CN104950071B - 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 resin middle hydroxyl value, more specifically to a kind of measure side of coumarone hydroxyl value Method.

Background technology

Chinese patent 200810213797.8 discloses a kind of esterifying reagent and measurement hydroxyl that hydroxyl value is determined for acid anhydrides method The method of value, has been directed to can be used for the esterifying reagent for determining polyalcohol hydroxyl value.However, only discussing esterifying reagent, do not relate to And to related suitable solvent and catalyst.

Chinese patent 200710078494.5 discloses a kind of using ester carbonyl stretching vibration peak measure PEPA hydroxyl The method of value, it uses infrared method, on-acylated method.

GB/T12008.3-2009's《Plastics PPG third portion：The measure of hydroxyl value》Using phthalic anhydride Method and near infrared spectroscopy are determined.Near infrared spectroscopy belongs to spectroscopic methodology, and phthalic anhydride method, when acylated, it is necessary to （115 soil 2）DEG C backflow 30min, and acylating reagent be phthalic anhydride, solvent then be pyridine, with volatility, toxicity, Catalyst is imidazoles.

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

The content of the invention

For disadvantages mentioned above present in prior art, it is an object of the invention to provide a kind of measure side of coumarone hydroxyl value Method, the solvent and catalyst of coumarone sample suitably can be all dissolved by selection, so as to quickly and accurately determine its hydroxyl Value.

To achieve the above object, the present invention is adopted the following technical scheme that：

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

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

B. using the catalyst to dimethylamino naphthyridine and DMF mixed configuration；

C. sample experiment is carried out：To weighCoumarone sample, IOH ' is placed in beaker to estimate hydroxyl value, and is added Enter the catalyst of 20~30mL, add tetrahydrofuran, the acylating reagent of 10~15mL of 20~30mL, stir 12~20min, then 3~5mL water is added, 10~15min is stirred, after adding the tetrahydrofuran of 20~30mL, is marked with the KOH/EtOH of 0.5mol/L Quasi- solution titration is to terminal；

D. blank assay is carried out simultaneously；

E. hydroxyl value content is calculated according to experimental data, computing formula is：

In formula, IOH is hydroxyl value content, mgKOH/g；C is the concentration of KOH/EtOH standard liquids, mol/L；V0 is blank reality Test the volume of consumed KOH/EtOH standard liquids, mL；The body of the KOH/EtOH standard liquids that V1 is consumed by sample experiment Product, 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 catalyst is the DMF solution to dimethylamino naphthyridine, and its concentration is 5~10g/L.

The tetrahydrofuran and the final mixed volume ratio of DMF added in described sample experiment are 1:1 ~2.5.

In the above-mentioned technical solutions, the assay method of coumarone hydroxyl value of the invention does acylating reagent, choosing using acetic anhydride Take tetrahydrofuran and DMF is engaged as solvent, to choose to dimethylamino naphthyridine be catalyst, by entering Row sample experiment and blank assay simultaneously calculate hydroxyl value content according to experimental data.Can quickly and accurately be determined using the method The hydroxyl value of coumarone indene resin class, and repeatability is good, RSD is up to 3.25%, and precision is high, recovery of standard addition 96~102% it Between.

Specific embodiment

Technical scheme is further illustrated with reference to embodiment.

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

The selection of one, acylating reagents

When chemical analysis determine hydroxyl value, principle is all the various chemical reactions that reaction reagent is carried out with hydroxy functional group. It has been summed up following several method：Acetic anhydride acylation method, phthalic acid anhydride acylation method, formylated method, bromination method, periodic acid Oxidizing process, coupling method, reactive hydrogen method etc..But mainly acetic anhydride acylation method, the adjacent benzene two commonly used in scientific research and actual production Formic acid anhydride acylation method.

The reaction of acetic anhydride acylation method is very fast, but reagent is more volatile, and is disturbed by low-carbon (LC) aldehyde.Phthalic anhydride acyl Change method is not disturbed by aldehydes and phenolic compound, and reagent is not volatile, but acylation reaction speed is slower.In view of experiment normal Carried out under temperature, and the reaction quick volatilization time is shorter, and also aldehydes and phenols content are relatively low in coumarone, and the toxicity of acetic anhydride is low In phthalic anhydride, phthalic anhydride easily absorbs water reduces acylated ability, and the present invention is using acetic anhydride as acylating reagent Raw material.

2nd, the selection of solvent

Coumarone indene resin solid-like in itself, it is finely ground it is rear it is powdered different solvents [ethyl acetate, acetone, acetonitrile, toluene, DMF（DMF）, tetrahydrofuran] in dissolubility it is also different, select the suitable solvent can not only be all molten Solution sample, it is ensured that the accuracy of result, can more shorten the time of sample dissolving, shorten the operating time.

The selection of the solvent of table 1

2g coumarones are weighed in beaker, solvents different in 20mL tables 1 are separately added into, finds coumarone in tetrahydrofuran Neutrality dissolves, in remaining reagent equal slow mechanism dissolved almost totally insoluble in acetonitrile.

Due to needing the excessive acetic anhydride of hydrolysis that adds water in experimental principle, so 3mL water is continuously added, second after finding to add water There is the globule in acetoacetic ester and toluene, and two-phase is not allowed, and this will cause acetic anhydride hydrolysis not exclusively to cause error.Go out in remaining solvent Existing muddiness, illustrates that coumarone is separated out.This can cause result error.

In view of coumarone dissolubility in tetrahydrofuran preferably, continuously adds 20mL tetrahydrofurans, discovery is analysed in acetone The coumarone for going out needs the 3min could to dissolve, and the coumarone of the precipitation in DMF dissolves immediately.

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

3rd, the selection of catalyst

The selection of catalyst is particularly significant, it directly affect minute length and measurement result it is accurate.For second The catalyst that acylated method determines hydroxyl value mainly has：Pyridine, perchloric acid, imidazoles, p-methyl benzenesulfonic acid, to dimethylamino naphthyridine （DMPA）.

Pyridine toxicity can be to human body and environmental pollution.Perchloric acid, its catalytic capability is too strong, can produce aliphatic alcohol polyether The ether bond rupture of product；Catalyzed by Imidazole ability is weaker, it is necessary to be heated to reflux half an hour in boiling water bath；P-methyl benzenesulfonic acid is at low temperature Reaction is incomplete.Numerous studies show that there is DMPA superpower nucleophilic to be acylated ability, and its catalytic capability is traditional catalyst pyridine 1000 times.Have the advantages that reaction condition is gentle and is easily controlled simultaneously.And DMPA is solid powdery, suction infringement probability It is small, therefore, present invention selection DMPA is catalyst.

In order to shorten the reaction time and ensure acylated complete, by consulting literatures, final selection is to dimethylamino naphthyridine Catalyst.

Its principle is as follows：

With to dimethylamino naphthyridine as catalyst, in tetrahydrofuran and DMF, acetic anhydride and hydroxyl Generation acylation reaction generates acetic acid, and excessive acetic anhydride is hydrolyzed with water.The acetic acid of generation（Part is generated by acylated hydroxy, another Part is hydrolyzed by excessive acetic acid acid anhydride and generated）Titrated with KOH/EtOH standard liquids again, finally calculate and try to achieve.

ROH+CH₃CO-O-COCH₃=CH₃COOH+CH₃COOR

CH₃CO-O-COCH₃+H₂O=2CH₃COOH

Hydroxyl value is defined：The milligram number of produced acid corresponding KOH when 1g samples are acylated is neutralized, unit is mgKOH/g

According to above-mentioned principle, the assay method of coumarone hydroxyl value of the invention includes step in detail below：

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

B. using the catalyst to dimethylamino naphthyridine and DMF mixed configuration；

C. sample experiment is carried out：To weighCoumarone sample, IOH ' is placed in beaker to estimate hydroxyl value, and is added Enter the catalyst of 20~30mL, add tetrahydrofuran, the acylating reagent of 10~15mL of 20~30mL, stir 12~20min, then 3~5mL water is added, 10~15min is stirred, after adding the tetrahydrofuran of 20~30mL, is marked with the KOH/EtOH of 0.5mol/L Quasi- solution titration is to terminal；

D. blank assay is carried out simultaneously；

E. hydroxyl value content is calculated according to experimental data, computing formula is：

In formula, IOH is hydroxyl value content, mgKOH/g；C is the concentration of KOH/EtOH standard liquids, mol/L；V0 is blank reality Test the volume of consumed KOH/EtOH standard liquids, mL；The body of the KOH/EtOH standard liquids that V1 is consumed by sample experiment Product, mL；M is sample mass, g.

By repeatedly testing repeatedly and calculating, used as one embodiment, described acylating reagent is the N, N- bis- of acetic anhydride NMF solution, its percent by volume is 10~15v/v%.Described catalyst is the N to dimethylamino naphthyridine, N- bis- NMF solution, its concentration is 5~10g/L.In addition, the tetrahydrofuran and N, N- diformazan that are added in described sample experiment The final mixed volume ratio of base formamide is 1:1~2.5.

Embodiment 1

Mixed with DMF using acetic anhydride and configure acylating reagent by 12v/v%；

5g/L mixed configuration catalyst is pressed using to dimethylamino naphthyridine and DMF；

It is accurate to weigh 12g coumarone samples in beaker, 30mL catalyst is added, 20mL tetrahydrofurans are added, add 12mL acylating reagents, stir 12min, add 3mL water, stir 15min, and 0.5mol/L KOH/ are used after adding 20mL tetrahydrofurans EtOH standard liquids are titrated to terminal.Do blank assay simultaneously.

The step of embodiment 2~4 is same as Example 1, and experiment condition and parameter are slightly different, and specifically refers 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
V0, mL	45.4353	56.2467	53.8434	49.7302
					V1, mL	32.4895	42.6924	41.2909	36.8482
IOH	30.38	31.81	29.45	30.24

It is good using repeatability of the invention separately from precision result（RSD is 3.25%）, precision is higher.

The precision of the method for table 2

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

In precise 6g（Accurately to 0.1mg）Finely ground coumarone grinding sample in add 0.60mL n-butanol marks Sample, the rate of recovery of the visible this method of hydroxy value measuring result is shown in Table 3 between 96~102%.

The degree of accuracy of this method of table 3

N-butanol, 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, it is simple, convenient using the assay method of coumarone hydroxyl value of the invention, can quickly and accurately survey Determine the hydroxyl value of coumarone indene resin class, and repeatability is good, and RSD is up to 3.25%, and precision is high, and recovery of standard addition is 96~102% Between.

Those of ordinary skill in the art it should be appreciated that the embodiment of the above be intended merely to explanation the present invention, And be not used as being limitation of the invention, as long as in spirit of the invention, the change to embodiment described above Change, modification will all fall in the range of claims of the present invention.

Claims (4)

1. a kind of assay method of coumarone hydroxyl value, it is characterised in that

Comprise the following steps：

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

B. using the catalyst to dimethylamino naphthyridine and DMF mixed configuration；

C. sample experiment is carried out：To weighCoumarone sample, IOH ' is placed in beaker to estimate hydroxyl value, and adds 20 The catalyst of~30mL, adds tetrahydrofuran, the acylating reagent of 10~15mL of 20~30mL, stirs 12~20min, adds 3~5mL water, stirs 10~15min, and after adding the tetrahydrofuran of 20~30mL, the KOH/EtOH standards with 0.5mol/L are molten Drop is surely to terminal；

D. blank assay is carried out simultaneously；

E. hydroxyl value content is calculated according to experimental data, computing formula is：

In formula, IOH is hydroxyl value content, mgKOH/g；C is the concentration of KOH/EtOH standard liquids, mol/L；V₀It is blank assay institute The volume of the KOH/EtOH standard liquids of consumption, mL；V₁By the volume of the KOH/EtOH standard liquids that sample experiment is consumed, mL；M is sample mass, g.

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

Described catalyst 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, it is characterised in that：

The tetrahydrofuran and the final mixed volume ratio of DMF added in described sample experiment are 1:1~ 2.5。