JP2003035667A - Measuring method for concentration of silanol group - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring method for the concentration of a silanol group in a substance containing moisture in a trace amount. SOLUTION: In the method, the concentration of the silanol group in a sample containing the moisture in the trace mount is measured by a near-infrared and infrared absorptiometric method. In the measuring method, an extinction (A1 ) at a band of a wave number of 3,500 to 3,800 cm<-1> as the characteristic absorption band of both water and the silanol group and an extinction (A2 ) at a band of a wave number of 5,100 to 5,400 cm<-1> as the characteristic absorption band of only the water are measured by a transmission method in a state that the sample is put into a cell, and the concentration of the silanol group in the sample is measured on the basis of an extinction (A4 ) which subtracts an extinction (A3 ) based on a moisture amount corresponding to the extinction (A2 ) from the extinction (A1 ).

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
Of the concentration of trace silanol groups in silicon halide compounds
Concerning the method of measuring silanol group concentration suitable for measurement
That uses the absorbance of infrared light and near-infrared light
It is. [0002] 2. Description of the Related Art Halide halides represented by silicon tetrachloride
Iodine compounds have high reactivity to water and are contained in air
Hydrogen chloride gas
And the Si-Cl bond becomes silanol group Si-O
Changes to H. Silicon halide compounds are
Not only is it an important starting material for the synthesis of iodine compounds,
For applications requiring high purity, such as CVD materials in the conductor industry
The silanol group concentration in the product.
Degree is an important quality determinant together with metallic trace impurities.
You. Conventionally, silanol groups contained in silicon compounds were determined.
There are several methods for measuring the chemical reactivity.
Some suggestions have been made. For example, methyl lithium
Reacts with silanol groups to quantify the generated methane
Is known to obtain the amount of silanol
(S.C.Antakli, J.Serpinet, Chromatographia, Vol.23, N
o.10, p.767-769 (1987)].
The method methylates not only Si-OH bonds but also Si-Cl bonds.
Therefore, it is impossible to analyze silanol groups selectively.
is there. In addition, methods using chemical reactivity are often
Silicon halides such as chlorosilanes with high chemical reactivity
Application to is difficult. [0003] 3000-3700cm by infrared absorption spectroscopy
^-1Utilizing the infrared characteristic absorption of silanol groups in
It is possible in principle to measure the silanol group concentration.
is there. However, the absorption in the above wavenumber region is
Was observed overlapping with the absorption by hydroxyl group
Therefore, measuring the infrared absorption intensity of only the silanol group
It is virtually impossible. Use near-infrared absorption band for this
Then the absorption of water and silanol is 5100-5200 respectively
cm^-1And 4500cm^-1Observed separately in the vicinity. The inventor
Use the above-mentioned light absorption to obtain silanol in silica.
Method for measuring the concentration of phenyl group by near-infrared absorption spectroscopy
(Japanese Patent Application No. 2000-021404). The
According to the invention, silanol groups are not affected by water.
Can be analyzed, but the near infrared absorption band is a forbidden transition.
Absorbance per molar concentration, that is, molar extinction coefficient
Only 1/10 to 1/100 of infrared absorption band, less than 1 mM
The analysis was difficult to perform. [0004] Solving the lack of sensitivity of infrared absorption spectroscopy
The length of the sample cell set in the optical path
The optical path length or cell length) to about 50 to 150 mm.
By using longer cells, higher absorbance can be obtained.
An observation method is disclosed (Japanese Patent Laid-Open No. Hei 9-31852).
No. 5). However, even in this case, the silanol group
Not only the absorbance derived from
Since the absorption intensity by the group also increases, the infrared
Accurately measure the infrared absorption intensity of only silanol groups from the absorption band
It cannot be specified. Therefore, the method uses a concentration
Prevents the entry of trace water from the standard sample preparation stage
Glove box replaced with an inert gas atmosphere
Inefficient work such as adjusting the concentration inside
There was a problem. [0005] SUMMARY OF THE INVENTION In the present invention, water
1 mM or less, for example 0.01 to 0.1 mM
It is possible to measure the concentration of trace silanol groups
Simple and suitable method for measuring silanol groups for quality control applications
For the purpose of providing. [0006] Means for Solving the Problems The present inventors have set forth the above object.
As a result of intensive studies to solve the
Infrared absorption spectrum and near infrared absorption where characteristic absorption is observed
Simultaneous measurement of spectra, large molar extinction coefficient, high sensitivity
Free hydroxy in the infrared region suitable for quantitative analysis
Sill group stretching vibration characteristic absorption band (wave number 3500-3800cm^-1Territory of
Range is used for the determination of silanol groups
In addition, due to the hydroxyl group of water that overlaps the absorption band
Absorption intensity [NIR spectrum reflecting only water concentration
Stretching and bending vibration coupling absorption band (wave number 5100-5400cm^-1
Calculated from the area)) is subtracted from the absorbance
According to the spectrophotometric method based on the obtained absorbance,
Quantitative analysis of silanol groups of 1 mM or less is possible.
And completed the present invention. That is,
Akira reported that the concentration of silanol groups in samples containing
In the method of measuring by infrared / infrared absorption spectrophotometry,
With the sample in the cell, water and silanol
Wave number 3500-3800cm, which is the characteristic absorption band of both groups^-1To the obi
Absorbance (A₁) And wave number 5 which is a characteristic absorption band of water only
100-5400cm^-1Absorbance in band (A_Two) And measure before
Absorbance (A₁), Absorbance (A_TwoCorresponding to)
Absorbance based on water content (A_Three) Minus absorbance
(A_Four), The silanol group concentration in the measurement sample
For measuring silanol group concentration, characterized by measuring
Is the law. [0007] BEST MODE FOR CARRYING OUT THE INVENTION
A sample is a substance that contains a trace amount of water,
Regardless of the type of solid, for example,
There is virtually no limit as it contains a certain amount of water.
Organic compounds or inorganic compounds, or
It may be a single compound or a mixture of multiple compounds. Book
In the present invention, a sample is placed in a cell, and the sample is placed near by a transmission method.
For measuring absorbance of infrared and infrared light
Samples need to be liquid, but dissolve in organic solvents, etc.
For solids, the absorbance of near-infrared and infrared light is measured as a solution sample.
Can be measured, so it is also a measurement target of the measurement method of the present invention.
You can. In the present invention, a particularly preferred measurement sample
Means that a very small amount of water (about 1 ppm or less) and silanol groups
Existing silicon halides such as silicon tetrachloride or disilicon hexachloride
And alkoxysilane. The above silicon tetrachloride
Element, disilicon hexachloride and alkoxysilane
Contact with moisture in the air when handling the sample for
Solution, and a new silanol group is generated.
Must be handled in an atmosphere where such hydrolysis does not occur.
is there. For example, put the sample in a cell for measuring infrared light
In the case, etc., in the glove box replaced with inert gas
It is preferred to perform the operation. In the present invention, measurement
Silicon tetrachloride, disilicon hexachloride and alcohol
The concentration of silanol groups in xysilane is 0.01 to 1
mM or so, to analyze such minute amounts with high accuracy.
In addition, these samples are measured directly without dilution
It is preferably used for certain samples. In the present invention, as described above, water and silicon
Wave number 3500-3800cm, both characteristic absorption bands of lanol group
^-1Wave number 51 which is a characteristic absorption band of infrared light of the band and water only
00-5400cm^-1The absorbance of the sample for near-infrared light in the band,
It is measured by the transmission method. The sample cell used at that time
Therefore, it is preferable that the optical path length is 1 to 50 mm,
When measuring with a sample volume, 1 to 20 mm is preferable.
No. Cell material: quartz glass, Pyrex
(Registered trademark) glass or calcium fluoride is preferred.
You. Measurement of absorbance of near-infrared light and infrared light
Can scan near-infrared light.
Any infrared spectrophotometer can be used. Below is an example of the equipment
And its preferred operating conditions. Equipment: MAGNA750 Fourier Transform Infrared made by Nicolet
X-ray spectrophotometer Light source: tungsten halogen lamp Beam splitter: calcium fluoride Detector: DTGS Measurement cell: 5 mm (quartz cell for liquid) Measurement wave number area: 7000-3000cm^-1 Wave number resolution: 8cm^-1 Number of accumulation: 32 times Measurement atmosphere: nitrogen Temperature during measurement: 25 ° C In the present invention, the wave number is 3500 to 3800 cm.^-1Absorption of
The band is the stretching vibration absorption band of the OH group, while the wave number 5100 to 54
00cm^-1Absorption band is absorbed by water stretching vibration and bending vibration
It is a belt. In the present invention, the OH stretching group of the silanol group
Wave number 3500-3800cm based on quasi-vibration ^-1Infrared absorbance measurement of
Is used to measure the concentration of silanol groups in the sample. Sucking
Conversion from luminous intensity to concentration (mM) is based on the silanol group concentration.
Known organosilanols (hereinafter referred to as reference substances)
Conventional method of comparing with the absorbance of an organic solvent solution
It is good to follow. In the present invention, it is obtained by measuring a sample.
Wave number 3500-3800cm^-1Measurement of infrared absorbance (A₁)
Indicates the stretching vibration of the OH group of water that coexists in addition to the silanol group.
(A)_w) And silanol group alone
Wave number of 3500-3800cm^-1Infrared absorbance (A_FourNeed to know)
Which can be obtained by the following equation (1). A_Four= A₁-A_w              (1) A in the above formula (1)_wContains a silanol group separately
Substances containing trace amounts of water, such as organic solvents such as carbon tetrachloride
As a measurement sample, wave number 5100-5400cm^-1Absorption band and
Wave number 3500-3800cm^-1Absorbance of each absorption band (each A_W1,
A_W2To determine the intensity ratio between the two absorbances
If it is determined in advance, the strength can be calculated by the following equation (2).
Degree ratio and A_Two(Wave number 5100 obtained by measurement of sample
~ 5400cm^{- 1}Absorbance of the absorption band). Postscript
A obtained by the measurement of Example 1_W2/ A_W1Value is 7.
37. A_w= A_Two× (A_W2/ A_W1(2) The absorbance (A)_Four) To silanol group concentration
Is generally used in absorption spectrophotometry.
It is preferable to use a calibration curve. Reference example described later
Uses trimethylsilanol as a reference substance
Using the carbon tetrachloride solution (silanol group concentration;
5.8 mM range).
Come, wave number 5100-5400cm^-1Absorption band and wave number 3500-3800
cm^-1After measuring the absorbance of the absorption band of formula (1),
And (2) using the infrared absorbance (A_Four), Get the concentration and
A_FourIs represented by a calibration curve. In the present invention,
Absorbance (A_Four) To obtain silanol group concentration from
As the reference substance used to create the
In addition to tylsilanol, triphenylsilanol, tri
Ethylsilanol, dimethylsilanediol, diethyl
Silanediol, 1,1,2,2.-tetramethyl-1,2-dihydrido
Roxydisiloxane, ditertiary butyl silanediol
, Triphenylsilanol or diphenylsilanedi
All can be used. The less reactive the reference compound
Trimethylsila
, Triphenylsilanol, 1,1,2,2, -tetrame
Cyl-1,2-dihydroxydisiloxane or ditercia
Libutylsilanediol is handled in the air at room temperature
This is particularly preferable because there is no problem. Hereinafter, the present invention will be described based on Reference Examples and Embodiments.
The invention will be specifically described. [Reference Example] Trimethylsilanol [Shin-Etsu
Chemical Industry Co., Ltd.] and absorb light to create a calibration curve.
The degree was measured. Silanol group concentration of 0 mM (solvent
Only), 5.83 mM, 0.583 mM, 0.117 mM, 0.0583 m
M, as a standard sample of carbon tetrachloride solution adjusted to 0.0117 mM
Using a Pyrex glass cell with an optical path length of 5 mm.
Wave number 5100-5400cm^-1Absorption band and wave number 3500-3800cm^-1
The absorbance of the absorption band was measured. 3500 for each standard sample
~ 3800cm^-1Absorption peak intensity (A₁) Or
Et al., Absorbance of water contribution (A_w) Minus absorbance (A
_Four) Is shown in Table 1. The above
Absorbance (A_w) Is 5100-5400cm^-1Absorbance measurement of
(A_Two) Multiplied by 7.37. The above 7.37
Is 5284 cm for the solvent-only sample^-1And 369
5cm ^-1Absorbance obtained by measuring the absorbance at
It is an intensity ratio of degrees. Absorbance (A_Four)
Plotting against the molarity of tilsilanol
Thus, the calibration curve of FIG. 1 was obtained. [0014] [Table 1] [0015] Example 1 Commercially available tetraethoxysila as a test sample
Dissolve 0.157 g of carbon reagent in carbon tetrachloride and add 10 mL solution
I made it. Infrared and near-infrared spectra of the obtained solution
Was measured. The absorbance obtained from each spectrum is
It was as follows. Infrared spectrum: A₁= 0.0532 Near infrared spectrum: A_Two= 0.0036 Absorbance A of water contribution_w= A_Two× 7.37 = 0.0265 A_Four= A₁-A_w= 0.0267 When converted to the concentration using the calibration curve in Fig. 1,
Has a silanol group concentration of 0.32 mM.
The concentration in ethoxysilane is 0.02 mmol / g. [0016] According to the method of the present invention, simple and quick
By infrared spectroscopy, the sample in the sample solution
It can measure the concentration of the laneau group with high accuracy up to a low concentration.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a coordinate plane in which the abscissa represents the concentration of silanol groups and the ordinate represents the absorbance in the absorption band of 3500 to 3800 cm ⁻¹ to which only silanol groups contributed. 4 is a calibration curve obtained by plotting measured values of several standard solutions of trimethylsilanol having different concentrations.

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Claims (1)

Claims: 1. A method for measuring the concentration of a silanol group in a sample containing a trace amount of water by a near-infrared / infrared absorption spectrophotometer, the method comprising the steps of: Wave number 3500-3800 which is a characteristic absorption band of both water and silanol group
absorbance at cm ^-1 band (A ₁₎ and the absorbance (A ₂₎ and measured at a wave number 5100～5400Cm ^-1 band is the characteristic absorption band of water only, absorbance from among the absorbance (A ₁₎ (A ₂ A) measuring the silanol group concentration in the measurement sample based on the absorbance (A ₄ ) obtained by subtracting the absorbance component (A ₃ ) based on the water content corresponding to (a).