Organic compounds -- part of the class 532-570 series – Organic compounds – Unsubstituted hydrocarbyl chain between the ring and the -c-...
Reexamination Certificate
2001-03-12
2002-03-26
Kifle, Bruck (Department: 1624)
Organic compounds -- part of the class 532-570 series
Organic compounds
Unsubstituted hydrocarbyl chain between the ring and the -c-...
C540S450000, C540S451000, C540S612000, C546S184000, C546S243000, C548S543000, C548S579000
Reexamination Certificate
active
06362333
ABSTRACT:
The present invention relates to a process for coproducing a cyclic lactam and a cyclic amine by coreacting an aliphatic alpha, omega-diamine and an aliphatic alpha, omega-aminonitrile with water in the gas phase in the presence of a heterogeneous catalyst.
The preparation of mixtures comprising an aliphatic alpha, omega-diamine and an aliphatic alpha, omega-aminonitrile by partial hydrogenation of an aliphatic alpha, omega-dinitrile, for example the preparation of mixtures comprising hexamethylene-diamine and 6-aminocapronitrile by partial hydrogenation of adiponitrile, is common knowledge. The workup of such mixtures to recover the diamine and the aminonitrile is possible only through deployment of appreciable technical resources.
Cyclic lactams, such as caprolactam, are known starting materials for the manufacture of industrially important plastics such as nylon. Cyclic amines, such as azepan, are widely used as intermediates for preparing pharmaceuticals, agrochemicals, corrosion inhibitors for nonferrous metals, vulcanization accelerants and as ingredients of textile assistants and sizes, antistats and finishes and also crosslinking agents for resins.
GB 1 358 862 (1974) discloses the preparation of lactams from specifically five- and more highly membered azacycloalkanes or from diamines and water over solid hydrogenation catalysts in the liquid phase at 150-400° C.
It is reported that piperidine/H
2
O/NH
3
in a weight ratio of 1/10/9 (molar ratio about 1/47/45) converts at 300° C. over Ra—Ni, Pt/C and Ru/Al
2
O
3
into piperidone with yields of around 50% in the course of 2-3 hours. In contrast, azepan (“hexamethyleneimine”, HMI)/H
2
O/NH
3
likewise in a weight ratio of 1/10/9 converts at 270° C. over Ra—Ni into only 17.6% of the theoretical amount of caprolactam in the course of 5 hours.
When the diamine used is hexamethylenediamine (“HMD”), the yield of caprolactam is at 10.7% even lower than from azepan and hence far below the industrially required level; azepan is evidently not formed in this reaction.
Processes for preparing azacycloalkanes from diamines, such as azepan from HMD, without the coproduction of cyclic lactams are common knowledge.
For instance, CA-A 920 606 describes the conversion of HMD into azepan over cobalt and nickel catalysts (Ra type and also on supports such as SiO
2
, Al
2
O
3
) in the presence of H
2
at HMD/H
2
=1:2-70, 150-250° C. and 1-20 bar.
Azepan selectivities of up to about 90% are obtained with incomplete conversions (up to 44%). By-products formed are predominantly bishexamethylenetriamine and polyamines.
According to U.S. Pat. No. 3,830,800, HMD in a solvent such as dioxane over RuO
2
/C likewise gives a good azepan selectivity of 91% only at low conversions (<50%).
DE-A 24 14 930 describes the HMD condensation over metals selected from the group consisting of Ni, Co, Fe, Mn, Ag, Cu, Pd as active components, with or without supports such as Al
2
O
3
or SiO
2
, in a high boiling solvent at 200° C. with simultaneous continuous distillative removal of the resulting azepan (boiling point 139° C. at atomospheric pressure) from the reaction mixture. Yields of up to 94% are reported.
DE-A 25 32 871 relates to the continuous condensation of HMD in an inert solvent over Ni or Co, with or without supports such as Al
2
O
3
or SiO
2
, at 80-150° C., the formation of oligo- and polyamines being prevented by continuously removing the azepan from the reaction mixture by azeotropic distillation with H
2
O).
U.S. Pat. No. 3,903,079 discloses condensing HMD by using HMD/NH
3
=1:15-30 (1:>2) at 250-400° C. over zeolites, loaded with 0.3-7% of metal cations selected from the group consisting of Cu, Pd, Mn, Ni or Cr, in the gas phase in a fixed bed or fluidized bed reactor to obtain azepan in yields of around 75%.
U.S. Pat. No. 470,900 describes the gas phase condensation of diamines to azacycloalkanes, including HMD to azepan, at 100-250° C. over Ni, Co, Fe or copper catalysts on supports without the use of NH
3
. An HMD/H
2
ratio of 1:20, 150° C. and a space velocity of 0.2 gave azepan yields of 90% over Ni/kieselguhr, while an azepan yield of 95% was obtained at an HMD/H
2
ratio of 1:20, 150° C. and a space velocity of 0.1 over Cu/kieselguhr.
EP-A 372 492 discloses preparing azepan from HMD at 160-260° C. in the presence of water vapor and hydrogen over Pd/Al
2
O
3
in the gas phase at a weight ratio of HMD to water of 20:80 to 99:1. Azepan yields of 92% were obtained.
Processes for converting cyclic amines, such as azepan, into cyclic lactams, such as caprolactam, are likewise known.
According to Chem. Ber. 109 (1976) 3707-27, pyrrolidine can be reacted with oxygen under Pt catalysis to obtain pyrrolidone in yields of 60%; for other cyclic amines, however, the same reaction leads to an utterly confusing product mixture.
U.S. Pat. No. 3,634,346 describes the conversion of a cyclic amine into the corresponding cyclic lactam by oxidation with a hydroperoxide in the presence of a metal ion catalyst. The best yields obtainable with this process (15.5% of 2-pyrrolidone from pyrrolidine), however, are completely unsatisfactory for industrial processes.
Processes for oxidizing cyclic amines to the corresponding cyclic lactams using Hg(II) compounds as described in U.S. Pat. No.-3,336,299 and Synth. Commun. 18 (1988) 1331-37 are completely unsatisfactory with regard to the yield and problematical with regard to the workup and disposal of the mercurial reaction residues.
This also applies to the oxidation with iodosobenzene described in Tetrahedron Lett. 29 (1988) 6913-16.
Processes for preparing cyclic lactams, such as caprolactam, from aliphatic alpha, omega-aminonitriles, such as 6-aminocapronitrile, are likewise known.
U.S. Pat. No. 2,357,484 describes the conversion of 6-aminocapronitrile into caprolactam at 200 to 350° C. in the presence of heterogeneous catalysts. The space-time yields obtained range from 0.02 to 0.03 g of product/ml of catalyst/h.
EP-A 150 295 and U.S. Pat. No. 4,628,085 disclose converting aminonitriles into cyclic lactams at 200 to 400° C. in the presence of catalyts. The starting mixture contains only up to 4% of aminonitrile.
WO-A 96/22974 describes the conversion of 6aminocapronitrile into caprolactam at 200 to 450° C. over catalysts which U.S. Pat. No. 4,628,085 describes as very short-lived in the case of silicon dioxide.
DE-A 19 632 006 discloses convering 6-amincapronitrile into caprolactam at 220 to 380 in the presence of heterogeneous catalysts. The catalyst loadings range from 0.1 to 1 g of reactant/ml of catalyst/h.
It is an object of the present invention to provide a process for coconverting an aliphatic alpha, omega-diamine and an aliphatic alpha, omega-aminonitrile into a cyclic amine and a cyclic lactam in a technically simple and economical manner.
We have found that this object is achieved by the process defined at the beginning.
The starting materials used in the process of the invention are preferably aliphatic alpha, omega-diamines of the general formula (I)
H
2
N—(CH
2
)
n
—NH
2
(I)
where n is 4, 5, 6 or 7, i.e., 1,4-diaminobutane, 1,5-diaminopentane, 1,6diaminohexane (“hexamethylenediamine”, “HMD”) and 1,7-diaminoheptane, most preferably 1,6-diaminohexane, or mixtures of such diamines (I).
The diamines may bear one or more substituents on the carbon, such as C
1
-C
6
-alkyl groups, cycloalkyl groups, such as cyclopentyl, cyclohexyl or cycloheptyl groups, or halogen. Preferably, the diamines are unsubstituted.
Such diamines and processes for their preparation are common knowledge.
Useful aliphatic alpha, omega-aminonitriles for the process of the invention are primarily those of the general formula (II)
H
2
N—(CH
2
)
m
—CN (II)
where m is 3, 4, 5 or 6, i.e., 4-aminobutyronitrile, 5-aminovaleronitrile, 6-aminocapronitrile (“ACN”) and 7-aminoenanthonitrile, most preferably 6-aminocapronitrile, or mixtures of such aminonitriles (II).
The aminonitriles may bear one or more substituents on the carbon, such as C
1-C
6
-alkyl groups, cycloalkyl groups, such as cyc
Ansmann Andreas
Fischer Rolf
Merger Martin
BASF - Aktiengesellschaft
Keil & Weinkauf
Kifle Bruck
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