Note: Descriptions are shown in the official language in which they were submitted.
083606
This invention relates -to the prepara-tion of
para styrenated diphenylamine. More par-ticularly it
relates to the use of acidic clays in the prepara-tion o~
para styrenated diphenylamine.
The prior art reveals the preparation of ~-methyl
styrenated diphenylamines, e.g., U.S. Patent 3,505,225, and
the use of said compounds as antioxidants. Diphenylamine
when substituted with styrene or ~-me-thyl styrene in either
one or both of -the para positions will provide age resist-
ance to materials susceptible to oxidative degradation
which is superior to that offered by the ortho substituted
diphenylamines. Although para subs-titution can be obtained
when alkylating diphenylamine with a-methyl styrene at low
temperatures, e.g, from about 120C. to 150C., using
acidic clays, very low amounts of para substitution result
when one atte~pts to react styrene, rather than a-methyl
styrene, with diphenylamine at these low temperatures. A
process which would provlde increased amounts of para sty-
renated diphenylamine is desirable.
The present invention provides a process for
producing s-tyrenated diphenylamine containing a substant- ;
ial amount of p-substituted diphenylamine comprising
reacting a combination comprising (a) diphenylamine and
(b) styrene in the presence of a catalytic amount of an
25 acid activated clay catalyst containing a major amount of ;
~ aluminum hydrosilicate, at a reaction tempera-ture of from
;, 170C. to 300C. wherein the level of styrene is from 1 to
~ 2.5 moles per mole of diphenylamine.
~ ~ ~ '
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~336(~
The present invention also provides a process
for producing a styrenated diphenylamine wherein the
~-methylbenzyl substi-tuent i5 selected from either or
both of the para posi-tions.
Further, according to the present invention
the preferred process incorporates a reaction temperature
of from 185C. to 275C., a more preferred temperature
is from 200C. to 250C.
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~L0836~6
Preferably 1.5 to 2 moles of styrene are charged per 1 mole
of diphenylamine.
The acidic clay used in the practice of the
present invention is extremely well known in the art as
Montmorillonite clay catalyst and is prepared from mineral,
Montmorillonite. A major amount of the acid clay is com-
- posed of aluminum hydrosilicate. The ~eneral composition
is of the type M[~102)X(SiO2)y]-ZH20 where M is metal cation
selected from K*, Na+, Ca+2, Fe+2~Fe+3~ etc. and Z is the
number of moles of water of hydrotion. The activity of the
clay catalyst is dependent upon several factors such as the
particle size~ moisture content, sur~ace area, acidity, etc.
A typical clay composition would be as follows.
ComponentWei~ht Percent
SiO2 70 - 75
A1203 15 - 20
Fe203
CaO - 15
K20
Examples of these catalysts are the activated
Montmorillonite catalyst of the K series produced by
Chemetron Corporation, and activated clay adsorbents of
Filtrol Corporation.
The reaction products of the present invention
are a mixture of p-monostyrodiphenylamine and p,p'-distyryl-
diphenylamine. Alpha-methyl styrene can be substituted for
a portion of the styrene but the styrene should always com-
prise at least 50 percent of the molar amount of the ole-
finic portion o~ the reaction system.
The reaction may be accomplished batchwise or on
~LCi8360~
a continuous basis at various pressures, including atmos-
pheric pressure. The product is an effecti~e antioxidant
which can be used in the stabilization of materials subject
to oxidation degradation, particularly diene rubbers such as
butadiene/nitrile rubbers, at elevated temperatures.
The clay catalysts are used and preconditioned in
a conventional manner, e.~., water is removed preferably
from the clay catalyst prior to use, for example, by azeo-
tropic distillation of benzene. Alternatively water can
also be removed by predrying the product at 100 C. to
200 C. in an o~en. In such a situation, no solvent is
necessary.
In a typical operation styrene is added slowly to
a hot mixture of diphenyla~ine and the catalyst at the
desired reaction temperature~
The amount of catalyst is not critical to the
; practice of the invention. ~aturally9 as with any process,
the catalyst level can be reduced to such a low level that
the reaction rate will either be extremely low or nil. As
a guideline7 but not a limitation, at least 8 parts by
weight of catalyst should be used per 100 parts by weight
of diphenylamine. More preferably at least 10 parts by
; - weight should be used. There is no upper limit on catalyst
level. For example, 100 parts of catalyst or more can be
used. However, merely as a practical matter, the amount of
catalyst should not exceed 20 or 25 parts.
It should be noted that some-times the addition of
an acid will increase -the effectiveness of some catalysts.
The following example illustrates but does not
limit the practice of the present invention.
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- 10836i06
All of the catalysts were of the generic structure
described earlier herein.
Exam~le 1
-A mixture of 50 grams of diphenylamirle~ 8 grams
of montmorillo~ite clay catalyst (Girdler designation KS ~
and 180 milliliters of benzene was heated to reflux temper-
ature with stirring. Water (0.3-0.5 milliliters) was re- ;~
moved from the catalyst by azeotroping it out with benzene.
Enough benzene was then removed to allow the pot to reach
the desired temperature. About 95-98 percent (175 milll-
liters) needed to be removed to add styrene at 220-225O C.
Fifty-rour grams o~ styrene was added during 30 minutes5
the mixture was stirred for an additio~al one to two hours
at 2Z0 C. Although not necessary to the success o~ the
process~ the reaction mixture containing styryldiphenyl-
- amines was left over the catalyst overnight at room temper-
ature. The mixture was heated the ne~t day~ cooled to
90-lOOo C. and filtered hot on a steam heated ~unnel to
remove solid catalyst. The flltrate is a dark or light
amber viscous product. The identity of the components of
the viscous product was done by gas chromatography and the
components identified primarily as mono- and distyryldi-
phenylamlne. m is product can be used as is as an anti-
oxidant. Howev~r~ it is desirable to strip of~ lights
(unreacted dlphenylamine, styrene, dimer of styrene~ etc.)
by heating the viscous li~uid at 200-2500 C. under 1-10
mlllimeters vacuum for two hours to obtain improvement in
act~vity.
Example 1 was repea-ted using various molar xatios
of styrene to diphenylamine, reaction temperatures,
1 [)8361~6
catalysts and amounts of catalys-ts and at different rates
of styrene addition. Different solvents, i.e.~ dichloro-
benzene and toluene were also evaluated. ~hese variables
along with -the results obtained~ i.e.~ amount of total
alkylation and amount of selective para subs-titution, are
shown in the following tables.
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~836~6
~ S ~, KSF/ ~, K-l ~ and K-30 ~are produced by the
Catalysts Di~ision of Chemetron Corporation and are based
on the mineral Mon-tmorillonite. All but K-306 are powdered.
K-30~ is in spherical form.
- ~ Runs 7, 8, 15 and 16 in Table II are illustra-
tions of attempts to prepare styrenated diphenylamines
using reaction conditions outside the scope of the present
invention. As indicated by the percent para substituted
diphenylamine and in some cases even the total percent
conversion, i.e., percent alkylation, the conditions of the
process of the present invention are quite important in
obtaining high values, particularly of para subs-titution.
Runs 7~ 8 and 9 indicate the importance of
reaction temperature. Run 15 indicates the importance of
~ .
~ the catalyst being in a form which provides adequate
- catalyst surface area, e.g.~ powdered form.
While certain representative embodiments and
details have been shown ~or the purpose of illustrating
the invention, it will be apparent to those skilled in
2a this art that various changes and modifications may be
made therein without departin~ from the spirit or scope
of the inVention.
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