METHOD FOR PERFORMING A CONDENSATION REACTION USING A SURFACE-REACTED CALCIUM CARBONATE CATALYST

Abstract

The present invention relates to a method for performing a condensation reaction by heterogeneous catalysis using a surface-reacted calcium carbonate catalyst and the use of a dry surface-reacted calcium carbonate as a catalyst. The condensation reaction involves reacting a first substrate comprising a CO double bond and a second substrate comprising an activated hydrogen to obtain a reaction mixture comprising one or more condensation products and one or more condensation byproducts.

Claims

1. A method for performing a condensation reaction by heterogeneous catalysis, the method comprising the steps of a) providing a first substrate comprising a CO double bond; b) providing a second substrate comprising an activated hydrogen; c) providing a surface-reacted calcium carbonate, wherein the surface-reacted calcium carbonate is a reaction product of ground natural calcium carbonate (GNCC) or precipitated calcium carbonate (PCC) with carbon dioxide and one or more H.sub.3O.sup.+ ion donors and wherein the carbon dioxide is formed in situ by the H.sub.3O.sup.+ ion donors treatment and/or is supplied from an external source, and wherein the surface-reacted calcium carbonate has a specific surface area of at least 10 m.sup.2/g, measured using nitrogen and the BET method according to ISO 9277:2010; d) activating the surface-reacted calcium carbonate of step c) at a temperature in the range from 100 to 500 C. to obtain a dry surface-reacted calcium carbonate; e) reacting the first substrate of step a) and the second substrate of step b) in the presence of the dry surface-reacted calcium carbonate of step d) to obtain a reaction mixture comprising one or more condensation products and one or more condensation byproducts.

2. The method of claim 1, wherein the first substrate is a compound ##STR00013## according to formula (1) wherein R.sup.1 is selected from the group consisting of i) a hydrogen atom, and ii) an organyl group R.sup.11, wherein R.sup.11 is optionally substituted by one or more groups selected from the group consisting of a halide group, a hydroxy group, an oxo group, an alkyl group, a vinyl group, an alkoxy group, an acyloxy group, a carboxyl group, an epoxy group, an anhydride group, an ester group, an aldehyde group, an amino group, a ureido group, an azide group, a phosphonate group, a phosphine group, a sulfonate group, a sulfinate group, a sulfonyl group, a sulfinyl group, a sulfide group or disulfide group, an isocyanate group or masked isocyanate group, a thiol group, a nitrile group, an amine group, a phenyl group, a benzyl group, a styryl group and a benzoyl group; and wherein X is selected from the group consisting of i) a hydrogen atom, ii) an organyl group R.sup.X, wherein R.sup.X is optionally substituted by one or more groups selected from the group consisting of a halide group, a hydroxy group, an oxo group, an alkyl group, a vinyl group, an alkoxy group, an aryloxy group, an acyloxy group, a carboxyl group, an epoxy group, an anhydride group, an ester group, an aldehyde group, an amino group, a ureido group, an azide group, a phosphonate group, a phosphine group, a sulfonate group, a sulfinate group, a sulfonyl group, a sulfinyl group, a sulfide group or disulfide group, an isocyanate group or masked isocyanate group, a thiol group, a nitrile group, an amine group, a phenyl group, a benzyl group, a styryl group and a benzoyl group, and iii) a leaving group LG.

3. The method of claim 1, wherein the second substrate is a compound according to formula (2) ##STR00014## wherein Z.sup.1 is an electron-withdrawing group, and wherein R.sup.2 is selected from the group consisting of i) a hydrogen atom, ii) an organyl group R.sup.21, wherein R.sup.21 is optionally substituted by one or more groups selected from the group consisting of a halide group, a hydroxy group, an oxo group, an alkyl group, a vinyl group, an alkoxy group, an aryloxy group, an acyloxy group, a carboxyl group, an epoxy group, an anhydride group, an ester group, an aldehyde group, an amino group, a ureido group, an azide group, a phosphonate group, a phosphine group, a sulfonate group, a sulfinate group, a sulfonyl group, a sulfinyl group, a sulfide group or disulfide group, an isocyanate group or masked isocyanate group, a thiol group, a nitrile group, an amine group, a phenyl group, a benzyl group, a styryl group and a benzoyl group, and iii) an electron-withdrawing group Z.sup.2, with the proviso that, if Z.sup.1 is an electron-withdrawing group other than an acyl group, a formyl group, an acetyl group or a nitro group, then R.sup.2 is an electron-withdrawing group Z.sup.2.

4. The method of claim 1, wherein the first substrate is a compound according to formula (1) ##STR00015## and the second substrate is a compound according to formula (2), ##STR00016## and wherein R.sup.1 is a hydrogen atom or an organyl group R.sup.11, wherein R.sup.11 is optionally substituted by one or more groups selected from the group consisting of a halide group, a hydroxy group, an oxo group, an alkyl group, a vinyl group, an alkoxy group, an acyloxy group, a carboxyl group, an epoxy group, an anhydride group, an ester group, an aldehyde group, an amino group, a ureido group, an azide group, a phosphonate group, a phosphine group, a sulfonate group, a sulfinate group, a sulfonyl group, a sulfinyl group, a sulfide group or disulfide group, an isocyanate group or masked isocyanate group, a thiol group, a nitrile group, an amine group, a phenyl group, a benzyl group, a styryl group and a benzoyl group, X is a hydrogen atom, R.sup.2 is a hydrogen atom or an organyl group R.sup.21, wherein R.sup.21 is optionally substituted by one or more groups selected from the group consisting of a halide group, a hydroxy group, an oxo group, an alkyl group, a vinyl group, an alkoxy group, an aryloxy group, an acyloxy group, a carboxyl group, an epoxy group, an anhydride group, an ester group, an aldehyde group, an amino group, a ureido group, an azide group, a phosphonate group, a phosphine group, a sulfonate group, a sulfinate group, a sulfonyl group, a sulfinyl group, a sulfide group or disulfide group, an isocyanate group or masked isocyanate group, a thiol group, a nitrile group, an amine group, a phenyl group, a benzyl group, a styryl group and a benzoyl group, and Z.sup.1 is an electron-withdrawing group selected from the group consisting of an acyl group, a formyl group, an acetyl group and a nitro group.

5. The method of claim 1, wherein the first substrate is a compound according to formula (1) ##STR00017## and the second substrate is a compound according to formula (2), ##STR00018## and wherein R.sup.1 is a hydrogen atom or an organyl group R.sup.11, wherein R.sup.11 is optionally substituted by one or more groups selected from the group consisting of a halide group, a hydroxy group, an oxo group, an alkyl group, a vinyl group, an alkoxy group, an acyloxy group, a carboxyl group, an epoxy group, an anhydride group, an ester group, an aldehyde group, an amino group, a ureido group, an azide group, a phosphonate group, a phosphine group, a sulfonate group, a sulfinate group, a sulfonyl group, a sulfinyl group, a sulfide group or disulfide group, an isocyanate group or masked isocyanate group, a thiol group, a nitrile group, an amine group, a phenyl group, a benzyl group, a styryl group and a benzoyl group, X is a hydrogen atom, Z.sup.1 is an electron-withdrawing group, R.sup.2 is an electron-withdrawing group Z.sup.2, and wherein Z.sup.1 and Z.sup.2 are independently from each other selected from the group consisting of an acyl group, a formyl group, a nitro group, a nitrile group, and an ester group.

6. The method of claim 1, wherein the first substrate and the second substrate are the same compound.

7. The method of claim 1, wherein the surface-reacted calcium carbonate of step c) has i) a volume median particle size (d.sub.50) from 0.5 to 50 m, and/or ii) a top cut (d.sub.98) value from 1 to 120 m, and/or iii) a specific surface area (BET) from 10 to 200 m.sup.2/g, as measured by the BET method.

8. The method of claim 1, wherein the dry surface-reacted calcium carbonate of step d) has i) a residual total moisture content from 0.01 wt.-% to 0.75 wt.-%, 0.02 and/or ii) a total number of basic sites from 0.01 to 0.6 mmol/g, based on the total dry weight of the surface-reacted calcium carbonate, determined by temperature-programmed desorption with ammonia, and/or iii) a total number of acidic sites from 0.01 to 0.6 mmol/g, based on the total dry weight of the surface-reacted calcium carbonate, determined by temperature-programmed desorption with carbon dioxide.

9. The method of claim 1, wherein the one or more H.sub.3G.sup.+ ion donors are selected from the group consisting of hydrochloric acid, sulfuric acid, sulfurous acid, phosphoric acid, citric acid, oxalic acid, an acidic salt, acetic acid, formic acid, and mixtures thereof.

10. The method of claim 1, wherein activation step d) is performed at a temperature from 150 C. to 400 C., and/or for a duration of at least 0.5 h, optionally at a pressure of less than 101.3 kPa.

11. The method of claim 1, wherein reaction step e) is performed i) in the absence of a solvent or in the presence of a solvent, and/or ii) in the liquid phase at a reaction temperature in the range from 20 C. to 250 C.

12. The method of claim 1, wherein in reaction step e) i) the dry surface-reacted calcium carbonate is added in an amount from 0.5 to 50 wt., based on the total weight of the first substrate, and/or ii) the first substrate and the second substrate are added in a molar ratio from 1:1 to 1:20.

13. A catalyst comprising a dry surface-reacted calcium carbonate, wherein the surface-reacted calcium carbonate is a reaction product of ground natural calcium carbonate-containing mineral (GNCC) or precipitated calcium carbonate (PCC) with carbon dioxide and one or more H.sub.3O.sup.+ ion donors and wherein the carbon dioxide is formed in situ by the H.sub.3O.sup.+ ion donors treatment and/or is supplied from an external source, and wherein the surface-reacted calcium carbonate has a specific surface area of at least 10 m.sup.2/g, measured using nitrogen and the BET method according to ISO 9277:2010, and wherein the surface-reacted calcium carbonate has been dried by heating at a temperature in the range from 100 to 500 C.

14. The catalyst of claim 13, wherein the dry surface-reacted calcium carbonate has i) a volume median particle size (d.sub.50) from 0.5 to 50 m, and/or ii) a top cut (d.sub.98) value from 1 to 120 m, and/or iii) a specific surface area (BET) from 10 to 200 m.sup.2/g, as measured by the BET method, and/or iv) a residual total moisture content from 0.01 wt.-% to 0.75 wt.-%, based on the total dry weight of the surface-reacted calcium carbonate, and/or v) a total number of basic sites from 0.01 to 0.6 mmol/g, determined by temperature-programmed desorption with ammonia, and/or vi) a total number of acidic sites from 0.01 to 0.6 mmol/g, determined by temperature-programmed desorption with carbon dioxide.

15. (canceled)

Description

EXAMPLES

[0377] Measurement Methods

[0378] In the following, measurement methods implemented in the examples are described.

[0379] Particle Size Distribution

[0380] Volume determined median particle size d.sub.50(vol) and the volume determined top cut particle size des(vol) was evaluated using a Malvern Mastersizer 3000 Laser Diffraction System (Malvern Instruments Plc., Great Britain). The d.sub.50(vol) or des(vol) value indicates a diameter value such that 50% or 98% by volume, respectively, of the particles have a diameter of less than this value. The raw data obtained by the measurement was analyzed using the Mie theory, with a particle refractive index of 1.57 and an absorption index of 0.005. The methods and instruments are known to the skilled person and are commonly used to determine particle size distributions of fillers and pigments. The sample was measured in dry condition without any prior treatment.

[0381] The weight determined median particle size d.sub.50(wt) was measured by the sedimentation method, which is an analysis of sedimentation behaviour in a gravimetric field. The measurement was made with a Sedigraph 5120 of Micromeritics Instrument Corporation, USA. The method and the instrument are known to the skilled person and are commonly used to determine particle size distributions of fillers and pigments. The measurement was carried out in an aqueous solution of 0.1 wt.-% Na.sub.4P.sub.2O.sub.7. The samples were dispersed using a high-speed stirrer and supersonicated.

[0382] Specific Surface Area (SSA)

[0383] The specific surface area was measured via the BET method according to ISO 9277:2010 using nitrogen, following conditioning of the sample by heating at 250 C. for a period of 30 minutes.

[0384] Prior to such measurements, the sample was filtered within a Buchner funnel, rinsed with deionized water and dried at 110 C. in an oven for at least 12 hours.

[0385] Intra-Particle Intruded Specific Pore Volume (in Cm.sup.3/g)

[0386] The specific pore volume was measured using a mercury intrusion porosimetry measurement using a Micromeritics Autopore V 9620 mercury porosimeter having a maximum applied pressure of mercury 414 MPa (60 000 psi), equivalent to a Laplace throat diameter of 0.004 m (nm). The equilibration time used at each pressure step was 20 seconds. The sample material was sealed in a 5 cm.sup.3 chamber powder penetrometer for analysis. The data were corrected for mercury compression, penetrometer expansion and sample material compression using the software Pore-Comp (Gane, P. A. C., Kettle, J. P., Matthews, G. P. and Ridgway, C. J., Void Space Structure of Compressible Polymer Spheres and Consolidated Calcium Carbonate Paper-Coating Formulations, Industrial and Engineering Chemistry Research, 35(5), 1996, p1753-1764).

[0387] The total pore volume seen in the cumulative intrusion data can be separated into two regions with the intrusion data from 214 m down to about 1-4 m showing the coarse packing of the sample between any agglomerate structures contributing strongly. Below these diameters lies the fine inter-particle packing of the particles themselves. If they also have intra-particle pores, then this region appears bi-modal, and by taking the specific pore volume intruded by mercury into pores finer than the modal turning point, i.e. finer than the bi-modal point of inflection, the specific intra-particle pore volume is defined. The sum of these three regions gives the total overall pore volume of the powder, but depends strongly on the original sample compaction/settling of the powder at the coarse pore end of the distribution.

[0388] By taking the first derivative of the cumulative intrusion curve the pore size distributions based on equivalent Laplace diameter, inevitably including pore-shielding, are revealed. The differential curves clearly show the coarse agglomerate pore structure region, the inter-particle pore region and the intra-particle pore region, if present. Knowing the intra-particle pore diameter range it is possible to subtract the remainder inter-particle and inter-agglomerate pore volume from the total pore volume to deliver the desired pore volume of the internal pores alone in terms of the pore volume per unit mass (specific pore volume). The same principle of subtraction, of course, applies for isolating any of the other pore size regions of interest.

[0389] Scanning Electron Microscopy (SEM)

[0390] The samples were prepared by diluting 50 to 150 l slurry samples with 5 ml water. The amount of slurry sample depends on solids content, mean value of the particle size and particle size distribution. The diluted samples were filtrated by using a 0.8 m membrane filter. A finer filter was used when the filtrate is turbid. A doubled-sided conductive adhesive tape was mounted on a SEM stub. This SEM stub was then slightly pressed in the still wet filter cake on the filter. The SEM stub was then sputtered with 8 nm Au. Subsequently, the prepared samples were examined by: a Sigma VP field emission scanning electron microscope (FESEM) (Carl Zeiss AG, Germany) and a variable pressure secondary electron detector (VPSE) and/or secondary electron detector (SE) with a chamber pressure of about 50 Pa. The investigation under the FESEM (Zeiss Sigma VP) was done at 5 kV (Au).

[0391] X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Thermogravimetric Analysis (TGA)

[0392] XRD patterns were recorded using a Bruker D2 Phaser powder X-ray diffractometer using Co radiation source, CoKa=1.789 . Measurements were carried out between 10-70 2 using a scan speed of 0.5 s per step. TGA was conducted using a Mettler Toledo TGA/DSC 3.sup.+. The samples were heated from 25 up to 600 C. with a ramp of 25 C. and a 10 min hold at 105 C. and 500 C., with an air flow of 80 ml/min. XPS experiments were carried out in a Kratos AXIS Ultra DLD spectrometer using a monochromatic A1 K radiation (hu=1486.6 eV) operating at 225 W (15 mA, 15 kV). Instrument base pressure was 510.sup.10 Torr.

[0393] Further Experimental Techniques

[0394] The Ca and P contents of the SRCC solids were prepared by dissolving a sample of the SRCC in aqua regia (a mixture of 1 part per volume of nitric acid (70 wt.-% in water) and 3 parts per volume of hydrochloric acid (35 wt.-% in water)), diluting the obtained solution with water until an about four-fold increase in volume, and analyzing the diluted solution via the inductively coupled plasma optical emission spectroscopy (ICP-OES) technique using a Perkin Elmer Avio 500 device. The Ca and P contents were determined using a calibration curve. The carbon content of the SRCC was obtained from EA and was carried out using a Fisons NA1500 NCS analyser. Infrared spectra were recorded using a Perkin Elmer Spectrum Two FT-IR spectrometer.

[0395] Adsorbed Ammonia and Adsorbed Carbon Dioxide Temperature Programmed Desorption (NH.sub.3-TPD and CO.sub.2-TPD)

[0396] The measurements were performed using a Micromeritics ASAP2920 apparatus. 0.1 g of sample was dried in situ under an He flow with a temperature ramp of 5 C. min.sup.1 up to 400 C.

[0397] For the NH.sub.3-TPD measurements, the sample was cooled to 100 C. At this point, 20 pulses of 5 cm.sup.3 10 vol.-% NH.sub.3 in He were dosed over the sample (corresponding to an NH.sub.3 flow of 25.3 cm.sup.3 min.sup.1). The sample was then heated to 600 C. with a ramp of 5 C. min.sup.1 to induce desorption of NH.sub.3. The amount of NH.sub.3 desorbed over time was determined using a thermal conductivity detector (TCD). The TCD concentration was plotted over time for the quantitative evaluation and over temperature to determine the temperature position of the desorption peaks. In both cases, a peak deconvolution was performed. To obtain the total amount of desorbed NH.sub.3, a baseline subtraction and full integration of the desorption feature has been performed. Peak deconvolution was performed using the software Fityk.

[0398] After obtaining the area under the curve (AUC, A) (from Fityk), the AUC is converted into a quantifiable amount of NH.sub.3 (n.sub.NH3 in mmol/g) using the below formulae:

A.sub.r=A/100%

V.sub.NH3,abs=A.sub.r.Math.V

V.sub.NH3=V.sub.NH3,abs/m.sub.sample

m.sub.NH3=V.sub.NH3.Math..sub.NH3

n.sub.NH3=m.sub.NH3/M.sub.NH3

.sub.NH3=0.76 kg/m.sup.3,M.sub.NH3=17 g/mol

A=obtained Area (%.Math.min), A.sub.r=Area (min), V=Flow 25.2 (cm.sup.3/min)

V.sub.NH3,abs=absolute amount of desorbed NH.sub.3 (cm.sup.3)

V.sub.NH3=amount of desorbed NH.sub.3 per g of sample (cm.sup.3/g)

[0399] For the CO.sub.2-TPD measurements, the sample was cooled to 50 C. and a procedure similar to the one described for NH.sub.3-TPD was employed. The number of basic sites was determined according to the calculation above, using the values .sub.CO2=1.98 kg/m.sup.3 and M.sub.CO2=44.01 g/mol. For calculating the number of acidic or basic sites, it was assumed that only one molecule of NH.sub.3 or CO.sub.2 can adsorb on a single site.

[0400] 2. Materials Used

[0401] Surface-Reacted Calcium Carbonate (SRCC)

[0402] SRCC1

[0403] SRCC1 is commercially available from Omya International AG with a d.sub.50(vol)=2.4 m, a des(vol)=9 m, and SSA=21 m.sup.2/g. The intra-particle intruded specific pore volume is 0.442 cm.sup.3/g (for the pore diameter range of 0.004 to 0.34 m).

[0404] SRCC2

[0405] SRCC2 has d.sub.50(vol)=6.6 m, a des(vol)=13.7 m, a SSA=56.7 m.sup.2g.sup.1 and an intra-particle intruded specific pore volume of 0.939 cm.sup.3/g (for the pore diameter range of 0.004 to 0.51 m).

[0406] SRCC2 was obtained by preparing 350 L of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground limestone calcium carbonate from Omya SAS, Orgon having a weight based median particle size d.sub.50(wt) of 1.3 m, as determined by sedimentation, such that a solids content of 10 wt.-%, based on the total weight of the aqueous suspension, is obtained.

[0407] Whilst mixing the slurry at a speed of 6.2 m/s, 11.2 kg phosphoric acid was added in form of an aqueous solution containing 30 wt.-% phosphoric acid to said suspension over a period of 20 minutes at a temperature of 70 C. After the addition of the acid, the slurry was stirred for additional 5 minutes, before removing it from the vessel and drying using a jet-dryer.

[0408] SRCC3

[0409] SRCC3 has d.sub.50(vol)=5.8 m, a d.sub.9s(vol)=15.4 m, a SSA=156.2 m.sup.2g.sup.1 and an intra-particle intruded specific pore volume of 1.070 cm.sup.3/g (for the pore diameter range of 0.004 to 0.34 m).

[0410] SRCC3 was obtained by preparing 10 L of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground marble calcium carbonate from Hustadmarmor Norway such that a solids content of 10 wt.-%, based on the total weight of the aqueous suspension, is obtained. The ground calcium carbonate had a weight based particle size distribution of 90% less than 2 m, as determined by sedimentation. Additionally, a phosphoric acid solution was prepared such that it contained 30% phosphoric acid, based on the total weight of the solution.

[0411] Whilst mixing the slurry, 1.8 kg of the phosphoric acid solution was added over 10 minutes. After 20% of the total acid solution was added, 53 g of citric acid anhydride powder was added to the slurry. Throughout the whole experiment the temperature of the suspension was maintained at 70 C.+/1 C. Finally, after the addition of the acid, the suspension was stirred for additional 5 minutes before removing it from the vessel and allowing it to cool.

[0412] SRCC4

[0413] SRCC4 has d.sub.50(vol)=3.8 m, a d.sub.9s(vol)=47.2 m, a SSA=86.7 m.sup.2g.sup.1 and an intra-particle intruded specific pore volume of 0.286 cm.sup.3/g (for the pore diameter range of 0.004 to 0.11 m).

[0414] SRCC4 was obtained by preparing 10 L of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground marble calcium carbonate from Karabiga, Turkey such that a solids content of 15 wt.-%, based on the total weight of the aqueous suspension, is obtained. The ground calcium carbonate had a weight based particle size distribution of 90% less than 1 m, as determined by sedimentation. In addition, a phosphoric acid solution was prepared such that it contained 30% phosphoric acid, based on the total weight of the solution.

[0415] Whilst mixing the slurry, 1.3 kg of the phosphoric acid solution was added over 10 minutes. Throughout the whole experiment the temperature of the suspension was maintained at 70 C.+/1 C. Finally, after the addition of the acid, the suspension was stirred for additional 5 minutes before removing it from the vessel and allowing it to cool.

[0416] SRCC5

[0417] SRCC5 has d.sub.50(Vol)=8.3 m, a d.sub.9s(vol)=18.7 m, a SSA=105.5 m.sup.2g.sup.1 and an intra-particle intruded specific pore volume of 1.565 cm.sup.3/g (for the pore diameter range of 0.004 to 0.66 m).

[0418] SRCC5 was obtained by preparing 10 L of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground marble calcium carbonate from Karabiga, Turkey such that a solids content of 15 wt.-%, based on the total weight of the aqueous suspension, is obtained. The ground calcium carbonate had a weight based median particle size d.sub.50(wt) of 1.4 m, as determined by sedimentation. In addition, a phosphoric acid solution was prepared such that it contained 30% phosphoric acid, based on the total weight of the solution.

[0419] Whilst mixing the slurry, 2.8 kg of the phosphoric acid solution was added over 15 minutes. Throughout the whole experiment the temperature of the suspension was maintained at 70 C.+/1 C. Finally, after the addition of the acid, the suspension was stirred for additional 5 minutes before removing it from the vessel and allowing it to cool.

[0420] Other Reagents

[0421] All commercial reagents were used as received without further purification. Butyraldehyde (>99.5%), malononitrile (>99%), nitromethane (>99%), mesitylene (98%) HAP-L nanopowder (<200 nm, particle size, >97%), HAP-H (5 m particle size) and TiO.sub.2 nanopowder (<100 nm particle size, 99.5%) were purchased from Sigma-Aldrich. Benzaldehyde (>98%), acetophenone (98%), calcium carbonate (CaCO.sub.3) (>98%) and MgO (98%) were obtained from Acros organics.

[0422] The SRCCs were activated by heating to 200 C. for 4 h in a laboratory oven under static air. The properties of the surface-reacted calcium carbonates (labeled before) and the dry surface-reacted calcium carbonates (labeled after) are shown in Tables 1-3. The properties of several commercially available catalysts are also shown in Table 1.

TABLE-US-00001 TABLE 1 Nitrogen physisorption measurements for SRCC catalysts. BET surface area Total pore volume (m.sup.2/g) (cm.sup.3/g) Entry Catalyst Before.sup.a After.sup.b Before.sup.a After.sup.b 1 SRCC1 21.0 19.3 0.032 0.133 2 SRCC2 56.7 58.1 0.101 0.417 3 SRCC3 156.2 160.3 0.304 0.865 4 SRCC4 86.7 85.5 0.193 0.181 5 SRCC5 105.5 106.7 0.673 0.650 6 MgO n.d. 239.5 n.d. 0.239 7 TiO.sub.2 n.d. 7.4 n.d. 0.033 8 CaCO.sub.3 n.d. 6.6 n.d. 0.049 9 HAP-L.sup.c 9.4 n.d. n.d. n.d. 10 HAP-H.sup.c 100 n.d. n.d. n.d. .sup.abefore thermal activation; .sup.bafter thermal activation at 200 C. for 4 h; .sup.ccommercially available information; n.d.not determined.

TABLE-US-00002 TABLE 2 Bulk and surface composition of the SRCC catalysts. ICP-OES XPS XPS Ca/P Ca/P Ca P atomic Ca P atomic Catalyst (wt %) (wt %) ratio (% at.) (% at.) ratio SRCC1 38.42 4.17 7.13 14.2 6.7 2.1 SRCC2 38.29 7.55 3.93 13.0 6.7 1.9 SRCC3 40.67 6.34 4.95 14.4 7.8 1.9 SRCC4 38.14 7.59 3.88 14.1 6.7 2.1 SRCC5 37.44 12.36 2.34 14.5 8.1 1.8

TABLE-US-00003 TABLE 3 Number of acidic and basic sites of the dry surface-reacted calcium carbonates determined by NH.sub.3 and CO.sub.2-TPD. CO.sub.2-TPD NH.sub.3-TPD Total number Total number of basic sites of acidic sites Entry Catalyst (mmol/g) (mmol/g) 1 SRCC1 0.05 0.03 2 SRCC2 0.08 0.09 3 SRCC3 0.33 0.19 4 SRCC4 0.15 0.13 5 SRCC5 0.08 0.12

[0423] 3. Organic Condensation Reactions

[0424] Aldol Condensation

[0425] The aldol condensation of butyraldehyde was performed in a batch reaction system, under vigorous magnetic stirring and a nitrogen atmosphere. Prior to the reaction, all the SRCC solids were thermally activated at 200 C. for 4 h. In a typical experiment, a 50 mL two-necked flask connected to a reflux condenser was filled with 55.6 mmol of butyraldehyde, 3 mol % of catalyst and 36 mmol mesitylene as the internal standard. After passing the N.sub.2 through the headspace of the reaction system and setting a constant-vigorous stirring rate, the reaction mixture was heated up to a temperature of 130 C. The progress of the reaction was monitored by taking samples from the reaction media at different intervals of time (2-22 h). The conversion of butyraldehyde was determined by .sup.1H NMR (CDCl.sub.3). The .sup.1H spectra (400 MHz) were recorded on an Agilent MRF400 or a Varian AS400 spectrometer at 25 C. The chemical shifts are reported in the standard 5 notation of parts per million, referenced to residual peak of the solvent, as determined relative to Me.sub.4Si (6=0 ppm).

[0426] Catalyst performance was evaluated at 130 C. for 22 h under solvent-free conditions. The results are presented in Table 4. No conversion was noted in the absence of any catalysts after 2 or 6 h, whereas a limited activity was seen at 22 h (entry 1). Entries 2 to 6 are commercially available solid base catalysts such as MgO, TiO.sub.2, CaCO.sub.3 and HAPs, respectively. Compared to commercially existing solid base catalysts, the SRCC catalysts SRCC3, SRCC4 and SRCC5 (entry 9-11) exhibited excellent catalytic activity. In most cases, full conversion after 22 h was achieved. A mixture of calcium carbonate and HAP catalysts was also tested (entry 12), which did not achieve the catalytic activity attained by the above mentioned SRCC catalysts.

TABLE-US-00004 TABLE 4 Screening of self-aldol condensation reaction of butyraldehyde into 2-ethylhexenal using various catalysts. Catalyst Time (h) amount 2 6 22 Entry Catalyst (g) X (%) Y (%) X (%) Y (%) X (%) Y (%) 1 0 0 0 0 8 6 2 MgO 0.07 0 0 30 29 71 70 3 TiO.sub.2 0.13 0 0 9 9 50 47 4 CaCO.sub.3 0.17 2 2 40 39 60 59 5 HAP-L 0.84 7 7 41 39 62 60 6 HAP-H 0.84 10 10 53 53 70 68 7 SRCC1 0.30 0 0 28 28 50 48 8 SRCC2 0.5 9 9 29 29 57 55 9 SRCC3 0.72 73 72 100 99 n.d. n.d. 10 SRCC4 0.74 18 18 70 69 88 85 11 SRCC5 0.73 58 57 91 89 100 98 12 CaCO.sub.3 + HAP-L 0.72 3 3 10 10 43 43 Reaction conditions: Temperature = 130 C.; Catalyst loading = 3 mol %; X = Conversion, Y = Yield; HAP-L = Hydroxyapatite with lower surface area (9.4 m.sup.2/g); HAP-H = Hydroxyapatite with higher surface area (100 m.sup.2/g); Entry 12, catalyst loading - CaCO.sub.3 = 0.5 mol %, HAP-L = 2.5 mol %; Conversion and Yield were determined by .sup.1H NMR (CDCl.sub.3) using mesitylene as an internal standard.

[0427] Other Condensation Reactions

[0428] To further demonstrate the scope of SRCC catalysts used in CC coupling reactions, the most active catalyst SRCC3 was tested in other prototypical condensation reactions. The reaction conditions were optimized similar to the self-aldol condensation reactions and the best results are displayed in the Table 5.

TABLE-US-00005 TABLE 5 [00012] Reaction conditions: Catalyst Loading = 3 mol %; Catalyst: SRCC3; T = Temperature; X = Conversion (%), Y = Yield (%); n.d. = not determined; Entry 1, substrate 1 = benzaldehyde, substrate 2 = malononitrile; Entry 2, substrate 1 = benzaldehyde, substrate 2 = acetophenone; Entry 3, substrate 1 = benzaldehyde, substrate 2 = nitromethane; Substrate ratio: 1:2; Conversion and Yield were determined by .sup.1H NMR (CDCl.sub.3) using mesitylene as an internal standard.