NL8003863A - FUNCTIONALLY SUBSTITUTED PHENOXYALKYL ALKOXYSILANES AND A METHOD FOR THEIR PREPARATION. - Google Patents

Description

-1- N.O. 28833 ft

Functionally substituted phenylalkyl-alkoxysilanes and a process for their preparation.

The invention relates to a new group of organosilicon compounds. In particular, the invention relates to new functionally substituted phenoxyalkyl, thiophenoxyalkyl and pyridyloxyalkylsilanes and to a process for their preparation.

The new compounds according to the invention have the formula 1 or 2, wherein R is a group of the formula -M2, -NR8, a group of the formula 3, a group of the formula -CHO, -GE, -C0E8, -GOOR8 , a chlorine, bromine or 10 iodine atom, a group of the formula 4-, 5 or 6, a group of the formula -S02R8, -S0R8, -ILO2 or an alkenyl group with 2-5 carbon atoms, R ^ an alkyl -, alkoxy or thioalkoxy group with 1-12 carbon atoms, R 1 a chloro, bromo or

Q

iodine atom or a group of the formula -C00R, -CU, -M2, -ER8 !!, -NR ?, or a group of the formula 7 or 8, R ^ a d. - alkyl group with 1-12 carbon atoms, R 'a metbylene or 6 alkylene group with 3-12 carbon atoms, R and R' independently of each other an alkyl, cyanoalkyl, alkenyl, cycloalkyl, aryl, alkaryl - or aralkyl group, where-20 in each alkyl group in the symbols R8 and R ^ 1 - 12 carbon-

O

atoms contain, R represents an alkyl, cycloalkyl, aryl, alkaryl or aralkyl group, wherein each alkyl group contains 1-12 carbon atoms, R 1 represents a group of the formula 9, a group of the formula -GH = GH-, a group of the formula 10 represents ΛΛ Λ-Ζ 25 or 11, wherein R and R; independently represent a hydrogen, chlorine, bromine or iodine atom or an alkyl 12 14 group with 1-12 carbon atoms and R and R independently represent a hydrogen atom or an alkyl group with 1-12 carbon atoms, Z represents an acid 30 represents a substance or sulfur atom or a group of the formula 12 or 13, m is an integer from 1 to 5, e is the value O, 1 or 2, p is the value 2 or 3, q is the value 1 , 2 or 3, and t is the value 0 or 1, with the proviso that a) when m is 2, one or both symbols R is a group with 35 cLe formula -M2, -NR8H, -ER8, a group with the formula 6, 14, 3 or 4 or a group of the formula -GOOR8 represent voorstellen and each of the remaining symbols R represents a cyano group, an 8003863 m -2-chlorine, bromine or iodine atom or a nitro group; f Λ b) when i 3 one of the symbols R is a group with the

O Q

formula H, -NR 1 represents a SroeP of formula 3 and the remaining two symbols R 1 represent a chlorine, bromine or iodine atom;

a

c) when m is 4 or 5, R represents a chlorine, bromine or iodine atom; Λ d) 'n is 1 or 2 when m equals 1 and R represents a group of the formula or -NO2; E) the sum of m and n is equal to or less than 5 and Ί 8 f) when p is 3, R is a group of the formula 3 -C00R, 2 6 7 4, 5 or 6, R represents an alkyl group , R and R 'independently represent a cyanoalkyl or alkenyl group and Z represents a group of the formula 12 or 13.

The invention also relates to a process for the preparation of the above-mentioned new compounds. According to this process, a haloalkylsilane of the formula 15. is reacted with an anhydrous alkali metal or alkaline earth metal phenoxide or thiophenoxide of the formula 16 or an anhydrous alkali metal or alkaline earth metal salt of a hydroxy or mercaptopyridine of the formula 17 at a temperature from room temperature to 200 ° G under an inert atmosphere and in the presence of a liquid reaction medium consisting essentially of at least one dipolar aprotic liquid, and optionally at least one liquid hydrocarbon with a boiling point of 40 to 200 ° C under normal pressure. The resulting reaction mixture is held at 40-200 ° C for a sufficient time to form the desired phenoxyalkyl or thiophenoxyalkyl-30 alkoxy silanes. The silane is then isolated from the resulting reaction mixture.

The above method is also applicable to the preparation of known silanes with functional groups, including the aminophenoxypropylsilanes of US Pat. No. 4,049,691.

The compounds of the invention are functionally substituted phenoxy, thiophenoxy, pyridyloxy and thio-pyridyloxyalkyl alkoxy silanes of formula 1 or 2 of the formula sheet. The functional substituent on the phenyl group, Λ40 which is represented by the symbol R in formulas 1 and 2, is 8003863 -3-QQ t, a group of the formula -NHgj -NB H, -NRij, a group having the formula 3> -OHO, -ON, -COR ^, -COOR ^, a chlorine, bromine or iodine atom, a group of the formula 4,

O Q

3 or 6, represent a group of the formula -SO2R, -SOR and -NOg -5. The various substituents represented by the symbols R through R are mentioned in the above passage, imino groups are preferred as substituents because of the large amount of uses of this group of compounds. The substituent 10 may be at the ortho, meta or para site relative to the oxygen or sulfur atom represented by the symbol Z in formulas 1 and 2. The phenoxy, thiophenoxy, pyridyloxy or thiopyridyloxy group is bonded to the silicon atom by an alkylene group, which group may represent a methylene group or a higher alkylene group having 3 to 2 carbon atoms in a straight or branched configuration. Compounds in which R 1 is an ethylene group have been found to be so unstable in the presence of even trace amounts of aqueous acids or bases that these compounds are unusable for practical purposes. In addition to the above alkylene group, the silicon atom can also be bonded to three alkoxide or aryloxide groups represented by OR 1 in formulas 1 and 2 or to two alkoxide or aryloxide groups and one hydrocarbyl or cyanoalkyl group. The term "hydrocarbyl group" includes alkyl, cycloalkyl, aryl, alkaryl, and aralkyl groups 6 * 7 as defined for the symbols R and R 'above.

The compounds of the invention are preferably prepared by reacting an alkali metal or alkaline earth metal salt, preferably the sodium or potassium salt, of the desired phenol, thiophenol, hydroxypyridine or thiopyridine with a haloalkylsilane of the formula 15 .

This reaction is highly exothermic and is preferably conducted under an inert atmosphere and in the absence of even traces of water since water is known to readily react with silanes having 2 or 3 alkoxy or aryloxy groups bonded to the silicon atom , reacts to form polymeric products. The reaction-40 medium is a dipolar aprotic liquid such as dimethyl-8003883-4-sulfoxide, Ν, Ν-dimethylformamide, tetramethyl urea, N-methylpyrrolidone or hexamethylphosphoramide. The dipolar aprotic liquid constitutes about 1 to 100% by weight of the reaction medium, preferably about 20 to 50% by weight. Each remaining part of the reaction medium consists essentially of at least one liquid hydrocarbon with a boiling point of 40 to about 200 ° C under atmospheric pressure. The purpose of this liquid hydrocarbon is to facilitate the removal by azeotropic distillation of any amount of water present in the reaction mixture. Preferably, the haloalkylsilane is gradually added to a reaction mixture containing the alkali metal salt. When the addition is complete and the exothermic reaction has settled, it is usually desirable to heat the reaction mixture at 70-150 ° C for several hours to effect a substantially complete conversion of the reactants to the desired functionally substituted phenoxyalkyl, thiophenoxyalkyl. , thiopyridyl oxyalkyl or pyridyloxyalkyl silane.

The compounds of the invention, many of which are a colorless, high-boiling viscous oil, are soluble in the reaction medium and readily isolable by removing the above-mentioned liquid hydrocarbon and the dipolar liquid. Some of the compounds may darken if exposed to light or air for a long time.

As mentioned, the above process is applicable to the preparation of phenoxyalkylsilanes, which may include known compounds.

The tri (hydrocarbyloxy) haloalkylsilanes or di (hy-

drocarbyloxy) haloalkylsilanes, which are used as one of the reactants for the preparation of the compounds of the invention, are either commercially available or can be readily obtained by reacting the corresponding haloalkyltrihalosilane or a silane of the formula 18, where X

p and X represent a chlorine, bromine or iodine atom, with an alcohol, R OH, containing 1 to 12 carbon atoms. Alternatively, the hydroxyl group may be attached to a carbocyclic or hetero-40 cyclic ring structure such as a cyclohexyl or phenyl group 8003863-5. The haloalkyl trihalosilanes can be prepared by reacting a haloalkene such as allyl chloride or methallyl chloride with a trihalosilane, HSiX 2 at room temperature and the presence of a platinum catalyst. Methods for preparing intermediate silanes are well known in the art. A detailed discussion of the reaction conditions therefore seems unnecessary.

Examples of the preferred functionally substituted phenols and thiophenols which can be used in the preparation of the compounds of the invention are amino phenols, amino thiophenols and amino chlorophenols in which the amino group at the ortho, meta or para positions relative to the hydroxyl group is the isomeric hydroxybenzaldehydes and the isomeric esters of hydroxybenzoic acid and mercaptobenzoic acid, wherein the alcohol moiety of the ester contains 1-12 carbon atoms. If the alcohol contains a phenyl group, the number of carbon atoms is 7-18. Other functional substituents which may be attached to the phenyl group are stated in this description and claims, respectively. In addition, the phenyl group can contain 1 or 2 alkyl, cycloalkyl or aryl groups.

Furthermore, the amino group of an aminophenol or amino-thiophenol can be pre-reacted to form an amide, imide, carbamate, sulfonamide or other group before the reaction of the phenol or thiophenol, in the form of its alkali or alkaline earth metal salt with the haloalkylalkoxysilane.

An anhydrous form of the alkali or alkaline earth metal salt of the phenol, thiophenol, hydroxypyridine or mercaptopyridine can be prepared using the free metal or a hydride or alkoxide of the metal, such as sodium hydride or methoxide. Any of these compounds can be added to a solution of the desired phenol, thiophenol or pyridine derivative in a dipolar aopic liquid, which may optionally contain a liquid hydrocarbon. The metal, metal hydride or metal alkoxide is advantageously used as a dispersion or suspension in a liquid hydrocarbon. The temperature of the reaction medium 8003863 -6- is maintained between room temperature and about 50 ° C to avoid an uncontrollable exothermic reaction.

The functionally substituted silanes of the invention are useful as coupling agents for binding an organic polymer to an inorganic material such as glass fibers or metal, as flocculants for water purification, as adhesives for glass fibers or fabrics, and as a constituent of brighteners and washing, 10 especially for cars. The compounds of the invention may be reacted with organopolysiloxane-containing, terminal hydroxyl or alkoxy liquids, mixed with random fillers to form elastomeric products, which are useful as coatings, sealants and articles-making products. to be.

a

Compounds in which R in the formulas 1 and 2 represents an amino or dialkylamino group (-NH 2 or -NR 2) are effective as agents which make polishes and waxes resistant to detergents.

The invention is further illustrated by the examples below.

Example I

Preparation of m-aminophenoxypronylmethyl dimethoxysilane A glass reactor was charged with 60 g (0.55 mol) p-aminophenol, 4-5.28 g of a 50 wt% aqueous solution of sodium hydroxide (0.54- mole (OH)), 112 ml of dimethyl sulfoxide and 120 ml of toluene. The resulting mixture was heated to boiling point under a nitrogen atmosphere for six hours to remove any water present by azeotropic distillation. The reaction mixture was then allowed to cool to about 75 ° 0 and 100.4 g (0.56 mol) of 3-chloropropyl-methyldimethoxysilane was added dropwise to the reaction mixture with stirring. The temperature of the reaction mixture was kept constant by heating and controlling the addition rate. After the addition, the reaction mixture was heated to 115 ° C for about 16 hours, then the reaction mixture was allowed to cool and filtered to remove any solid material present. Then 4-0, the solvents were removed under a pressure of about 15 mm 8003863-7 mercury at a temperature of about 6CrC. The pressure was then reduced to 3-4 mm mercury, removing the material with a boiling point of 230-235 ° C. This fraction weighed 112 g, corresponding to an yield of 80% based on the starting materials. Analysis by vapor phase chromatography indicated that the purity of the product was greater than 98%. The infrared and MR spectra of the product were compatible with the proposed structure.

Example II

Preparation of 5.5-bis (carbomethoxy) phenoxyproovl-trimethoxy silane

Using the method described in Example I, a reactor was charged with 115.5 S (0.55 mol) of 3,5-kis (carbomethoxy) phenol, 43.28 g of a 50% aqueous solution of sodium hydroxide (equivalent to 0.54 mol RaOH), 112 ml dimethyl sulfoxide and 1200 ml toluene. The resulting mixture was heated to a boiling point under a nitrogen atmosphere for six hours to remove substantially all of the water present by aze-20 otropic distillation. The reaction mixture was then allowed to cool to about 75 ° C and 109 g (0.555 mole) of chloropropyl trimethoxysilane was added dropwise to the reaction mixture. After the addition, the temperature of the reaction mixture was raised to 115 ° C and held constant for 16 hours, after which the reaction mixture was allowed to cool to room temperature. Then the reaction mixture was filtered and the toluene, dimethyl sulfoxide and other volatiles were removed under reduced pressure, brought about by a water jet pump. The liquid residue was then distilled under a pressure of 3-4 mm mercury, the fraction having a boiling point of 240-270 ° C was collected and weighing 95 g. Fractional distillation of this material 35 yielded 75 g of a viscous colorless oil, which was collected in the boiling range of 250-252 ° C under a pressure of 3 mm of mercury. The infrared and MR spectra of the product were compatible with the proposed structure. The vapor phase chromatogram indicated that the purity of the product 40 was at least 98%. On standing, the product gradually solidified.

Example III

Preparation of o-propenylphenoxypropyl trimethoxysilane

Using the method used in Example 1, a reactor was charged with 73.7 g (0.55 mole) o-allylphenol, 43.28 g of a 50% aqueous solution of sodium hydroxide (0, 54 moles NaOH), 112 ml dimethyl sulfoxide and 120 ml toluene. The resulting mixture was heated to boiling point under nitrogen for six hours to remove all the water present by azeotropic distillation. The reaction mixture was then allowed to cool to about 75 ° C and 109 g (0.56 mol) of 3-chloropropyl-trimethoxysilane was added dropwise while stirring the reaction mixture. After the addition, the reaction mixture was heated to 115 ° C for 16 hours, then the reaction mixture was allowed to cool and filtered to remove solid material. The solvents were then removed under a pressure of about 15 mm of mercury at a temperature of about 60 ° C. The pressure was then reduced to 2 mm of mercury, after which the material with a boiling point of 146 ° C was collected. The weight of this fraction corresponded to a yield of 90% based on the starting materials. Analysis by vapor phase chromatography indicated that the purity of the product was greater than 98%. The infrared and NMR spectra of the product were compatible with the proposed structure. Example IV

Preparation of m-aminophenox7-2-methylpropyl-methyl-dimethoxy-silane Using the method described in Example 1, a reactor was charged with 60 g (0.55 mol) p-amino-phenol, 43.28 g of a 50 % aqueous solution of sodium hydroxide (0.54 mol NaOH), 112 ml dimethyl sulfoxide and 120 ml toluene. The resulting mixture was heated to boiling point under nitrogen for six hours to remove the entire amount of water present by azeotropic distillation. The reaction mixture was then allowed to cool to about 75 ° C and 117 (0.56 mol) 2-methylchloropropylmethyl dimethoxysilane was added dropwise with stirring of the reaction mixture. After the addition 8003363> 9% gene, the reaction mixture was heated at 115 ° C for 16 hours, then the reaction mixture was allowed to cool and filtered to remove solid material. The solvents were then removed under a pressure of about 15 mm mercury and a temperature of about 60 ° C. The pressure was then reduced to 2 mm of mercury, after which the material with a boiling point of 165 ° C was removed. Analysis by vapor phase chromatography indicated that the purity of the product, a pale yellow viscous liquid, was greater than 98%.

Example V

Preparation of o-carbomethoxyphenoxypropyl-methyrdimethoxy-silane

Using the method described in Example I, a reactor was charged with 83.7 g (0.55 mol) of methyl p-hydroxybenzoate, 43.28 g of a 50% aqueous solution of sodium hydroxide (0 , 54 moles NaOH), 112 ml dimethyl sulfoxide and 120 ml toluene. The resulting mixture was heated to boiling point under nitrogen for six hours to remove the entire amount of water present by azeotropic distillation. The reaction mixture was then allowed to cool to about 75 ° 0 and 109 g (0.58 mol) of 3-chloropropyl-trimethoxysilane was added dropwise while stirring the reaction mixture. After addition, the reaction mixture was heated to 115 ° C for about 16 hours, then the reaction mixture was allowed to cool and filtered to remove solid material.

The solvents were then removed under a pressure of about 15 mm of mercury at a temperature of about 60 ° C.

Then the pressure was reduced to 2 mm of mercury, after which the material with a boiling point of 230 - 235 ° C was collected. The weight of this fraction corresponded to a 92% yield based on the starting materials. Analysis by vapor phase chromatography indicated that the purity of the product was greater than 98%. The infrared and NMR spectra of the product were compatible with the proposed structure.

Example VI

Preparation of m-succinimidophenoxypropyl-trimethoxysilane 40 A solution of 200 g of succinic anhydride, 218 g of 8003863 -10-m-aminophenol and one liter of glacial acetic acid was heated for 16 hours in a reactor equipped with a mechanically driven stirrer and a water-cooled reflux condenser. He allowed the reaction mixture to cool to room temperature. The solid product was pulverized, washed with water to remove the acetic acid and then dried. The resulting m-succinimidophenol (105.1 g; 0.55 mol) was charged to a reactor together with 4-3.28 g of a 50% aqueous solution of sodium hydroxide, 112 ml of dimethyl sulfoxide and 120 ml of toluene. which was equipped with a nitrogen supply tube, a water-cooled reflux condenser and a Dean-Stark trap. The resulting mixture was heated to boiling point under nitrogen for six hours to remove the entire amount of water present by azeotropic distillation. The reaction mixture was then allowed to cool to about 75 ° C and 109 g (0.56 mol) of 3-cb-chloropropyl-trimethoxysilane was added dropwise while stirring the reaction mixture. After the addition, the reaction mixture was heated to 115 ° C for 16 hours, then the reaction mixture was allowed to cool and filtered to remove solid material. The solvents were then removed under a pressure of about 15 mm of mercury at a temperature of about 60 ° C. Then the pressure was reduced to 0.5 mm of mercury, after which the material with a boiling point of 228 ° C was collected.

Analysis by vapor phase chromatography indicated that the purity of the product, a white solid, was greater than 98%. The infrared and NMR spectra of the product were compatible with the proposed structure.

8003863

Claims (20)

1. Silanes, characterized by the formula 1 or 2, wherein R ^ a group of the formula -RH ^, -Nr |, a group 5 of the formula 3j, a group of the formula -OHO, -CN, -COR® , Q -GOOR, a chlorine, bromine or iodine atom, a group of the formula 4.5, -SOR®, -NO2 and an alkenyl group with 2-5 carbon atoms, or R an alkyl, alkoxy or thioalkoxy group with 1 - 12 carbon atoms, R ^ a chlorine, bromine or iodine atom or a group of the formula -GOOR®, -GR, -HHg, -NR%, -Ir |, a group of the formula 7 or 8, 4 R is an alkyl group of 1-12 carbon atoms, 2. Silanes according to claim 1, characterized in that R represents a group of the formula -NE ^, -NR ^ or -OHO. Silanes according to claim 1, characterized in that Έ? represents a propylene group. 4. Silanes according to claim 1, characterized in that R and Rr represent an alkyl group with 1-4 carbon atoms. 25 Silanes according to claims 1 to 4, characterized in that R and Rr represent a methyl group. 6. Silanes according to claim 1, characterized in that n has the values 0 or 1. 7. Silanes according to claim 1, characterized in that n has the value 1 and R represents a methyl group. 8. Silanes according to claim 1, characterized in that R represents a CH 2 COO group and m has the value 2 and n the value 0. Process for preparing silanes, characterized in that silanes of the formula 1 or 2 are prepared in a manner known per se, in which the substituents have the meanings set out in the preceding claims. 10. A process for preparing silanes, characterized in that silanes of the formula 1 or 2 are prepared, in which the substituents have the meanings set out in the preceding claims by substantially equimolar amounts of anhydrous alkali metal. Or alkaline earth metal salt of a compound of the formula 16 or 17 with a haloalkylsilane of the formula 15, wherein M represents an alkali metal and X represents a chlorine, bromine or iodine atom and the reaction of the above alkali metal or alkaline earth metal salt of the 10 performs the above compound and the silane under substantially anhydrous conditions at a temperature from room temperature to 200 ° C in a liquid reaction medium, which at least partly consists of at least a dipolar aprotic liquid, the remainder of the above liquid reaction medium mainly consists of a liquid hydrocarbon with a boiling point of 40 to At about 200 ° G, the reaction medium obtained is kept at a temperature of 40 to 200 ° C for a period of time sufficient to substantially convert the alkali metal compound and the silane into the desired functional phenoxyalkyl, thiophenoxyalkyl or pyridyloxyalkylsilane. and said silane is recovered by filtration of the reaction medium and the liquid reaction medium of the liquid phase is evaporated. 11. Process according to claim 9 or 10, characterized in that R represents a group of the formula -NE ^, -NRg or -CIO. 12. Process according to claim 9 or 10, characterized in that R 1 'represents a propylene group. 13. Process according to claim 9 or 10, characterized in that R and R 'represent an alkyl group with 1-4 carbon atoms. A method according to claim 12, characterized in that R and R 'represent a methyl group. A method according to claim 9 or 10, characterized in that X represents a chlorine atom. R 1 represents a methylene or alkylene group of 3-12 carbon atoms, 6 7 R and R 4 independently represent an alkyl, cyanoalkyl, alkenyl, cycloalkyl, aryl, alkaryl or aralkyl group, wherein each alkyl group contains 1 12 carbon atoms, 8 20. represents an alkyl, cycloalkyl, aryl, alkaryl, or aralkyl group, wherein each alkyl group contains 1-12 carbon atoms, R 1 a group of the formula 9, a group of the formula -CI = CH -, a group of the formula 10 or 11, wherein R and 13 25 independently represent a hydrogen, chlorine, bromine or iodine atom or an alkyl group of 1-12 carbon atoms, and 12 14 R and R independently 'k represent each other a hydrogen atom or an alkyl group with 1-12 carbon atoms, 30. represents an oxygen, sulfur atom or a group of the formula 12 or 13, m is an integer from 1 to 5 including the values 1, 2 and 3, n represents the value 0, 1 or 2, 55. represents the value 2 or 3, q represents the value 1, 2 or 3, and t represents the value e represents 0 or 1, with the proviso that wanneer a) when m is 2, one or both of the symbols R represents a group of the formula -ïïïg, -RR%, -NR ^, the groups of the formula 6, 40 14, 3 and 4 or a group of the formula -C00R® 8 0 0 3 8 6 3 -12- and any remaining symbol R represents a cyano group, a chlorine, bromine or iodine atom or a nitro group, b) when m is 3 R ^ represents a group of the formula -NEL ·, -NR%, Q «-NES or a group of the formula 3 and the two remaining symbols R represent a chlorine, bromine or iodine atom, c) when m 4 or 5, 2 represents a chlorine, bromine or iodine atom, d) n has the value 1 or 2 when m is 1 and E represents a group 10 of the formula -NE ^ or -NO2, e) the sum of m and n is equal to or less than 5, and f) when p is 3, E is a group of formula 3> a group Q of formula -COOE, a group of formula 4, 5 or 6 2 6 7, E represents an alkyl group and E and R 'independently a cya represent analkyl or alkenyl group and Z represents a group of the formula 12 or 13. Process according to claim 9 or 10, characterized in that M represents a sodium atom. 17. Process according to claim 9 or 10, characterized in that the dipolar aprotic liquid is di-8003863 -14-methylsulfoxide, ΪΤ, R-dimethylformamide, tetramethylurea and / or hexamethylphosphoramide. 18. Process according to claim 9 or 10, characterized in that the reaction between the alkali metal compound and the silane is carried out under an inert atmosphere. Process according to claim 9 or 10, characterized in that the dipolar aprotic liquid forms 1 - 100% by weight of the reaction medium. 10 A method according to claim 9 or 10, characterized in that R represents a CH 2 COO group and m has the value 2 and n have the value 0. * ** * * 8003863 r '_ _L L · \ d = / ^ R3-p tT 3-p 3. Kn 0 II n \ C / rS xc II o L · L · L JL L · oo J5CLR6 Jr8 JoR8 ^ COOR8 ^ COR8 "N \ r10 'N \ rO' N \ r (0" Mv ^ r «'N \ r«> A. JL. JL · JL JL Γ f ^ oo —9 — ο— ~ f ^ \ - s- X r * rm XX 8 JL J4.J5 ZM - <C00R8 XR8SiX ° R6) R R8-XS_R. \ R «^ _p n” - JL 3 Λ r3 ----- r4 x 'r8s; / R3-p ’^ 4 8003863