CZ2010258A3 - Self-organizing mononuclear layer and process for preparing thereof - Google Patents

Abstract

Described is an ordered self-organizing monomolecular layer of an organic compound on a substrate whose surface is coated with gold metal, formed by trialkyltin molecules. This layer exhibits stability in organic solvent environments such as n-hexane or ethanol and resistance to both oxidizing and strong reducing agents. Further described is a method for preparing said self-organizing monomolecular layer of an organic compound by adsorption of trialkyl tin salts of trifluoromethanesulfonic acid, trifluoroacetic acid and / or paratoluenesulfonic acid on said surface, wherein the number of carbon atoms in the salts used is in the range of 1 to 36.

Description

Self-organizing monomolecular layer and process for its preparation

Technical field

The invention relates generally to a new type of thin organic film on an inorganic surface and in particular to a specific self-organizing monomolecular layer and to a process for its preparation.

BACKGROUND OF THE INVENTION

Small molecules of organic matter are currently increasingly used in the industry called molecular electronics as the active components of electronic components. The basic organizational structure of organic molecules used for similar devices is well-ordered self-assembling monomolecular layers (SAMs). They consist of an ordered layer of amphiphilic molecules, one end of which, represented by the 'head' of the molecule, exhibits a specific affinity for the substrate. A functional group (e.g. OH, NH ₃ , COOH) is attached to the opposite end of the molecule, usually a long aliphatic chain. The most commonly used molecules are alkyl chain alkanethiols and attached through the SH head group to a noble metal substrate to which the sulfur atom has a strong affinity. Very often, it is an interaction of sulfur with a gold atom that is mediated by a <semi-covalent bond (see, eg, Love et al., Chem. Rev. 2005, 105, 1103x1170). Thiol molecules adsorb very readily to the gold atoms from solution (e.g. ethanol), and the formed densely ordered monomolecular layers may exhibit very different chemical properties depending on the functional groups used at the chain ends outside the substrate.

Such bonding of the Z atom bearing one organic R group such as alkyl to the surface of the substrate provides surface structures of the RZM _n type, where M _n denotes one or more metal atoms. An example of a Z atom is elements of Group VI A of the Periodic Table of the Elements, and in particular sulfur.

As an alternative to the binding of individual organic molecules to gilded substrates via the sulfur atom in the thiocyanates (Ciszek et al., J. Am. Chem. Soc. 2004, 126, 13172), SAM formation has been tried (adsorption from solution or solvent vapor)

Through selenium atoms (Huang et al., Langmuir 1998,14, 4802; Shaporenko et al., J. Phys. Chem. B 2005, 109, 3898; Monnell et al., J. Phys. Chem. B 2004, 108 Clark et al., Surface Science 2002, 498, 285; Protsailo et al., Langmuir 2002, 18, 9342; Han, SW and Kim, K., J. Colloid Interface Sci. 2001, 240, 492), tellurium (Weidner et al., J. Phys. Chem. C 2007, 111, 11627) and silicon (Owens et al., J. Phys. Chem. B 2003, 107, 3177 and J. Am. Chem. Soc. 2002 , 124, 6800; Katsonis et al., Chem. Eur. J. 2003, 9, 2574), or carbon atoms in acetylene compounds (Zhang et al., J. Am. Chem. Soc., 2007, 129, 4876) , diazonium salts (Shewchuk and McDermott, Langmuir 2009, 25, 4556; Laforgue et al., Langmuir 2005, 21,6855) and isocyanates (Stapleton et al., Langmuir 2005, 21, 11061).

Binding of individual molecules to form SAM on gold and other metal surfaces via a divalent sulfur atom is readily feasible and well documented (Love et al., Chem. Rev. 2005, 105, 1103; Ulman, Chem Rev. 1996, 96, 1533; Ultrathin Organic Films, Academic Press: San Diego, 1991). This type of bond has many advantages, such as ease of formation under standard laboratory conditions (under normal atmospheric pressure and room temperature), but also disadvantages. These include the limited long term resistance of thiolates to air oxidation (Joseph et al., Chem Mater. 2009, 21, 1670; Willey et al., Surface Science 2005, 576, 188; Huang, et al., Langmuir 1998, 14, 4802) and fairly poor electron transfer through a partially polar bond of an (electronegative) sulfur and metal atom that limits the use of such bonded SAMs, for example, in molecular electronics based on the binding of individual molecules to metal surfaces (substrates).

The steric requirements for simple alkyl chains allow, after binding to the substrate via a sulfur or silicon atom, the formation of broad domains of substantially impermeable, tightly arranged layers of long alkane chains somewhat deflected from the surface normal. Described coupling of an organic group via a silicon atom (Owens et al., J. Phys. Chem. B 2003, 107, 3177 and J. Am. Chem. Soc. 2002, 124, 6800; Katsonis et al., Chem. Eur. J 2003, 9, 2574) works with monoalkylsilanes and requires solvent vapor deposition.

Recently, the adsorption of the trifluoroacetate salts of certain organomercury cations to gold has been described, accompanied by the release of the trifluoroacetate anion (Zheng et al., J. Am. Chem. Soc. 2004, 126, 4540; Mulcahy et al., J. Phys. Chem. C 2009, 113, 20698; Mulcahy et al., Adopted for publication). Infrared and X-ray photoelectron

-3 spectroscopy confirmed that adsorption of complexes is mediated by the interaction of mercury atoms with the gold substrate (surface). Other organometallic salts were not tested for similar adsorption.

SUMMARY OF THE INVENTION

The present invention relates to an ordered self-organizing monomolecular layer on a substrate, the surface of which is coated with gold, characterized in that said monomolecular layer consists of trialkyltin molecules corresponding to the general formula of formula (C _n H 2 _{n + 1} ) ₃ Sn, where n is in the range of 1 to 36, wherein the tin atom is adjacent to the substrate and the alkyl chains are oriented away from the substrate.

It is a feature of the invention that the trialkyltin preferably corresponds to the general formula (CH ₃ ) _x Sn (C ₁₈ H ₃₇ ) _y , wherein x is from 0 to 2, y is from 1 to 3, wherein x + y = 3.

Preferably, the ordered self-organizing monomolecular layer of trialkyltin molecules has a thickness of 0.1 to 5 nm.

An advantage of the self-organizing monomolecular layers of the present invention over the prior art self-organizing monomolecular layers is that it is stable in the environment of organic solvents such as n-hexane or ethanol and resistant to both reducing and oxidizing agents.

The present invention further provides a process for preparing an ordered self-organizing monomolecular layer on a substrate having a gold surface, said monomolecular layer consisting of trialkyltin molecules wherein the tin atom is adjacent to the substrate and the alkyl chains are oriented away from the substrate. by adsorbing a trialkyl tin salt having a number of carbon atoms in the alkyl range of 1 to 36 to adsorb onto the metal-coated substrate surface.

A feature of the process of the present invention is that the trialkylcinta salt corresponds to the general formula (C _n H ₂ n + 1) ₃ Sn -Y, where n is between 1 and 36 and Y is selected from the group of strong acid salts including triflate (OTf). , trifluoromethanesulfonic acid salt), trifluoroacetate (OCOCF ₃ , trifluoroacetic acid salt) and tosylate (OTs, p-toluenesulfonic acid salt).

An aspect of the present invention is that the trialkyl tin salt preferably has the formula _{(CH3) x} (C _ls H ₃ 7) _y Sn y where x ranges from 0 to 2, y is from 1-3, wherein x + y = 3, and Y is selected from the group consisting of triflate (OTf, trifluoromethanesulfonic acid salt), trifluoroacetate (OCOCF ₃ , trifluoroacetic acid salt) and tosylate (OTs, p-toluenesulfonic acid salt).

In a preferred embodiment, a process for preparing a self-organizing monomolecular layer

a) immersing the substrate in a solution of a trialkyltin tin salt having a number of carbon atoms in the alkyl range of 1 to 36 in an organic solvent;

b) subsequently washing the substrate with an organic solvent and drying the substrate with an adsorbed layer of trialkyltin molecules.

Preferably, in step a) a solution of the trialkyltin tin salt of trifluoromethanesulfonic acid, trifluoroacetic acid and / or paratoluenesulfonic acid is used in a concentration range of 1 mol. ¹ to 1.10 MOLT ^1, having a number of carbon atoms in the alkyl moiety ranges from 1 to 36th

Preferably, the organic solvent used in step a) is selected from the group consisting of hydrocarbon, ether, haloalkane derivative, carboxylic acid nitrile or nitro compounds and the solvent selected from the same group of substances is also used for washing in step b).

The present invention generally relates to the attachment of alkyl residues to a substrate with a gold-coated surface via a tin atom. The electropositive nature of the ligand atom is such an advantage for electron transfer, which also affects the properties generated by SAM.

Were synthesized covalent trialkylstannyl trifluoromethanesulfonic acid salts (triflates), trifluoroacetic acid (trifluoroacetates) and paratoluenesulfonic (tosylates), containing per molecule three alkyl substituents consisting of 1 to 3 chain C _I8 II ₃ and 7 0 to 2 methyl groups. These salts showed the ability to adsorb from solution to gold at room temperature and atmospheric pressure to form an ordered self-organizing layer on the gilded surface. This capability was characterized using ellipsometry, FT1R spectroscopy, contact angle measurement and electron blocking measurement.

All of the synthesized trialkyltin salts formed upon cleavage of the acid residue similar to a stable self-organizing monomolecular layer and in no case the formation of a multilayer (multilayer) was observed. The monomolecular layers prepared in this way differed from similar self-organizing layers formed of alkanethiols. The monomolecular layers prepared according to the invention were thinner, less organized, less hydrophobic and weakly blocking electron transfer. Their stability to some solvents, bases and acids was somewhat lower than that of 1-octadecanethiol monomolecular layers, but their resistance to elevated temperature, strong reducing agents and oxidizing agents, including air, was higher.

The trialkyl silicate salts prepared for comparison in a similar manner showed no tendency for adsorption to gold under the same conditions.

No evidence suggests that the removable group Y remains bound in the monomolecular layer, see infrared spectra of individual SAMs, Ex8. Most likely it is removed during adsorption as the Y 'anion, and its type does not affect the properties of the resulting monomolecular layer, CCOXCig1-4JySnAu or (CH3) _x (C18H37) ySn-AUo, where o is greater than 1. If the group Y is released as an anion, it can be assumed that the electron necessary to form the anion originates from a metal, but this has not been directly demonstrated .

The monomolecular self-organizing layers of the present invention are much thinner than similar layers made of 1-octadecanthiol and less aligned as evidenced by a smaller measured contact angle for water (ex. 7), weaker electron blocking (ex. 9), less resistance against removal of such layers by the use of additives (ex. 4), by ellipsometric measurement of the thickness of the formed layer (ex. 6) and by measuring infrared spectra, see ex. 8.

The permeability of the monomolecular layers prepared according to the invention is higher compared to the permeability of a similar layer made of 1-octadecanethiol, as seen in particular from Example 9, where the electron transfer blocking was measured (Fig. 4 (1)).

The monomolecular self-organizing layers of the present invention exhibit greater stability to solvents such as n-hexane and ethanol, but not to methylene chloride, water (Fig. 5 (2)) or basic agents. Surprisingly, they are not desorbed upon exposure to 80 to 90% acids. Better resistance than 1-octadecanethiol layers has also been demonstrated against oxidizing agents, especially hydrogen peroxide, but also partially to ambient air. The monomolecular layers of the invention are resistant to strong reducing agents such as sodium borohydride (ex. 4).

The endpoints of self-organizing trialkyltin tin monomolecular layers formed from molecules containing one, two or three long chains are almost identical, only the blocking of electron transfer shows some differences (ex. 9). The similarity also applies to the layer thickness measured by ellipsometry (ex. 6). The results may be slightly misleading since the refractive index is likely to slightly increase in the order of layers formed from salts 7, 6, 5 (octadecyldimethyltin, dioctadecylmethyltin, trioctadecyltin SAM), but generally measured thickness in the range 0.6 to 0.7 nm represents a mere 1/3 of the thickness of the layer formed from 1-octadecanethiol and suggests that the alkyl chains lie on the gold surface.

As a substrate, commercially available 200 nm gold coated platelets from Platypus Technologies were used, and similar results were obtained with other materials such as gold on mica, platinum and silver on glass, copper on glass.

In addition to coating the substrate with a thin layer of gold, alternative use of a thin layer of silver, palladium and platinum may also be considered.

-7Overview of figures in drawings

Giant. 1: Cyclic voltammogram at 100mV / s, Fe (CN) ₆ ] ³ ' ^{/ 4} on a pure gold electrode (dotted) and on an electrode with adsorbed layer of compounds 1 (black), 5c (gray), 6c (light gray) and 7c ( dark gray) after two hours immersion in a solution of the substance. The x-axis shows the working electrode voltage in mV relative to the Ag / AgCl electrode, and the y-axis shows the current in the micro-amperes.

Giant. 2: Stability of adsorbed monomolecular layers of compounds 1 (black), 5 (gray), 6 (light gray) and 7 (dark gray) after immersion in various solutions overnight, always after rinsing and drying. On the y-axis, the value of R is plotted, indicating the percentage of monomolecular layer remaining on the gilded surface, calculated from the integral intensity of the IR spectra bands in the region of 2800 to 3000 cm ^-1 . The x-axis shows the solutions used. A: dry CH 2 Cl 2; B: wet CH 2 Cl 2; C: n-hexane; D: ethanol; E: water; F: 0.1 mol.1 H ² SO 4; G: 0.1 mol / ^l NaOH; Mmol: 1 mmol.l ^-1 KMnOc I: 30% (v / v) H2O2; J: 10 mmol.T ¹ NaBH <K: Seven-day exposure to air in the laboratory.

Giant. 3: Partial degradation of the monomolecular layer of compound 7c during exposure to the following agents: CH 2 Cl 2 (,), ethanol (D,)); water (E, ·) and 30% (v / v) hydrogen peroxide (I, Φ). On the y-axis, the value of R is plotted, indicating the percentage of monomolecular layer remaining on the gilded surface, calculated from the integral intensity of the IR spectra bands in the region of 2800 to 3000 cm ^-1 . The x-axis shows the time in hours.

Giant. 4 A, B: Thermal desorption of monomolecular layers of compounds 1 (black), 5c (gray), 6c (light gray) and 7c (dark gray), on the surface of the gold-coated substrate after 1 hour at 20, 80, 140 and 200 ° C. Part A presents at the top of the figure IR spectra of the adsorbed layer (1, black) and at the bottom 7c (dark gray); Part B gives the percent of the monomolecular layer remaining on the gilded surface, calculated from the integral intensity of the IR spectra bands in the region of 2800 to 3000 cm ^-1 (plotted on the y-axis) relative to the temperature used plotted in degrees on the x-axis.

and:'

Giant. 5 A, B: Kinetics of monolayer formation at room temperature (20 ° C) for 5 * 7 substances as compared to 1-octadecanethiol (1, ▼). (A) Effect of the leaving group: triflate (7a, ♦).

trifluoroacetate (7b,?), and tosylate (7c,?). (B) Effect of the number of long chains on the Sn atom

-8 tosylate 5c (A), 6c (·), 7c (). On the x-axis the time in minutes is plotted, on the y-axis the thickness of the resulting monomolecular layer is plotted in nm.

Giant. 6A, B: Eipsometrically measured thickness (A) and static water contact angle (B) of the adsorbed monomolecular layers of compounds I and 5 to 7 on the gilded substrate after 2 hours immersion in a solution of the substance.

Giant. 7: ATR-FTIR spectra of the monomolecular layers of Compounds 1 (black), 5 (gray), 6 (light gray) and 7 (fatigue gray) adsorbed onto a gold-coated substrate surface. On the x-axis is wavelength in cm ^-1, the absorbance on the y axis. Top down are the spectra of the layer spectra formed from compounds 1, 7a, 7b, 7c, 6a, 6b, 6c, 5a, 5b, 5c, shifted by 0.01 absorbance units, in descending order.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

Synthesis of trialkyltin salts

Tetraalkyl tin (II) compounds (Meals, J. Org. Chem. 1944, 9 211), 3 and 4 were synthesized from commercially available tin chlorides and the corresponding Grignard reagent.

SH = 0 at x = 4 (CH ₃ HSN (C ₁₈ H _{3Z) y} 3 x = 2, y = 2 x "1, y = 3 = 1 -octadecanethiol

Tin tin triflates (5a, 6a, 7a), tin trifluoroacetates (5b, 6b, 7b) and tin tosylates (5c, 6c and 7c) were prepared by keeping tetraalkyltin (II) tin refluxing with the corresponding acid in solution. dichloromethane (Sasin et al., J. Org. Chem. 1958, 23, 1366), see Scheme 1. Trifluoroacetic acid was used in a slight excess to compensate for volatility.

Scheme 1. Synthesis of trialkyltin salts

Y-H (CH _{3) a} Sn (C ₁₈ H _{37) y} ---------------- (CH _{3) x} (C _1s H _{3 R) y} Sn-Y 2 = 0. y = 4 3 x = 2. Y = 2 4 x s 3, y - 1 x = 0, y = 3 5a 5b 5c OTf - a x = 1, y = 26a 6b 6c OCOCF ₃ = b x = 2, y - 1 7a 7b 7c OTs = c

Synthetic materials were obtained from Sigma-Aldrich or Alfa-Aesar and were used unchanged unless otherwise indicated. 1-Bromoctadecane was distilled over CaCl 2, tetrahydrofuran (THF), toluene and pentane were distilled from ketyl benzophenone, dichloromethane (DCM) and acetonitrile (ACN) were freshly distilled over CaH 3 or P 2 O 5, trifluoromethanesulfonic acid was distilled over a small amount of P 2 O 5. The resulting salts were characterized as follows: NMR spectra were measured on Bruker 400 MHz Ultrashield, Bruker Avance II 500 MHz and Bruker Avance II 600 MHz; then it was related to the solvent signal. FTIR spectra were recorded on a Bruker Equinox 55. Melting points were determined using a Stuart SMP3 or Kofler block and were not further adjusted, mass spectrometry data was obtained using LTQ Orbitrap XL or LCQ Fleet (both from Thermo Fisher Scientific), or on Q-TOF micro (Waters) or Reflex IV (Bruker Daltonics). Elemental analyzes were performed on a Perkin Elmer 2400 II.

Example 1A

Methyltrioctadecycin (2), cited by Mulcahy et al., Accepted for publication. Magnesium shavings (0.96 g, 0.04 mol) and a catalytic amount of I2 were charged to a three neck round bottom flask equipped with a reflux condenser. The flask was heated until violet vapors appeared

I2. THF (20 mL) was then added, followed by 1-bromoctadecane (13.6 mL, 0.04 mol) and the mixture was heated to reflux under argon for 5 hours. After cooling to room temperature, SnCl 3 (0.7 mL, 0.006 mol) was added dropwise. The mixture was kept under reflux for 5 h and then stirred overnight at room temperature. Hexane (50 mL) was then added and the reaction mixture was washed with saturated NH 4 Cl solution (15 mL), water (3 × 25 mL) and saturated NaCl solution (15 mL). The hexane layer was dried over anhydrous Na 2 SO 4, filtered and

-10 concentrated under reduced pressure to give a white solid crystallized from ethyl acetate (6.0 g, 90% yield). The melting point was 47 * 49 ° C (according to reference 25: 47 ° C). IR (KBr, cm ^-1 ): 2956, 2918, 2873, 2850, 1468, 1455, 1418, 1378, 1342, 721,598, 513, 501. 1 H NMR (499.8 MHz, CDCl 3): δ 0.72 ( m, 8H), 0.81 (t, J = 7 Hz, 12H), 1.05 1.35 (m, 120H), 1.41 (m, 8H). ¹³ C NMR (125.7

MHz, CDCl3): δ 9.17, 14.13, 22.72, 27.02, 29.32, 29.41, 29.71, 29.74, 29.77, 31.97, 34.49. ^{119 1} H NMR (186.4 MHz, CDCl 3): δ -13.45. Elemental analysis: calculated for C72H14gSn: C 76.35; H, 13.17. Found: C, 77.03; H, 13.45.

Example 1B

Dioctadecyldimethyltin (3). Magnesium shavings (0.76 g, 0.031 mol) and catalytic amount of U were placed in a three neck round bottom flask equipped with a reflux condenser and heated until violet vapors I2 appeared. THF (20 mL) was added followed by 1-bromooctadecane (10.84 mL, 0.03 mol). The mixture was heated to reflux for 5 hours and then a solution of MeaSnCl 2 (2.5 g, 0.011 mol) (Me = methyl) in THF (5 mL) was added dropwise. The mixture was kept under reflux for 5 h and then stirred overnight at room temperature. Hexane (50 mL) was then added and the reaction mixture was washed with saturated NH 4 Cl solution (15 mL), water (3 x 25 mL) and saturated NaCl solution (15 mL). The hexane layer was dried over anhydrous Na 2 SO 4, filtered and concentrated under reduced pressure to give a white solid crystallized from ethyl acetate (6.92 g, 93% yield). The melting point was 39 * 41 ° C. IR (KBr, cm -1): 2955, 2917, 2871, 2849, 1472, 1463, 1452, 1440, 1421, 1413, 1377, 1193, 1186, 761, 729, 720, 526, 518. 1 H NMR (499.8)? MHz, CDCl3); δ 0.01 (s, 6H), 0.81 (m, 4H), 0.89 (t, J = 7Hz, 6H), 1.2H1, 35 (m, 60H), 1.49 (m, 4H). ¹³ C NMR (125.7 MHz, CDCl 3): δ 11.14, 10.50, 14.13, 22.72, 26.80, 29.31, 29.40, 29.68, 29.70, 29.75, 31.96, 34.18. ¹⁹ Sn NMR (186.4 MHz, CDCl 3): δ 2.98. HRMS-EI (high resolution mass spectrum) calculated for CMI-Sn (M CH 3): 641.5047, found: 641.5063.

Example 1C

Octadecyltrimethyltin (4). Magnesium shavings (0.18 g, 7.53 x 10 ^-3 moles) and a catalytic amount of h were charged to a three neck round bottom flask equipped with a reflux condenser. The flask was heated until I2 vapors appeared. THF (20 mL) was then added, followed by 1-bromooctadecane (2.57 mL, 7.53 ^x 10 ^-3 mol) and the mixture was heated to reflux for 5 hours. Then a solution of MeSnCl (1.0 g, 5.02 χ 10 ^-3 mol) in THF (5 mL) was added dropwise. The mixture was kept under reflux for 5 h and then stirred overnight at room temperature. Hexane (50 mL) was then added and the reaction mixture was washed with a saturated solution

-11NH 4 Cl (15 mL), water (3 × 25 mL) and saturated NaCl solution (15 mL). The hexane layer was dried over anhydrous Na 2 SO 4, filtered, and concentrated under reduced pressure to give a semi-solid. Purification by column chromatography gave the product (1.66 g, 79% yield).

IR (KBr, cm ^-1 ): 2956, 2923, 2852, 1466, 1455, 1444, 1433, 1417, 1378, 1200, 1188, 764, 731, 720, 525, 510. 1 H NMR (499.8 MHz, CDCl 3) ); Δ 0.06 (s, 9H), 0.85 (m, 2H), 0.90 (t, J = 7.1 Hz, 3H), 1.23 ^: -1.37 (m, 30H), 1 52 (m, 2H). ¹³ C NMR (125.7 MHz, CDCl 3): δ -10.32, 11.15, 14.17, 22.78, 26.78, 29.38, 29.48, 29.74, 29.77, 29.80, 29.82, 32.04, 34.12. ^{19 C} NMR (186.4 MHz, CDCl 3): δ - 1.21. HRMS-APCl calculated for C11H46SnNa (M + Na): 441.2525, found: 441.2647.

Example ID

Trioctadecyltin triflate (5a). Tetraoctadecyltin (1 g, 8.85 x 10 ^-4 mol) was dissolved in hot dried DCM and a solution of CF 3 SO 3 H (0.025 g, 0.18 x 10 ^-3 mol) in dried DCM (1 mL) was added dropwise; subsequently, the resulting solution was kept under reflux for 48 hours. The DCM was evaporated on a rotary evaporator to give a white solid which was crystallized from DCM / ACN (0.82 g, 90% yield). Melting point: 77-78 ° C. IR (KBr, cm ^-1 ): 2956, 2918, 2872, 2850, 1468, 1378, 1321, 1261, 1203, 1097, 1025, 804, 721, 656, 632, 582, 518. 1 H NMR (499.8) MHz, THF-1 / b): δ 0.89 (t, J = 7 Hz, 9H), 1.29 (bs, 92H), ¹³ C NMR (125.7 MHz, THF-Jb): δ - 14 , 63, 20.78, 23.73, 26.56, 30.35, 30.49, 30.79, 30.80, 30.83, 30.85, 30.86, 35.15, 121.07 , (q, J C-F = 319.1). ¹⁹ F NMR (470.3 MHz, THF-1A): δ - 75.16. ^{119 1} H NMR (186.4 MHz, CDCl 3): δ -15.75. HRMS-ESI calcd for C 8 H 18 Cl (M - OTf): 879.7702, found: 879.7713. Elemental analysis: calculated for C5H11FiClSSS: C, 64.24; H, 10.88; F 5.54; S 3.12, found C 64.33; H, 10.76; F, 5.97; S, 3.47.

Example 1E

Trioctadecyltin trifluoroacetate (5b). tetraoctadecyltin (1g, 8.83 x 10 -1 mol) was dissolved in hot DCM (10 mL). Trifluoroacetic acid solution (0.15 g, 1.33 x 10 ^-3 mol) was added dropwise from the syringe, and the resulting mixture was then kept under reflux for 48 hours. An aliquot was then removed and the product was crystallized from DCM / ACN. ^{The 19} H NMR spectrum showed a constant presence of some starting material. The whole operation was repeated until the starting material had completely reacted (usually an additional 0.5 equivalents of trifluoroacetic acid was needed). The reaction mixture was then concentrated under reduced pressure, and the obtained residue was dissolved in DCM, and was then concentrated

Přidán 'added ACN to give a dark yellow solid (0.81 g, 92% yield.). The melting point was 70 DEG-72 DEG

5 ° C. IR (KBr, cm @ ^-1 ): 2956, 2919, 2850, 1670, 1650, 1468, 1379, 1213, 1191, 1159, 852, 840, 795, 728, 696, 675, 605, 523, 475. 499.8 MHz, CDCl3): δ 0.88 (t, J = 7.0 Hz, 9H),

I, 201.36 (m, 90H), 1.40 (m, 6H), 1.67 (m, 6H). ¹³ C NMR (125.7 MHz, CDCl 3): δ 14.11, 17.71, 22.70, 25.36, 29.14, 29.39, 29.52, 29.65, 29.68, 29 , 72, 29.73, 31.94, 33.99, 115.18, (q, J C-F ⁼ 288.1), 161.33, (q, J C-F = 39.9). ^{. 9} F NMR (470.3 MHz, CDCl 3): δ - 71.02. ^1.9 Sn NMR (186.4 MHz, CDCl 3): δ 172.31. HRMS-APCI calcd for C 44 H 77 Sn (M - CCOCF 3): 879.7702, found: 879.7719. Elemental analysis: calculated for C 6 H 11 F 5 O 2 Sn: C 67.79; H

II, 28; F, 5.74; Found: C, 68.16; Η 11.56; F, 6.11.

Example 1F

Trioctadccyltin tosylate (5c). A mixture of tetraoctadecyltin (1 g, 0.88 χ 10 ^-3 mol) and paratoluenesulfonic acid (0.152 g, 0.88 χ 10 ^-3 mol) was refluxed in DCM (10 mL) for 48 hours. The reaction mixture was concentrated under reduced pressure to give a thick liquid which was dissolved in hot ethyl acetate and allowed to stand overnight. The precipitated white solid was filtered and dried overnight under reduced pressure at 60 ° C. A white solid was obtained (0.90 g, 98% yield), m.p. 56-58 ° C.

IR (KBr, cm ^-1 ): 2955, 2919, 2850, 1601, 1497, 1468, 1378, 1194, 1131, 1044, 1015, 815, 721, 694, 569. 1 H NMR (499.8 MHz, CDCl 3): δ 0.89 (t, J = 6.8 Hz, 9Hz), 1.10 * 1.35 (m, 96H), 1.49 (bm, 6H), 2.36 (s, 3H), 7, 16 (m, 2H); 7.60 (m, 2H). ¹³ C NMR (125.7 MHz, CDCl 3): δ 14.11, 20.55, 21.37, 22.70, 25.53, 29.41, 29.70, 29.71, 29.78, 29 , 79, 29.82, 29.84, 29.86, 29.89, 31.95, 34.12, 126.06, 128.98, 139.46, 141.61. HRMS-APCI calcd for C 18 H 18 Sn (M - OTs): 879.7702, found: 879.7697. Elemental analysis: calculated for C 16 H 18 Cl 2 SS 5: C 69.75; H, 11.32; S, 3.05; Found: C, 70.16; H, 11.76; S, 2.83.

Example 1G

Dioctadecylmethyltin triflate (6a). The procedure described in Example 1D yielded 73% yield. Mp 56 ° and 58 ° C. IR (KBr, cm ^-1 ): 2954, 2917, 72850, 1468, 1414, 1378, 1257, 1179, 1034, 769, 721, 654, 644, 581, 523. 1 H NMR (600.1 MHz, CDCl 3) δ 0.70 (s, 3H), 0.88 t, 7.0 Hz, 6H), 1.22-1.38 (m, 60H), 1.41 (m, 4H), 1.68 ( m, 4H). ¹³ C NMR (150.9 MHz, CDCl 3): δ - 0.20, 14.12, 21.39, 22.70, 25.14, 29.22, 29.39, 29.65, 29.69, 29, 75, 29.76, 29.77, 29.78, 31.94, 33.72, 118.80, (q, J C-F 317.8). ¹⁹ F NMR (376.5 MHz, CDCl 3): δ - 78.25. ¹⁹ H NMR (186.4 MHz, CDCl3): δ 160.74. HRMS-ESI calcd for C 18 H 30 S 6 (M - OTf): 641.5042, found: 641.5049. Elemental analysis: calculated for C 18 H 21 F 5 Cl 2 S 1 S: C 57.79; Η 9.83; F, 7.22; S 4.06; Found: C, 57.74; H, 10.11; F, 7.30; S, 4.02.

Example 13 1H

Dioctadecylmethyltin trifluoroacetate (6b). The procedure described in Example 1E yielded 82% yield. Mp 60 ° -62 ° C. IR (KBr, cm ^-1 ): 2955, 2919, 2850, 1670, 1650, 1468, 1378, 1194, 1158, 854, 840, 796, 728, 672, 604, 536, 473. 1 H NMR (499.8) MHz, CDCl 3: δ 0.62 (s, 3H), 0.88 t, J = 7.1 Hz, 6H), 1.21 $ 1.35 (m, 60H), 1.42 (m, 4H) 1.67 (m, 4H). ^I3 C NMR (125.7 MHz, CDCl₃): δ - 3.88, 14.11, 18.17, 22.70, 25.23, 29.11, 29.37, 29.49, 29.63, 29, 65, 29.67, 29.71, 31.93, 33.79, 115.12, 161.24. ¹⁹ F NMR (470.3 MHz, CDCl 3): δ - 71.05. ¹⁹ H NMR (186.4 MHz, CDCl3): δ 183.89. HRMS-EI calcd for Cas H5 F5 O5 Si: 739.4663, found: 739.4639. Elemental analysis: calculated for C 19 H 20 FN 2 O 2 S: C 62.15; H, 10.30; F, 7.56; Found: C, 62.31; H, 10.55; F, 7.27.

Example II

Dioctadecylmethyltin tosylate (6c). The procedure described in Example 1F yielded 85% yield. Mp 397'41 ° C. IR (KBr, cm ^-1 ): 2954, 2917, 2850, 1601, 1468, 1378, 1192, 1132, 1045, 1015,815,720,695,607, 568, 525. ¹ H NMR (499.8 MHz, CDCl 3): δ 0, 56 (s, 3H), 0.89 (t, J = 6.9 Hz, 6H), 1.1 / 71.35 (m, 64H), 1.48 (m, 4H), 2.37 (s, 3H) 7.17 (m, 2H); 7.56 (m, 2H). ¹³ C NMR (125.7 MHz, CDCl 3) δ - 0.32, 14.11, 21.10, 21.38, 22.70, 25.43, 29.39, 29.70, 29.76, 29 , 78, 29.80, 29.82, 29.84, 29.86, 31.94, 33.91, 125.95, 129.05, 139.38, 141.77. HRMS-APCI calculated for C37H17Sn (M-OTs): 641.5042, found: 641.5042. Elemental analysis: calculated for C ClClSSSSn: C, 65.09; H 10.43; S, 3.95; Found: C, 65.27; H, 10.68; S, 3.65.

Example 1J

Octadecyldimethyltin triflate (7a). The procedure described in Example 1D yielded 75% yield. Mp 49.7 51 ° C. IR (KBr, cm ^-1 ): 2952, 2915, 2849, 1470, 1376, 1258, 1179, 1039, 1034, 840, 768, 718, 655, 644, 580, 544, 520. 1 H NMR (499.8) MHz, CDCl 3: δ 0.75 (s, 6H), 0.88 (t, 7 Hz, 3H), 1.217], 38 (m, 30H), 1.42 (m, 2H), 1.68 ( m, 2H). ¹³ C NMR (125.7 MHz, CDCl 3): δ 0.82, 14.11, 21.56, 22.69, 24.99, 29.15, 29.37, 29.58, 29.67, 29 70, 29.72, 29.73, 31.93, 33.47, 118.67 (q, J C-R = 317.5). ¹⁹ F NMR (470.3 MHz, CDCl 3): δ - 74.04. HRMS-ES1 calcd for C 20 H 17 Sn (M-OTf): 403.2381, found: 403.2383. Elemental analysis: calculated for C 11 H 11 F 3 Cl 2 S 2: C 45.75; H, 7.86; F 10.34; S, 5.82; Found: C, 45.60; H, 7.99; F 10.32; S, 5.69.

-14Example 1K

Octadecyldimethyltin trifluoroacetate (7b). The procedure described in Example 1E yielded 89% yield. Mp 79> 81 ° C. IR (KBr, cm ^-1 ): 2953, 2921, 2851, 1678, 1652, 1467, 1453, 1379, 1215, 1201, 1191, 1154, 854, 839, 796, 770, 726,667, 605, 555, 526, 476; 1 H NMR (499.8 MHz, CDCl 3): δ 0.63 (s, 6H), 0.84 (t, J = 7.0 Hz, 3H), 1.20 ΐ 1.30 (m, 30H) 1.41 (m, 2H), 1.65 (m, 2H). ¹³ C NMR (125.7 MHz, CDCl 3): δ - 2.69, 14.12, 18.52, 22.69, 25.14, 29.08, 29.36, 29.46, 29.60, 29.63, 29.66, 29.69, 31.92, 33.63, 115.04, 161.18. ¹⁹ F NMR (470.3 MHz, CDCl 3): δ - 71.09, ¹¹⁹ Sn NMR (186.4 MHz, CDCl 3): δ 191.57. HRMS-EI calcd for C 21 H 41 O 3 S 2 S: 501.2002; found: 501.2001. Elemental analysis: calculated for C ₂₂ H 41 F ₃ O ₂ S 2: C 51.28; H, 8.41; F 11.06, found C 51.29; H, 8.53; F, 10.89.

Example 1L

Octadecyldimethyltin tosylate (7c). The procedure described in Example 1F yielded 74% yield. Mp 64 ° C. IR (KBr, cm ^-1 ): 2953, 2919, 2850, 1600, 1497, 1470, 1397, 1378, 1191, 1131, 1044, 1014, 815, 781, 761, 719, 695, 568, 542, 521, 496. 1 H NMR (499.8 MHz, CDCl 3): δ 0.56 (s, 6H), 0.88 (t, J = 6.8 Hz, 3H), 1.10% ^? 1.33 (m, 32H), 1.46 (bm, 2H), 2.38 (s, 3H), 7.19 (m, 2H), 7.55 (m, 2H). ¹³ C NMR (125.7 MHz, CDCl 3) δ 0.77, 14.10, 21.24, 21.39, 22.68, 25.29, 29.31, 29.37, 29.64, 29, 68, 29.73, 29.75, 29.76, 29.78, 31.92, 33.67, 125.30, 129.14, 139.09, 142.00. ^1.9 Sn NMR (186.4 MHz, CDCl 3): δ 83.08. HRMS-EI calcd for C 10 H 50 O 15 SSn: 574.2503; found: 574.2493. Elemental analysis: calculated for C 10 H 50 O 5 SSn: C 56.55; H, 8.79; S 5.59; Found: C, 56.26; H, 8.74; S, 5.20.

Example 2

Product structure

One of the tetraalkyl tin salts was already known (2, cited by Mulcahy et al., Accepted for publication) and the analytical data obtained for compounds 3 and 4 confirmed the tetrahedral arrangement of the chains around the tin atom.

For salts 5-7, the chemical shift of ¹¹⁹ Sn NMR for CDCl 3 solutions ranged from 75 to 165 ppm, which can be considered typical of the quasitetraedric arrangement of trimethyltin tin compounds with the fourth tin coordinating atom (Kapoor, et al., Polyhedron 1995, 14). 489). All triacetate compounds (5b, 6b, 7b), triflate 6a and tosylate 7c were in the same category. For triflate 5a, a strong shift was measured in tetrahydrofuran

-15k higher values (about 200 ppm), which characterizes the formation of a five-fold coordination complex with solution molecules (Chandrasckhar and Thirumoorthi, Eur. J.Inorg. Chem. 2008, 4578).

The data for the spectra of compounds 5 to 7 are summarized in Table 1. The signals for ¹⁹ Sn for tosylates 5c and 6c and for triflate 7a could not be measured.

Table 1. NMR data for tin (IV) salts of 5 * 7 '

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-18Example 3

Creation of adsorbed monomolecular layer

Glass substrates coated with 200 nm gold were obtained from Platypus Technologies. Before use, they were purified in a 3: 1 solution of sulfuric acid and hydrogen peroxide at 90 ° C, then washed extensively with water (18.2 ΜΩ) and absolute ethanol and dried in a stream of nitrogen. Trialkyltin tin monomolecular layers were formed by immersing the same gilded substrates in a solution of trialkyltin tin salts at a concentration of 1 * 10 &lt; ^-5 & gt ^; mol / ^l in dried Cr2O for about two hours. . After removal from this solution, the gilded substrates were thoroughly washed with either absolute ethanol or CH 2 Cl 2 and dried in a stream of nitrogen prior to analysis.

The monomolecular layers of 1-octadecanethiol (1) were formed on gilded substrates by immersing the substrates in a solution of octadecanethiol at a concentration of 1 × 10 ^-5 mol / ^l in absolute ethanol for approximately 2 hours. After removal from this solution, the gilded substrates were thoroughly washed with either absolute ethanol or CH 2 Cl 2 and dried in a stream of nitrogen prior to analysis.

Example 4

Stability of monomolecular layers

Self-assembled monolayers (SAMs) formed from salts 5-7 were prepared as described in Example 2. To measure their stability, a glass substrate with a SAM bound to a thin layer of gold was immersed for 15-18 hours at alternatively to dry CH 2 Cl 2, moistened with CH 2 Cl 2, n-hexane, ethanol, water, 0.1 molar · ¹ ILSO 3. 0.1 mol.l ^-1 . NaOH, 1 mmol · ¹ ΚΜπΟί, 30% (v / v) H ² O 2, or 10 mmol.r ¹ NaBH ¹ , then removed from the solution, rinsed thoroughly with either the appropriate solvent (CH 2 Cl 2, hexane, ethanol) or in the case of aqueous solutions with larger amounts of water (18.2 ΜΩ) and absolute ethanol and dried in a stream of nitrogen before measuring the IR spectrum.

The samples were also exposed to ambient laboratory atmosphere for 7 days. They were then washed with absolute ethanol and dried before measuring IR spectra. IR was measured by the loss of absorbance in the region between layers 2800 and 3000 cm ^-1 as a function of time after exposure to either

-19 laboratory atmosphere (1 week) or various reagents (solvents) for 15-18 hours after washing and drying.

The results obtained for the trialkyltin monomolecular layers were compared with those obtained for SAM consisting of 1-octadecanethiol (1). Numerous determinations using all three removable groups yielded identical results and FIG. 2 shows the results obtained for tosylate compounds as averages of at least three measurements.

Also, in cases where the monomolecular layers were partially or fully desorbed, no signs of new adsorption bands were found. Giant. 3 illustrates the time dependence of the loss of IR intensity for the adsorbed layer of salt 7 in water, ethanol, methylene chloride and hydrogen peroxide.

Example 5

Temperature desorption

To determine the temperature desorption of the trialkyltin monomolecular layers, the layers were kept under nitrogen atmosphere for 1 hour at 80, 140 and finally 200 ° C. Before measuring the IR spectrum, the gold-plated substrates were washed with absolute alcohol and dried in a stream of nitrogen.

The observed reductions in total IR signal intensity are shown in FIG. 4. No changes in the shape of the IR spectra were found in the monomolecular layers formed from salts 5 to 7, but the SAM spectrum formed from 1-octadecanthiol 1 changed after heating to 80 ° C and became substantially identical to the SAM spectra formed from salts 5 to 7.

Example 6

Ellipsometric determination of layer thickness

All measurements were performed using a Variable Angle Stokes Ellipsometer (Gaertner Scientific) with a 633 nm HeNe laser at an initial angle set at 70 °. The optical constants of the gilded substrates were measured for all freshly purified substrates. A refractive index of 1.47 was assumed for the films. Ellipsometric measurements were performed in at least five different areas of each sample.

Figure 5 shows a gradual increase in the ellipsometric thickness of the surface layer as the gilded substrate is immersed in a solution of trialkyltin salts 5-7. The adsorption was self-limiting and the adsorbed layer was stopped under the conditions used after approximately 1 hour. Tosylates appear to form the adsorbed layer most rapidly, but no significant difference was found in the final thickness or other properties of the layers formed from triflates, trifluoroacetates and tosylates (see Figure 5A).

Although compounds carrying only one long alkyl chain on the tin atom appear to adsorb most rapidly, the number of long chains on the tin atom has little or no effect on the final layer thickness, determined ellipsometrically (Figure 5B).

The boundary ellipsometric thicknesses of adsorbed monomolecular layers of alkyl tin derivatives 5 to 7 of 0.6 to 0.7 nm and of 1-octadecanthiol 1 of approximately 2.2 nm, shown in Fig. 6A, are only of relative importance, since optical constants of trialkyltin structures. These values were determined using a refractive index of 1.47, which is typical for shorter alkyl chain tetraalkyltin (cit. Mulcahy et al., Accepted for publication).

Example 7

Contact angle

The static contact angle H2O (18.2 ΜΩ) was determined using a CAM101 (KS V Instruments) using a 1 r 2 μΐ water drop. Measurements were performed in at least five different areas of each sample.

The water contact angles on the 5 + 7 salts of the trialkyltin monomolecular layers ranged from 92-97 °, which are significantly lower than the 113 ° observed for the 1-octadecanethiol monomolecular layer (Fig. 2B). Again, no significant dependence was found on the nature of the removable group or the number of long alkyl chains on the tin atom.

Example 8

Infrared spectroscopy

-21FTIR-ATR spectra (1000 scans and a resolution of 4 ^cm-1) were recorded using a Nicolet 6700 FT-IR (from Thermo Electron Corporations) MCT detector in the range of 650 * 4000 ^cm-1, cooled with liquid nitrogen. Data were obtained on an optional Seagull variable-angle device (Harrick Scientific Inc) and a 12.5 mm Ge hemisphere. Prior to each measurement, the Ge crystal was cleaned with ethanol and the reference spectrum of the crystal in contact with air was measured.

To confirm the presence of monomolecular layers on the surface of the gold-coated substrate, a Fourier transform of infrared spectroscopy using the Single reflection attenuated total reflectance (ATR) method was used. The obtained infrared spectra of layers formed from salts 5 to 7 on the gilded surface showed only vibrations attributable to the groups Cil · and CH2 (valence vibrations at 2855, 2926, 2961 cm -1) and strain vibrations at 1378, 1418 and 1468 cm ^-1 ) and were not found no evidence of typical peaks of triflate, trifluoroacetate or tosylate residues.

Particularly informative is the area CH of the valence vibrations between 2800 and 3000 cm ^-1 and FIG. 7 therefore shows a comparison of the spectra of layers formed from salts of &gt; = 7 on a gilded substrate with the spectrum of the comparative monomolecular layer of 1-octanecanethiol (1).

For salts 5-7 bands were in-Cll ·) in _the (CH 2), Vi / destination ·), and _with (CH3) observed at 2926, 2855, 2961, and 2871 ^cm-1, irrespective of the type of the leaving group . The band Vs (1 · 1) was weak in the spectrum of 1-octadecanethiol 1 and present only as a faint shoulder in the spectra of the layers formed from the 5 f 7 salts.

Example 9

Electrochemical determination

The ability to block electron transfer by cyclic voltammetry (CV) using the [Fe (CN) 6] ³ 7fFe (CN) e] ⁴ 'system as redox probe was measured to determine the permeability of the adsorbed layers. · Electrochemical measurements were performed on the AutoLab potentiostat PGSTAT302N (Metrohm Autolab) using a conventional three-electrode glass cell at room temperature. A gold electrode (in bare form or carrying an adsorbed layer), platinum wire and an Ag / AgCl electrode (saturated with KCl) were used as the auxiliary and reference electrodes.

Electron blocking experiments were performed using a 0.1 mol / ^L solution of KCl containing 2 mmol.F ¹ K i [Fe (CN);], purified prior to measurement with argon. A scanning speed of 100 mV / s was used for all measurements.

Giant. 1 compares the responses to [Fe (CN) 6] ³ in 0.1 mol.F ¹ of the KCl solution observed on the gold electrode, which was immersed for 2 hours in a trialkyl tin tosylate solution. The adsorbed layer reduced the current response relative to the bare electrode, especially when the tin atom carried three long alkyl chains, but the blocking of electron transfer was not complete even when the electrode was immersed overnight.

In contrast to these results, SAM, formed from 1-octadecanethiol 1, suppressed the electrochemical response substantially completely, with only the charging current remaining.

Industrial applicability

Self-organizing trialkyltin monomolecular layers adsorbed onto a metal-coated substrate via a tin atom are useful, for example, as active components of electronic components.

-23Overview of literature:

1. Love, J.C .; Estroff, L.A .; Kriebel, J.K .; Nuzzo, R.G .; Whitesides, G.M. Chem. Roar. 2005, 105, 1103.

2. Ulman, A. Chem. 1996, 96.1533.

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5. Willey, T.M .; Vance, A.L .; van Buuren, T .; Bostedt, C .; Terminello, L.J .; Fadley, C.S. Surface Science, 2005, 576, 188.

6. Huang, F. K .; Horton, R.C .; Myles, Jr., D.C .; Garrell, R.L. Langmuir 1998, 14, 4802.

7. Ciszek, J.W .; Stewart, Μ. P .; Tour, JM Am. Chem. Soc. 2004, 126, 13172.

8. Shaporenko, A .; Ulman, A .; Terfort, A .; Zhamikov, M.J. Phys. Chem. B 2005, 109, 3898.

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10. Clark, B.K .; Standard, J.M .; Gregory, B.W .; Hali, A. D. Surface Science 2002, 498,285.

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Claims (10)

PATENT CLAIMS An ordered self-organizing monomolecular layer on a substrate coated with gold, characterized in that said monomolecular layer consists of trialkyltin molecules which correspond to the general formula (C _n H 2 _n + i) 3 Sn, where n is in the range of 1 to 36, wherein the tin atom is adjacent to the substrate and the alkyl chains are oriented away from the substrate. Arranged self-organizing monomolecular layer according to claim 1, characterized in that the trialkyltin preferably corresponds to the general formula (CH ₃ ) _x Sn (C 18 H 37) _y , wherein x is from 0 to 2, y is from 1 to 3, wherein x + y = 3. An ordered self-organizing monomolecular layer according to claim 1 or 2, characterized in that it has a thickness of 0.1 to 5 nm. A process for the preparation of an ordered self-organizing monomolecular layer as claimed in claims 1 to 3, characterized in that a trialkyltin salt having a number of carbon atoms in the alkyl range of 1 to 36 is adsorbed onto the metal-coated substrate surface. 5. A process according to claim 4 wherein the trialkyltin tin salt corresponds to the general formula ( _Cn H2 _n + i) ₃ Sn-Y, wherein n is from 1 to 36 and Y is selected from the group consisting of triflate as the acid salt. trifluoromethanesulfonic acid, trifluoroacetate as the trifluoroacetic acid salt and tosylate as the p-toluenesulfonic acid salt. Process according to Claim 4 or 5, characterized in that the trialkyltin tin salt preferably corresponds to the general formula (CH ₃ ) _x (C 18 H 37) _y Sn-Y, wherein x is from U to 2, y is from 1 to 3 wherein x + y = 3, and Y is selected from the group consisting of triflate as the trifluoromethanesulfonic acid salt, trifluoroacetate as the trifluoroacetic acid salt, and tosylate as the p-toluenesulfonic acid salt. A process according to any one of claims 4 to 6, comprising the steps of: (a) immersing the substrate in a solution consisting of an organic solvent and a trialkyltin salt having a number of carbon atoms in the alkyl range of 1 to 36; (26b) the substrate is subsequently washed with an organic solvent and then the substrate with the adsorbed layer of trialkyltin molecules is dried. 8. The method according to claim 7, characterized in that in step a) a solution trialkylstannyl trifluoromethanesulfonate, trifluoroacetate, and / or paratoluenesulfonic acid in a concentration range 1 mol.l ^-1 to 1.10 ^'6 mokl' ^1, wherein the number of carbon atoms the alkyl salt used ranges from 1 to 36. Process according to Claim 7, characterized in that the organic solvent used in step a) is selected from the group consisting of hydrocarbon, ether, haloalkane derivative, carboxylic acid nitrile or nitro compounds and the solvent selected from the same group of substances is also used. washing in step b). Process according to Claim 9, characterized in that dichloromethane is preferably used as the organic solvent.