Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a process for hydroxy-
lating 3-chloro-2-methyl-propene-1, straight-chain or branched
monoolefins, wllich are either unsubstituted or substituted by 1
to 2 hydroxyl groups and contain 4 to 7 carbon atoms and a terminal
or internal double bond, straight-chain or branched monoolefins,
which are either unsubstituted or substituted by 1 to 2 hydroxyl
groups and contain 8 to 10 carbon atoms and an internal double
bond, or straignt-chain or branched diolefins containing 4 to
10 carbon atoms.
By hydroxyldtion is meant that two hydroxyl groups
are added on to the olefinic double bonds. Vicinal diols are
thus formed in the hydroxylation of the monoolefins. If one or
two hydroxyl groups are already present, then the corresponding
triols or tetrols are formed. Unsaturated diols or saturated
tetrols are formed in the hydroxylation of the diolefins.
The process according to the invention is characterized
in that the olefin to be hydroxylated is reacted at a temperature
between 30 and 80C with less than 2 moles of formic acid and
less than 2 moles of hydrogen peroxide per mole of double bond
to be hydroxylated, that formic acid is used in a concentration
between 20 and 100 percent-and hydrogen peroxide in a concentra-
tion of less than 50 percent by weight and that the concentration
of the hydrogen peroxide in the aqueous phase of the reaction
mixture is kept below 15 percent during the entire reaction.
The reaction is preferably carried out at a temperature
between 45 and 60C. The formic acid is preferably used in an
amount of 0.2 to 0.8 mole per mole of double bond to be hydroxy-
lated. The hydrogen peroxide is used with advantage in an amount
of 1.1 to 1.5 moles per mole of double bond to be hydroxylated.
Hydrogen peroxide having a concentration of 15 to 40 percent by
weight is preferably used.
The starting materials used for the process according
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to the invention are 3-chloro-methyl-propene-1 straight-chain
monoolefins containing 4 to 7 carbon atoms, such as butene-l,
butene-2, pentene-l, hexene-l, heptene 1 and heptene-3 and
branched-chain monoolefins containing 4 to 7 carbon atoms, such
as 2-methyl-propene-1, 3-methyl-butene-1, 3,3-dimethyl-butene-1,
2,3-dimethylbutene-1, 2,3-dimethyl-butene-2, 2-methyl pentene-l,
2-methyl pentene-2, 3-methyl pentene-2 and 2-ethyl butene-l.
The monoolefins used can aiready have been substitu-ted by 1 to 2
hydroxyl groups. Examples of these substances are buten-1-ol-3,
buten-2-ol-1 (crotyl alcohol), butene-2--diol-1,4, 3-methyl buten-
3-ol-1, 3-methyl buten-2-ol-1 and 2-methyl-buten-3-ol-2. While
in the monoolefins con-taining a maximum of 7 carbon atoms the
double bond can be in any position, thus at the chain end or
internally in the chain, mono-olefins containing 8 to 10 carbon
atoms can be reac~ed by means of the process according to the
invention only if the double bond is internally in the chain.
Examples of these substances are 2,4,4-trimethyl pentene-2,
1,2-di-(tert. butyl)-ethylene and decene-5. The monoolefins
containirg 8 to 10 carbon atoms can also be substituted by 1 to
2 hydroxyl groups as in 2-ethyl hexen-2-ol-1. Finally according
to the process of the invention straight-chain or branched
diolefins containing 4 to 10 carbon atoms such as butadiene,
isoprene, hexadiene-1,5 and decadiene-l,9 can be reacted to the
corresponding tetrols.
The process according to the invention is preferably
carried out at standard pressure. ~owever, since the reaction
temperature should not be lower than 30C in order to obtain an
acceptable rate of reaction, it is obvious that for olefins having
a boiling point lower than 30C, the use of excess pressure is
required. In this case it is expedient to so select the reac-
tion temperature that the pressure does not exceed 10 bars.
Despite the mild reaction conditions the reactions according to
the process of the invention surprisingly are very smooth and
result in high yields of the desired diols, triols or -tetrols
within reasonable reaction times.
~ hen carrying out the reaction in practice preferably
the entire formic acid to be used is used together with the
olefin as the starting material and the hydroyen peroxide is
slowly added portionwise. However, it is also possible to start
with a portion, for example, approximately one third of the total
amount of the olefin to be hydroxylated, together wlth the total
amount of formic acid and to add slowly, portionwise -the hydro-
gen peroxide and the residual amount of the olefin to be hydroxy-
Iated. The reaction mixture is stirred intensively. An adequate
post-reaction time after combining all the reactants in the
reactor is recommended in order to improve the reaction rate.
After the reaction has been completed the reaction
products usually are present in the aqueous yhase in -the dissolved
form. For many purposes these aqueous solutions can be further
used directly. However, noi only has the residual content of
hydrogen peroxide an adverse effect in most cases but it is also
desirable to isolate, in a purer form, the diols, triols or
tetrols obtained. Various measures are then suitable for the
further treatment.
If a second phase separates from the reaction mixture,
then a phase separation can be carried out. In many cases it is
then advisable to decompose, to a grea-t extent, the hydrogen
peroxide, which is contained substantially only in the aqueous
phase. The decomposition can be brought about by allowing the
mixture to stand for a lengthy period at elevated temperature
(digestion) or by the action of a suitable catalyst (for example
by passing over a supported platinum fixed bed catalyst) or by
a combination of these two measures.
The reaction mixture then is expediently neutralized
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and extracted with a suitable solvent, for example, ethyl
acetate. The solvent is distilled from the extract and, if
required, the residue of crude diol, -triol or tetrol is freed
from water still contained therein by heating under reduced
pressure. As an alternative, the neutralization of the formic
acid contained in the reaction mixture can be dispensed with.
In that case it is expedient either to carry out the thickening
operation continuously in the manner of a distillation with
steam and to continue it until the distillate contains only small
amounts of formic acid or the formic acid is separated discon-
tinuously in sucll a way that after separating the bulk of formic
acid the residue is once more mixed with water, thickened again,
repeating this operation several times. The residue of crude
diol, triol or tetrol can then be freed from the volatile com-
ponents still contained therein by heating under reduced pressure.
The crude diols, triols or tetrols thus obtained have
degrees of purity of approximately 88 to 96%. If ~urther purifica-
tion is required, then this can be carried out in the usual
manner by recrystallization or by fractional distillation under
reduced pressure.
The process according to the invention will be further
described with reference to the following Examples in which,
unless otherwise stated, data in percent relate to percent by
weight in all the cases.
Example 1
1 mole (72 g) of crotyl alcohol was mixed with 0.5
mole (23 g) of a 98% formic acid and 1.5 moles (340 g) of a 15%
H2O2 in a stirring apparatus, with a reflux condenser mounted
thereon, and stirred for 8 hours at 60C. The system was single-
phase and contained 3.9% of H2O2. The mix-ture was passed over
an NW 40 column of 30 cm length. The column was filled with 100
ml of fixed-bed catalyst (0.1% of platinum on Berl saddles).
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After passing through H2O2 could no longer be detected analyti-
cally.
The mixture was then boiled for 2 hours with reflux
and concentrated in vacuo (bottom temperature up to 100C at
12 torrs). There remained a residue of 102 g, which was sub-
sequently distilled in high vacuum (0.1 torr). The fraction
yoing over at a temperature between 125 and 130C (i.e. 92 g)
consisted of methyl glycerin.
Example 2
In an apparatus according to Example 1, 1 mole (91 g)
of 3-chloro-2-methyl-propene-1 was mixed with 0.75 mole (35 g)
of a 98% formic acid and 1.5 moles (128 g) of a 40% H2O2 were
added at 60C in the course of 6 hours. Post-reaction: 4 hours
at 60C. The mixture was catalytically freed from H2O2 and con-
centrated by distillation - as described in Example 1. At a
bottom temperature of 100C (12 torrs) a residue of 125 g remained
and was subsequently subjected to total distillation at 12 torrs.
The fraction going over at a temperature between 103 and 107C
(i.e. 103 g) consisted of 3-chloro-2-methyl-propane diol-1,2.
Example 3
In an apparatus according to Example 1, 1 mole (70 g)
of pentene-l was mixed with 1 mole of formic acid, 1.5 moles
(128 g) of a 40% H2O2 were added with vapour cooling (approxi-
mately 30C) in the course of 8 hours. After a post-reaction
time of 8 hours the system had become single-phase. The system
was catalytically freed from H2O2, neutralized with 90 g of a
40% NaOH and extracted four times, using 100 ml of ethyl acetate
each time. The ethyl-acetate extracts were combined and freed
from the solvent by distillation. A crude pentane-diol residue
of 84 g was obtained. Its amount could be further increased in
that the aqueous phase was concentrated to approximately one half
and then again extracted thoroughly with ethyl acetate.
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In the total distillation (12 torrs) 84 g of crude
diol yielded an amount of 78 g of pure pentane-diol-1,2 which
went over at 115 to 117C.
The test was repeated in a modified stirring apparatus
which was provided Witil a pressure-maintaining valve after the
reflux condenser. This valve opened at 2 atmospheres excess
pressure. The hydroxylation of l-pentene could thus be carried
out with the amounts specified above at a temperature of 50C.
Under these conditions bo-th the time for dosing in the H2O2 and
the post-reaction time could be reduced to one half. The continu-
ation of the test, which had been carried out at slightly increased
pressure, produced practically the same yields as the pressure-
less test.
Example 4
In an apparatus according to Example 1, 1 mole (84 g)
of 2,3-dimethyl-butene-2 was mixed with 0.6 mole (28 g) of a 98%
formic acid and 1.5 moles (255 g) of a 20% H2O2 were added at
55C in the course of 4 hours. After a post-reaction time of
4 hours the system had become single-phase. However, 4.2 g of
olef;n could be removed by distillation (reaction rate = 95%).
After the usual catalytic H2O2 decomposition the mix~
ture was neutralized with 50 g of a 25% NaOH and extracted four
times consecutively, using 100 ml of ethyl acetate each time.
The remaining aqueous phase was concentrated to one half by
distillation and again extracted four times, using 50 ml of
ethyl acetate each time. All the ethyl acetates were combined
and freed from water, which still was in solution by azeotropic
distillation. After distilling off the low-boiling component a
bottom product (98 g, m.p. = 38 to 41C) remained. It had a
diol content (pinacol) of 98go (yield 87%).
Example 5
In an apparatus according to Example 1, 1 mole (98 g)
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of heptene-3 was mixed with 1 mole (47 g) of a 98% formic acid.
In the course of 5 hours 1.5 moles (146 g) of a 35% H2O2 were
added at 55C. Even after stirring for 2 hours at 60C the
mixture remained two-phase. The mixture was catalytically
freed from residual H2O2 and neutralized with 85 g of a 40% NaOH.
The aqueous phase was extracted four times with ethyl acetate,
using 100 ml each time. It was -then concentrated to one half
and again extracted twice with ethyl acetate. All the ethyl
acetate extracts were combined with the organic phase and freed
from the low-boiling components by distillation. A bottom pro-
duct (crude heptane-diol-3,4 = 132 g) remained. It was con-
verted by purifying fractionation (b.p.l2 = 111 to 113C) into
the pure heptane-diol-1,3 in a yield of 86%.
Example 6
In an apparatus according to Example 1, 1 mole (129 g)
of 2-ethyl-hexen-2-ol-1 was mixed with 0.7 mole (33 g) of a 98%
formic acid and in the course of 4 hours 1.5 mole (255 g) of a
20% H2O2 were added at 55C. The mixture was then stirred for a
further 4 hours at 60C and still remained two-phase. The
aqueous phase was separated and the organic phase was washed
twice with water (50 ml each tim~).
All the combined aqueous phases were catalytically
freed from H2O2 and neutralized with 65 g of 40% NaOH. The
aqueous phase was then thoroughly extracted with ethyl acetate.
The ethyl-acetate extract was combined with the organic phase
and freed from the low-boiling components by distillation. The
remaining bottom product weighed 143y and could be converted by
high-vacuum distillation (0.1 torr, 90 to 92C) into pure 2-
ethyl hexane-triol-1,2,3.
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