Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-08-25
2001-06-12
Keys, Rosalynd (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S309000, C568S324000, C568S426000, C568S438000
Reexamination Certificate
active
06245945
ABSTRACT:
DESCRIPTION
The present invention relates to processes for selective hydrolysis of acetals and ketals in the presence of phthalides, which comprise reacting a mixture (M) comprising
a) a phthalide of the formula (I)
where:
R
1
, R
2
, R
3
and R
4
: are independently hydrogen, C
1
-C
4
-alkyl or halogen,
and
b) an acetal or ketal of the formula (II)
where:
R
5
and R
6
: are independently C
1
-C
6
-alkyl, C
6
-C
10
-aryl or together ethylene, and
R
7
and R
8
: are independently C
1
-C
6
-alkyl, or one radical is a hydrogen and the other is a phenyl radical where from 1 to 3 hydrogen atoms of the phenyl radical may be replaced by C
1
-C
6
-alkyl radicals or C
1
-C
4
-alkoxy radicals, or
R
7
and R
8
are together C
3
-C
6
-alkanediyl, and a hydrogen atom may be replaced by a hydroxyl group,
at from 10 to 200° C. in the presence of from 1 to 10 mol of water, based on the amount of acetal or ketal of the formula (II), to hydrolyze the acetal or ketal of the formula (II) to the corresponding aldehyde or ketone.
The present invention further relates to an overall process for preparing purified phthalides and aldehydes or ketones, of which the selective hydrolysis is an integral part and wherein a compound (III) selected from the group consisting of phthalic acid and phthalic acid derivatives of the general formula (III)
where:
R
1
, R
2
, R
3
and R
4
are each as defined for the formula (I)
R
9
and R
10
are
a) independently —COOH or COOX, where X is C
1
-C
4
-alkyl,
b) either —COONY
4
while the other is CONH
2
, Y is C
1
-C
4
-alkyl or hydrogen,
c) together —CO—O—CO—,
and from 0 to 20% by weight, based on the acetal or ketal of the formula (II), of a compound (IV) selected from the group consisting of methylbenzene, ring-substituted derivatives of methylbenzene where from 1 to 3 hydrogen atoms of the phenyl radical may be replaced by C
1
-C
6
-alkyl radicals or C
1
-C
4
-alkoxy radicals, cyclohexanone and 2-butanone are reacted electro-chemically in an undivided electrolysis cell to form a mixture (M), comprising phthalides of the formula (I) and aldehydes or ketones of the formula (II).
Phthalides of the formula (I) and aldehydes or ketones of the formula (II) (compounds I and II) are useful intermediates, especially for the synthesis of crop protection agents.
These compounds are preparable in a particularly economical way from the compounds (III) and (IV) in electrochemical cosyntheses in an undivided electrolysis cell, in which case the compounds (I) and (II) are obtained in the form of the mixture (M) (cf. DE-A-19618854 and the German application with the file reference 19741423.0).
However, separation of the resulting mixture (M) using technically simple customary separation processes such as distillation is very difficult, since the acetals/ketals and phthalides form azeotropes in some instances.
It is an object of the present invention to provide a technically simple and very economical separation process where the loss of product of value is minimal.
We have found that this object is achieved by the above-described process for separating the mixture (M) and the overall process for preparing the compounds (I) and (II).
The fact that the process of the present invention achieves the object must be surprising to those skilled in the art. First, it was unforeseeable that the aldehydes or ketones are significantly simpler to separate from the phthalides by distillation than the corresponding acetals or ketals. Secondly, the hydrolysis of acetals or ketals (II) in the presence of phthalides (I) would not have been expected to be economical.
The hydrolysis of acetals and ketals is described, for example, in J.Org.Chem. 59 (1994), 3098-3101. According to this reference, acetals and ketals are hydrolyzed in the presence of acids, acidic catalysts or auxiliaries, for example zeolites or ion exchangers, under harsh conditions in some instances, for example in super- critical water, in order that useful space-time yields may be obtained.
From this, it would have been expected that existing processes for hydrolyzing acetals or ketals of the formula (II) would not be economical under reaction conditions sufficiently mild to ensure that virtually only the acetal or ketal group and not the ester group of the phthalide is attacked, since the reaction times would be too long. On the other hand, harsher reaction conditions would be expected to cause the formation of by-products (hydrolysis of the phthalide).
The selective hydrolysis is particularly efficient in the case of those mixtures (M) comprising a phthalide of the formula (I) where R
1
, R
2
, R
3
and R
4
are all hydrogen.
Preference is given to acetals or ketals of the formula (II) wherein R
7
and R
8
have the following meanings:
one radical R
7
or R
8
is hydrogen and the other is selected from the group consisting of p-methoxyphenyl, p-methylphenyl, p-t-butylphenyl, o-methylphenyl and o-methoxyphenyl,
the radicals R
7
and R
8
are together 1-hydroxypentane-1,5-diyl, or
one radical R
7
or R
8
is methyl and the other is 1-hydroxyethyl.
p-tert-Butylbenzaldehyde dimethyl acetal is particularly preferred.
The mixtures (M) comprise generally from 10 to 60%, preferably from 30 to 50%, by weight of a phthalide of the formula (I) and from 10 to 60 mol %, preferably from 30 to 50 mol %, of an acetal or ketal of the formula (II).
The mixtures (M) may further comprise from 0 to 20% by weight, based on the phthalide of the formula (I), of a compound (III) selected from the group consisting of phthalic acid and phthalic acid derivatives of the general formula (III)
where:
R
1
, R
2
, R
3
and R
4
are each as defined for the formula (I)
R
9
and R
10
are
a) independently —COOH or COOX, where X is C
1
-C
4
-alkyl,
b) either —COONY
4
while the other is CONH
2
, Y is C
1
-C
4
-alkyl or hydrogen,
c) together —CO—O—CO—,
and from 0 to 20% by weight, based on the acetal or ketal of the formula (II), of a compound (IV) selected from the group consisting of methylbenzene, ring-substituted derivatives of methylbenzene where from 1 to 3 hydrogen atoms of the phenyl radical may be replaced by C
1
-C
6
-alkyl radicals or C
1
-C
4
-alkoxy radicals, cyclohexanone and 2-butanone.
In the mixtures (M), the radicals R
1
to R
4
in the compounds of the formulae (I) preferably have the same meanings as in the compounds of the formula (III).
The compounds of the formula (IV) are preferably compounds which serve as starting compounds for the electrochemical conversion to the corresponding compounds of the formula (I).
The selective hydrolysis is carried out in the presence of from 1 to 10 mol of water, based on the molar quantity of acetals or ketals of the formula (II). The reaction temperature is within the range from 10 to 200° C., preferably within the range from 80 to 140° C. The pressure at which the reaction is carried out is uncritical and is generally within the range from 0.5 to 10 bar.
The selective hydrolysis may be carried out in the presence of catalytic amounts of a mineral acid, of an organic acid or of an acidic ion exchanger, but preferably without the addition of catalyst.
The selective hydrolysis may be carried out in the presence of an inert organic solvent, for example acetone, or without a solvent.
The hydrolysis is preferably carried out according to one of the following variants:
Variant A:
The mixture (M) and the water are, via heat exchangers, separately preheated and fed into the reactor. The mixing can be influenced through internal fitments or stirrer optimization. Residence times are set to range from 10 sec to 10 min at a pressure of 3-20 bar and temperatures of 80-180° C. The reaction solution is expanded into a flash drum, the alcohol which is formed becoming substantially vaporized in the process.
Variant B:
Variant B1 of the present invention is a continuous hydrolysis under atmospheric pressure in a stirred reactor having a column fitted on top:
The mixture (M) and the water required for hydrolysis (stoichiometric amount up to 10-fold molar excess) are separately introduced into the vessel and reacted at from 1
Hannebaum Heinz
Putter Hermann
Weiper-Idelmann Andreas
BASF - Aktiengesellschaft
Keys Rosalynd
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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