CA1152510A

CA1152510A - Unsaturated alcohols and their use in the preparation of oxolanes

Info

Publication number: CA1152510A
Application number: CA000367777A
Authority: CA
Inventors: Alexander F. Orr
Original assignee: Shell Canada Ltd
Current assignee: Shell Canada Ltd
Priority date: 1980-01-21
Filing date: 1980-12-31
Publication date: 1983-08-23
Also published as: JPS56120628A; IT1135081B; BR8100286A; DE3101461A1; IT8119203A0; CH650761A5; NL8100220A; FR2474025B1; FR2474025A1

Abstract

ABSTRACT

Novel compounds of the general formula (I) in which each of R1 and R2 independently represents a hydrogen atom or an optionally-substituted alkyl, cycloalkyl or aryl group, or R1 and R2 together represent an alkylene group; each or R3 R4, R5 and R independently represents a hydrogen atom or an optionally-substituted alkyl, alkoxy or aryl group; R7 represents an optionally-substituted alkyl group; and R8 represents a hydrogen atom or an optionally-substituted alkyl group, may be cyclised to form an oxolane of the general formula (II)

Description

s~

This invention relates to novel unsaturated alcohols and their use in the preparation of oxolanes.
German Offenlegungsschrift No. 2749974 and European Patent Application No. 0000002, disclose that certain oxolane derivatives are useful as herbicides.
Such oxolanes have the general formula R6 Rl I R3 R9 R8 > \ O / ~ Rl ~I) Ar - CH - CH

where the groups Rl to R9 have varlous meanings, and Ar is a phenyl, or sub-stituted phenyl group. United Kingdom Patent Applicatlon No. 7900613 discloses similar oxolanes In w~ich Ar is a substituted or unsubstituted fully unsaturated ring having 5 or 6 atoms in the ring of ~hich one is a nitrogen atom and the remainder are carbon atoms. Generally, the most interesting compounds for use as herbicides are those compounds of the above formula in which R7 is an alkyl, or substituted alkyl group. Such compounds can be prepared by reacting an oxolane~

alcohol of the general formula R6 _ R3 HO - CH ~ O ~ ~2 with a compound of formula Ar - CH - Hal where Hal is a halogen atom. :~
The oxolane alcohols are however rather difficult to synthesise. A

,~. 1 ~ '1~ ' - : : .

, 1~5;~5~L0 novel class of ole~inic alcohols which can be converted into the desired oxolane alcohols has now been found.

Therefore the invention provides a compound of the general formula IR~ Rl ~ IRl 2 R - CH = C - C - C - C - R ~I~
R6 R4 bH
~herein each of Rl and R2 independently represents a hydrogen atom or an alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, aryl or substitu~ed aryl group, or Rl and R2 together represent an alkylene group; each of R3, R~, R5 and R independently represents a hydrogen atom or an alkyl, substituted alkyl, alkoxy, substituted alkoxy, aryl, or substituted aryl group; R7 represents an alkyl, or substituted alkyl group; and R8 represents a hydrogen atom or an alkyl, or substituted alkyl group. The substituents are selected from halogen atoms and alkyl, alkoxy, alkoxy-alkoxy, aryl, and aryloxy groups, The substituents in a substituted group referred to in this specification may for example be one or more substituents independently selected from halogen atoms, especiall~ chlorine and fluorine atoms, and alkyl, alkoxy, alkoxy-alkoxy, aryl and aryloxy groups. Alkyl, cycloalkyl, aryl, alkylene, alkoxy, alkoxyalkoxy and aryloxy groups preferably each contain up to 8 carbon atoms. The preferred aryl and aryloxy groups are phenyl and phenoxy groups.
Preferably each of Rl and R2 independently represents a hydrogen atom, an alkyl group having up to 6 carbon atoms, or a phenyl, or subst~tuted phenyl group, or Rl and R2 together represent an alkylene group having up to 6 carbon atoms. More preferahly, each of Rl and R2 independently represents a hydrogen atom, a methyl group or an ethyl group, or Rl and R2 together represent a pentamethylene group.
Preferably each of R3, R~, R and R independently represents a hydrogen atom or an alkyl or an alkoxy group having up to 6 carfion atoms optionally substituted ~y an alkoxy or alkoxy-alkoxy group having up to 6 ~ - 2 --, . ~

- ~

:
,....
~:

~3L15 ~ 3Ls~

carbon atoms. More preferably, three of R3, R4, R5 and R represent hydrogen atoms and the ourth represents a hydrogen atom or a methoxy group optionally substituted by a methoxyethoxy group.
Preferably R7 represents an alkyl group having up to 6 carbon atoms ~hich may be unsubstituted or substituted. More preferably R7 represents a methyl, ethyl, halomethyl or methoxymethyl group.
Preferably R8 represents a hydrogen atom.
As stated above, the compounds of the general formula I can be cyclised to form oxolane alcohols. The ~nvention therefore also provides a process for the preparation of a compound of the general formula HO - CH O R ( I) : .

: . . . -:

11~i2~
-i hi h Rl R2 R3 R4 R5 R6 R7 and R8 have the meanings given for the general formula I, which comprises reacting a compouna of the general formula I ~ith an electrophilic epoxidis-ing agent.
Suitable electrophilic epoxidising agents include hydrogen peroxide, alkali metal peroxides or hypohalites, metal perbo-rates, peroxyacetyl nitrate and silver oxide. Especially suit-able electrophilic epoxidising agents are peroxyacids, for example aliphatic peroxyacids such as peroxyacetic acid or peroxy-formic acid, or, preferably, aromatic peroxyacids such as unsub-stituted or substituted peroxybenzoic acid. Particularly useful such agents are halogen-substituted peroxybenzoic acids, for example acids in which the phenyl ring is substituted by one or two chlorine and/or bromine atoms. Meta-chloroperoxybenzoic acid is preferred.
The reaction is suitably carried out in the presence of an inert solvent, for example a liquid hydrocarbon, chlorinated hydrocarbon, ether or ester, such as benzene, toluene, methylene chloride, carbon tetrachloride, diethyl ether or ethyl acetate.
Mixtures of solvents may be employed.
The reaction is preferably carried out at a temperature in the range of Prom -10 C to 80 C, especially 0 to 20 C. It may in some cases be convenient to carry out the reaction at the reflux temperature of the solvent used.
The molar ratio of the compound of the general formula I and the electrophilic epoxidising agent is not of critical im~ort-ance. Preferably the compound of the general formula I and the electro-philic epoxidising agent are mixed in approximately equimolar quantities, or a slight excess of the epoxidising agent is used. Preferably the molar ratio of the compound of the general formula I to the electrophilic epoxidising agent is in the range of from 1:1 to 1:2 especially 1:1 to 1:1.5. Useful yields can however be obtained using a molar ratio of up to 1:10 or higher.
If desired, the resulting compound of the general formula II
may be extracted from the reaction mixture by any suitable work-: ~

~z~

up procedure. However, it may be advantageous to carry out a further chemical reaction using the compound of the general formula II either after its isolation or directly in situ in the reaction mixture. In a preferred embodimen~ of the cyclisation process according to the invention, at least part of the resulting compound of the general formula II is converted into an alkali metal or alkaline earth metal salt thereof, and reacted ~ith a compound of the general formula Ar - CH - ~lal (III) in which Hal represents a halogen atoms, R9 represents a hydrogen atom or an alkyl, or substituted alkyl group, and Ar represents a phenyl, or substituted phenyl group or a suBstituted, or unsuBstituted, fully unsaturated heterocyclic group having 5 or 6 ring atoms of which one is a nitrogen atom and the remainder are carbon atoms; to give a compound of the general formula R ¦ ¦ R

Rl9 R ~ ~ ~ Rl ~IV) in ~h~ch Rl to R9 are Ar having the meanings given above~ ;
Preferably R represents a hydrogen atom.
Preferably Ar is unsu~stituted or is substituted by one or more of the same or different substituents selected from halogen atoms, especially chlorine or fluorine atoms, and alkyl groups having up to 6 carb-on atoms, especially methyl or ethyl groups. For example, Ar may represent a phenyl, or substituted phenyl group~ espec~ally an unsu~stituted phenyl group or a 2-met~yl~, 2-fluoro-,

2-chloro- or 2,6-d~chloro-phenyl group, - : - ' ` .' .

.

~S25~

By substituted fully unsaturated heterocyclic groups there should be understood substituted, or unsubstituted pyridylj pyrrolyl and azacyclopenta-dienyl groups. Thus the group Ar may for example represent one of the groups:

CH3 ~

If Ar represents a heterocyclic group, this group i5` preferably bonded to the rest of the molecule through a carbon atom, and the nitrogen atom`in the ring is preferably adjacent to this carbon atom. For example, Ar may represent a 2-pyridyl group which is unsubstituted or substituted in the 3 or 6 position by a chlorine or fluorine atom or by a methyl or et~yl group, Reaction of the salt of the compound of the general formula II with the compound of the genera]. formula III is most conveniently carried out either with-out isolation of the compound of the general formula II from the reaction mixture resulting from the cyclisation reaction~ or by reaction of the crude product resulting from evaporation of the solvent from said reaction mixture.
The oxolane alcohol of formula II may be converted into a salt thereof by reaction with a base, Alkali metal hydroxides, alkoxides or hydrides are suitable bases~ The alcohol may be converted into its salt prior to admix1ng it ~ith the compound of formula III, or the salt may be formed in situ hy admixmg the compounds of the formulae I~ and III in the presence of a base. Any suitable~
solvent-may fie used for the reaction, for example an aromatic hydrocarbon such as benzene or toluene. The reaction may for example be carried out at~a temp-erature in the range of from 50 to 150C. Conveniently, the reaction is carried out at the reflux temperature of the solvent used.
The compounds of the general formula I may be prepared by methods analogous to known methods, The precise-method chosen ~ - 6 -,.. , , - ~
, . , -~

~ 15Z51~

will of course depend on the desired meanings of the substituents R to R . Three suitable methods are as follows.
l. A method which proceeds most satisfactorily when at least one of R3 and R is hydrogen and Rl and R are other than hydrogen, or when all of Rl, R2, R3 and R are hydrogen, and which is generally not suitable when one of R3 and R is alkoxy, involves the reaction of an epoxide of the general formula \C /- -\C
R4/ \ R1 with a Grignard reagent of the general formula R7 R5 ;
R8 _ CH = C - C - MgHal (VI) where Hal is a chlorine, bromine or iodine atom, under the usual conditions necessary when using Grignard reagents.
2. A method of preparing compounds in which at least one of R
and R is other than a hydrogen atom involves the reaction of a compound of the general formula R8 _ C~ = C - C - C - C - X (VII) ~ ' 2 ::
in which X has the same meanlng as the symbol R in the general formula I, or X is an alkoxy group, with a Grignard reagent of the general~formula :
R1MgHal tVIII) :

:

SZ~

in which Hal represents a chlorine, bromine or iodine atom and R has the meaning given for the general formula I with the exception of a hydrogen atom. If X represents an alkoxy group, a compound of general fo:rmula I is produced in which R2 has the same meaning as Rl, since the alkoxy group X is lost from the molecule as two groups Rl are added.

3. In order to prepare compounds of the general formula I in which both Rl and R2 represent hydrogen atoms, an ester of formula VII in which X is an alkoxy group may be reacted with a selective reducing agent, for example lithium alumin-ium hydride.
It may in some cases be most convenient to prepare a compound of the general formula I by first preparing a corresponding compound in which one of the groups R -R has a different meaning from that desired, and subsequently converting said group into the desired group.
The following Examples illustrate the invention. NMR values given are values relative to tetramethylsilane in CDC13.
Example 1 Preparation of 2-ethyl-4-methoxyethoxymethoxy-5-hydroxy-5-methyl-hex-l-ene CH2 - O - (CH2)2 _ O CH3 CH = C - CH2 - CE - C - CH
OH
~ ' (a) 5.9 g sodium were dissolved in 300 ml absolute ethanol and ethyl acetoacetate (31.72 g) was added. The mixture was stirred for 15 minutes, 2-bromomethylbut-1-ene (40 g) was added over 30 minutes, and the mixture was then refluxed for 2 hours. The mixture was then poured onto brine, extracted .
:
.~

.
: ~ ' :: ,. .

;2~ Cl _ 9 _ several times with diethyl ether, washed with brine, dried and evaporated down. Distillatio~ of the residue under vacuum gave 29 g, corresponding to a 60% yield, of 2-ethyl-

4-methylcarbonyl-~-ethoxycarbonylbut-1-ene, boiling point 120-127 C at a pressure of 10 mm Hg.
(b) The product from (a) (25 g) was added to 6.2 g of a 50%
solution of sodium hydride in oil dissolved in benzene (250 ml) and stirred for two hours. Dibenzoyl peroxide, (C6H5C02)2, (20.4 g) in benzene (200 ml) was added over 30 minutes. The mixture was stirred for a further 2 hours, and then poured onto water and extracted several times with diethyl ether, dried, and distilled under vacuum to give 24 g, corresponding to a yield in step (b) of 89.5%, of 2-ethyl-4-methylcarbonyl-4-ethoxycarbonyl-4-ben~oyloxybut-1-ene, boiling point 160C at a pressure of 1 mm Hg.
(c) Sodium (250 mg) was dissolved in dry ethanol (250 ml) and the product from (b) above (22.65 g) was added. The mixture was stirred overnight and then refluxed for 2 hours. A~mon-ium chloride (0.5 g) and water (0.25 ml) were added and stirring was continued for ~ hour. The mixture was then filtered and the solvent was evaporated. The residue was dissolved in diethyl ether, the mixture was filtered and the ether evaporated off to leave 2-ethyl-4-hydroxy-4-ethoxy-carbonylbut-l-ene which was identified by ~MR. This residue was dissolved in methylene chloride (200 ml) containing methoxyethoxymethyl chloride (12.5 ml) and ethyl diisopropyl-amine (22.5 ml) and the mixture was stirred overnight. A
further 5 ml methoxyethoxymethyl chloride and 10 ml ethyl diisopropylamine were added. The mixture was refluxed for 3 3 hours and then poured onto water, washed with 10% hydro~
chloric acid and then brine, dried over potassium carbonate and evaporated down. The residue was eluted down a sil1ca ;
gel column using methylene chloride. The solvent was then evaporated and the product was disti'led. 14.5 g of 2-ethyl-4-methoxyethoxymethoxy-4-ethoxycarbonyl-but-1-ene, - :.- ~ : - ':.
-" li5;~

boiling point 158-162 C at a pressure of 12 mm Hg, were obtained.
(d) Magnesium (3.3 g) was dissolved in a solution of methyl iodide (19.1 g) in diethyl ether, and an ethereal solution of 14 g of the ester prepared in (c) above was added to the refluxing solution over 20 minutes. The mixture was then stirred ~or a further 2 hours. Saturated ammonium chloride solution was then added, the mixture was extracted with diethyl ether, washed with brine, dried over magnesium sulphate and evaporated down. The residue was distilled to obtain 9.5 g of the title compound, boiling at 115-120 C at a pressure of 2 mm Hg. Its N~ spectrum was as follows:
O.g(3H,triplet); 1.2(6H,singlet); 1.8-2.3(4H,complex) 3.2(IH,broad); 3.3(3H,singlet); 3.5(5H,complex);
4.7(4H,complex).
Example 2 Preparation of 2,2-dimethyl-3-methoxyethoxymethoxy-5-hydroxy-methyl-5-ethyloxolane The olefinic alcohol prepared in Example 1 (9.5 g) was dissolved in metbylene chloride and added to m-chloroperoxy-benzoic acid (8.65 g of 85% pure material) in methylene chloride at 0 C over 30 minutes. The mixture was stirred for 20 hours, and then washed successively with aqueous solutions of sodium sulphite, sodium bicarbonate and sodium chloride, and dried. The solvent was evaporated to leave a crude product which was iaenti-fied as a mixture of isomers of the desired product using ~MR, as follows: 0.9(3H,triplet); 1.2(6H,doublet); 1.4-2.5(5H,complex);
3.3(3H,singlet); 3.4-4.1(7X,complex); 4.7(2X,singlet) The product was reacted without further purification as described in Example 3.
Example 3 Preparation of 2,2-dimethyl-3-methoxyethoxymethoxy-5-benzyloxy-methyl-5-ethyloxolane The whole of the crude product obtained in Example 2 was dissolved in toluene (80 ml) and was added with stirring to a ` /

: ;:
- - , . , : . ~ :
- : , : .
.. ~ - :

2~

solution of sodium hydride (2.15 g o~ a 50~ suspension in oil) in dry toluene (150 ml) over 15 minutes.
The mixture was refluxed for 40 minutes, and benzyl bromide (8.25 g) in toluene (50 ml) was then added dropwise. Refluxing and stirring was continued for 18 hours. The mixture was then poured onto brine, extracted with diethyl ether and dried over magnesium sulphate. The solvent was removed to give 17.5 g of crude material, which was purified on a silica gel column using acetone/petrol as eluant, to give 8.2 g of the pure desired product. ~MR showed that a mixture of geometric isomers was present.
NMR
0.9(3H,triplet); 1.2(6H,doublet); 1.4-2.4(4H,complex);
3.3(3H,singlet); 3.5(6H,complex); 4.1(1H,broad triplet);
4.5(2H,singlet); 4.7(2H,singlet); 7.2(5H,singlet) Elemental Analysis C H
Calculated for C20H3205 68.15 9.5 Found 67.5 9.7 Example 4 2-Methyl-4-methoxyethoxymethoxy-5-hydroxy-5-methylhex-1-ene The title compound was prepared by a method analogous to that described in Example 1, using 2-bromomethylpropene as starting material.
NMR
1.1(6H,singlet); 1.7(3H,broad singlet); 2.2(2H,complex).
3.3(3H,singlet); 3.5(6H,complex); 4.7(4H,broad doublet).
Example 5 2,2-Dimethyl-3-methoxymethoxymethoxy-5-benzyloxymethyl-5-methyl-oxolane The title compound was prepared by a method analogous to that described in Example 2 using the compound of Example 4 as starting material. NMR showed the product to be a mixture of geometric isomers.

- : . :

.

~1~2~

NMR
1.2(9H,singlet); 1.5-2.5(2H,complex); 2.3(3H,singlet); 3.4(6H, complex); 3.9(1H,broad triplet); 4.~(2H,single-t); 1~.6(2H,broad singlet); 7.2(5H,singlet).

5 Elemental Analysis C H
Calculated for ClgH3005 67.4 8.94 Found 67.4 9.3 Example 6 Preparation of 2-ethyl-5-hydroxy-5-spirocyclohexyl-pent-1-ene C2~ OH

2 C C~2 - CH2 - C ~
~ .
3.21 g magnesium were added to 75 ml diethyl ether and cooled to 0C. Under an atmosphere of nitrogen, 2-bromomethylbut-1-ene (13.3 g) in diethyl ether (50 ml) was added over 3 hours. The cooling bath was then removed and stirring was continued for a further hour. Methylenecyclohexane oxide (5 g) in diethyI ether (25 ml) was added over 20 minutes and stirring was continued ~or a further 30 minutes. The mixture was then poured onto aqueous ammonium chloride, and the organic phase was separ&ted, washed with brine, dried over sodium sulphate and evaporated down. The residue was distilled under reduced pressure to give ll.lo g of a crude product which was purified by chromatography using 2 acetone in petrol as eluent. 7.85 g of the desired product, corresponding to an 81% yield, were obtained. Its ~MR spectrum~
is as follows~
I.0(3H,triplet); 1.5(12H,broad singlet); 2.0(5H,complex); 4.6(2H, broad singlet).
Example 7 Preparation of 2-spirocyclohexyl-5-hydroxymethyl-5-ethyloxolane The olefinic alcohol prepared in Example 6 (5.5 g) was 30 dissolved in methylene chloridè (20 ml) and added dropwi~se~to m- ~ ;
chloroperoxybenzoic acid (6.5 g)~ in methylene chloride (120 ml) at 0C. The mixture was left overnight at room temperature and -J
~ ' :' :.. .. . . . . . . . .. .

:, : - : . : , , .
` ` ' ` I
,, ', , ' . ' ', 51~

then filtered, washed successively wit~ brine containing sodium sulphite, a~ueous sodium carbonate, and brine, dried over magnes-ium sulphate, and evaporated down. The residue was distilled to give 5.6 g o~ the desired product, boiling point 85-86 C at a -pressure of 0.9 mm Hg.
Example 8 Preparation of 2-ethyl-5-nydroxy-5-ethyl-hept-1-ene CH2 = C - CH2 - CH2 - lC C2X5 The process described in Example 6 was repeated replacing the epoxide with O .:

The desired compound was obtained in 88.6% yield, and had an ~MR
spectrum as follows:
l.O(lOH,multiplet); 1.6(6H,mul-tiplet);
2.0(4H,multiplet); 4.7(2H,broad singlet).
Elemental Analysis C H
Calculated for CllH220 77.6 13.02 Found 76.4 13.2 Example 9 Pre~aration of 2,2-diethyl-5-hydroxymethyl-5-ethyloxolane Tne process described in Example~7 was repeated using the product of Example 8 as starting material. The product was obtained in 80.5% yield.
Exam~le 10 Preparation of 2-ethyl-3-met`noxyethoxymethoxy-5-hydroxy-5-methylhex-l-ene :
-Magnesium (2.36 g) was dissolved in 120 ml diethyl ether containing methyl iodide (6.2 ml). 2-Ethyl-3-methoxyethoxy-methoxy-4-ethoxycarbonylbut-1-ene (9.84 g) dissolved in 20 ml diethyl ether was added dropwise over 20 minutes, the rate o~

:

.: ' . ~ , : :

' ~ : ~ :' ``` ~152~

- 14 _ addition being such that a gentle reflux was maintained. A heavy oily precipitate separated out. Excess saturated ammonium chloride solution was added, the mixture was extracted with diethyl ether, washed with brine, dried over magnesium sulphate and evaporated down. The crude product was purified on a silica gel column using 5~ acetone in petrol as eluant. 7.5 g of the desired product were obtained.
N~R
1.1(3H,triplet); 1.3(6H,doublet); 1.6-2.2(4H,complex);
10 3.3(3H,singlet); 3.4(5H,complex); 4.5(1H,multiplet);
4.6~2H, broad singlet); 4.9(lX,broad singlet); 5.0(1H,broad singlet).

`:,1 : :
~ ~ :

- -: ::

. .

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A compound of the general formula (I) in which each of R1 and R2 independently represents a hydrogen atom or an alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, aryl, or substituted aryl group, or R1 and R2 together represent an alkylene group; each of R3, R4, R5 and R6 independently represents a hydrogen atom or an alkyl, substituted alkyl, alkoxy, substituted alkoxy, aryl, or substituted aryl group;
R7 represents an alkyl, or substituted alkyl group; and R8 represents a hydrogen atom or an alkyl, or substituted alkyl group; any substituent in R1 to R8 above being selected from halogen atoms and alkyl, alkoxy, alkoxy-alkoxy, aryl and aryloxy groups.

2. A compound as claimed in claim 1, in which each of R1 and R2 independently represents a hydrogen atom, an alkyl group having up to 6 carbon atoms or a phenyl, or substituted phenyl group, or R1 and R2 together represent an alkylene group having up to 6 carbon atoms; any substituent in R1 or R2 above being selected from halogen atoms and alkyl, alkoxy, alkoxy-alkoxy, aryl, and aryloxy groups.

3. A compound as claimed in claim 2, in which each of R1 and R2 independently represents a hydrogen atom, a methyl group or an ethyl group, or R1 and R2 together represent a pentamethylene group.

4. A compound as claimed in claim 1, 2, or 3, in which each of R3, R4, R5 and R6 independently represents a hydrogen atom or an alkyl or alkoxy group having up to 6 carbon atoms optionally substituted by an alkoxy or alkoxyalkoxy group having up to 6 carbon atoms.

5. A compound as claimed in claim 1, 2, or 3, in which R7 represents a methyl, ethyl, halomethyl of methoxymethyl group.

6. A compound as claimed in claim 1, 2, or 3, in which R8 represents a hydrogen atom.

7. A process for the preparation of a compound of the general formula (II) in whichh R1, R2, R3, R4, R5, R6, R7 and R8 have the meanings given for the general formula I of claim 1, which comprises reacting a compound of the general formula I with an electrophilic epoxidising agent.

8. A process as claimed in claim 7, in which the epoxidising agent is an aliphatic or aromatic peroxyacid.

9. A process as claimed in claim 8, in which the epoxidising agent is meta-chloroperoxybenzoic acid.

10. A process as claimed in claim 7, 8, or 9, carried out at a temperature in the range of from -10 to 80°C.

11. A process as claimed in claim 7, 8, or 9, in which the molar ratio of the compound of the general formula I to the epoxidising agent is in the range of from 1:1 to 1:2.

12. A process as claimed in claim 7, 8, or 9, which also comprises a further step in which at least part of the resulting compound of the general formula II is converted into an alkali metal or alkaline earth metal salt thereof, and reacted with a compound of the general formula (III) in which Hal represents a halogen atom, R9 represents a hydrogen atom or an alkyl, or substituted alkyl group, and Ar represents a phenyl, or substituted phenyl group or a substituted or unsubstituted fully unsaturated ring having 5 or 6 carbon atoms in the ring of which one is a nitrogen atom and the remainder are carbon atoms; any substituent in R9 or Ar above being selected from halogen atoms and alkyl, alkoxy, alkoxy-alkoxy and aryl and aryloxy groups; to give a compound of the general formula (IV) in which R9 and Ar have the meanings given above and R1 to R8 are as defined in

claim 7.