Situ process for making multifunctional fuel additives

Disclosed is an in situ or "one pot" process for making a fuel additive comprising reacting an excess of at least one N-primary alkylalkylene diamine with maleic anhydride in the presence of from 20 to 36 weight percent of a mineral oil reaction diluent at a temperature ranging from ambient to about 225.degree. F. and recovering a product containing a primary aliphatic hydrocarbon amino alkylene substituted asparagine, an N-primary alkylalkylene diamine in the reaction oil with the product having a by-product succinimide content not in excess of 1.0 weight percent, based on the weight of asparagine present.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention is concerned with a multifunctional fuel additive which is 
useful when employed in a liquid hydrocarbon fuel for an internal 
combustion engine. Owing to its reduced imide content, the additive does 
not degrade the water separation properties of the fuel. 
2. Description of the Prior Art 
The most pertinent art relating to this invention is coassigned U.S. Pat. 
No. 4,207,079, issued June 10, 1980. Said patent discloses and claims 
primary aliphatic hydrocarbon asparagine compounds possessing a high level 
of corrosion inhibition and carburetor detegency properties. The 
disclosure of said patent is incorporated herein by reference. 
In the process disclosed in said patent, approximately two moles of a 
N-primary alkylalkylene diamine are reacted with a mole of maleic 
anhydride at a temperature ranging from about room temperature up to about 
110.degree. C. maximum, preferably from about 60.degree. to 100.degree. C. 
The reaction preferably is carried out in a mineral reaction diluent and 
the products are then blended, without separation or purification, with 
about a 33 weight percent excess of the diamine thereby forming an 
additive containing about 33 weight percent asparagine as the active 
ingredient, about 33 weight percent of diamine and about 34 weight percent 
of mineral oil. In the process used for preparing the asparagine there are 
also results from 5 to 10 percent by weight of by-product succinimides 
which are not separated therefrom to minimize production costs. The 
present invention constitute an improvement over that of the 
above-mentioned patent and is based on the unexpected discovery that 
preparing the asparagine compound in the presence of excess diamine 
reduces the succinimide content and improves the water separation 
characteristics of the additive. 
SUMMARY OF THE INVENTION 
The present invention provides an in situ process for making a 
multifunctional fuel additive comprising reacting from 4.0 to 4.5 moles of 
an N-primary alkylalkylene diamine with one mole of maleic anhydride in 
the presence of from 20 to 36 weight percent of a mineral oil reaction 
diluent at a temperature ranging from ambient to about 225.degree. F. and 
recovering a product containing a primary aliphatic hydrocarbon amino 
alkylene substituted asparagine and excess N-primary alkylene diamine in 
the reaction oil and having a by-product succinimides content not in 
excess of 1.0 weight percent, based on the weight of asparagine present. 
Use of excess diamine in the process suppresses the formation of 
succinimides yielding a product having better handling characteristics and 
water separation properties. The invention also provides a motor fuel 
containing from about 0.0002 to 0.2 weight percent of the above additive.

DESCRIPTION OF BEST MODE OF PRACTICING THE INVENTION 
Maleic anhydride is an article of commerce and is preferably used here in 
its unsubstituted form. However, derivatives thereof where substitutable 
hydrogens have been replaced by substituents which are inert under the 
reaction conditions including alkyl, haloalkyl, nitro, cyano, also are 
suitable for use as reactants herein. The products resulting from the 
reaction of such substituted anhydrides with diamines are equivalent for 
the purpose of this invention to those obtained with unsubstituted 
anhydrides. 
The N-primary alkyl-alkylene diamine reactant used in this process is 
represented by the formula: 
EQU R,R'--N--C.sub.3 H.sub.6 --NH.sub.2 
in which R is a primary aliphatic hydrocarbon radical having from about 6 
to 30 carbon atoms and R' is hydrogen or a methyl radical. Preferred 
N-primary alkyl-alkylene diamines are those in which R is a straight chain 
primary alkyl radical and R' is hydrogen. As employed herein the term 
N-alkyl-alkylene diamine covers both N-monoalkyl-alkylene diamine and the 
N-dialkyl-alkylene diamine structure when R' is a methyl radical. 
The most preferred N-alkyl-alkylene diamines are represented by the 
formula: 
EQU R--NH--CH.sub.2 CH.sub.2 --CH.sub.2 --NH.sub.2 
in which R is a straight chain primary alkyl aliphatic hydrocarbon radical 
having from 16 to 20 carbon atoms. 
Examples of suitable N-alkyl-alkylene diamines include N-oleyl-1,3-propane 
diamine, N-lauryl-1,3-propane diamine, N-stearyl-1,3-propane diamine and 
N-dodecyl-1,3-propane diamine. 
The reaction diluent used can be any available mineral oil but preferably 
is an oil having an SUS at 100.degree. F. of 100 and a specific gravity of 
0.88. 
Preferred process parameters are as follows: 
______________________________________ 
Diamine/maleic anhydride ratio 
4.41/1.00 
Diamine charge time 2.0 hours 
Diamine charge temperature 
150-190.degree. F. 
Reaction time 2.0 hours 
Reaction temperature 195-205.degree. F. 
Reaction pressure 0-5 psig 
______________________________________ 
In carrying out the present process, the reaction diluent is supplied to a 
closed reactor and solid maleic anhydride is charged therein at ambient 
temperature (75.degree. F.). The reactor's vapor space is purged with 
nitrogen and the contents are heated to 150.degree. F. with the reactor 
mixer off to melt the maleic anhydride. The mixer is turned on and the 
diamine is charged over a two hour period while maintaining the bulk 
liquid temperature below 190.degree. F. Molten maleic anhydride is also 
satisfactory for use in the process. When molten maleic anhydride is used, 
the processing sequence is as follows: (1) The reaction diluent is 
supplied to a closed reactor and the reactor mixer is turned on. (2) The 
reaction diluent is heated to around 150.degree. F. and the reactor vapor 
space is purged with nitrogen during the heat-up. (3) Molten maleic 
anhydride is charged to the preheated diluent oil and (4) The diamine is 
charged over a two hour period, while maintaining the bulk liquid 
temperature below 190.degree. F. Upon completion of the diamine charge, 
the reactor contents are held at 195.degree.-205.degree. F. for about a 2 
hour reaction period. The product is then cooled to about 125.degree. F. 
and filtered on a polish filter. 
The asparagine product is represented by the formula: 
##STR1## 
in which R is a primary aliphatic hydrocarbon radical having from about 6 
to 30 carbon atoms, R' is hydrogen or a methyl radical. Preferably R is a 
straight chain radical having from 16 to 20 carbon atoms. 
Examples of specific compounds of the invention produced in this reaction 
include the following: 
N,N'-di-(3-n-oleylamino-1-propyl)asparagine 
N,N'-di-(3-n-dodecylamino-1-propyl)asparagine 
N,N'-di-(3-n-octylamino-1-propyl)asparagine 
N,N'-di-(3-stearylamino-1-propyl)asparagine 
N,N'-di-(3-decylamino-1-propyl)asparagine 
N,N'-di-(3-laurylamino-3-propyl)asparagine 
N,N'-di-(3-behenylamino-1-propyl)asparagine 
Mixtures of these produced by reacting more than one diamine with maleic 
anhydride also are suitable. 
The process of the invention is illustrated in tabular form below. Examples 
of material balances for the initial bench scale and 30 gallon pilot unit 
reactor batches of additive are as follows: 
______________________________________ 
30 Gallon 
Bench Scale Pilot Unit 
______________________________________ 
Charge Weight, gms (lbs) 
Oil (100 EPSHF).sup.2 
1347.2 (60.7) 
Maleic Anhydride (MAA) 
157.0 (7.2) 
Diamine.sup.1 2470.0 (109.9) 
Total 3974.2 (177.8) 
Recovery Weight, gms (lbs) 
Product 3970.0 (175.1) 
Filtration Loss -- (1.2) 
Samples -- (1.5) 
Total 3970.0 (177.8) 
Overall Recovery, Wt % (basis 
99.9 100.0 
reactants) 
______________________________________ 
.sup.1 N--oleyl1,3-propanediamine. 
.sup.2 SUS at 100.degree. F. of 100; sp. gr. 0.88. 
Time-Temperature Cycle 
Time-temperature cycle for the initial bench scale and 30 
gallon pilot unit reactor batches of product are presented 
below: 
30 
Gallon 
Bench Pilot 
Equipment Scale Unit 
Run No. 20327 20351 
______________________________________ 
(1) Charge 100 EPSHF & MAA, 
Time, hrs 
0.25 0.50 
Temp, F. 77 85-95 
(2) Purge W/N.sub.2 and Heat-Up 
Time, hrs 
2.0 2.25 
Temp, F. 77-151 96-150 
(3) Charge Diamine 
Time, hrs 
2.0 2.8 
Temp, F. 150-196 150-190 
(4) Heat-up Time, hrs 
1.0 0.5 
Temp, F. 196-200 190-200 
(5) Reaction Time, hrs 
2.0 2.0 
Temp, F. 199-202 196-202 
(6) Cooldown Time, hrs 
4.5 2.5 
Temp, F. 200-110 202-125 
(7) Filter Time, hrs 
.sup.a 0.1 
Temp, F. -- 125 
Total 11.75 10.65 
Time, hrs 
______________________________________ 
.sup.a Product was not filtered. 
Product Test Data 
30 Gallon 
Test Method Bench Scale 
Pilot Unit 
______________________________________ 
Appearance Visual Bright & Bright & Clear 
Clear 
Water, Wt % D1744 0.3 1.2 
Lumetron Turbidity 
ST-289 0.5 1.0 
Pour, F D97 -- -10 
Sp. Gr. 60/60 F 
ST-202 0.8929 0.8888 
Kin. Vis. cST at 40 C. 
D445 57.40 50.70 
at 100 C. D445 8.80 8.30 
TBN ST-312 178 180 
TAN D974 17.3 15.2 
Flash, COC, F 
D92 310 375 
Color, ASTM D1500 4.0 3.0 
Nitrogen, Wt % 
ST-374 5.7 6.2 
______________________________________ 
The base fuel, which is useful for employing the additive of the invention, 
is a mixture of hydrocarbons boiling in the gasoline boiling range. This 
base fuel may consist of straight-chain or branched-chain paraffins, 
cycloparaffins, olefins, and aromatic hydrocarbons, and any mixture of 
these. The base fuel can be derived from straight-run naphtha, polymer 
gasoline, natural gasoline or from catalytically reformed stocks and boils 
in the range from about 80.degree. to 450.degree. F. The composition and 
the octane level of the base fuel are not critical and any conventional 
motor fuel base can be employed in the practice of this invention. 
In general, the additive of the invention is added to the base fuel in a 
minor amount, i.e., an amount effective to provide both corrosion 
inhibition and carburetor detergency to the fuel composition. The additive 
is effective in an amount ranging from about 0.0002 to 0.2 weight percent 
based on the total fuel composition. An amount of the neat additive 
ranging from about 0.001 to 0.01 weight percent is preferred, with an 
amount from about 0.001 to 0.003 being particularly preferred, the latter 
amounts corresponding to about 3 to 8 PTB (pounds of additive per 1000 
barrels of gasoline) respectively. 
The fuel composition of the invention may contain any of the additives 
normally employed in a motor fuel. For example, the base fuel may be 
blended with an anti-knock compound, such as a methyl-cyclopentadienyl 
manganese tricarbonyl or tetraalkyl lead compound, including tetraethyl 
lead, tetramethyl lead, tetrabutyl lead, and chemical and physical 
mixtures thereof, generally in a concentration from about 0.025 to 4.0 cc. 
per gallon of gasoline. The tetraethyl lead mixture commercially available 
for automotive use contains an ethylene chloride-ethylene bromide mixture 
as a scavenger for removing lead from the combusion chamber in the form of 
a volatile lead halide. 
The fuel composition of the invention prevents or reduces corrosion 
problems during the transportation, storage and the final use of the 
product. The fuel of the invention also has highly effective carburetor 
detergency properties. When a fuel of the invention is employed in a 
carburetor which already has a substantial build-up of deposits from prior 
operations, a severe test of the carburetor detergency property of a fuel 
composition, this motor fuel is effective for removing substantial amounts 
of the preformed deposits. 
It is to be understood that the examples presented herein are intended to 
be merely illustrative of the invention and not as limiting it in any 
manner; nor is the invention to be limited by any theory regarding its 
operability. The scope of the invention is to be determined solely by the 
appended claims.