JPH03242306A - Preparation of two zone porous substance by catalytic halosilylation - Google Patents

Abstract

PURPOSE: To easily obtain a two-area porous material by mixing a porous support having an OH group with a solvent and a Lewis base catalyst, adding a specific halosilane to the mixture, forming a silyl group of a first type on the outside surface of this support and supplying a silyl group of a second type to its inside surface.

CONSTITUTION: The hydroxyl group-contg. porous support selected from a porous metalloid oxide, metal oxide, etc., is prepd. This porous support is then suspended in a solvent and after the Lewis base catalyst is added thereto, the halosilane which is the halosilane of the amt. of the not exceeding two molecules per unit nM² of the porous support in this suspension and has the silyl group of the first type is added to the suspension to form the silyl group of the first type on the outside surface of the support by a catalytic reaction. The silyl group of the second type is then supplied to the inside surface of the support and thereafter, the treated support is separated, by which the two-area porous material having the outer area including the outside surface of the porous material and the inner area including the inside surface of the porous material is obtd.

COPYRIGHT: (C)1991,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention provides an outer zone having a first type of silyl group fixed to the outer surface of a porous material and a first type of silyl group fixed to the inner surface of the porous material. and an inner zone having a second type of silyl group, and the dual zone material so produced. More particularly, the present invention relates to a method for catalytically halosilylating the primarily external surface of a porous support having hydroxyl groups and producing a two-zone material.

[Prior Art and Problems to be Solved by the Invention] Co-pending U.S. Pat. A bisurface (more accurately termed bizone) porous material is disclosed that is made by treating a kimono with a sub-stoichiometric amount of an ultrafast silylating agent. The silylating agent is so reactive that the resulting surface groups become immobilized in the outer regions of the porous support before the silylating agent has time to migrate deep into the porous inner regions. selected from those that are available. A subsequent silylation reaction can be used to convert the residual hydroxyl groups present primarily in the inner zone to a second fixed group of another type. D.E.LeydenliWilliams
& Tangney “5ilanes+5urfa”
ces &Interfaces' (1986) Gor
Don & Breach Publisher.

See also p. 471ff.

In co-pending US patent application Ser. No. 598,120, the ultrafast silylating agent disclosed is a reactive silane intermediate. Co-pending U.S. patent application Ser.
It is a silane with These readily available leaving groups reduce the activation energy required for reaction with surface hydroxyl groups, thus making it more difficult for the silane to be captured by covalent bond formation in the outer regions of the porous material. ie increase the degree to which it can be captured early on as it diffuses into the material.

Co-pending U.S. Patent Applications Nos. 154,754 and 5981
As stated in the 20-year-old specification, traditional silylation reactions are generally not fast enough to allow selective silylation of the outer surface of a porous support. "Traditional silylation"
is Plueddemann + “E”
ncyclopedia of Chemical T
technology” 3rd edition, Vol. 20, p. 962-96
3. Broedmann explains that silylation is the displacement of active hydrogen from an organic molecule by a silyl group [the active hydrogen is usually OH, NH or SH, and the silylation agent is usually a trimethylsilyl halide or a nitrogen-functional compound]. . Mixtures of multiple silylating agents may be used; mixtures of trimethylchlorosilane and hexamethyldisilazane are more reactive than either agent alone, and the by-products combine to form neutral ammonium chloride. "I will."

Halosilanes, although specifically attempted, have proven insufficient to produce two-zone materials. For example, Hunnicu (M, L, Hunnicu)
tt) and Harris (J9M, Harris) +”Rea
activity of Organosilane R
agents on Microparticulate
e 5ilica r Anal, Chem,,
Vol. 58 (1986) discusses the use of halosilanes in an attempt to explain the control of pore diffusion in the silylation of silica.

Honeycutt and Harris discuss the consequences of competitive surface reactions between two organosilane mixtures and silica gel.

The organosilane mixtures used include mixtures of two haloalkylsilanes, such as (1-bromomethyl)dimethylmonochlorosilane, (1-chloromethyl)dimethylmonochlorosilane or (3-chloropropyl)dimethylmonochlorosilane, as well as mixtures of haloalkylsilanes and Hexamethyldisilazane (HMDS) or trimethylchlorosilane (
Mixtures with alkylsilanes such as 7MC5) are also included. In many cases, a catalyst such as pyridine was added prior to adding the silane to the silica slurry for base-catalyzed reactions. Hunnicutt and Harris
It was shown that their reactions do not inhibit pore diffusion. Thus, they were unable to produce bizonal materials for their chosen differential distribution of immobilized groups.

This result is believed to be due to several factors.

Most importantly, mixtures of chlorosilanes of the type used by Honeycutt and Harris do not react sufficiently rapidly and differentially even when the reaction is catalyzed with pyridine.

Furthermore, the reaction conditions were not adjusted to produce a two-zone material in that both chlorosilanes were selectively trapped together in the outer zone.

First, the solvent they used was chloroform, which is very polar and is known to be a proton donor in hydrogen-bonded complexes. Such solvents probably act by isolating reactive sites (silanols) on the surface and thus slowing down the reaction rate.
It has been found to reduce inhibition of pore diffusion. Protic solvents such as ethanol are even more harmful because the halosilanes are solvolyzed and converted to less reactive ethoxysilanes. Second, Honeycutt and Harris used an excess of silane, averaging 36 molecules per square nanometer (nM2) of silica surface area, which saturates the silica and thus creates an unstructured rather than two-zone structure. Third, the rate of addition of silane to the silica slurry was extremely fast, approximately 0.3 molecules/IBM"-1Iin, which would have given a uniformly saturated surface treatment. Therefore, individual silica particles would have been exposed to an unusual dosage of silane, and the resulting interparticle heterogeneity would have eliminated any intraparticle heterogeneity (two-zone structure) that might have otherwise occurred. Therefore, even if Honeycutt and Harris carried out what can be described as a catalyzed halosilane reaction, Honeycutt and Harris did not understand how the two-zone material could be produced by such a reaction mechanism. It does not tell those skilled in the art how to make it.

And yet, in order to provide differentially selective adsorbents on the outer and inner surfaces, for example for specific chromatographic or catalytic applications, it is desirable to have only one type of silyl group on the outer surface. And it is known that it is desirable to produce bizonally porous materials having another type of silyl group primarily on the inner surface. It would also be desirable to do so using relatively inexpensive and readily available halosilane reactants.

However, to date it has not been possible to use halosilane reactants for this purpose.

Therefore, there remains a need for a method for halosilylating primarily the outer surface of a porous support having hydroxyl groups to produce bizonally porous materials.

[Means and effects for solving the problem] The present invention has the following features:
That need is met by providing a method for making two-zone materials by using catalyzed halosilanes. Preferred halosilanes for use in the present invention are:
having silyl groups of the first type and, after catalyzed silylation, producing silyl groups of the first type primarily on the outer surface of the porous support. Thus, preferred halosilanes include at least one organic or organic functional group, such as perfluorobutylethylenedimethylsilyl, chloropropylsilyl, 5iCJaO(CLCHtO)
-R (in which a is from 0 to 10 and R is an alkyl, aryl or acetyl group) and CHzCH-CHz Me2 (in which Me is a methyl group) have something Preferred is the formula M e 3- @ Cz Ha
A silyl group having CyI X z□1 in which X is a halogen, n is 1 or more, Me is a methyl group, and m is 1-3.

Halosilanes also have one or more silicon-bonded leaving groups, at least one of the leaving groups being a non-fluorine halogen, i.e. chlorine, bromine or iodine, which when catalyzed Reacts with hydroxyl groups on the outer surface of the porous support.

Hybrid leaving groups in which at least one is a non-fluorine halogen and the others are slowly leaving groups such as eg alkoxy or acetoxy groups are also suitable.

Thus, preferred halosilanes have the formula LJe3-msicJnca+Xts+x, where L is a non-fluorine halogen, Me is a methyl group, and X is a halogen which may be the same as or different from L. , n is 1 or more, and m is 1-3. Halosilanes can be added in solution-based mixtures.

The halosilane mixture is a porous support, such as a porous metalloid oxide, a porous metal oxide or a mixture thereof (preferably in granular form, most preferably granular silica), combined with a solvent. Add to the porous support suspension made by mixing. Preferred solvents are aprotic solvents that solvolyze the halosilane. Most preferred are non-polar solvents such as hexane, octane, decane, toluene or mixtures thereof.

Such non-polar solvents do not retard the reaction rate because their interaction with surface reactive sites is minimal. The porous support suspension preferably also contains a catalyst. The catalyst is a Lewis base catalyst,
Preferred are basic amines such as pyridine, imidazole or ammonia. Nucleophiles known to greatly promote solvolysis of silanes, such as hexamethylphosphoramide or dimethyl sulfoxide (DMSO), are also effective.

As a result of contacting the catalyst-containing suspension of the porous support with hydroxyl groups with the halosilane, silyl groups of the first type are produced primarily on the outer surface of the porous support. This alone is sufficient to create a two-zone material if silica is used as the porous support and as long as the silanol groups remain unreacted in the inner zone. Preferably, however, the porous support is subsequently contacted with a second silane having a second type of silyl groups (different from those of the first type). The silane diffuses into the interior of the porous support and forms a covalent bond by reacting with the hydroxyl groups of the porous support to generate a second type of silyl group on the inner surface of the porous support. It should be possible to do so.

Preferred is a second silane having the formula R, SiX, where R is independently from hydrogen, alkyl of 1 to 20 carbon atoms, phenyl, vinyl, and allyl. X is a hydrolyzable group selected from chlorine, alkoxy groups of 1 to 4 carbon atoms, acetoxy groups, amines and amide groups, and e has a value of 1.2 or 3. Other organofunctional silanes may also be used.

When a second silane having a second type of silyl group is subsequently contacted with the porous support, it reacts primarily with the hydroxyl groups on the inner surface of the porous support. This is because most of the hydroxyl groups on the outer surface have already been consumed by the catalyzed halosilylation. It provides a good quality two-zone material in that the inner zone contains "predominantly" silyl groups of the second type, while some reaction with the hydroxyl groups remaining on the outer surface may occur.

In practice, the amount of surface area considered to be in the inner area relative to the amount of surface area considered to be in the outer area of the porous support may vary.

Preferably for the purposes of this invention, the inner region comprises approximately the inner 90% of the surface area of the porous material and the outer region comprises approximately the outer 10% of the surface area of the porous material.
%. Using a larger amount of halosilane will result in a greater degree of penetration into the interior of the porous support, causing reaction with a larger number of hydroxyl groups on the surface of the porous support, and would create a larger outer area that would take up a larger proportion of the surface area of. Thus, the outer region can range from 0.5% to 50% of the surface area, and the inner region can range from 50% to 99.5% of the surface area.

In any case, it is possible to control the degree of catalyzed halosilylation by adjusting the size of the outer zone. This allows the production of two-zone materials with varying degrees of capacity for separation, such as for use as packing materials in liquid chromatography and elsewhere.

Accordingly, it is an object of the present invention to provide an improved method for making two-zone porous materials using catalyzed halosilylation and to provide two-zone materials made by the method.
Other objects and advantages of the invention will become apparent from the following detailed description and claims.

Porous materials that have been found useful in this invention are materials that are porous solids having hydroxyl groups on their surface. Such materials are, for example, silica, silica gel, alumina, stannia, titania, zirconia, and the like. These materials can also be porous glasses, porous ceramics or plastics, as long as the materials have hydroxyl groups on their surface or produce hydroxyl groups on their surface.

The form of the porous material is not critical; both granular porous materials, filaments, slabs, disks, blocks, spheres, films, and other such forms can be used in the present invention. It is also considered within the scope of this invention to treat particulate material according to the method of this invention and to subsequently form the treated particulate material into slabs, discs, blocks, spheres, films, membranes, etc. to make sheets and other similar things.

Preferred for this invention are porous metalloid oxides, metal oxides or mixtures thereof, e.g.
Such as silica, alumina, zirconia and titania in all relevant forms. The most preferred is
The pore size can vary, for example from 50 to 2,000 pores and the particle size can vary, for example from 34 to 10,100 pores.
It is a granular silica that can be of various types.

As previously mentioned, the first step in making the bizonally porous materials of the present invention is to create a solvent suspension of the porous support. The solvent is preferably an aprotic solvent, most preferably a non-polar solvent such as hexane, octane, decane, toluene or mixtures thereof. Preferably, porous silica particles with a particle size of 3 to 1000 m are mixed with the solvent in an amount of 0.1 to 40 w/v%.

Also as mentioned above, a Lewis base catalyst may be added at this stage. The catalyst may be amine-like pyridine or ammonia, but imidazole is the more preferred catalyst. Nucleophiles, e.g. hexamethylphosphoramide, which are known to form complexes with halosilanes under certain conditions, as well as others, e.g., which are known to greatly promote solvolysis of silanes. Something like dimethyl sulfoxide can also be used.

The amount of catalyst to be used should be at least 0.05 molecules per square nanometer of silica surface. The preferred amount of catalyst used is 0.2 to 4.8 molecules/nMZ.

The porous support suspension hehalosilane is then added, preferably in the form of a solution-based mixture, preferably using the same solvent used in the porous support suspension. This halosilane has the first type of silyl group. Preferred halosilanes have the formula L@Me3-@
5iCJ4CJzn+ r, in which L is a non-fluorine halogen, Me is a methyl group, X is a halogen that may be the same as or different from L, and n is 1 or more; , and m is 1-3.

Most preferred are CaF, C, H4SiMezCl,
That is, although it is a fluoroalkylsilane containing C and F, CFs, CgFs, C5Ft, etc. may also be used.

Fluoroalkylsilanes are most preferred in that they can be used to produce bizonally porous materials with fluoroalkylsilyl groups in the outer zone. Co-pending U.S. Patent Application No. 063 filed on May 17th
When used as a reverse phase packing material for high pressure liquid chromatography serum analysis as disclosed in US Pat.

Halosilane ranges from 0.01m/nM” to 2.0m/nM
Preferably, the porous support is contacted with 0.2 m/nM halosilane, or 0.2 molecules of halosilane per square nanometer of surface area of the porous support.

Catalyzed halosilylation can be carried out for a period of 1 minute up to 24 hours. Generally, for purposes of this invention, it is preferred to conduct the catalyzed halosilylation over a period of approximately 30 minutes to 6 hours to ensure uniform treatment of the outer surface of the porous material.

The temperature at which the catalyzed halosilylation is carried out is not strictly critical (it can range from 0°C to 400°C; preferred is a reaction mixture temperature from room temperature to 200°C). .

Generally, the outer zone can be the outer 0.5% to 50% of the surface area of the porous support. That said, there is often a not-so-significant difference between the outer and average surface compositions due to random variations in the analytical results. Furthermore, the real difference between the two compositions is
It must be large enough to have a significant effect on the properties of the material.

In view of these issues, meaningful bizonal characteristics are obtained only if one of the following conditions is met:

(a) rl(E)/rl(A)2:1.5, r, (E)
2: 0.3 molecules/nM” and r, (A)≧0.1 molecules/
nM” (b) r', (E) /r', (A) 2:1.5
, r', (E), = (15% of the saturation of the surface of the porous material
), and r, (A) , ll = (5% of the saturation of the surface of the porous material), where r (E) is the outer surface density (molecules/nM”) as estimated by electron spectrochemical analysis. ), and r”, (
A) and r'', (A) are similar measurements of average surface density determined by bulk analysis, and subscript numbers 1 and 2 are, respectively, initially immobilized by reaction with a catalyzed halosilane. and then immobilized by reaction with a second silane.

Concentration is the number of molecules per square nanometer (m/nM”)
expressed in an appropriate unit such as

R1(E)=Aj/A.

where xI is the amount of a certain atomic group (subscripted 1) measured in moles per gram of silica by bulk elemental analysis, and S is expressed in square meters per gram of silica. is the specific surface area, and R1(E
') is the ESCA measurement ratio of the surface atomic composition AJ of element j to that A of element r. Element j is selected to be unique to group 1, and element r is selected to be primarily derived from the porous substrate. Silicon was selected as the control element r, which is due to the immobilized silane
This is because the contribution to 1 is relatively small. similar quantity r'
, (A) and R@, (A) are found by measurements on silica with a fixed group 1 without compositional gradients. Such materials are easily prepared by exhaustive treatment with a single silylating agent.

Also included within the scope of this invention are constructs that are intermediates. These constructs consist of a porous material to which the fixed silicon-containing groups have reacted and whose porous inner surface contains hydroxyl groups. Modified by lowering the requirement that the quantities listed above be equal.

These intermediates are useful products for the above-disclosed method for providing a two-zone material using reactive silanes to treat internal pore surfaces.

Thus, although it is possible to consider the unreacted silanol groups inherent in the inner surface of a porous silica support to be the inner region, it is preferable that the second type of silyl groups are primarily located on the outer surface. A porous support having silyl groups of a first type is contacted with a silane having silyl groups of a second type and capable of diffusing into the interior of the porous support.

The purpose of this preferred step is to allow the second silane to diffuse into the pores of the porous support and to react with the hydroxyl groups covalently bonded to the inner surface. . If water is added during this reaction step, it can actually become a hydrolysis product with the silanol groups of the silane reacting with the hydroxyl groups of the inner zone.

Since the hydroxyl groups in the accessible outer areas of the porous material have been effectively removed by the catalyzed halosilylation, the second silane cannot obtain accessible reaction sites on the outer surface of the porous support. . Thus, the second silane can utilize only the hydroxyl groups remaining on the inner surface of the porous support for reaction.

This step therefore involves the diffusion of a second silane having a second type of silyl group into the pores and the reaction there of with the hydroxyl groups of the inner zone (or the silane is hydrolyzed). It must then be carried out for a period long enough to allow the hydrolyzate to diffuse into the pores and react.

This step can be carried out for a period of minutes up to several hours. The preferred reaction time for this step for this invention is from 10 minutes to 24 hours, most preferably from 1 to 6 hours.

The temperature at which this step is carried out is not critical. As one would expect, increasing the temperature increases the reaction rate. Increasing the temperature too much does not appear to promote undesirable side reactions. Thus, the temperatures used in this step range from 0°C to 400°C.
It can range up to C. Most preferred is a reaction reflux temperature of about 70-120°C.

The amount of the second silane having the second type of silyl group useful in this invention depends on how many of the surface hydroxyls inside the pores are desired to be treated. An excess of the second silane can be used since it does not replace any of the outer surface groups obtained by the catalyzed halosilylation.

Reactive silanes useful in this step are those types of silanes that are recognized as conventional silylating agents. For example, the second silane can be any of the reactive silanes used in step 2 of U.S. Patent Application No. 154,754, filed February 11, 1988.

Preferred as the second silane is the general formula Rn-3iX
-, in which R is independently selected from hydrogen, alkyl groups of 1 to 20 carbon atoms, phenyl groups, vinyl groups, and allyl groups, and
is a hydrolyzable group selected from chlorine, alkoxy groups having 1 to 4 carbon atoms, acetoxy groups, amines and amide groups, and e has a value of 1.2 or 3. Other organofunctional silanes may also be used.

Specific silanes that are useful herein include the following: Namely, trimethylchlorosilane, dimethyldichlorosilane, hexamethyldisilazane, N, N'
-bis(trimethylsilyl)urea, N-)limethylsilyldiethylamine, N-trimethylsilylimidazole, N, O-bis(trimethylsilyl)acetamide, N
, O-bis(trimethylsilyl)trifluoroacetamide, N-methyl-N-)limethylsilyltrifluoroacetamide, t-butyldimethylsilylimidazole, N-trimethylsilylacetamide, N-trimethylsilylpiperidine, hexamethyldisilazane, O-trimethylsilyl acetate, 0-trimethylsilyltrifluoroacetate, N-)limethylsilyldimethylamine, N-)limethylsilylmorpholine, N-trimethylsilylpyrrolidone, and N-)limethylsilylacetanilide.

Yet another aspect of the invention is the use of an organofunctional silane to silylate the porous material in this step. Such silanes useful in this invention include, for example, (α-methacryloxypropyl)trimethoxysilane, (4-aminopropyl)triethoxysilane, T-(β-aminoethylamino)propyltrimethoxysilane, (T-glycidoxypropyl)trimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, (β-mercaptoethyl)trimethoxysilane, (T-mercaptopropyl)trimethoxysilane, (r -chloropropyl)trimethoxysilane, or those of the following formula, i.e., CHz = CHCaH4CHJH(CHz)! NH(
CHz) 5Sj(OCH:+)3・HCI.

(CH30) ssi (CL) J (CHs) zc
+ sHs, cl (CHs) 3si (CHz) s
N (CHs) zc+ zHtscdo (CH30)
3Si (CHz) JCHs (C+zHzs) zC
l-(CH30) ssi (CHz) 9CH31(
CHsO) 3si(CHz)+qCHs and other similar ones. These silanes provide the inner zone with a variety of useful chemistries that can be effectively combined with the beneficial transport properties of the groups in the outer zone.

For example, outer groups can enhance the ion selectivity of chelating groups that are covalently bonded to the inner surface.

Once it is determined that the reaction in this step is essentially complete, the product is typically separated from the reaction mixture. Thus, the final step of the process is to separate such products from the reaction mixture. This can be accomplished in a number of ways; for example, the liquor can be decanted, the porous material washed, and the liquor subsequently decanted, or the reaction mixture can be filtered to separate the liquor from the solid product. The final product can be used in this form or it can be dried. If the final product is in a form other than granules, it can be used as is. , or it can be further shaped and molded without losing its beneficial properties.If the final product is in granular form, it can be used as is or it can be compressed. It can be sintered, sintered, or otherwise shaped.

〔Example〕

The following examples are provided for illustrative purposes only so that those skilled in the art may fully appreciate and understand the invention described herein. These examples should not be construed as limiting the invention, which is expressly defined in the claims.

Six examples of this new method for obtaining two-zone materials are presented. Also shown are three examples in which "uncatalyzed" chlorosilanes are unable to provide two-zone materials. Two different porous silicas were used as described below. What is that silica?
That is, 1) Baker #3405-
1 chromatography grade, 60-200 mesh, pore size 60, specific surface area 300 Mz/g,
and 2) Amicon #84224,
20I! m particles, pore diameter 250 m, specific surface area 320 m
2/g.

Part 1: Preparation of C4F9CZH4MezSi/5iOH two-zone material 1.00 g (2,40H/nM2
1.2 Xl0-3 eq.
0.017 g of cc of octane (2,5X 10-
500cc with air motor driven paddle, addition funnel and condenser with Nt sweep on top
into an indented round bottom flask. The mixture was stirred for 10 minutes and heated at 125°C to reflux the solvent to form a silica suspension. Next, 3
0.034 g (1,OX10
-4 equivalents or 0.20 m/nM of C4FqCJJez
A freshly prepared solution of SiCj2(PFBCl) was
The mixture was added over 15 minutes while stirring vigorously. Then,
The reaction mixture was refluxed for 45 minutes without stirring. After cooling, the silica was separated by filtration and washed three times with octane and three times with diethyl ether. Finally, the treated silica was dried in a vacuum oven at 80° C. for 3 hours before analysis or further work.

Bulk analysis yielded an F value of 1.04% by weight, corresponding to an average surface concentration of 0.12m/nM'' for PFB. External surface analysis by ESCA yielded an F value of 0.75% by weight for PFB.
0.54 F/S, corresponding to a concentration at the outer surface of "m/nM"
The value of t was obtained. Thus, this material satisfies the modified condition (a) for two-zone materials.

The value of bulk analysis is calculated as 300M, including the specific surface area of silica.
/g values were used to convert to the average surface concentration. Calculation of outer surface concentration is 1.11 F/Si (ESCA)
and 10.74% F by weight.

These reference values were obtained for Baker silica which was thoroughly treated with the N-methylacetamide derivative of the chlorosilane described above to ensure that no compositional gradients were present.

! lLi: 0.35 g of silica and 10 octane treated as in Example 1 for the preparation of PFB/T-S two-zone material
0 cc was placed in a 200 cc round bottom flask equipped with a condenser with a N2 sweep on top. This slurry was stirred for 1 minute and 0.13CC (8,4X 10
-' equivalents or twice the equivalents of OH) of N-methyl-N-trimethylsilylacetamide (TMSA) was added and the flask was heated to reflux for 2 hours. After cooling, the treated silica was separated, washed and dried as above.

From bulk analysis, PFB of 0.13 m/nM and 2.
Values of 1.04 wt.% F and 4.26 wt.% C were obtained, corresponding to an average surface concentration of TMS ()trimethylsilyl) of 25 m/nM. Analysis of the outer surface by ESCA revealed that 0.04 wt.% F and 4.26 wt.% C were obtained. 0 corresponding to a PFB of 69m/nM”
, 49F/St was obtained. Thus, this material satisfies condition (a) for a two-zone material.

■-UNI PPB/5iOH Two-compartment substance preparation example 1 imidazole was added to 20.3+H pyridine (0.5 m/n
The same procedure as in Example 1 was used except that M was replaced.

Bulk analysis yielded an F value of 1.38 wt%, corresponding to an average surface concentration of 0.17 m/nM'' in PFB; analysis of the outer surface yielded a value of 0.32 m/nM''. Values of 0.23F/Si were obtained. Thus, this material met the modified condition (a) for a two-zone material.

Based on: Unsuccessful Preparation of PFB/5iOH Bizonal Material The same procedure as Example 1 was used, except that the imidazole catalyst was omitted.

Bulk analysis yielded an F value of 0.29% by weight, corresponding to an average surface concentration of 0.035 m/nMz for PFB. Analysis of the outer surface yielded a value of 0,057 F/St, corresponding to 0.08 m/nM''. Thus, this material was tested under conditions (a) or (b) or modified conditions (a). ) or (b), and should not be considered a two-zone substance.

■-5: Preparation of PFB/5iOH two-compartment material The same procedure as in Example 1 was used, except as noted above.

That is, 1.00 g (2.40 H/nM") was refluxed twice in dilute nitric acid, followed by thorough washing with distilled water to remove the initial catalytic activity of this particular silica.
(3×10-” equivalents) of similarly dried Amicon silica (the above activity is related to the formation of disiloxane from trimethylsilanol and has no effect on the kinetics of surface silylation). ) 0.018 g (2,7 x 10-' equivalents or 0.5 m/nM") of imidazole and 0.036 g
(1, I Xl0-'equivalent or 0.2 m/nM'') of PFBCf was used.

Bulk analysis yielded an F value of 1.58 wt%, corresponding to an average surface concentration of 0.18 m/nM'' for PFB. Analysis of the outer surface by ESCA yielded an F value of 0.60 m/nM.
A value of 0.39F/Si corresponding to the PFB of M2 was obtained. Thus, this material satisfies the modified condition (a) for two-zone materials.

The value of the bulk analysis was converted to an average surface concentration using a value of 320 M''/g as the specific surface area for this particular silica.
) and a reference value of 12.86% F by weight. These reference values were obtained for Amicon silica which was thoroughly treated with an excess of the N-methylacetamide derivative of the chlorosilane described above to ensure that no compositional gradients were present. Concentration conversions in Examples 6 and 7 were performed in the same manner.

Li: Preparation of PFB/TMS two-zone material Example 5 above
0.35 g of treated silica was added to 0.14 cc of TMSA (8,9
0-' equivalents or 2 times equivalents of OH), washed,
And let it dry.

From bulk analysis, PFB of 0.17 m/nM and 2.
Values of 1.47 wt% F and 4.69 wt% C were obtained, corresponding to an average surface concentration of TMS of 28 m/nM. Analysis of the outer surface by ESCA revealed that 0.56 m
A value of 0.37F/St was obtained, corresponding to a PFB of /nM''.

Thus, this material met the modified condition (a) for a two-zone material.

Example 7: Failure to prepare a PFB/5iOH two-zone material Example 5 without the presence of intentionally added catalyst
The procedure was repeated.

Bulk analysis yielded an F value of 0.56 wt%, corresponding to an average surface concentration of 0.06 m/nM'' in PFB. Analysis of the outer surface by ESCA yielded an F value of 0.11 m/nM''.
A value of 0.07F/Si was obtained, which corresponds to a PFB of nM". Thus, this material can be used under conditions (a) or (b).
) or modified conditions (a) or (b) and should not be considered a two-zone substance.

fLL: cp, c, u4Me! Preparation of st/TMS two-zone material 1.00 g (1.00 g at 2,40H/nM”
．． 2Xl0-'equivalent OH)
．． 017g (2,5Xl0-' equivalent or 0.5 molecule/
nM”) of imidazole in a 500 cc fluted round bottom flask equipped with an air motor-driven paddle, an addition funnel, and a condenser with an N2 sweep on top. The mixture was stirred for 10 min and heated at 69° Heat to reflux at C. While at reflux, add 16.9111 (or 0.2 m/nM) of C in 15 cc of hexane.
FxCHzCHzMezSiCi! , (designated TFSC42) was added over 5 minutes,
This was followed by stirring for 1 minute. Then add 15c to this mixture
0.18 cc (2,8 m/nM in hexane of c
TMsCIl from 2) was added and refluxed for 2 hours without stirring.

The solids were removed from the cooled mixture by filtration and washed twice with hexane, 50150 acetonitrile/water to remove salts, acetonitrile, and finally diethyl ether. The treated silica was dried in a vacuum oven at 80°C for 3 hours and subjected to analysis.

From the bulk analysis, 0.11 m/nM” of TFS and T
Values of 0, 30 wt% F and 2.66 wt% C were obtained, corresponding to an average surface concentration of 1.38 m/nM” for MS. External surface analysis by ESCA revealed that 0, 30 wt% F and 2.66 wt% C for TFS
．． A value of 0.161 F/Si was obtained, corresponding to 64 m/nM''.

Thus, this material has the condition for a two-zone material (a
) was met.

The value of the bulk analysis is expressed as the specific surface area of Baker silica.
The value of 00M”/g was used to convert to the average surface concentration. The calculation of the outer surface concentration was 0.412F/5i (ESCA
) and 4.10% F by weight. These reference values were determined using excess TFSA at room temperature.
A sample of silica was obtained which was thoroughly processed twice to ensure that no compositional gradients were present. Example 9
Concentration conversion was performed in the same manner.

■-■: TFS/TMS Two-zone Material Sub-zone Material Example A preparation was attempted following the procedure set forth in Example 8, except that the catalyst (imidazole) of Example 8 was not added.

Bulk analysis yielded values of 0.11 wt% F and 0.60 wt% C, corresponding to average surface concentrations of 0.039 m/nM” for TFS and 0.27 m/nM” for TMS. . The analysis of the outer surface by ESCA shows that 0.
0,016F/5 corresponding to a TFS of 064m/nM2
The i(7) value was obtained. In this way, this substance has the condition (
a) or (b) or modified conditions (a) or (b) could not be met and should not be considered a two-zone substance.

Although the invention has been described in detail and with reference to its preferred embodiments, it will be obvious that modifications and changes may be made thereto without departing from the scope of the invention as defined in the claims. .

Claims (1)

[Claims] 1. A method comprising steps a) to e) below, having an outer region comprising an outer surface of a porous material and an inner region comprising an inner surface of the porous material. dual z
one) method of making porous materials into steel. a) providing a porous support having hydroxyl groups selected from the group consisting of porous metalloid oxides, porous metal oxides and mixtures thereof; b) mixing this porous support with a solvent; c) Creating a porous support suspension which also contains a Lewis base catalyst c) Adding 2.00 molecules per unit nM^2 of porous support in this suspension to this suspension. an amount of a halosilane having a first type of silyl group and catalyzed by the catalyst to produce the first type of silyl group primarily on the outer surface of the porous support. d) providing a second type of silyl group primarily on the inner surface of the porous support as described above; e) subsequently separating the porous support thus treated, thereby 2. The method of claim 1, wherein step 2 of providing said bizonally porous material, said porous support being particulate silica. 3. The method of claim 1, wherein the rate of addition of the halosilane does not exceed 0.2 molecules/min per nM^2 of porous support in the suspension. 4. A bilayer having an outer region comprising an outer surface of a porous material and an inner region comprising an inner surface of the porous material, prepared by a method comprising steps a) to e) below. A composition consisting of a regionally porous material. a) providing a porous support having hydroxyl groups selected from the group consisting of porous metalloid oxides, porous metal oxides and mixtures thereof; b) mixing this porous support with a solvent; c) Creating a porous support suspension which also contains a Lewis base catalyst c) Adding 2.0 molecules per nM^2 of porous support in this suspension to this suspension. an amount of a halosilane having a first type of silyl group and catalyzed by the catalyst to produce the first type of silyl group primarily on the outer surface of the porous support. d) providing a second type of silyl group primarily on the inner surface of the porous support as described above; e) subsequently separating the porous support thus treated, thereby Step 5 of providing said two-zone porous material, comprising steps a) to d) below, having an outer zone comprising an outer surface of the porous material and comprising an inner surface of the porous material. A method of steelmaking an intermediate useful in preparing a two-zone porous material having an inner zone. a) providing a porous support having hydroxyl groups selected from the group consisting of porous metalloid oxides, porous metal oxides and mixtures thereof; b) mixing this porous support with a solvent; c) Creating a porous support suspension which also contains a Lewis base catalyst c) Adding 2.0 molecules per unit nM^2 of porous support in this suspension to this suspension. an amount of a halosilane having a first type of silyl group and catalyzed by the catalyst to produce the first type of silyl group primarily on the outer surface of the porous support. d) followed by step 6 of separating the porous support thus treated and thereby providing said intermediate, said porous support being granular silica, as claimed in claim 5. the method of. 7. The method of claim 5, wherein the rate of addition of the halosilane does not exceed 0.2 molecules/min per nM^2 of porous support in the suspension.