Note: Descriptions are shown in the official language in which they were submitted.
214 S2~
HOECHST AXTIENGESELLSCHAFT HOE 94/F 071 J Dr. Bi/we
Description
Process for preparing 2,2'-bis(diphenylphosphinylmethyl)-
1,1'-binaphthyls and new compounds from this class of
substances.
The present invention relates to an improved process for
preparing 2,2'-bis(diphenylphosphinylmethyl)-1,1'-bi-
naphthyls and also new compounds from this class of
substances.
2,2'-Bis(diphenylphosphinylmethyl)-1,1'-binaphthyl
(formula I) is an important precursor for the preparation
of 2,2'-bis(diphenylphosphinomethyl)-1,1'-binaphthyl
(formula II), a bidentate phosphine (phosphane) which is
used as a ligand for catalysts, for example in the
coupling of haloaromatics catalyzed by metal complexes.
~ ~PPh2 ¢ ~ PPh2
( I ) ~PPh2 ~pph2
2,2'-Bis(diphenylphosphinylmethyl)-1,1'-binaphthylcanbe
prepared in the following manner. The starting material
is the correspo~; ng aromatic methyl compound, namely
2,2'-dimethyl-1,1'-binaphthyl, and the methyl group is
brominated using N-bromosuccinimide to give 2,2'-bis-
(bromomethyl)-1,1'-binaphthyl (formula III). In this
reaction, which is described a number of times in the
literature and is carried out in the pre~ence of a free-
radical former but without the action of light, tetra-
chloromethane is generally used as solvent (M. E. Jung et
al., Tetrahedron Lett. 29 (1988) 6199; H. J. Bestmann et
al., Chem. Ber. 107 (1974) 2926; J.-P. Mazaleyrat, Chem.
Commun. 1985, 317; T. Hayashi et al., J. Am. Chem. Soc.
110 (1988) 8153).
2I~5253~
-- 2
Owing to the comparatively low boiling point of tetra-
chloromethane, namely 76.5C, a reaction at higher
temperatures can only be carried out under pre~sure,
which requires additional technical complication.
Furthermore, the yield of 2,2'-bis(bromomethyl)-1,1'-
binaphthyl achievable by thi~ process i~, at about 60 %,
not very high.
The bromination of 2,2'-dimethyl-1,1'-binaphthyl gives,
besides the desired product (formula III) essentially two
byproducts, presumably 2-bromomethyl-2'-methyl-1,1'-
binaphthyl and 2-dibromomethyl-2'-bromomethyl-1,1'-
binaphthyl.
Although the isolation of 2,2'-bis(bromomethyl)-1,1'-
binaphthyl in pure form can be succes~fully carried out
by crystallization or by col-~mn chromatography, this is
at the cost of, on the one hand, considerable yield
losses or, in the ca~e of column chromatography, very
high technical complication.
The unpublished European Patent Application
EP 93 116 788.6, which goes back, inter alia, to the
unpublished German Patent Application P 43 08 562.8,
describes the preparation of 2,2'-bi~(bromomethyl)-1,1'-
binaphthyl by reaction of 2,2'-dimethyl-1,1'-binaphthyl
with N-bromosuccinimide in the presence of benzoyl
peroxide, but without the action of light, in chloroben-
zene. After the reaction i8 complete, the golvent i8
evaporated, the residue is taken up in ethyl acetate and
washed first with 10 % strength Na2SO3 solution then with
saturated Na2CO3 ~olution and finally with saturated NaCl
solution. After drying and recrystallization, this gives
a yield of 65 %. However, thi~ proceRs proves to be
complicated (evaporation of the ~olvent, transfer of the
residue into another solvent and w~h;ng three times with
an aqueous sodium salt ~olution each time), in addition
the yield also leave~ something to be de~ired.
2195255
_ - 3 -
The bromination of 2,2'-dimethyl-1,1'-binaphthyl gen-
erally leads to a product mixture which is problematical
to handle. It has thus been found that the removal of the
solvent, even when carried out under gentle conditions
(vacuum), leads to a mixture which is thermally unstable
and begins to decompose exothermically above a tempera-
ture of only 50C.
It is known from Houben-Weyl, Me~hoAen der organischen
Chemie, volume V/4, pages 333 and 334, that aralkyl
bromides in the pure state are colorless substances
usually having little thermal stability and some of them
cannot be distilled without decomposition, even in vacuo.
Naphthylmethyl bromides are generally less ~table then
benzyl bromide~.
For this reason, the isolation of the crude product
formed in the bromination is encumbered by a considerable
hazard potential which, in particular for the large
amounts of starting materials or raw materials handled on
an industrial scale, poses an unpredictable risk.
~r RO-P(Ph-(R )n)2 ( IV)
[~e,
To prepare 2,2'-bis(diphenylphosphinylmethyl)-1,1'-bi-
naphthyl (formula I), pure 2,2'-bis(bromomethyl)-1,1'-bi-
naphthyl, i.e. not a mixture of various b I ;nAted
binaphthyls, can be subjected to the Arbusov reaction
with methyl diphenylphosphinite (formula IV, where R is
CH3 and n is 0) without addition of a solvent. As
described in JP 7 939 059 or CA 91,91764 v, the two
abovementioned components are heated in a ratio of 1:6.7
for three hours at 130C to give the desired product
(formula I). The reaction is, however, problematical,
2~2~5
-- 4
since, as can be seen from Experiment 4 of JP 7 939 059,
an explosive reaction occurs at 87C. The yield achieved
i8 only 30 %. The process is not suitable for an indus-
trial process, neither with regard to the required
process safety nor with regard to the yield.
There is therefore a need to develop a proces~ for
preparing 2,2'-bis(diphenylphosphinylmethyl)-1,1'-binaph-
thyls which does not have the abovementioned disadvan-
tages, can also be carried out simply and reliably and
enables the desired product to be obtained in high yield
and purity.
This object i8 achieved by a process for preparing 2,2'-
biæ(diphenylphosphinylmethyl)-1,1'-binaphthyl~. It
comprises reacting a reaction mixture prepared in a
solvent by reaction of 2,2'-dimethyl-1,1'-binaphthyl with
a brominating agent and containing 2,2'-bis(bromomethyl)-
l,l'-binaphthyl and further brominated binaphthyls, if
desired after removal of unreacted brominating agent,
reacted brominating agent and/or solvent, with an alkyl
diphenylphosphinite of the formula (IV) R0-P(Ph-(R')n)2,
where R is an alkyl radical having from 1 to 5, in
particular from 1 to 3, carbon atoms, Ph is phenyl, R' is
an alkyl radical having from 1 to 4 carbon atoms, CF3,
fluorine, chlorine or bromine, in particular methyl, CF3
or fluorine, and n is 0, 1 or 2, at from 70 to 180C in
the presence or absence of a further solvent.
An advantage of the process of the invention is that in
the preparation of the reaction mixture, isolation of the
2,2~-bis(bromomethyl)-1,1'-binaphthyl (formula III) is
omitted and in this way a quite complicated separation
operation, which owing to the thermal instability of the
reaction product formed in the bromination also presents
a safety risk, is avoided. Furthermore, with suitable
selection of the solvent, the solvent used in the
reaction can remain in the reaction mixture. It does not
have to be removed from the reaction mixture.
21~52~5
-- 5
However, it i8 also possible to replace, if required, the
solvent originally used in the bromination step by a
further solvent and to completely or partially distil off
the solvent originally used. In this way, although the
solvent originally used is replaced by the further
solvent, a quite complicated separation operation (isola-
tion of the 2,2'-bis(bromomethyl)-1,1'-binaphthyl) can
nevertheless be avoided.
The reaction mixture contains, independently of the
method of bromination, the brominated compounds usually
formed in a bromination, namely, besides the desired
product, essentially pre~umably the two abovementioned
brominated byproducts and also the solvent. The reaction
mixture generally obtained contains from 60 to 85 mol %,
in particular from 65 to 83 mol %, of 2,2'-bis(bromo-
methyl)-1,1'-binaphthyl and from 40 to 15 mol %, in
particular from 35 to 17 mol %, of further brominated
binaphthyls, with the solvent ~till present not being
taken into account.
The one byproduct, presumably 2-bromomethyl-2'-methyl-
1,1'-binaphthyl, makes up from 1 to 20 mol %, in particu-
lar from 3 to 18 mol %, and the other byproduct, presum-
ably2-dibromomethyl-2'-bromomethyl-1,1'-binaphthylmakes
up from 3 to 20 mol %, in particular from 5 to 17 mol %.
The method of bromination also influences to a certain
extent both the amount of the brominated binaphthyls
formed and also the ratio in which the two abovementioned
byproducts are formed.
~n general, the amount of solvent used is of no great
importance. However, a sufficient amount should be used.
In general it i8 sufficient to use 2,2'-dimethyl-1,1~-
binapthyl and the solvent in a weight ratio of 1:(3 to
40), in particular 1:(4 to 20), preferably 1:(5 to 15).
Solvents which can be used are generally those which are
inert under the reaction conditions of the bromination.
2I~525~
-- 6
Use can be made of monochlorinated or polychlorinated
benzene, a monochlorinated or polychlorinated aliphatic
hydrocarbon, an ester of an aliphatic carboxylic acid
having from 1 to 6 carbon atoms and an alkyl alcohol
having from 1 to 4 carbon atoms or mixtures thereof as
solvents. Examples of such solvents are chloroform,
dichloromethane, tetrachloromethane, chlorobenzene,
ortho-, meta- and para-dichlorobenzene, methyl formate,
ethyl formate, methyl acetate, ethyl acetate, propyl
acetate, methyl propionate, ethyl propionate and propyl
propionate. Well-suited solvents are chlorobenzene or
dichlorobenzene or any mixture of these solvents. Chloro-
benzene is particularly useful.
In some cases, esters of the abovementioned type, in
particular methyl and ethyl esters of aliphatic carboxy-
lic acids having from 1 to 3 carbon atoms, can also be
used with good results.
In the preparation of the reaction mixture, the bromina-
tion can be carried out under the action of light having
a wavelength of from 10-5 to 10-8 m, in particular from
10-6 to 2x10-7. It i~ here usual to allow the reaction of
2,2'-dimethyl-1,1'-binaphthyl to proceed at from -10 to
75C. In many cases, it is found to be sufficient to
react 2,2'-dimethyl-1,1'-binaphthyl with the brominating
agent at from -5 to 50C, in particular from O to 40C.
The light source used for the bromination can be a
conventional W irradiator, for example a daylight lamp,
a doped or undoped mercury vapor lamp or low-pressure
mercury vapor lamp. On the other hand, 2,2'-dimethyl-
1,1'-binaphthyl and the brominating agent can be reacted
in the absence of light, but in the presence of a free-
radical former at from 25 to 150C, in particular from
40 to 135C.
The bromination can be carried out using a customary
brominating agent, for example bromine,
2I I ~S
-- 7
N-bromosuccinimide, 1,3-dibromo-5,5-dimethylhydantoin,
brominated Meldrum's acid.
It has been found to be favorable to react 2,2'-dimethyl-
1,1'-binaphthyl with N-bromosuccinimide as brominating
agent. 2,2'-Dimethyl-1,1'-binaphthyl and N-bromosuccini-
mide are usually used in a molar ratio of 1:(1.5 to 2.5),
in particular 1:(1.8 to 2.3), preferably 1:(1.9 to 2.2).
In the course of the bromination, N-bromosuccinimide
forms succinimide which, if desired after cooling the
solution containing the reaction product, is removed by
filtration. A further possibility is to remove the
succinimide formed by extraction with water. For this
purpo~e, from 10 to 100% by weight of water, based on
reaction mixture, are usually used.
A particularly simple and at the same time effective
method of removing succinimide is to separate the succi-
nimide formed from the reaction mixture in a first step
by filtration and in a second step by extraction with
water. This uses comparatively little water and accor-
dingly also gives little wastewater.
The bromination carried out under the action of lightgives the desired product in a yield of about 80 %. In
addition, it usually gives from 1 to 6 % of a brominated
substance, pre~umably 2-bL~.o_.cthyl-2'-methyl-1,1'-
binaphthyl, and from 7 to 13 % of a further byproduct,presumably 2-dibromomethyl-2'-bromomethyl-1,1'-
binaphthyl.
The correspon~i ng reaction mixture (A) used in the
Arbusov reaction presumably contains, besides small
amounts of substances not identified in more detail, the
abovementioned bromo compounds dissolved in the solvent,
for example in chlorobenzene and/or dichlorobenzene, in
particular in chlorobenzene.
In place of the reaction mixture (A) prepared under the
21~525S-
-- 8
action of light, it is also possible to use a reaction
mixture (B) which can be obtained, for example, by
reaction of 2,2'-dimethyl-1,1'-binaphthyl with N-bromo-
succinimide in the presence of a solvent under the action
of a free-radical former (free-radical initiator) and by
subæequent removal of succinimide, with good results in
the Arbusov reaction (reaction with the alkyl diphenyl-
phosphinite). Such a reaction mixture (B) can be prepared
by reacting 2,2'-dimethyl-1,1'-binaphthyl with N-bromo-
succinimide, for example in a molar ratio of 1:(1.5 to2.5), in particular 1:(1.8 to 2.3), preferably 1:(1.9 to
2.2), at elevated temperature, usually at temperatures of
from 25 to 150C, in particular from 40 to 135C, under
the action of a free-radical initiator in chlorobenzene
and/or dichlorobenzene, removing ~uccinimide formed, but
without removing the chlorobenzene and/or dichlorobenzene
used as solvent.
Suitable free-radical initiators are the customary free-
radical formers, for example organic peroxides, hydro-
peroxides, azobisisobutyronitrile.
The bromination carried out under the action of the free-
radical initiator gives the desired product in a yield of
from about 63 to 67 %. In addition, it generally gives
from 10 to 20 % of a brominated product, presumably
2-bromomethyl-2'-methyl-1,1'-binaphthyl, and from 8 to
15 % of a further byproduct, presumably 2-dibromomethyl-
2-bromomethyl-1,1'-binaphthyl. The reaction mixture (B)
used in the Arbusov reaction presumably contains, besides
small amounts of substances not identified in more
detail, the abovementioned bromo compounds dissolved in
chlorobenzene and/or dichlorobenzene, in particular
chlorobenzene.
The ~uccinimide formed from the N-bromosuccinimide is
separated from the bromination mixture, if desired after
cooling, by filtration. Another possibility is to carry
out the subsequent removal of succinimide by extraction
with water.
21~525~
g
A particularly simple and effective variant is to
separate succinimide from the bromination mixture in a
first step by filtration and in a second step by
extraction with water.
Unreacted free-radical formers can be removed, for
example, by scrubbing with an aqueous Na2S03 solution.
The abovedescribed procedure gives the reaction mixture
(B).
To carry out the Arbusov reaction, the reaction mixture,
for example the reaction mixture (A) or the reaction
mixture (B), is reacted with an alkyl diphenylphosphinite
(formula IV), as already mentioned above, at from 70 to
180C. In many cases, it is sufficient to carry out the
reaction at from 100 to 170C, in particular from 120 to
160C. The reaction proceeds according to the following
equation:
I ~ l~e, ~ ~ h - ( 11 ) " )
2 Ito-~(~h-(~ [~ ;(Fh-(R')")~
( I I I ) ( lV) ( 10)
The alkyldiphenylphosphinite of the formula (IV) uRed is
usually a (Cl-C5)alkyl diphenylphosphinite or a mixture
of these esters. Suitable alkyl diphenylphosphinites are,
without claiming completene~, methyl diphenylphos-
phinite, ethyl diphenylphosphinite, isopropyl diphenyl-
phosphinite, n-propyl diphenylphosphinite, ethyl bis(3-
fluorophenyl)phosphinite, ethyl bis(4-fluorophenyl)-
phosphinite, ethyl bis(2-methylphenyl)phosphinite and/or
ethyl bis(3-trifluoromethylphenyl)phosphinite.
The alkyl diphenylphosphinite is generally used in a
21 ~5~55
- 10 -
molar ratio of (1.8 to 4):1, in particular (1.9 to 3):1,
preferably (2 to 2.5):1, based on the 2,2'-dimethyl-1,1'-
binaphthyl. However, in many cases it is possible to use
the alkyl diphenylphosphinite (formula IV), based on
2,2'-dimethyl-1,1'-binaphthyl used, in the stoichiometric
ratio or in a slight excess.
Before the reaction mixture resulting from the bromina-
tion stage is used in the subseguent Arbusov reaction
(reaction with the alkyl diphenylphosphinite), it is
advisable, as mentioned above, in many cases to remove
the unreacted brominating agent and/or the reacted
brominating agent and/or the solvent used in the bromina-
tion stage.
Unreacted brominating agent, for example bromine, can be
removed by vaporization, reacted brominating agent, for
example succinimide, can be removed by filtration and
extraction. The solvent used in the bromination stage is
replaced by a further solvent which has a boiling point
higher than that of the solvent originally used. The
further solvent is added prior to the reaction or during
the reaction or after the reaction of the reaction
mixture with the alkyl diphenylphosphinite and the
solvent originally used is subsequently distilled off.
This removal of the original solvent can be carried out
prior to the Arbusov reaction or even during the Arbusov
reaction or after the Arbusov reaction. If a solvent
which is inert to the Arbusov reaction is used as ori-
ginal solvent, it can be removed during the Arbusov
reaction or the removal can even be omitted. Such sol-
vents are, for example, chlorobenzene, dichlorobenzeneand mixtures thereof; when they are used a removal i~ not
absolutely necessary.
Solvents which are not inert to the Arbusov reaction have
to be removed prior to carrying out the Arbusov reaction.
Such solvents are, for example, monochlorinated or
polychlorinated aliphatic hydrocarbons.
Suitable further solvents are generally solvents which
have a boiling point higher than that of the solvent
2145255
11
originally used and which are inert under the conditions
of the Arbusov reaction. These include aromatic hydrocar-
bons, for example toluene, o-xylene, m-xylene, p-xylene,
mixtures of these xylenes, ethylbenzene and/or me~itylene
and high-boiling aliphatic hydrocarbons, for example
petroleum ether having a boiling point ~ 100C, decalin,
ligroin and/or isooctane.
The Arbusov reaction can thus be carried out in the
presence or absence of a further solvent.
In some cases it has been found to be advantageous to add
the further, nonpolar solvent which has a boiling point
higher than that of the solvent originally used during
the Arbusov reaction (reaction with the alkyl diphenyl-
phosphinite) and to simultaneously distill off the
solvent originally used, for example chlorobenzene and/or
dichlorobenzene. Suitable solvents for this purpose are,
for example, aromatic compounds having boiling points
higher than chlorobenzene and/or dichlorobenzene, for
example o-xylene, m-xylene, p-xylene, mixtures of these
xylenes and/or mesitylene. This allows the yield of 2,2'-
bis(diphenylphosphinylmethyl)-l,1'-binaphthylisolatedto
be increased somewhat further.
It is surprising that the brominated binaphthyls, for
example the brominated byproducts present in both the
reaction mixture (A) and in the reaction mixture (B)
generally do not interfere in the Arbusov reaction and
also do not impair the quality of the desired final
product (formula I). Furthermore, it i~ unexpected that
the use of a solvent, for example the use of chloroben-
zene and/or dichlorobenzene, in the Arbusov reactionleads to a significant increaRe in yield. While the
process of JP 7 939 059 gives a yield of only 30 %, the
process of the invention gives a yield of from 90 to 95 %
of desired product, in each case based on 2,2'-bis(bromo-
methyl)-1,1'-binaphthyl. In addition, the danger of the
reaction occurring explosively is avoided.
21~5~5~
To carry out the Arbusov reaction, the reaction mixture,
for example reaction mixture (A) or the reaction (B) or
mixtures of the two reaction mixtures, is usually
initially charged and heated to the prescribed tem-
perature. It is advantageous to select a temperaturebelow the boiling point of the solvent used. After
reaching the reaction temperature, the alkyl diphenyl-
phosphinite is 610wly added dropwise to the initially
charged reaction solution. As the reaction proceeds, it
results in the formation of alkyl bromide which is
continuously distilled from the reaction product. If
desired, the mixture can also be boiled under reflux for
some time after the end of the addition of the alkyl
diphenylphosphinite, 80 as to complete the reaction.
If it is intended that the solvent originally used be
removed during the Arbusov reaction, a temperature above
the boiling point of the original solvent but below that
of the further solvent added is selected. In this way,
both the alkyl bromide and also the solvent originally
used distills off.
The process of the invention makes it possible to obtain
the new compounds of the formula (Ia)
~R')
(~/ )2
)2
where R' is an alkyl radical having from 1 to 4 carbon
atoms, CF3, fluorine, chlorine or bromine, in particular
methyl, CF3 or fluorine, and n i8 1 or 2, in a sur-
prisingly simple manner by reaction of 2,2'-bis(bromo-
methyl)-1,1'-binaphthyl of the formula (III) with the
corresponding diphenylphosphinic ester of the formula IV.
2145255
- 13 -
New compounds in this category which may be mentioned
are, in particular,
2,2'-bis[bis(3-fluorophenyl)phosphinylmethyl]-1,1'-
binaphthyl,
2,2'-bis[bis(4-fluorophenyl)phosphinylmethyl]-1,1'-
binaphthyl,
2,2'-bis[bis(2-methylphenyl)phosphinylmethyl]-1,1'-
binaphthyl and
2,2'-bis[bis(3-trifluoromethylphenyl)phosphinylmethyl]-
l,l'-binaphthyl.
The following examples illustrate the invention without
limiting it.
Experimental part:
Example 1
Preparation using a reaction mixture A
With exclusion of moisture, 282.4 g (1.0 mol) of 2,2'-
dimethyl-l,l'-binaphthyl and 373.8 g (2.1 mol) of
N-bromosuccinimide are suspended in 1.7 1 of chloro-
benzene in a 4 1 glass flask and are illuminated with a
W immersion lamp for 8 hours at from 5 to 10C. The
precipitated succinimide is filtered off, the solution is
extracted twice with 200 ml of water each time, dried
using sodium sulfate and filtered. The filtrate (reaction
mixture A) is transferred to a 4 l four-neck flask
fitted with stirrer, dropping funnel, reflux condenser
and internal thermometer and is heated to 125C. 460.5 g
(2.0 mol) of ethyl diphenylphosphinite are then slowly
added dropwise, with ethyl bromide distilling off. After
the end of the addition, the mixture is heated under
reflux for a further two hours and is then cooled to 0C.
The solid is filtered off, washed with cold chlorobenzene
and dried in vacuo. This gives 512 g (purity: ~ 99 %) of
2,2'-bis(diphenylphosphinylmethyl)-1,1'-binaphthyl as
colorless crystals having a melting point of from 287 to
21~52~
- 14 -
289C, correspo~;ng to 75 % total yield based on 2,2'-
dimethyl-1,1'-binaphthyl used.
Composition according to GC analysis (in mol %)
without solvent:
80 % of 2,2'-bis(bLu~.u~.cthyl)-l,l'-binaphthyl
2 % of 2-bromomethyl-2'-methyl-1,1'-binaphthyl
13 % of 2-dibromomethyl-2'-bromomethyl-1,1'-
binaphthyl.
Example 2
Preparation using a reaction mixture A
With exclusion of moisture, 282.4 g (1.0 mol) of 2,2'-
dimethyl-1,1'-binaphthyl and 373.8 g (2.1 mol) of
N-bromosuccinimide are suspended in 1.7 1 of chloro-
benzene in a 4 1 glass flask and are illuminated with a
W immersion lamp for 8 hours at from 5 to 10C. The
precipitated succinimide is filtered off, the solution i8
extracted twice with 200 ml of water each time, dried
using sodium sulfate and filtered. The filtrate (reaction
mixture A) is transferred to a 4 1 four-neck flask
fitted with stirrer, dropping funnel, reflux condenser
and internal thermometer and i8 heated to 125C. 488.6 g
(2.0 mol) of propyl diphenylphosphinite are then slowly
added dropwise, with n-propyl bromide distilling off.
After the end of the addition, the mixture is heated
under reflux for a further two hours and iæ then cooled
to 0C. The solid is filtered off, washed with cold
chlorobenzene and dried in vacuo. This gives 502.5 g of
2,2'-bis(diphenylphosphinylmethyl)-1,1'-binaphthyl
(purity: ~ 99 ~) as colorless crystals having a melting
point of from 287 to 289C, correspo~;ng to 73.5 % total
yield based on 2,2'-dimethyl-1,1'-binaphthyl used.
Composition according to GC analysis (in mol %)
without solvent:
68 % of 2,2'-bis(bromomethyl)-1,1'-binaphthyl
15 % of 2-bromomethyl-2'-methyl-1,1'-binaphthyl
2145255
- 15 -
13 % of 2-dibromomethyl-2'-bromomethyl-1,1'-
binaphthyl.
Example 3
Preparation using a reaction mixture B
With exclusion of moisture, 282.4 g (1.0 mol) of 2,2'-
dimethyl-l,l'-binaphthyl, 373.8 g (2.1 mol) of
N-bromosuccinimide and 500 mg of benzoyl peroxide are
suspended in 1.7 1 of chlorobenzene in a 4 1 glass flaæk
and are stirred for 3.5 hours at the boiling point. The
precipitated succinimide is filtered off, the solution is
extracted twice with 200 ml of water each time and once
with 100 ml of Na2S03 solution, dried using sodium
sulfate and filtered. The filtrate (reaction mixture B)
is transferred to a 4 1 four-neck flask fitted with
stirrer, dropping funnel, reflux condenser and internal
thermometer and is heated to 125C. 460.5 g (2.0 mol) of
ethyl diphenylphosphinite are then slowly added dropwise,
with ethyl bromide distilling off. After the end of the
addition, the mixture is heated under reflux for a
further two hours and is then cooled to 0C. The solid is
filtered off, washed with cold chlorobenzene and dried in
vacuo. This gives 443.8 g (purity: ~ 99 %) of 2,2'-bis-
(diphenylphosphinylmethyl)-l,l'-binaphthyl as colorless
crystals having a melting point of from 287 to 289C,
correspon~;n~ to 65 % total yield based on 2,2'-dimethyl-
l,l'-binaphthyl used.
Composition according to GC analysis (in mol %)
without solvent:
68 ~ of 2,2'-bi 5 (bromomethyl)-1,1'-binaphthyl
15 % of 2-bromomethyl-2'-methyl-1,1'-binaphthyl
13 % of 2-dibromomethyl-2'-bromomethyl-1,1'-
binaphthyl.
21 4525~
- 16 -
Example 4
2,2'-Bis[bis(3-fluorophenyl)phosphinylmethyl]-1,1'-
binaphthyl
While stirring under nitrogen, 8.8 g (33 mmol) of ethyl
bis(3-fluorophenyl)phosphinite are slowly added dropwise
to a solution of 7.27 g (16.6 mmol) of 2,2'-bis(bromo-
methyl)-l,l'-binaphthyl in 40 ml of o-xylene, which
solution has been heated to 120C, with ethyl bromide
distilling off. After the end of the addition, the
mixture is heated under reflux for a further two hours
and is then cooled to 0C. The solid is filtered off,
washed with cold o-xylene and dried in vacuo. This gives
11.5 g (91 %) of colorless crystals having a melting
point of 280-284C.
31P-NMR: ~ (CDCl3) = 27.3 ppm
Example 5
2,2'-Bis[bis(4-fluorophenyl)phosphinylmethyl]-1,1'-
binaphthyl
While stirring under nitrogen, 10.70 g (0.04 mol) of
ethyl bis(4-fluorophenyl)phosphinite are added dropwise
to a solution of 8.80 g (0.02 mol) of 2,2'-bis(bromo-
methyl)-l,l'-binaphthyl in 40 ml of o-xylene, which
solution has been heated to 135C. After the end of the
addition, the mixture is heated under reflux for a
further 1.5 hours. After cooling to room temperature, the
precipitated crystals are filtered off with suction and
wa~hed with xylene. This give~ 14.1 g (94 %) of colorle~s
crystals having a melting point of 211-214C.
31P-NMR: ~ (CDCl3) = 28.2 ppm
21~525-~
Example 6
2,2'-Bis~bis(2-methylphenyl)phosphinylmethyl]-1,1'-bi-
naphthyl
While stirring under nitrogen, 21.5 g (83 mmol) of ethyl
bis(2-methylphenyl)phosphinite are slowly added dropwise
to a solution of 18.4 g (42 mmol) of 2,2'-bis(bromo-
methyl)-1,1'-binaphthyl in 100 ml of o-xylene, which
solution has been heated to 120C, with ethyl bromide
distilling off. After the end of the addition, the
mixture is heated under reflux for a further two hours
and is then cooled to 0C. The solid is filtered off,
washed with cold o-xylene and dried in vacuo. This gives
25.1 g (81 %) of colorless crystals having a melting
point of 231-234C.
31P-NMR: ~ (CDCl3) = 30.5 ppm
Example 7
2,2'-Bis[bis(3-trifluoromethylphenyl)phosphinylmethyl]-
1,1'-binaphthyl
While stirring under nitrogen, 20.1 g (55 mmol) of ethyl
bis(3-trifluoromethylphenyl)phosphinite are slowly added
dropwise to a solution of 11.0 g (25 mmol) of 2,2'-
bis(bromomethyl)-1,1'-binaphthyl in 80 ml of o-xylene,
which solution has been heated to 120C, with ethyl
bromide distilling off. After the end of the addition,
the mixture is heated under reflux for a further
two hours and i8 then cooled to 0C. The solid i9
filtered off, washed with cold o-xylene and dried in
vacuo. This gives 16.1 g (68 %) of colorless crystals.
31P-NMR: ~ (CDCl3) = 27.1 ppm
Example 8 (Arbusov in ethyl acetate)
While stirring under nitrogen, 88.5 g (385 mmol) of ethyl
21~52~5
- 18 -
diphenylphosphinite are slowly added dropwise to a
solution of 77.0 g (I75 mmol) of 2,2'-bis(bromomethyl)-
1,1'-binaphthyl in 400 ml of ethyl acetate, which 801u-
tion has been heated to 78C, and ethyl bromide is
simultaneously distilled off via an 80 cm Vigreux column.
After the end of the addition, the mixture i8 heated
under reflux for a further two hours and is then cooled
to 0C. The solid is filtered off, washed with cold ethyl
acetate and dried in vacuo. This gives 85.0 g (71 %) of
colorless crystals having a melting point of 287-289C.
