Substituted acylating agents and their production

Polybutenyl substituted succinic acylating agents are formed by reacting (a) an acidic reactant represented by the general formula EQU R--CO--CH.dbd.CH--CO--R' wherein R and R' are independently --OH, --O-lower alkyl, a halogen atom, or taken together are a single oxygen atom, with (b) a polymer composed mainly or entirely of polyisobutene, at least 50% of the polyisobutene content of the polymer having an end group represented by the formula ##STR1## The mole ratio of acidic reactant:polymer is at least 1:1; and the reaction mixture is maintained under superatmospheric pressure during at least a substantial portion of the reaction period. The reaction rate is high, the yields of desired product are high, and despite the fact that superatmospheric pressures and elevated temperatures are used, the process forms only small amounts of tars or resinous co-products, even when employing as much as a 20% or more molar excess of maleic anhydride. Any unreacted acidic reactant such as maleic anhydride, maleic acid, fumaric acid, etc, can be, and preferably is, recovered from the reaction mixture, and thus is available for use either as recycle to the process or for other uses. Inasmuch as chlorine is not used in the process, the expense and difficulties associated with handling chlorine on a plant scale are eliminated, and the product is less corrosive than corresponding products formed by use of chlorine.

Technical Field 
This invention relates to novel and eminently useful substituted acylating 
agents of the polybutenylsuccinic acid type, and to novel and eminently 
useful methods for their production. 
Background 
Heretofore processes have been described for the thermal reaction between 
polybutenes (predominantly polyisobutenes) and maleic anhydride or like 
reactants whereby polybutenyl succinic anhydrides are formed. Some of the 
work along these lines is described, or at least referred to, for example 
in U.S. Pat. Nos. 3,018,247; 3,018,250; 3,018,291; 3,172,892; 3,184,474; 
3,185,704; 3,194,812; 3,194,814; 3,202,678; 3,216,936; 3,219,666; 
3,272,746; 3,287,271; 3,311,558; and in British Pat. No. 1 492 337. 
However as pointed out in U.S. Pat. Nos. 3,215,707 and 3,231,587, from the 
standpoint of commercial usefulness the alkylation of maleic anhydride 
with an olefinic hydrocarbon is very time-consuming and limited in its 
applicability to relatively low molecular weight olefinic hydrocarbon 
reactants, i.e., those having less than about 12-15 carbon atoms. These 
two patents further state that the higher molecular weight olefinic 
hydrocarbons are apparently not sufficiently reactive with maleic 
anhydride to be useful as an alkylating agent, and that higher molecular 
weight hydrocarbon-substituted succinic acid compounds are almost 
invariably prepared by reacting maleic anhydride with a halogenated high 
molecular weight hydrocarbon reactant. Indeed, in U.S. No. 4,234,435 it is 
reported that the process as described in these two patents is presently 
deemed best for preparing the substituted succinic acylating agents. 
British Pat. No. 1 492 337 points out that while such acylating agents can 
be prepared by thermally reacting a polymer having an average molecular 
weight above about 200 with maleic anhydride at a temperature above 
200.degree. C., the reaction rate of such reactions is low and that 
attempts to improve the reaction rate by increasing the temperature and/or 
by using superatmospheric pressure results in degradation of maleic 
anhydride to useless carbon dioxide, water and tarry solids. 
U.S. Pat. No. 3,476,774 reports in Example 1 that reaction under nitrogen 
between polybutene and maleic anhydride conducted in a pressure vessel at 
234.degree. C.-236.degree. C. for 6 hours and 40 minutes in 
o-dichlorobenzene solvent gave an alkenyl succinic anhydride product that 
had particles of sludge suspended in it. Improvements in yield are 
reported in Examples 2-4 of the patent wherein a thermal stabilizer 
(4,4'-methylenebis(2,6-di-tert-butyl-phenol)) was incorporated in the 
reaction mixture. 
U.S. Pat. No. 4,883,886, in discussing the addition reaction between 
viscous polyalkenes and anhydride reactants such as maleic anhydride, 
states that a known problem frequently encountered in this reaction is 
thermal decomposition and polymerization of the unsaturated anhydride 
reactant at temperatures above about 150.degree. C. According to the 
patentee, such thermal decomposition is accompanied by evolution of water 
vapor and oxides of carbon, and in a closed reaction vessel is accompanied 
by an increase in internal pressure. The patentee continues: 
"Under some observed conditions, the thermal decomposition can be so rapid 
as to be explosive. In the absence of explosive thermal decomposition, a 
carbon-containing tarry residue is also formed in addition to water vapor 
and oxides of carbon. * * * Such thermal decomposition and attendant 
isomerization or polymerization of the unsaturated anhydride reactant has 
been observed as occuring during its addition reaction with polymeric 
olefins, e.g., polybutenes and others, in a closed reaction vessel. The 
carbon-containing residue varies in nature from somewhat granular when the 
decomposition is only slight to a tarry material mainly adhering to 
internal surfaces of the reaction vessel when the decomposition is more 
extensive but well below explosive magnitude. The granular type residue 
amounts to about from 0.1 to about 0.3 weight percent of the total charge 
and is generally dispersed in the alkenyl-substituted saturated anhydride 
addition compound product diluted with unreacted components of the olefin 
polymer, and is readily separated therefrom by filtration. However, the 
tarry residue product, which for the most part fouls the internals of the 
reaction vessel can be as high as 2-3 weight percent of the total charge. 
The tarry material not adhering to the internal surfaces of the reactor 
fouls the filter and interferes with filtration of the desired reaction 
product. Both types of residue are undesirable because of the above noted 
fouling characteristics and because their formation results in yield 
reduction of the desired alkenyl-substituted anhydride addition product." 
The patentee refers to a number of other patents describing catalysts or 
agents which decrease such unwanted by-product formation, and utilizes 
such materials in a particular process in order to suppress the formation 
of tars and undesired side products. 
U.S. Pat. No. 4,152,499 discloses that polybutenes having a higher 
proportion of terminal double bonds than conventional polybutenes can be 
produced by polymerizing isobutene with boron trifluoride as the 
intitiator, if (a) the polymerization is carried out at -50.degree. C. to 
+30.degree. C., (b) from 1 to 20 mmoles of boron trifluoride are used per 
mole of isobutene, and (c) the means polymerization time is confined to 
from 1 to 10 minutes. The patent further discloses that suchpolybutenes 
can be reacted with the stoichiometric amount of amleic anhydride, or a 
slight excess thereof, "in the ocnentional manner" at from 170.degree. C. 
to 250.degree. C., and that such polybutenes when head with maleci 
anhydride for 4 hours at 200.degree. C. with stirring, followed by 
removing excess maleic anhydride under greatly reduced pressure exhibited 
a substantially greater activity than two commercial isobutene polymers. 
W. German Offenlegungsschrift 29 04 314 teaches the desirability of 
conducting the polymerization of the isobutene in the same manner except 
using a polymerization time limited to 1 to 40 seconds, and that to 
prepare mineral oil additives, "the polyisobutenes is reacted in known 
fashion with the stoichiometric amount or a slight excess of maleic acid 
anhydride at 170 to 250.degree. C. 
It has also been disclosed heretofore that a specified thermal 
maleinisation reaction can be used to assess the quality (reactivity) of a 
polybutene polymer. In this procedure polybutene (50g) is reacted with 
maleic anhydride (9.8g), a 1:2 mole ratio, for 24 hours in a stirred 
reaction tube immersed in a bath of specified hydrocarbons under reflux at 
210.degree. C. The reaction is conducted under nitrogen, and the reaction 
mixture is stirred at a specified number of revolutions per minute. A 
specifically designed apparatus is suggested for use in this procedure. 
The procedure results in the formation of both polybutenyl succinic 
anhydride and a complex resinous co-product formed from maleic anhydride.

The Invention 
It has been found that substantial advantages can be realized by reacting 
an acidic reactant, such as maleic anhydride, with a substantially 
aliphatic polymer comprised principally or entirely of polyisobutenes in a 
mole ratio of acidic reactant(s) : polymer is at least 1 : 1, provided 
that at least 50% (preferably at least 75%) of the polyisobutenes content 
of such polymer has an end group represented by the formula 
##STR2## 
and the reaction mixture is maintained under superatmospheric pressure 
during at least a substantial portion of the reaction period. Most 
preferably, the polymer consists essentially of polyisobutenes (i.e., it 
contains at least 50 mole % and more preferably at least 60 mole % of 
polymerized isobutene) and at least 50% (more desirably at least 75%) of 
the total polymer(s) is polyisobutenes having such end group. 
In order to determine in any given polyisobutenes the proportion thereof 
that contains the above identified end group, use can be made of Infra-Red 
Spectroscopy and, more preferably, C.sub.13 Nuclear Magnetic Resonance. In 
C.sub.13 NMR, typical olefin chemical shifts appear between 100 and 160 
ppm. Structural identification can be confirmed by comparison with 
C.sub.13 spectra of known olefins. See for example, Atlas of Carbon-13 NMR 
Data, edited by E. Breitmaier, G. Haas and W. Voelter, Spectra numbers 
30-107. Quantitation can be accomplished by suppression of the NOE 
produced by proton attachment to carbon. Sufficient delay time is allowed 
for complete carbon relaxation. 
Preferably, the entire reaction or substantially the entire reaction is 
conducted under superatmospheric pressure, such as by conducting the 
entire reaction or substantially the entire reaction in a closed reaction 
system at superatmospheric pressure. Most preferably, the process is 
conducted such that the superatmospheric pressure on the reaction mixture 
decreases after passing through an initial peak pressure, and then 
increases to another elevated pressure, especially where the latter 
elevated pressure is higher than the initial peak pressure. 
For best results, (a) at least a substantial portion of the reaction is 
conducted at a pressure in the range of about 1 to about 75 psig or more 
(and preferably in the range of about 4 to about 50 psig), (b) the 
temperature of the reaction mixture is maintained in the range of about 
220 to about 265.degree. C. throughout substantially the entire reaction 
period, and (c) the mole ratio of the acidic reactant(s) : the polymer(s) 
is in the range of 1.1 1 to about 3 : 1, and preferably in the range of 
1.1 : 1 to 1.9 1. It is to be understood however that departures from the 
foregoing ranges of pressure, temperature and/or proportions may be 
utilized in any given situation where such departure is deemed desirable 
under the given circumstances involved. All that is required in the 
practice of this invention is that the reaction be conducted under 
reaction conditions, including superatmospheric pressure, that enable the 
reaction to proceed without encountering excessive decomposition or 
excessive by-product formation (e.g., excessive tar or polymer formation). 
It is particularly preferred to employ the reactants in mole ratios of 
acidic reactant to polyisobutenes such that the product contains an 
average molar ratio of succinic groups to polyisobutenes chains below 1.3 
: 1. 
Preferred acidic reactants that can be used in the process are those 
represented by the general formula 
EQU R--CO--CH.dbd.CH--CO--R' 
wherein R and R' are independently --OH, --O--lower alkyl, a halogen atom, 
or taken together are a single oxygen atom. Thus use can be made of such 
compounds as maleic acid, fumaric acid, the lower alkyl (C.sub.1-7) esters 
of such acids, the acid halides (preferably the acid fluorides or 
chlorides) of such acids, maleic anhydride, or mixtures of any two or more 
of any such compounds. Other similar compounds which can be used are 
itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, 
mesaconic acid, the lower alkyl esters and the acid halides of such acids, 
and the like. Maleic anhydride is the most preferred reactant for use in 
the process. 
Among the advantages of this invention is that the reaction rate is high, 
the yields of desired product are high, and despite the fact that 
superatmospheric pressures and substantially elevated temperatures are 
used, the process forms only small amounts of tars or resinous 
co-products, even when employing as much as a 20% or more molar excess of 
maleic anhydride. Indeed, any unreacted acidic reactant such as maleic 
anhydride, maleic acid, fumaric acid, or the like can be, and preferably 
is, recovered from the reaction mixture, and thus is available for use 
either as recycle to the process or for other uses. Moreover, inasmuch as 
chlorine is not used in the process, the expense and difficulties 
associated with handling chlorine on a plant scale are eliminated, and the 
product is less corrosive than corresponding products formed by use of 
chlorine. 
Another advantage of this invention is that thermal stabilizers or other 
additive materials to reduce tar formation are not required. Indeed, many 
of the known materials to reduce tar formation are halogen-containing 
substances (see for example U.S. Pat. Nos. 3,927,041; 3,935,249; 
3,953,475; 3,954,812; 3,960,900; 3,985,672; 4,008,168; 4,086,251; 
4,414,397; 4,434,071; and 4,496,746). Halogen-containing components are 
generally undesirable because they tend to leave halogen-containing 
residues in the product. 
Thus products with almost no tarry co-products or halogen-containing 
residues can be formed in exceptionally high yields in the process of this 
invention without use of such extraneous materials as thermal stabilizers 
and tar suppressors which add to the cost of the operation and can leave 
undesirable impurities in the product. In fact, it has been found possible 
to achieve higher conversions of maleic anhydride to alkenyl succinic 
anhydride by use of the process of this invention without a thermal 
stabilizer than the conversions reported in U.S. Pat. No. 3,476,774 
(Examples 2-4) wherein a thermal stabilizer was used. For example, the 
yields based on conversion of maleic anhydride to the desired product 
reported in Examples 2-4 of the patent average 80%. In contrast, a group 
of 8 runs pursuant to this invention conducted in Examples 6-8 presented 
hereinafter give a conversion on the same basis averaging 92%. 
The polybutenes or like polymers utilized in the practice of this invention 
may have number average molecular weights in the range of 500 to 100,000 
or more. The preferred polymers are those having number average molecular 
weights in the range of 700 to 5,000, and the most preferred polymers are 
those having number average molecular weights in the range of 800 to 
1,300. 
If desired, the reaction can be conducted in an inert liquid reaction 
medium or diluent such as one or more saturated aliphatic, saturated 
cycloaliphatic, or aromatic hydrocarbons, e.g., mineral oil, etc. 
Preferably, however, the reaction is conducted in the absence of an 
ancillary reaction solvent or diluent. A small amount of catalyst such as 
aluminum trichloride, triethylaluminum, methylaluminum sesquichloride, 
diethyl-aluminum chloride, or the like, may be employed in heprocess. 
The practice and advantages of this invention will become still further 
apparent from eh following illustrative examples, which are not intended 
to limit, and should not be construed as limiting, the scope of this 
invention. 
In these examples all parts and percentages are by weight unless otherwise 
specified. also the "cook period" referred to in the examples is 
designated as the point where the reaction mass reaches its specified 
reaction temperature, and thus at this point the cook time is equal to 0. 
The polybutene used in Examples 1-6 was a substantial pure polyisobutyleen 
with a weight average molecular weight of about 9995. approximately 78% of 
the polymer had an end group as depicted in Formula I above. In Examples 
6-8 the polybutene employed was a substantially pure polyisobutylene with 
a weight average molecular weight of about 1300. This polybutene also 
contained about 78% of polymer having the above-depicted end group. 
Conventional commercially-available polyisobutenes contains less than 
about 10% of polymer containing such end group. 
EXAMPLE 1 
Into an autoclave were charged 1200 parts of polybutene (PIB), 130.7 parts 
of maleic anhydride (MA) and 0.12 part of aluminum trichloride. The mole 
ratio of MA:PIB was thus 1:1. A vacuum (-26 inches of water) was applied 
to the autoclave for 10 minutes to remove the oxygen (air), and while 
holding the system under a low vacuum the autoclave was heated. When the 
autoclave temperature reached 90.degree. C., the agitator was turned on. 
When the temperature reached 225.degree. C., the pressure within the 
autoclave was 12.5 psig. Thereupon the reaction mixture was kept at 
225.degree. C. for 5 hours while continuously agitating the reaction 
mixture. The pressure profile on the reaction mass during this period was 
as follows: 
______________________________________ 
Cook Time, minutes 
Pressure, psig 
______________________________________ 
0 12.5 
5 13.0 
15 8.0 
25 5.0 
40 4.5 
50 3.5 
65 2.0 
80 1.0 
95 0.5 
135 0 
150 -0.5 
170 0 
185 0.5 
210 1.5 
235 3.0 
255 4.0 
300 6.0 
______________________________________ 
The resultant reaction product was subjected to vacuum stripping to remove 
volatiles (primarily unreacted maleic anhydride). The polybuteneyl 
succinic anhydride reaction product had an acid number before stripping of 
0.92, and an acid number after stripping of 0.76. 
EXAMPLE 2 
The general procedure of Example 1 was repeated, the chief difference being 
that the reactants were kept at 240.degree. C. during the major portion of 
the reaction period. The pressure profile on the reaction mass during the 
reaction was as follows: 
______________________________________ 
Cook Time, minutes 
Pressure, psig 
______________________________________ 
0 17.0 
5 14.0 
25 6.0 
35 4.5 
45 3.0 
55 2.5 
75 2.0 
90 2.0 
105 2.0 
135 3.5 
170 5.0 
205 5.0 
250 6.0 
300 7.0 
______________________________________ 
The resultant reaction product was subjected to vacuum stripping to remove 
volatiles (primarily unreacted maleic anhydride). The polybuteneyl 
succinic anhydride reaction product had an acid number before stripping of 
0.92, and an acid number after stripping of 0.82. 
EXAMPLE 3 
Using the same reactants and the same general procedure as in Example 1, 
the reactants were employed in a MA:PIB mole ratio of 1.1:1 (143.8 parts 
of MA and 1200 parts of PIB). The pressure profile on the reaction mass 
during the reaction at 225.degree. C. was as follows: 
______________________________________ 
Cook Time, minutes 
Pressure, psig 
______________________________________ 
0 12.0 
5 14.5 
10 12.0 
30 6.0 
60 3.5 
90 2.0 
120 1.0 
150 1.0 
180 1.0 
210 1.0 
240 1.5 
270 3.0 
300 4.5 
______________________________________ 
The polybuteneyl succinic anhydride reaction product had an acid number 
before vacuum stripping of 1.04, and an acid number after stripping of 
0.81. 
EXAMPLE 4 
In this run the same reactants as in Example 1 were reactant 240.degree. C. 
at a mole ratio (MA:PIB) of 1.1:1. the pressure profile on the reaction 
mass during the reaction was as follows: 
______________________________________ 
Cook Time, minutes 
Pressure, psig 
______________________________________ 
0 17.0 
10 15.0 
25 10.0 
30 9.0 
45 7.5 
55 7.0 
65 6.0 
80 5.5 
95 6.0 
115 6.0 
135 8.5 
155 10.0 
180 13.5 
195 16.0 
215 19.0 
235 22.5 
250 25.5 
265 28.0 
280 31.5 
300 34.0 
______________________________________ 
The acid number of the polybuteneyl succinic anhydride reaction product 
before vacuum stripping was 1.02. After stripping the product had an acid 
number of 0.91. 
EXAMPLE 5 
The same reactants as in Example 1 were reacted at 240.degree. C. at a mole 
ratio (MA:PIB) of 1.2:1 (155.65 parts of MA and 1190 parts of PIB). The 
pressure profile on the reaction mass during the reaction was as follows: 
______________________________________ 
Cook Time, minutes 
Pressure, psig 
______________________________________ 
0 18.0 
5 17.5 
35 7.0 
60 5.0 
90 4.5 
120 5.0 
150 6.0 
180 7.0 
210 10.0 
240 13.5 
270 17.0 
300 21.0 
______________________________________ 
The acid numbers of the polybutenyl succinic anhydride reaction product 
were 1.09 before stripping, and 0.95 after stripping. 
EXAMPLE 6 
Into an autoclave were charged 1211.8 parts of polybutene (PIB), 118.9 
parts of maleic anhydride (MA) and 0.12 part of aluminum trichloride. The 
mole ratio of MA:PIB was thus 1.3:1. A vacuum (-26 inches of water) was 
applied to the autoclave for 10 minutes to remove the oxygen (air), and 
while holding the system under a low vacuum the autoclave was heated. When 
the autoclave temperature reached 105.degree. C., the agitator was turned 
on. When the temperature reached 240.degree. C., the pressure within the 
autoclave was 17.0 psig. Thereupon the reaction mixture was kept at 
240.degree. C. for 5 hours while continuously agitating the reaction 
mixture. The pressure profile on the reaction mass during this period was 
as follows: 
______________________________________ 
Cook Time, minutes 
Pressure, psig 
______________________________________ 
0 17.0 
15 14.0 
30 10.5 
45 8.0 
70 6.5 
95 6.5 
115 8.0 
150 12.0 
195 19.0 
230 26.0 
260 33.0 
300 40.5 
______________________________________ 
The reaction product was subjected to vacuum stripping o remove volatiles 
(primarily unreacted maleic anhydride). The acid numbers o the 
polybuteneyl succinic anhydride reaction product were 0.84 before 
stripping, and 0.78 after stripping. 
EXAMPLE 7 
The same reactants as in Example 6 were reacted in the same general manner 
at 240.degree. C. at a mole ratio (MA:PIB) of 1.5:1 (135.3 paets of MA and 
1195.4 parts of PIB). The pressure profile on the reaction mass during the 
reaction was as follows: 
______________________________________ 
Cook Time, minutes 
Pressure, psig 
______________________________________ 
0 15.5 
5 16.0 
20 12.5 
40 10.0 
45 9.5 
60 8.5 
80 8.5 
110 10.0 
140 14.0 
180 20.5 
205 26.5 
245 37.0 
255 40.0 
270 43.0 
300 50.0 
______________________________________ 
The acid numbers of the polybutenyl succinic anhydride reaction product 
were 0.91 before stripping, and 0.83 after stripping. 
Table 1 summarizes the total tar content and the strip acid number of the 
respective products of Examples 1-5, and provides a comparison of the 
corresponding values on a product made under the same general reaction 
conditions (including superatmospheric pressure) using a PIB that 
contained less than 10% of above-depicted end group, and wherein the mole 
ratio (MA:PIB) was 1:1. 
The procedure for determination of total tar content used herein was as 
follows: After completion of the reaction run, the reactor head and 
attached agitator are removed, and the reactor contents are transferred 
from the autoclave to storage and analysis bottles. The appearance of the 
reactor and its component parts is immediately rated by at least two, and 
preferably three, trained technical personnel. The rating takes place in a 
specific manner, namely: 
1) Each of the three major internal components of the autoclave--i.e., the 
sides, the bottom, and the agitator, is independently rated. 
2) The rating is based upon the visual appearance of the component and the 
amount of tar present. The rating scale ranges from 1 to 10, with "1" 
representing a perfectly clean component showing no evidence of tar 
formation. The rating of "10" represents a heavily tarred component which 
is completely covered with tar. In general, an intermediate rating 
corresponds to the area of the surface covered by the black tar. For 
example, a rating of "7" means that approximately 70% of the surface is 
covered with tar. 
3) Each person making the evaluations works independently of the other 
person(s) and thus records his/her observations without consultation with, 
or knowledge of the ratings made by, the other person(s). 
4) The rating numbers for the three individual components are added 
together for each individual evaluator and the sum of all of these totals 
are averaged (i.e., divided by the number of evaluators) to yield an 
average total tar rating reported herein. 
5) The average total tar rating scale is as follows: 
3 to 5 --Excellent; very clean reactor, tar formation minimal or 
non-existent 
6 to 10 --Good; some tar formation 
11 to 14 --Fair; significant level of tar formation 
15 to 20 --Poor; medium to heavy tar formation 
20 to 30 --Very Poor; heavy to severe tar formation 
TABLE 1 
______________________________________ 
Key Properties of Polyisobutenyl Succinic Anhydrides 
Strip 
Reaction MA:PIB Maximum Total Acid 
Example 
Temperature 
Ratio Pressure 
Tars No. 
______________________________________ 
1 225.degree. C. 
1.00 13.0 psig 
4 0.76 
2 240.degree. C. 
1.00 17.0 psig 
4 0.82 
3 225.degree. C. 
1.10 14.5 psig 
3 0.81 
4 240.degree. C. 
1.10 34.0 psig 
3 0.90 
5 240.degree. C. 
1.20 21.0 psig 
3 0.95 
Control 
225.degree. C. 
1.00 15.0 psig 
7 0.60 
______________________________________ 
EXAMPLE 8 
The same reactants as in Example 6 were reacted in the same general manner 
at 240.degree. C. at a mole ratio (MA:PIB) of 12.3:1 (118.9 parts of MA 
and 1211.8 parts of PIB) except that the aluminum chloride catalyst was 
not used. Agitation of the reactants was commenced when the temperature 
reached 60.degree. C. The pressure profile on the reaction mass during the 
reaction was as follows: 
______________________________________ 
Cook Time, minutes 
Pressure, psig 
______________________________________ 
0 16.5 
10 11.5 
35 7.0 
50 6.0 
75 6.0 
100 7.0 
130 9.0 
165 11.5 
195 14.5 
240 20.0 
260 22.0 
280 25.0 
300 27.0 
______________________________________ 
The acid number of the polybutenyl succinic anhydride reaction product 
before stripping was 0.84, and after stripping, 0.77. Average total tars 
was 4. 
EXAMPLE 9 
This example demonstrates that unreacted maleic anhydride can be recovered 
from the reaction mixture and recycled for use in subsequent runs. In 
particular, an initial batch run was made followed by two recycle batch 
runs in which the maleic anhydride from the prior run was used as part of 
the total maleic anhydride charge. In this series of runs the same 
reactants as in Example 6 were used. The charges to the reactor were: 
Run 1 --MA, 118.9 parts; PIB, 1211.8 parts; AlCl.sub.3, 0.12 part. 
Run 2 --Fresh MA, 107.6 parts, recycled MA, 11.7 parts; PIB, 1211.8 parts; 
AlCl.sub.3, 0.12 part. 
Run 3 --Fresh MA, 106.4 parts, recycled MA, 12.5 parts; PIB, 1211.8 parts; 
AlCl.sub.3, 0.12 part. 
Agitation of the reactants was commenced when the temperature reached 
60.degree.-70.degree. C. The pressure profile on the reaction mass during 
the reaction was as follows: 
______________________________________ 
Run 1 Run 2 Run 3 
Cook Cook Cook 
Time Pressure Time Pressure 
Time Pressure 
minutes 
psig minutes psig minutes 
psig 
______________________________________ 
0 19.0 0 20.0 0 16.0 
10 14.5 10 16.0 10 14.0 
25 9.5 25 9.0 20 9.5 
35 8.0 40 7.5 40 7.0 
60 5.5 65 5.0 55 5.0 
95 5.5 85 5.0 85 5.0 
130 7.5 120 6.0 100 5.0 
150 9.0 155 9.0 120 5.0 
180 12.0 175 11.5 170 9.0 
225 19.0 215 17.0 200 11.0 
255 23.0 240 21.0 230 16.0 
260 28.0 260 23.5 285 23.5 
300 30.0 280 27.0 300 25.0 
300 30.0 
______________________________________ 
Table 2 includes a summary of the results of this series of runs. 
TABLE 2 
______________________________________ 
Highlights of Recycle Process 
Run % MA Total Stripped 
Unreacted 
No. Recycled Tars Acid No. 
PIB, % 
______________________________________ 
1 None 3 0.75 27.2 
2 9.8 3 0.73 24.0 
3 10.5 3 0.73 24.2 
______________________________________ 
EXAMPLE 10 
The procedure of Example 4 was repeated yielding the following pressure 
profile: 
______________________________________ 
Cook Time, minutes 
Pressure, psig 
______________________________________ 
0 17.0 
10 15.0 
25 10.0 
30 9.0 
45 7.5 
55 7.0 
65 6.0 
80 5.5 
95 6.0 
115 6.0 
135 8.5 
155 10.0 
180 13.5 
195 16.0 
215 19.0 
235 22.5 
250 25.5 
265 28.0 
280 31.5 
300 34.0 
______________________________________ 
The reaction mixture before stripping had a total tar content of 3. The 
acid number of the polybuteneyl succinic anhydride product after vacuum 
stripping was 0.91. 
The reaction product mixtures formed in the process of this invention are 
of particular advantage in that they contain little or no tars; they 
usually give a rating by the above procedure of 3 or 4. thus the interior 
surfaces of the reactor are free or essentially free of tars or other 
resinous coatings, and moreover the effective utilization of the raw 
materials used in the process is high. Moreover, after removal of residual 
unreacted acidic reactant (i.e., the maleic anhydride or like carboxylic 
reactant) charged to the reactor (if any remains unreacted) such as by 
distillation or stripping at reduced pressure, the remainder of the 
product generally will have an acid number of at least 0.7, preferably at 
least 0.8, and in the most preferred cases, at least 0.9. Such product can 
be used without further treatment or purification either as an additive or 
as a raw material for use in the production of dispersant additives. 
The polybutenyl succinic acids or acid derivatives thereof (polybutenyl 
succinic anhydrides, polybutenyl succinic acid halides, polybutenyl 
succinic acid lower alkyl esters) are useful as corrosion inhibitors for 
liquid fuels such as gasoline and middle distillate fuels (diesel fuel, 
burner fuel, turbine fuel, jet fuel, kerosene, etc.). In addition they are 
especially useful in the manufacture of polybutenyl succinic acid esters 
and polybutenyl succinimides by reaction with alcohols or amines, 
preferably alkylene polyamines such as ethylene or propylene diamines, 
diethylene triamine, triethylene tetramine, tetraethylene pentamine, 
pentaethylene hexamine, etc. Such polybutenyl succinic acid esters and 
polybutenyl succinimides are especially useful as ashless dispersants in 
lubricating oils and functional fluids. 
Methods for producing polybutenes useful in the practice of this invention 
are described in U.S. Pat. No. 4,152,499 and in W. German 
Offenlegungsschrift 29 04 314, the disclosures of which are incorporated 
herein by reference. Suitable products are understood to be available 
under the trade designation "Ultravis". 
While this invention has been discussed with reference to use of 
polybutenes as the polyolefin reactant, use can be made of other 
polyolefins having an end group configuration comparable to that depicted 
hereinabove, such as isopentene polymers, isohexene polymers, 
isobutene-propylene copolymers, isobutene-ethylene copolymers, 
isobutene-ethylene-propylene terpolymers, isobutene-amylene copolymers, 
and the like. 
This invention is susceptible to considerable variation in its practice 
within the spirit and scope of the ensuing claims, the forms hereinbefore 
described constituting preferred embodiments thereof.