Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PROCESS FOR THE MANUFACTURE OF PHENOL-
ISOBUTYRALDEHYDE CONDENSATION PRODUCTS
Background of the Invention
1. Field of the Invention
This invention relates to a process for the
manufacture of phenol-isobutyraldehyde condensation
products. More specifically, this invention relates to such
a process wherein problems presented by odor are eliminated
or substantially reduced.
2. Prior Art
Condensation products of phenols and isobutyralde-
hyde are well known in the prior art. They are generallyprepared by condensation of isobutyraldehyde with the phenol
in the presence of acid catalysts, subsequent neutralization
of the resultant products and remGval of the resulting
reaction water by distillation. Such process is described
in German Published Applications 2,805,763 and 2,805,684.
A drawback of the above described manufacturing
methods is the formation of by-products which are produced
in quantities of up to 2 percent. These include, for
instance, 2,2-dimethylcoumaran which result in considerable
odor problems in many technical applications, for instance,
in the printing ink industry.
Accordingly, it is a purpose of the instant
invention to provide a process for the manufacture of
phenol-isobutyraldehyde condensation products wherein odor
problems are eliminated or substantially reduced.
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- Summary of the Invention
In accordance with the present invention, the above
stated purpose is surprisingly achieved by steam distillation
wherein the undesirable by-products can be removed quantita-
tively from the end products following the above-described
prior art process steps.
Thus the present invention provides a process for
the manufacture of condensation products of phenols and
isobutyraldehyde by reacting the phenol and isobutyraldehyde
at an elevated temperature in a mole ratio of 0.5:1 to 1.5:1
in the presence of acid or compounds hydrolyzable to acids as
catalysts, subsequent neutralization and removal of the
resultant reaction water by distillation wherein the reaction
products obtained in this manner are also subjected to a
water-vapor distillation.
Description of the Preferred Embodiments
The possibility of solving the odor problem by
steam distillation is surprising insofar as one skilled in
the art would assume that under the conditions of such an
operation - the effect of water and steam at temperatures
above 100C for one or more hours - might chemically alter
the products, e.g., by hydrolysis or repeated formation of
; the referenced dimethylcoumaran.
The condensation products, referred to herein as
resins for simplicity sake, are initially produced in a
well known manner such as described in the above-referenced
publications. For this purpose/ the appropriate phenol and
the catalyst are placed in the reaction vessel and iso-
butyraldehyde added wither continuously or in steps. This
process may be implemented either without pressure or under
pressure. The reactants may also be added to the reaction
~` vessel during the course of the reaction, or all at once.
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The mole ratio of isobutyraldehyde to phenol is about 0.5:1
to 1.5:1, preferably about 0.7:1 to 1.3:1. The reaction
temperatures are generally between about 80 and 120C, and
the reaction period is about 1 to 6 hours.
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The softening points of the condensates obtainable
in this manner, are generally between about 60 and 180C.
Suitable phenols which may be used for the manufacture of
such phenol-isobutyraldehyde condensates particularly
include those having the formula:
OH
~ R
In this formula, R stands for a hydrogen, chlorine or
bromine atom or an alkyl group having 1 to 18 carbon atoms
in any of their isomeric forms which are in the o-, m- or p-
position to the hydroxyl group, an alicyclic group with 5 to18 carbon atoms, for instance, the cyclopentyl-, cyclo-
hexyl-, methylcyclohexyl- or butylcyclohexyl group, an
aromatic group or aralkyl group having 6 to 18 carbon atoms
such as the phenyl-, ~-methylbenzyl-, benzyl- or cumyl
~roup. In addition to this, phenolic alkyl, cycloalkyl,
aryl and aralkyl ketones as well as phenolic alkyl, cyclo-
alkyl, aryl and aralkyl carboxylic acids may be used.
Suitable catalysts include acids or substances
;~` which may be hydrolyzed into acids, such as concentrated
hydrochloric acid, sulfuric acid, aromatic sulfonic acids as
well as halogenated phosphorus, such as phosphoric tri-
. chloride, phoshoric xychloride, and phosphoric penta-
chloride. The required cataly~t quantity generally arount~
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.,
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to less than 5, particularly 0~1 to l percent by weight,
relative to the amount of phenol plus isobutyraldehyde.
It is possible to use a solvent such as xylene
which does not participate in the reaction and by which the
resultant water can be separated. However, the water can
also be removed by means of excess isobutyraldeh~de as
solvent. It is therefore more advantageous to work with
mole ratios of isobutyraldehyde to phenol above l. This
guarantees that the phenol, as the more valuable starting
product, will largely react. In addition to this, the
softening points will then be above 90C which is of
advantage for most applications.
After adding the isobutyraldehyde, the resultant
water is removed to the desired degree of condensation at
increased temperatures (80 to 120C). Following this, the
reaction mixture is neutralized and all volatile products
are removed by distillation under reduced pressure if
necessary. It is simplest to neutralize the material with
ammonia or amines but alkali lye may also be used. If the
latter is used, the neutral salts must, in some cases, be
removed if they are not desirable in the end product, The
neutralization is necessary since large quantities of
cleavage products will form upon heating the resultant
novolak in the acid range, for instance, upon removing the
high boiling impurities. These are primarily unsubstituted
and/or suùstituted 2,2-dimethylcoumaran.
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In accordance with this invention, the material is
now subjected to a steam distillation during which the
resultant by-products and/or possibly unreacted raw
materials such as phenol are driven out of the resin. The
distillation is advantageously carried out under normal
pressure with steam having a temperature of up to 160C
within a period of 1 to 3 hours.
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Example I
This example illustrates the manufacture of
phenol-isobutyraldehyde condensation products in accordance
with the prior art wherein 437.5 kilograms of phenol and 4.7
kilograms of p-tolulene sulfonic acid are placed in a
reaction vessel and heated to 50C. 368.5 kilograms of
isobutyraldehyde are dripped into the resultant melt with
the temperature rising to approximately 80C. Following
this, the water is removed at approximately 100C for 4
` hours in a rotating evaporator. Subsequently, 20.6 kilo-
grams of concentrated ammonia solution are added while the
mixture is stirred and initially residual water and excess
isobutyraldehyde are distilled off under normal pressure,
and then the higher boiling components are removed by
distillation under reduced pressure at temperatures up to
160C.
Example II
This example illustrates the practice of the
instant invention. The initial procedure is the same as
that described in Example I above. The ammonia solution
necessary for the neutralization is added in two batches,
15.3 kilograms prior to the distillation under normal
pressure and 5.3 kilograms prior to the vacuum distilla-
. tion. As an additional step, in accordance with the instant
invention, a steam distillation follows for a period of one
hour.
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The resins produced in the above examples are as
follows:
Example II
Example I (According to
(Com~arative) this Invention)
Softening Point according
to DIN 52011 120C 128C
Nonvolatile Component
(2 hours 125C) 98.4% 99.8%
Color dark reddishyellow to
brown light brown
Odor +) odor odor free
+) For the odor test, both resins were dissolved on a 50percent basis in ethanol. The solution is applied to
uncoated paper and is dried at room temperature for 5
minutes. After this, the samples were enclosed in a twist-
off glass and the odor was evaluated.
