CH ₃COOH

Hydroxyl value defines: in and during 1g sample acidylate produce the milligram number of sour corresponding KOH, unit is mgKOH/g

According to above-mentioned principle, the assay method of coumarone hydroxyl value of the present invention comprises following concrete steps:

A. the acylating reagent of acetic anhydride and DMF mixed configuration is adopted;

B. the catalyzer to dimethylamino naphthyridine and DMF mixed configuration is adopted;

C. sample experiment is carried out: will take coumarone sample, IOH ' is for estimating hydroxyl value, be placed in beaker, and add the catalyzer of 20 ~ 30mL, add the tetrahydrofuran of 20 ~ 30mL, the acylating reagent of 10 ~ 15mL, stir 12 ~ 20min, add 3 ~ 5mL water again, stir 10 ~ 15min, then after the tetrahydrofuran adding 20 ~ 30mL, be titrated to terminal with the KOH/EtOH standard solution of 0.5mol/L;

D. carry out blank assay simultaneously;

E. experimentally data calculate hydroxyl value content, and computing formula is:

$\mathrm{IOH}=\frac{c(V_O-V_1)*56.11}{m}$

In formula, IOH is hydroxyl value content, mgKOH/g; C is the concentration of KOH/EtOH standard solution, mol/L; The volume of the KOH/EtOH standard solution that V0 consumes for blank assay, mL; The volume of the KOH/EtOH standard solution that V1 consumes for sample experiment, mL; M is sample mass, g.

Through repeatedly repeatedly testing and calculating, as an embodiment, described acylating reagent is the DMF solution of acetic anhydride, and its percent by volume is 10 ~ 15v/v%.Described catalyzer is the DMF solution to dimethylamino naphthyridine, and its concentration is 5 ~ 10g/L.In addition, the final mixed volume of the tetrahydrofuran added in described sample experiment and DMF is than being 1:1 ~ 2.5.

Embodiment 1

Adopt acetic anhydride to mix with DMF and configure acylating reagent by 12v/v%;

Adopt and 5g/L mixed configuration catalyzer is pressed to dimethylamino naphthyridine and DMF;

Accurately take 12g coumarone sample in beaker, add 30mL catalyzer, add 20mL tetrahydrofuran; add 12mL acylating reagent, stir 12min, add 3mL water; stir 15min, after adding 20mL tetrahydrofuran, be titrated to terminal with 0.5mol/L KOH/EtOH standard solution.Do blank assay simultaneously.

Embodiment 2 ~ 4 step is identical with embodiment 1, and experiment condition and parameter are slightly different, specifically refer to table 1

Table 1

Test parameters	Embodiment 1	Embodiment 2	Embodiment 3	Embodiment 4
					Acylating reagent concentration, v/v%	12	10	11	12
Catalyst concn, g/L	5	10	5	10
					Sample weighting amount, g	12.0053	12.0045	12.0081	12.0014
Catalyst amount, mL	30	20	25	25

Tetrahydrofuran consumption one, mL	20	23	26	30
					Acylating agent consumption, mL	10	15	13	11
Mixing time one, min	12	18	14	15
					Water consumption, mL	3	3	5	5
Mixing time two, min	15	14	12	15
					Tetrahydrofuran consumption two, mL	20	23	26	30
V 0，mL	45.4353	56.2467	53.8434	49.7302
					V 1，mL	32.4895	42.6924	41.2909	36.8482
IOH	30.38	31.81	29.45	30.24

Another from precision result, adopt repeatability of the present invention good (RSD is 3.25%), precision is higher.

The precision of table 2 the method

Sample size, g	Titration volumes, mL	Hydroxyl value, mgKOH/g
			0	44.2467	——
12.0047	31.6000	29.68
			12.0055	31.0194	31.04
12.0068	31.1288	30.78
			12.0056	31.7437	29.34
12.0045	30.6924	31.81
			12.0024	31.6533	29.56
RSD%	——	3.25
			mean	——	30.37

At precise 6g(accurately to 0.1mg) porphyrize coumarone grinding sample in add 0.60mL normal butyl alcohol standard specimen, the recovery of the visible this method of hydroxy value measuring result between 96 ~ 102%, in table 3.

The accuracy of table 3 this method

Normal butyl alcohol, mL	Sample size, g	Titration volumes, mL	Recovery of standard addition, %
				0	0	45.4353	——

0	12.0053	32.4895	——
				0.6	6.0095	26.4798	96.01
0.6	6.0065	26.3232	97.24
				0.6	6.0007	25.8331	101.06

In sum, adopt the assay method of coumarone hydroxyl value of the present invention, simple, convenient, can measure the hydroxyl value of coumarone indene resin class quickly and accurately, and repeatability is good, RSD reaches 3.25%, and precision is high, and recovery of standard addition is between 96 ~ 102%.

Those of ordinary skill in the art will be appreciated that, above embodiment is only used to the present invention is described, and be not used as limitation of the invention, as long as in spirit of the present invention, all will drop in Claims scope of the present invention the change of the above embodiment, modification.

Claims (4)

1. an assay method for coumarone hydroxyl value, is characterized in that,

Comprise the following steps:

A. the acylating reagent of acetic anhydride and DMF mixed configuration is adopted;

B. the catalyzer to dimethylamino naphthyridine and DMF mixed configuration is adopted;

C. sample experiment is carried out: will take coumarone sample, IOH ' is for estimating hydroxyl value, be placed in beaker, and add the catalyzer of 20 ~ 30mL, add the tetrahydrofuran of 20 ~ 30mL, the acylating reagent of 10 ~ 15mL, stir 12 ~ 20min, add 3 ~ 5mL water again, stir 10 ~ 15min, then after the tetrahydrofuran adding 20 ~ 30mL, be titrated to terminal with the KOH/EtOH standard solution of 0.5mol/L;

D. carry out blank assay simultaneously;

E. experimentally data calculate hydroxyl value content, and computing formula is:

$\mathrm{IOH}=\frac{c(V_O-V_1)*56.11}{m}$

In formula, IOH is hydroxyl value content, mgKOH/g; C is the concentration of KOH/EtOH standard solution, mol/L; The volume of the KOH/EtOH standard solution that V0 consumes for blank assay, mL; The volume of the KOH/EtOH standard solution that V1 consumes for sample experiment, mL; M is sample mass, g.

2. the assay method of coumarone hydroxyl value as claimed in claim 1, is characterized in that:

Described acylating reagent is the DMF solution of acetic anhydride, and its percent by volume is 10 ~ 15v/v%.

3. the assay method of coumarone hydroxyl value as claimed in claim 1, is characterized in that:

Described catalyzer is the DMF solution to dimethylamino naphthyridine, and its concentration is 5 ~ 10g/L.

4. the assay method of coumarone hydroxyl value as claimed in claim 1, is characterized in that:

The final mixed volume of the tetrahydrofuran added in described sample experiment and DMF is than being 1:1 ~ 2.5.