Nu-dialkylaminoalkyl alkenyl succinimides

United States Patent Office

3,018,291

Patented Jan. 23, 1962

3,018,291 N-DIALKYLAMINOALKYL ALKENYL SUCCINIMIDES

Robert G. Anderson, Novato, Frank A. Stuart, Orinda, 5 and Alan Y. Drummond, Richmond, Calif., assignors to California Research Corporation, San Francisco, Calif., a corporation of Delaware

No Drawing. Filed Aug. 24, 1959, Ser. No. 835,400

Claims. (Cl. 260—326.5)

This invention pertains to a new class of compounds particularly useful as lubricating oil addition agents. These new compounds are N-dialkyl-aminoalkyl alkenyl succinimides.

Alkenyl succinic anhydrides and numerous derivatives 15 thereof are well known in the art. For example, alkenyl succinic anhydrides in which the alkenyl radical contains from 5 to 20 carbon atoms are taught as corrosion inhibitors in lubricating oil compositions. Also, products obtained by reacting such alkenyl succinic anhydrides 20 with monoamines are taught as ferrous corrosion inhibitors for lubricating oil compositions.

However, the above known alkenyl succinimides are not useful as detergents in lubricating oil compositions. In contrast thereto, the alkenyl succinimides described 25 herein are new compounds which are useful as detergents in lubricating oil compositions.

Thus, it is a primary object of this invention to present as new compounds, alkenyl succinimides which are particularly useful as detergents in lubricating oil com- 30 positions.

In accordance with this invention, we have discovered the new compounds, N-dialkylaminoalkyl monoalkenyl succinimides, are effective lubricating oil addition agents.

The N-dialkylaminoalkyl monoalkenyl succinimides 35 of this invention are particularly effective as detergents in lubricating oil compositions. By the use of lubricating oil compositions containing these alkenyl succinimides, diesel and gasoline engine parts remain remarkably free of deposits and varnish even under severe op- 40 erating conditions.

The new compounds of this invention, which are further described as N-dialkylaminoalkyl monoalkenyl succinimides wherein the alkenyl radical contains from 30 to 200 carbon atoms, and wherein said dialkyl amino 45 alkyl radical contains a total of 3 to 10 carbon atoms can be represented by the formula:

li-CH-c/R- \ /50

N—R —N

CHr-C^/R« %

where R is an alkenyl radical containing from 30 to 200 carbon atoms, R' is a divalent alkylene radical, and R²and R³ are alkyl radicals. The sum of the carbon atoms in R', R² and R³ is 3 to 10; that is, R', R² and R³ contain a total of no more than 10 carbon atoms.

It is preferred that R is a polymer of an olefin containing from 2 to 5 carbon atoms, wherein the polymer has a molecular weight from 400 to 3000, more particularly from about 900 to about 1200. Such olefins are exemplified by ethylene, propylene, 1-butene, 2butene, isobutene, and mixtures thereof. Since the methods of polymerizing the olefins to form polymers thereof is immaterial in the formation of the new compound described herein, any of the numerous processes available can be used therefor.

R' alkylene radicals include the divalent methylene radical, ethylene radical, propylene radical, butylene radical, etc. R² and R³ alkyl radicals include methyl, ethyl, propyl, etc. It is particularly preferred that R' contains 3 carbon atoms, and that R² and R³ each contain 1 carbon atom.

Amine reactants used in the formation of the polyamine radical of the succinimide include dimethylaminomethylamine, dimethylaminoethylamine, dimethylaminopropylamine, dimethylaminobutylamine, dimethylaminoheptylamine, diethylaminomethylamine, diethlaminopropylamine, diethylaminoamylamine, dipropylaminopropylamine, methylpropylaminoamylamine, propylbutylaminoethylamine, etc.

The preparation of the monoalkenyl succinimides herein can be described generally by the following equations, wherein a polyolefin is reacted with maleic anhydride to form the monoalkenyl succinic anhydride, which is then reacted with a dialkylaminoalkylamine to form the desired monoalkenyl succinimide; using a polymer of isobutene as an example of the alkenyl radical, and using dimethylaminopropylamine to exemplify the dialkylaminoalkylamine.

CH, / CH₃\ CHaCH—C / I \ 1II \

CHs—C—CHa—L-CHj—C J-CHa-C=CH₂ +O——>

\ CHa/»CH—/

CHa

CHa . n .

CHa—C—CHa-J-CHa-C--y—CH=C—CHa—

CH— 7

CHa— /

II

CHa\ --CHa—C—CHa—i-CHa—C--j-CH=C-CHa— CH— c''

CHa

CHa

HaC

NCHaCHaCHr-NHa—

HaC

CHa—C . . n

CHa—C—CHa—J-CHa—C--J— CH=C—CHa— CH— C

CHa

CHa

CHa

CHa— C

NCHaCHjCHr-N

CHa

3,018,291 wherein n is a number having a value of about 7 to about 50.

The above reaction between a polyolefin and maleic anhydride is an uncatalyzed addition reaction which should not be confused with a copolymerization reaction 5 such as that obtained with a vinyl monomer and maleic anhydride. While the general reaction of an olefin and maleic anhydride is well known for olefins of low molecular weight (e.g., olefins of 18 carbon atoms), no previous work has been done with maleic anhydride and the high 10 molecular weight olefins as described herein.

The reaction set forth and described hereinabove can proceed in a mol ratio of the polyolefin to the maleic anhydride of 1:1 to 1:10; preferably from 1:1 to 1:5. The reaction temperature can vary from 300° F. to 450° F. 15 Because of the greater yield of products obtained thereby, it is preferred to use the higher temperature range (e.g., 375° F. to 450° F.).

In the second step of the reaction as exemplified by Equation II hereinabove, the yield of the imide is ex- 20 tremely high even though the reactants are used in equal molar ratios.

The reaction described by Equation II hereinabove can be made at 220° F. to 500° F., preferably from 300° F. to 400° F. The alkenyl succinic anhydride and the poly- 25 amine are reacted in about equal molar quantities. An excess of the amine can be used, and the unreacted amine removed by distillation.

Since the reaction between the polyolefin and maleic anhydride may not go to completion, the resulting alkenyl 30 succinic anhydride may contain some unreacted polyolefin. As it may not be desirable to separate out this unreacted polyolefin at this stage, the resulting imide formed by reaction of the alkenyl succinic anhydride and the diamine will contain this polyolefin as an impurity which 35 can be a diluent in the formation of lubricating oil compositions. However, if it is so desired, this unreacted polyolefin can be removed by precipitation, for example, by acetone or methanol from a hydrocarbon solution.

The preparation of the alkenyl succinimides of di- 40 alkylamino alkyl amine is illustrated in the following examples.

mides. The polyamine was a dimethylaminopropylamine, and the alkenyl radical on the alkenyl succinimide was a polybutene, the molecular weight of which is noted in Table I.

TABLE I

Polyisobutene, Mol. Wt.

Amt. of Reactants (grams)

PIBSAi Amine

Reaction Temp., °F.

Percent Nitrogen

Found

Theory

1. Ca350____________

2. Ca 700____________

334 21.3 500 4.1 4.0

500 44.0 335 1.8 1.4 ¹ Polyisobutenyl succinic anhydride.

As lubricating oil additives, these alkenyl succinimides can be used in amounts of 0.1% to 80%, by weight; preferably 0.25 % to 5 %, by weight.

Table II hereinbelow sets forth data showing the effectiveness of the new compounds of this invention as lubricating oil additives.

The monoalkenyl succinimide used was an N-dimethylaminopropyl alkenyl succinimide wherein the alkenyl radical had a molecular weight of approximately 1000, which alkenyl radical was a polymer of isobutene.

The base oil was an SAE 10 base oil.

The data were obtained in a caterpillar L-l test under Mil-L-2104 conditions for 120 hours.

The “PD Nos.” refer to the piston discoloration rating. After the engine test the three piston lands are examined visually. To a piston land which is completely black is assigned a PD number of 800; to one which is completely clean, a PD number of 0; to those intermediate between completely black and completely clean are assigned PD numbers intermediate in proportion to the extent and degree of darkening.

The “GD Nos.” refer to the percentage deposits in the piston ring grooves; and 0 evaluation being a clear groove; and a number of 100 being a groove full of deposits.

Table 11

EXAMPLE L—PREPARATION OF POLYBUTENYL SUCCINIC ANHYDRIDE

A mixture of 1000 grams (1 mol) of a polybutene having a molecular weight of about 1000 and 98 grams (1 mol) of maleic anhydride was heated at 410° F. in a nitrogen atmosphere with agitation for a period of 24 hours. The reaction mixture was cooled to 150° F., and 50 700 cc. of hexane added; after which the mixture was filtered under vacuum. After vacuum distillation to remove the hexane from the filtrate, the product was maintained at 350° F. at an absolute pressure of 10 mm. Hg for one hour to remove traces of maleic anhydride. The 55 crude polybutenyl succinic anhydride thus prepared had a saponification number of 79.

EXAMPLE IL—PREPARATION OF N-DIMETHYLAMINOPROPYL POLYBUTENYL SUCCINIMIDE

A mixture of 21.3 grams (0.21 mol) of dimethylaminopropylamine and 150 grams (0.09 mol) of the polybutenyl succinic anhydride of Example I hereinabove, was blended with agitation in a nitrogen atmosphere, and the mixture was heated at 500° F. for a period of one hour, after _6gwhich the absolute pressure was reduced to about 200 mm. Hg at this temperature during a period of 30 minutes to facilitate the removal of water and excess amine. The reaction mixture was then allowed to reach room temperature at this reduced pressure. The reaction product con- γθ tained 1.7% nitrogen (theory=1.8%). The identity of the N-dimethylaminopropylalkenyl succinimide was established by means of infra-red spectroscopy.

Table I hereinbelow presents further data concerning the preparation of N-dialkylaminoalkyl alkenyl succini- 75

Additive

Succinimide, Wt. percent_____________________

Test R^s’ilts: GO No_______________________________—PD No____________________________________

1.5 0.0

39

30,0,0 800,800,800 . It is readily seen from the data set forth hereinabove that lubricating oil compositions containing the succinimides described herein are markedly effective as lubricating oil additives for the lubrication of internal combustion engines.

In addition to the alkenyl succinimides of this invention, lubricating oil compositions may also contan other detergents, dithiophosphates, viscosity index improving agents, rust inhibitors, oiliness agents, grease thickening agents, etc.