DE2420474C3 - - Google Patents

Description

in which R ^{1 represents} hydrogen, halogen, a lower alkyl or alkoxy radical, with alcohols of the general formula

R ^ -OH ' ⁵

in which R ² denotes an optionally substituted aliphatic radical having at least 2 carbon atoms or a cycloaliphatic radical, characterized in that the benzoin is reacted with the alcohol and thionyl chloride at an elevated temperature.

2. The method according to claim 1, characterized in that the reaction is carried out in the temperature range from about 70 to 90 ° C. : <;

The invention relates to a process for the production of benzoin ethers.

It's from the Journal of the Chemical Society (London). Vol. 91 (1907). S. 1384 ff. And Vol. 93 (1908), pp. 950 ff, known. Benzoin converts to benzoin methyl ether with methanol in the presence of hydrogen chloride for 3s set. It is also known from DT-OS 19 04 740 that this reaction is unsatisfactory in its yield when transferring to secondary alcohols such as isopropanol, sec-butyl alcohol and cyclohexanol the corresponding benzoin ether delivers in better yield. The benzoin ethyl ether can also be used according to the Journal of the Chemical Society (London), Vol. 93 (1908), P. 1604, can be obtained in the same way with a yield of about 75% of theory. Others too Benzoin alkyl ethers have already been produced in this way (Chemical Abstracts, Vol. 70, 1969, 114 744 w, and Vol. 78, 1973, 29 351 m; DT-OS 21 07 934).

The disadvantages of the known process are the long reaction times required and the considerable Excess alcohol, which must generally be used to counteract the influence of the Reaction formed water to the reaction equilibrium to the desired reaction product shift.

There is therefore a significant need for a better process for making benzoin ethers, who are interested, for example, as initiators for photopolymerization (cf. DT-AS 16 94 149; DT-OS 19 04 740).

It has been found that benzoin ethers can be easily converted into benzoins general formula

O OH

the R ¹ for hydrogen. Halogen, a lower alkyl or alkoxy radical, with alcohols of the general formula

R ^: OH 111)

in the r ^? an optionally substituted aliphatic radical having at least 2 carbon atoms or a cycloaliphatic radical is obtained when the benzoin is reacted with the alcohol and thionyl chloride at elevated temperature.

Halogen which may be mentioned is fluorine, chlorine, bromine and iodine, preferably chlorine.

The lower alkyl and alkoxy radicals are those with up to 6, in particular 3, carbon atoms; Examples include: methyl, ethyl, propyl, Isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, amyl, isoamyl, n-hexyl and the other isomeric pentyl and hexyl residues. The scope of meaning of the alkoxy radicals corresponds to the alkyl radicals. Preferred may be mentioned: methyl, ethyl, methoxy and ethoxy.

Optionally substituted aliphatic radicals are straight-chain and branched alkyl radicals with 2 up to 18 carbon atoms, preferably with 2 to 10 and in particular with 2 to 4 carbon atoms; for example may be mentioned: ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, amyl, isoamyl, octyl, nonyl, Lauryl, myristyl, palmityl, stearyl.

Optionally substituted cycloaliphatic radicals are those with up to 12, in particular up to 8 carbon atoms in question such as cycloheptyl, cyclooctyl, cyclodecyl and cyclododecyl. Preferred are cyclopentyl and cyclohexyl.

As substituents of the optionally substituted aliphatic and cycloaliphatic radicals come in particular halogen (fluorine, chlorine, bromine, iodine), preferably chlorine, are possible.

The preferred starting compound of the formula I is benzoin itself.

Using the example of the reaction of benzoin with isopropanol, the method according to the invention is through the following formula scheme explains:

O OH

^{/ y S>} --C ■ CH -f ^% y

OH

CH ₃ CTI CH., + SOCI ₂
CH, - CH CH,
OO

C CH

SO,

+ 2HCI

The process according to the invention is carried out at an elevated temperature. Advantageously, you can use the Range of the boiling temperature of the thionyl chloride (7TC / 76O Torr) about 70 to 90 ° C, preferably between 75 and 80'C, work. Of course, the reaction can also take place at lower temperatures use and also be carried out. It is also possible to use it according to the boiling point Finding alcohol to work at a higher temperature.

In general, the inventive method carried out at normal pressure. However, it is also possible and may optionally be advantageous in increased pressure to work. The resulting gaseous reaction by-products can be removed under the autogenous pressure work and the pressure according to the height by appropriately throttled discharge of the Adjust reaction gases.

According to the reaction equation, alcohols of the formula II and thionyl chloride are more stoichiometric Amount required based on benzoin In general, it is advantageous to use an excess of alcohol to work towards benzoin. You can choose any excess of alcohol, but is one large excess is generally not appropriate. It is advantageous to use the alcohol in an amount from 2 to 8, preferably from 3 to 5 moles per mole of benzoin and in particular from about 4 moles per mole of benzoin.

Thionyl chloride is generally expediently with a slight excess over the stoichiometrically required amount used The excess can be up to 0.6 mol over the stoichiometrically amount required, in particular, thionyl chloride is expediently used in an amount of from 1 to 13 Moles per mole of benzoin.

As a result of the formation of HCl as a by-product, it is also possible to use less than that stoichiometric to use the required amount of thionyl chloride; this can be the case when working under elevated conditions Pressure can be beneficial.

In general, the process according to the invention is carried out as follows. Benzoin and alcohol the General formulas 1 and II are presented and heated to the reaction temperature and the subsequent Addition of thionyl chloride kept at this temperature. Thionyl chloride is used in proportion to its consumption metered in, the rate of addition corresponding to the evolution of gas in the Reaction (hydrogen chloride and sulfur dioxide) easily and simply regulated with the help of known measuring methods can be. In general, the reaction mixture must be heated to the reaction temperature keep.

The gases hydrogen chloride and sulfur dioxide formed during the reaction can be extracted in a known manner collected and rendered harmless as exhaust gases or used in some other way. Of course it is expedient to remove any entrained proportions of the starting compounds of the invention Reaction - be it in liquid or gaseous form - previously separated from the exhaust gas in the usual way and fed back into the reaction.

Working up the reaction mixture, which is generally still excess in addition to the reaction product May contain alcohol and thionyl chloride as well as hydrogen chloride and sulfur dioxide in dissolved form take place in the usual way. For example, products that boil less than benzoin ether can be used optionally be distilled off under reduced pressure. However, it is also possible by adding Water a large part of these ports than aqueous Separate solution, while the reaction product remains as an organic phase.

The benzoin ether can also be isolated and purified by customary methods, for example by distillation or recrystallization; if appropriate, the distillation can also be carried out under reduced pressure Apply pressure, while mixtures of lower aliphatic values are particularly advantageous for recrystallization Alcohols can be used with water. Optionally, the solution of the reaction product before crystallization with hooves common clearing agents> or adsorbents such as charcoal, kieselguhr are cleaned and filtered, which of course are customary Can use filter aids.

The crude reaction product obtained can also be used directly up to the desired concentration with appropriate Alcohol-water mixtures are diluted so that the crystallization of the benzoin ether from them Solutions takes place

The isolation and purification of the reaction product is state of the art and not essential to the invention.

Of course, the method according to the invention also be carried out continuously; you can use the three reaction components in the desired Ratio simultaneously in a reaction zone

-One introduce, with the throughput for example like this can be measured that a mean residence time of about 1/2 hour, based on the volume of the Reaction zone, results. The configuration of the apparatus for the continuous process can be carried out in the usual way respectively; for example in a reaction vessel, in a cascade of vessels or in a reaction tube. Included the equipment can be configured according to the state of the art. In general you can use simple and inexpensive equipment; z. B. one can do the continuous implementation make the method according to the invention so that benzoin, thionyl chloride and alcohol in the selected ratio are metered into a reaction vessel at the same time and the throughput so is measured that. based on the reaction volume, an average residence time of about 1/2 hour results, the reaction product after filling the entire reaction volume with the reaction mixture while keeping the level constant over a Overflow is deducted. In general, this continuous implementation of the Process according to the invention a conversion of more than 95% of theory.

The feasibility of the method according to the invention is surprising because it is from H on be n W e y 1, Methods of Organic Chemistry, 4th Edition, Vol. VI / 2, p. 431 (1963), it is known that thionyl chloride with alkanols with elimination of hydrogen chloride easily to chlorosulfinic acid esters and sulfurous acid

so esters reacts, with the chlorosulfinic acid ester thermally are very unstable, so that, as a result of the elimination of sulfur dioxide, only the corresponding Can isolate chloroalkanes. In addition, thionyl chloride is formed by gentle heating Benzoin easily the chloro-deoxy-benzoin, as from Beilstein's Handbuch de 'Organic Chemistry, 4 Edition, Vol. 8, p. 169 (1925) is known; However, chloro-deoxybenzoin does not react with alcohol Benzoin ether, as our own experiments have shown; aucti in the implementation of chloro-deoxy-benzoin mil Benzoin ether is not produced in any appreciable amount of sodium alcoholate.

The technical progress of the claimed process lies in the compared to the state of the art significantly shorter reaction times, higher yields and the formation of merely gaseous reaction Byproducts. The essential use of thionyl chloride instead of hydrogen chloride

has the advantage that the formation of the benzoin ether on takes a different chemical path, in which the reaction equilibrium is practically complete in many cases on the part of the end products. This benefit was not expected because of other known compounds such as sulfuryl, phosphorus oxychloride. Phosgene, acyl chloride and methanesulfonic acid chloride, which also react with water and alcohol to form HCI, cannot replace thionyl chloride in the process according to the invention.

The benzoin ethers that can be obtained by the process of the invention correspond to general formula

O OR ^:

C -C--

R'ill)

in which R ¹ and R ^{2 have} the meaning given above. Some of them are already known: however, the new benzoin ethers of the general formula can also be advantageous according to the process according to the invention

CC

are obtained in which R ^{3 is} a chlorine-substituted alkyl radical having at least 2 carbon atoms or a chlorine-substituted cycloalkyl radical and R ^{1 has} the meaning given above.
Examples include:

jS-chloroethyl,

jS-chloro-n-propyl-,

y-chloro-n-propyl-,

/ J-chloroisopropyl,

^ '- dichloroisopropyl,

/J.y- dichloropropyl,

jS-chloro-n-butyl-,

jJ-chloro-sec-butyl- and

y-chloro-n-butyl benzoin ether.
In the examples below, a benzoin with a melting point of 132.5 to 133.5 ° C. was used which, according to infrared spectrometric analysis, had a benzoin content of more than 98% and in which less than 2 percent by weight benzil was found by thin-layer chromatography; the water content was less than 0.3 percent by weight (according to Fischer).

example 1

in one with stirrer, reflux condenser, dropping funnel and adjustable electric heating provided 0.5 L three-necked flasks 106 g (0.5 mol) of benzoin in 120 g (2.0 mol) of isopropanol suspended and within about 1/2 hour at 75 to 80 ° C with stirring 71.5 g (0.6 mol) of thionyl chloride were evenly added. This was followed by 1/2 hour at the same temperature stirred. The escaping reaction gases (sulfur dioxide and hydrogen chloride) were in absorbed aqueous sodium hydroxide solution.

The reaction solution was then in a water jet vacuum up to a sump temperature of 100.degree evaporated. 131 g of crude product with a melting point of 72p to 76.2'C were obtained as the residue; Thin-layer chromatographic analysis in addition to benzoin isopropyl ether about 4% benzoin, 3.5% benzil and each contained about 1% of two unknown compounds s

This crude product was dissolved at about 60 to 70 ^° C. in a mixture of 800 g of isopropanol and 200 g of water. The solution was used to neutralize traces of adhering hydrogen chloride and to clarify it

ίο with 1 g sodium bicarbonate and! og diatomaceous earth added and filtered hot. On cooling, the benzoin isopropyl ether crystallized out, it was filtered off and then washed several times with ice-cold aqueous about 60 to 65 percent by weight isopropanol and then dried in vacuo. 99 g (78% of theory) of benzoin isopropyl ether were thus obtained obtained from melting point 78 to 79 ° C, the after Thin-layer chromatographic analysis each less than 0.1% benzoin, benzil and two others not contained identified impurities.

Example 2

In the apparatus described in Example 1, 106 g (Op mol) of benzoin and 120 g (2.0 mol) of isopropanol were used 723 g (0.61 mol) thionyl chloride are added at -10 "C. There was no evolution of gas; this only started when it was heated to around 40 ° C. The mixture was up to stop the gas evolution on a temperature door held at about 40 ° C and stirred (about 30 minutes), then heated to about 75 ° C and 1 hour stirred at the same temperature. Then up to a sump temperature of about 100 ° C in Concentrated in vacuo The residue obtained was 122 g of benzoin isopropyl ether as a crude product contained about 15% unreacted benzoin according to analysis by thin layer chromatography.

By recrystallizing the crude product from a mixture of 250 g of isopropanol with 40 g of water After washing the crystals with the same mixture and drying, 69.5 g of benzoin isopropyl ether were obtained obtained from melting point 77 to 78 ° C, which according to thin-layer chromatographic analysis only still contained about 0.5% benzoin.

Example 3

In the apparatus described in Example 1 were 106 g (O ^ mol) of benzoin and 115 g (2.5 mol) of ethanol (anhydrous, denatured with toluene) with 72 g (0.605 mol) of thionyl chloride with stirring at about 75 to 8O ⁰ C. added in the course of about 0.5 hours and then the reaction ^ mixture was stirred for about 0.5 hours at the same temperature. Subsequently, the mixture was concentrated to a bottom temperature of about 100 ° C in vacuo ° C obtained, which, according to thin-layer chromatographic analysis, is about 5% in addition to benzoin ethyl ether

to benzil, less than 5% benzoin and traces of an unknown compound.

After recrystallization from ethanol, the purified compound melted at 60 to 62 ° C.

_6j Analysis: CieHieO2 (Mol 240)

Calculated: C 80.0, H 6.7, O 13.3%;

found: C 80.2, H 6.8, O 13.5%;

C 80.5, H 6.9, O 13.8%.

Example 4

In the apparatus described in Example 1 wurder 106 g (0.5 mol) of benzoin are suspended in 120 g (2.0 mol) of n-propanol, with stirring at about 75 to 8O ⁰ C in the course of 0.5 hour with 72 g (0.605 mol) of thionyl chloride are added and the reaction mixture is then stirred at the same temperature for 0.5 hours. Subsequently, the reaction solution was up to a bottom temperature of about 100 ⁰ C and evaporated in vacuo. The residue obtained was 129 g of crude benzoin n-propyl ether which, according to analysis by thin-layer chromatography, contained about 3% benzoin, about 2% benzil and about 1 to 2% each of two unknown compounds as impurities.

Fractional distillation of the oily crude product in vacuo gave 109 g (79% of theory) Benzoin n-propyl ether with a boiling point of 135 ° C / 0.4 Torr obtained; / 70 °: 1.5609, melting point 21-22'C.

Example 5

In the apparatus described in Example 1 were 212 g (1.0 mol) of benzoin are suspended in 370 g (5.0 mol) of sec-butyl alcohol, in the course of 0.5 hours while stirring at about 75 to 8O ⁰ C with 143 g (1.2 mol) of thionyl chloride are added and the reaction mixture is then stirred for about 1/2 hour at the same temperature. The mixture was then evaporated in vacuum up to a bottom temperature of about 100 ⁰ C jo and thus 259 g of crude benzoin sec-butyl ether obtained, the% as impurities after dünnschichtchromatografischer analysis about 4 benzil, about 4% benzoin and about 5% of an unknown Compound included.

After recrystallization from methanol, 230 g (82% of theory) of benzoin sec-butyl ether were produced Melting point 45 to 46 ° C obtained.

Example 6

In the apparatus described in Example 1, 212 g (1.0 mol) of the benzoin used in Example 1 were added suspended in 500 g (5.0 Mo!) of cyclohexanol and in the course of about 0.5 hours with stirring at 75 to 80 ° C with 143 g (1.2 mol) of thionyl chloride and then at the same temperature for about 0.5 hours The reaction solution was subsequently stirred in vacuo up to a bottom temperature of about Concentrated to 100 ° C and 341 g of residue obtained in this way about 35 g of volatile components (residual cyclohexanol) and its thin-layer chromatogram, in addition to benzoincyclohexyl ether, contained about 2% benzil, about 2.5% Benzoin and about 4% of an unknown compound.

Fractional distillation of the residue under reduced pressure gave 235 g (75% of theory) benzoin cyclohexyl ether in the boiling range from 172 to 174 ° C./0.1 Torr; π $ : 1.7503.

Example 7

212 g (1.0 mol) of benzoin were dissolved in 402 ^ g (5.0 mole) of chloroethanol and in a heated with reflux condenser, stirrer, internal thermometer and dropping funnel, three-necked flask provided to 8O ⁰ C. Then (1.2 moles), 143 g of Thionyl chloride was added dropwise over 2 hours with stirring at this temperature and then stirred for a further 30 minutes at the same temperature. Subsequently, the excess chloroethanol was distilled off under reduced pressure and the distillation residue was taken up in 200 ml of chloroform, washed three times with water and dried over sodium sulfate. After the solvent had been distilled off, the residue was distilled in vacuo. 170.1 g (63% of theory) of benzoin (/? - chloroethyl) ether with a boiling point of 164 ° C. / 0.3 Torr were obtained.

receive.

Analysis: CibHi5CIO2 (Mol 274.7)
Calculated: C 69.96, H 5.87%:
found: C 70.4, H 5.61%.

NMR spectrum (measured in deuterochloroform) 3.63 (m, 4H); 5.71 (s, 1H); 7.1 to 7.6 (m, 6arom.H); 7.8 to 8.1 (m.4arom.H).

Example 8

212 g (1.0 mol) of benzoin were dissolved in 463 g (5.0 mol) l-Chlorpropanol- (2) and heated in the manner described in Example 7 apparatus at about 8O ⁰ C. 143 g of thionyl chloride were then slowly added dropwise with stirring over the course of 2 hours and the mixture was then stirred for a further 30 minutes at the same temperature. Excess 1-chloropropanol- (2) was then distilled off under reduced pressure and the residue was taken up in 200 ml of chloroform, washed three times with water and dried over sodium sulfate. After the solvent had been distilled off, the residue was distilled in vacuo. In this way, 186.5 g (65% of theory) of benzoin (α-chloroisopropyl) ether with a boiling point of 162 ° C./0.09 Torr were obtained; Melting point 48 ° C.

Analysis: Ci? H 17CIO2 (Mol 288.8)
Calculated: C 70.7, H 5.94%;
found: C 70.8, H 5.91%.

NMR spectrum (measured in deuterochloroform) 1.20 to 1.60 (2d, 3H); 3.6 to 3.7 (d2H); 3.5 to 4.3 (m, 1 H); 6.7 and 6.82 (s, 1H); 7.0 to 7.65 (m, 6arom.H); 7.9 to 8.15 (m, 4arom.H).

As a result of the presence of a pair of diastereomers, all signals of aliphatic protons appear twice.

Example 9

212 g (1.0 mol) of benzoin were dissolved as described in Example 7 apparatus in 645 g (5.0 mol) of 1,3-dichloropropanol (2), heated to about 8O ⁰ C and maintained at this during the course of about 2 hours 143 g of thionyl chloride were added with stirring at the same temperature for 30 minutes and then excess 1,3-dichloropropanol- (2) was distilled off under reduced pressure. The residue was taken up in 200 ml of chloroform, washed three times with water and dried over sodium sulfate Solvent was then distilled off and the residue was fractionally distilled in vacuo. For example, 188 g (58% of theory) of benzoin (?, 0'-dichloroisopropyl) ether were distillate at a boiling temperature of 167 to 170 ° C./0.27 Torr obtained that solidified on cooling; Melting point 52 ° C (after recrystallization from isopropanol).

Analysis: CuHieChO ^ Mol 323.2)
Calculated: C 63.2, H 4.97%; Found: C 633, H 4.97%.

609 641/320

NMR spectrum (measured in deuterochloroform) 4.2 (s, 4H); 4.0 to 4.3 (m.lH); 6.0 (s.lH); 7.2 to 7.6 (6arom.H); 7.9 to 8.1 (4arom.H).

Example 10

In the apparatus described in Example 7, 212 g (1.0 mol) of benzoin were dissolved in 645 g (5.0 mol) of 2,3-dichloropropanol- (i) and with stirring at 80 ^° C. over the course of 2 hours with 143 g of thionyl chloride are added and the mixture is then stirred for another 2 hours. The excess 2,3-dichloropropanol- (l) was then distilled off under reduced pressure and the residue was taken up in 200 ml of chloroform, washed three times with water and then dried over sodium sulfate. The solvent was then distilled off under reduced pressure and the residue that remained was fractionally distilled in vacuo. In the temperature range from 156 to 164 ° C / 0.7 Torr, 229.1 g (71% of theory) of benzoin (j3,}> - dichloro-n-propyl) ether were obtained; Melting point 64 to 65 ° C (after; recrystallization from ethanol).

Analysis: Ci7Hi6CbO:? (Mol 323.2) Calculated: C 63.2, H 4.97%;
found: C, 63.3. H 4.81%.

NMR spectrum (measured in deuterochloroform) 3.85 (d, 2H): 3.80 (d, 2H); 4.20 (m, 1H); 5.75 (s, 1H); 7.4 (m, 6H); 8.0 (m, 4H).

Example 11

Into a flask equipped with stirrer, reflux condenser and two dropping funnels, 250 mL round bottom flask is added 21.5 g (0.1 MoI) of benzoin and 74 g (1.0 mol) of tert-butanol and heated with stirring to about 8O ⁰ C. Then add 14.3 g (0.12 mol) of thionyl chloride from one dropping funnel and 37.0 g (0.5 mol) of tert-butanol from the other dropping funnel slowly at this temperature with stirring over the course of about 3 hours . Tert-butyl chloride is partially distilled off in the process. Mixture is then stirred for an additional hour at about 8O ⁰ C and then cooled to room temperature, the unreacted benzoin partially fails. The precipitate is filtered off, the filtrate is washed neutral with aqueous sodium hydrogen carbonate solution, dried over sodium sulfate and then excess tert-butanol is distilled off in a water jet vacuum. The residue of about 4 g is chromatographed with 800 ml of cyclohexane / butyl acetate (9: 1) over a silica gel column with a particle size of 0.02 to 0.5 mm in diameter. 50 ml fractions are taken in each case; fractions 5 and 6 contain the benzoin ether.

1.8 g (9% of the benzoin tert-butyl ether with a melting point of 107 ° C.) are obtained.

Analysis: C18H20O2 (Mol 268.3)
Calculated: C 80.56, H 7.51%; found: C 78.5, H 840%.

NMR spectrum (measured in deuterochloroform) 1.29 (S.9H); 5.64 (s.lH); 7.2 to 7.7 (m.6arom.H); 7.9 to 8.15 (m.4arom.H).

Example 12

106 g (0.5 mol) of benzoin are suspended in 260 g (2.0 mol) of n-OctanoI and is within about '/ 2 hour at 75 to 8O ⁰ C 713 g (0.6 mol) of thionyl chloride then added dropwise a Another half an hour at this temperature is then stirred

the reaction solution concentrated in a water jet vacuum to ζ a bottom temperature of about 100'C, de oily residue (190 g) in 100 ml of ether absorbed the essential solution three times with water then extracted three times with saturated aqueous sodium hydrogen carbonate solution and then eating over drying! Dried sodium sulfate. The nacl Concentrate the dry ethereal solution and the 165 g residue were fractionated in vacuo distilled; in the boiling range 175 to 180 ° C / 0.4 to 0.5 gate 135 g (80% of theory) of benzoin n-octyl ethers were obtained.

Example 13

106 g (0.5 mol) of benzoin and 286 g (2.2 moles) of n-octano were about / reacted at about 130 ⁰ C within of 'two hours with 72.5 g (0.61 mol) of thionyl chloride under stirring. Subsequently, a further half hour at about 13O ⁰ C was stirred, then concentrated the reaction solution in a water jet vacuum to Einei bottom temperature of 120 ° C. The residue remained 160 g of crude product in the form of an oil which, according to analysis by thin-layer chromatography, contained not only benzoin-n-octyl ether as the main substance, but also about 5% benzil, but no unreacted benzoin.

Example 14

106 g (0.5 mol) of benzoin are suspended in 288 g (2.0 mol) of n-nonanol and heated at about 75 to 8O ⁰ C.

71.5 g (0.6 mol) of thionyl chloride were added dropwise at this temperature within about half an hour and then stirred for about 1/2 hour. Uann the reaction solution with a water jet vacuum up to a sump temperature of 100 ° C

evaporated, the remaining oily residue of _ 195 g taken up in 100 ml of ether, three times with water and extracted three times with saturated aqueous sodium hydrogen carbonate solution and the essential Solution dried over dry sodium sulfate

4c net. _After stripping off the ether, 170 g of cuckoo remained, which were fractionally distilled in vacuo. Thus, in the boiling range 188 to 190 ° C./0.45 ion-126 g (76% of theory) benzoin-n-nonyl ether were obtained.

Example 15

270 g (1.0 mole) of stearyl alcohol! and 53 g (0.25 mol) of benzoin were converted as a melt at about 120 ⁰ C with stirring by adding 35 g (0.294 mol) of thionyl chloride within half an hour.

1 ^ V ⁰ U ^{eating was stirred for another} half an hour at RO and then completely degassed in a water jet vacuum at the same temperature. As a residue, 318 g of a mixture of benzoin

Stearyiather and excess stearyl alcohol obtained which, according to thin-layer chromatographic analysis, in addition to the benzoin stearyl ether, about 2% benzil and less than 1% unreacted benzoin and also an unidentified impurity in

contained a very small amount

50 g of this mixture were suspended in 200 ml of acetone and the undissolved material was sucked off was concentrated and the residue was taken up in 50 ml of acetone. The suspension obtained was filtered

and the filtrate is concentrated. After this residue has been taken up in 30 ml of acetone, filter and concentrate of the filtrate 9 g of benzom stearyl ether contaminated with stearyl alcohol were obtained, which in 40 ml of cyclohe-

xan / ethyl acetate (9: 1) and purified in the manner described in Example 11 by column chromatography. 2.5 g of pure benzoin stearyl ether with a melting point of 35 ° C. were obtained; Purity and absence of stearyl alcohol were s IR spectroscopy confirmed.

Example 16

In a heatable 1 l flask with a stirrer, Is provided with a reflux condenser and a side overflow corresponding to a reaction volume of 0.7 1, are made from 2 metering funnels, the funnel tubes of which are led to the bottom of the piston, 1.3 l per hour a suspension of 582 g (2.74 mol) of benzoin in 660 g (11.0 mol) of isopropanol and 236 ml of thionyl chloride, corresponding to 392 g (3.3 mol) at a reaction temperature at about 75 ° C. The reaction solution was continuously taken off at the side overflow. The mean residence time was about 0.5 hours.

For work-up, the acidic, isopropanol-containing solution which ran off was diluted in batches with about 5 times its volume in 80% hot water. Here, the crude benzoin isopropyl ether separated as an oil which was separated and washed with about 8O ⁰ C hot water. The crude product obtained in this way contained, according to analysis by thin layer chromatography, about 2.5 to 3.5% benzoin, about 1% benzil and about 2% of an unknown compound.

The crude product obtained was recrystallized as described in Example 1. The yield of pure Benzoin isopropyl ether corresponded to 79% of theory.

Claims (1)

Patent claims: 1. Process for the preparation of benzoin ethers by reacting benzoins of the general formula O OH -CC - R ¹