Bis-(alkylsalicylidene)ethylene or phenylene diamines and transition metal complexes thereof

Preparation of N,N'-bis(alkylsalicylidene)ethylene or phenylene diamines, and transition metal complexes thereof, particularly copper, and their use as an additive to diesel fuel to reduce soot formation in diesel exhaust.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to novel N,N'-bis(alkyl 
salicylidene)ethylene or phenylene diamines and the transition metal 
complexes thereof, particularly Cu, Mn and Fe and the use of the complexes 
as an additive to diesel fuels. 
2. Description of the Related Art 
The use of various metal compounds, particularly transition metal compounds 
such as compounds of manganese, lead, copper, zinc, cobalt and nickel, to 
name a few, in fuels to reduce soot formation and improve combustion 
properties of the fuel is known. U.S. Pat. No. 4,673,412 teaches an 
oil-soluble, transition metal complex of a Mannich base and an oxime 
wherein the molar ratio of I:II is from about 1:10 to about 10:1 are 
useful in association with diesel fuels or fuel oils which give good 
storage stability and at the same time effectively reduce the ignition 
temperatures for soot particulates. The transition metal complexes of the 
N,N'-bis(alkylsalicylidene)ethylene or phenylene diamines according to the 
present invention are useful as additives in diesel fuel to reduce soot 
formation in diesel exhaust in the absence of mannich bases. 
SUMMARY OF THE INVENTION 
It has been surprisingly discovered that the transition metal complexes of 
N,N'-bis(alkylsalicylidene)ethylene or phenylene diamines are effective 
additives in fuels, especially diesel fuel, in reducing the soot content 
of the exhaust from the combustion of fuels containing the complexes. The 
N,N'-bis(alkylsalicylidene)ethylene or phenylene diamines according to the 
invention have the formula I 
##STR1## 
wherein R.sub.1 is hydrogen or an alkyl group having from 1 to about 10 
carbon atoms; R.sub.2 is an alkyl group having from 1 to about 25 carbon 
atoms; R.sub.3 is --CH.sub.2 CH.sub.2 -- or 
##STR2## 
and x and y are integers from 1 to 3, preferably 1. R.sub.1 is preferably 
hydrogen or methyl while R.sub.2 is preferably an alkyl group having about 
8 to about 15 carbon atoms. The total number of carbon atoms in the 
R.sub.1 and R.sub.2 groups should be sufficient to render the transition 
metal complexes thereof soluble in a diesel fuel such as kerosene. As a 
practical matter the total number of carbon atoms in the R.sub.1 and 
R.sub.2 groups will range from about 8 to about 50, preferably about 8 to 
about 30. 
The transition metal complexes of the compounds of formula I have the 
formula II and III 
##STR3## 
wherein R.sub.1 and R.sub.2, x and y are as defined above and M is a 
transition metal preferably Cu, Mn or Fe, with Cu being most preferred.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Other than in the operating examples, or where otherwise indicated, all 
numbers expressing quantities of ingredients or reaction conditions used 
herein are to be understood as modified in all instances by the term 
"about". 
The N,N'-bis(alkylsalicylidene)ethylenediamines according to the invention 
are made by reacting alkyl substituted salicylaldehydes or alkyl 
substituted 2-hydroxyacetophenones with ethylenediamine in the presence of 
an acid catalyst such as para-toluenesulfonic acid and a solvent which 
serves as a reaction solvent and forms an azeotrope with water to effect 
the removal of the water of reaction such as toluene. The alkyl 
substituted salicylaldehydes can be made by the method taught in U.S. Pat. 
No. 4,638,096, the entire contents of which are incorporated herein by 
reference. The alkyl substituted acetophenones can be made by the method 
of British Patent GB 1,458,695, the entire contents of which are 
incorporated herein by reference. The transition metal complexes of the 
N,N'-bis(alkylsalicylidene)ethylenediamines according to the invention can 
be made by dissolving an N,N'-bis(alkylsalicylidene)ethylenediamine in an 
aliphatic or aromatic kerosene, such as, preferably, Escaid.RTM. 110, a 
trademark product of Exxon-U.S. An aqueous solution of a water soluble 
salt of the transition metal and ammonium hydroxide is then added to the 
kerosene solution and the combined liquid phases are stirred together for 
2 hours at room temperature after which the 2 liquid phases are allowed to 
separate. The kerosene phase, which contains the metal complex, is then 
separated. 
The transition metal complex is added to a diesel fuel or fuel oil in an 
amount to reduce soot formation, particularly in diesel exhaust, generally 
in an amount to provide up to about 200 ppm of the transition metal, 
preferably less than about 100 ppm, i.e. about 50 to about 100 ppm 
The following examples are meant to illustrate but not limit the invention. 
EXAMPLE 1 
Preparation of N,N'-bis(5-dodecylsalicylidene)ethylenediamine 
Dodecylsalicylaldehyde (557 g, 93% pure 1.8 moles), ethylene diamine (54 g, 
0.9 moles), para-toluenesulfonic acid hydrate (3.6 g, 0.02 moles), and 
toluene (1 liter) were combined in a 3-liter, 3-neck round bottom flask 
equipped with an overhead stirrer, a Dean-Stark trap, and a heating 
mantel. There was a slight exotherm (40 degrees C.) upon combining the 
starting materials. The reaction was then heated to reflux, accompanied by 
vigorous stirring. After 2.5 hours, 32 ml of water were collected in the 
Dean-Stark trap and the reaction allowed to cool. The reaction was poured 
into a large separatory funnel and washed twice with 2% sodium bicarbonate 
(300 mls) and twice with water (300 mls). The toluene was then removed 
under reduced pressure (rotoevaporation, 2 mbar/70.degree. C., 3 hours) to 
yield 557 g of the final product. IR and NMR showed only a trace of 
starting aldehyde (&lt;1%). 
EXAMPLE 2 
Preparation of N,N'-bis(5-nonylsalicylidene)ethylenediamine 
The procedure of Example 1 was followed using nonylsalicylaldehyde (560 g, 
93% pure, 2.1 moles), and ethylenediamine (63 g, 1.05 moles) to yield 555 
g of final product. 
EXAMPLE 3 
Preparation of 
N,N'-bis(2-hydroxy-5-nonyl-.alpha.-methylbenzylidene)ethylenediamine 
The procedure of Example 1 was followed using 5-nonylhydroxyacetophenone 
(631 g, 83% pure, 2 moles) and ethylenediamine (60 g, 1 mole) to yield ca. 
600 g of final product. 
EXAMPLE 4 
Preparation of the Copper Complex of 
N,N'-bis(5-dodecylsalicylidene)ethylenediamine 
N,N'-bis(5-dodecylsalicylidene)ethylenediamine (236 g, ca. 93% pure, 0.35 
moles) was dissolved in 258 g of Escaid.RTM. 110 at 60.degree. C. in a 
2-liter round bottom flask. An aqueous solution of copper sulfate (500 g 
water; 85.6 g of CuSO.sub.4 -5H.sub.2 O) and concentrated ammonium 
hydroxide (72 g of 30% in water) were added to the flask. The solution was 
stirred for 2 hours at room temperature using an overhead stirrer and the 
phases allowed to split overnight. In order to obtain a good phase split 
an additional 129 g of Escaid.RTM. 110 was added. The organic layer was 
separated and washed twice with 50 mls water. The organic solution was 
placed on a rotoevaporator at 20 mbar/70.degree. C. for 2 hours to remove 
trace amounts of water. The loaded reagent in Escaid.RTM. 110 and the 
aqueous phase were analyzed for copper. 
Loaded reagent in Escaid.RTM. 110:32,200 ug Cu/g 
Aqueous phase:3,530 ug Cu/g 
EXAMPLE 5 
Preparation of the Copper Complex of 
N,N'-bis(5-nonylsalicylidene)ethylenediamine 
N,N'-bis(5-nonylsalicylidene)ethylenediamine (236 g, ca. 93% pure) was 
dissolved in 258 g of Escaid.RTM. 110 at 60.degree. C. in a 2-liter round 
bottom flask. An aqueous solution of copper sulfate (500 g water; 85.6 g 
of CuSO.sub.4 -5H.sub.2 O) and concentrated ammonium hydroxide (72 g of 
30% in water) were added to the flask. The solution was stirred for 2 
hours at room temperature using an overhead stirrer. The aqueous layer no 
longer possessed the indicative blue color, so an additional 100 ml of the 
CuSO.sub.4 solution was added. The organic layer was separated and washed 
twice with 50 mls water. The organic solution was placed on a 
rotoevaporator at 20 mbar/70.degree. C. for 2 hours to remove trace 
amounts of water. The loaded reagent in Escaid.RTM. 110 and the aqueous 
phase were analyzed for copper. 
Loaded reagent in Escaid.RTM. 110:42,400 ug Cu/g 
Aqueous phase:5,200 ug Cu/g 
EXAMPLE 6 
Preparation of the Copper Complex of 
N,N'-bis(2-hydroxy-5-nonyl-.alpha.-methylbenzylidene)ethylenediamine 
N,N'-bis(2-hydroxy-5-nonyl-.alpha.-methylbenzylidene)ethylenediamine (268 
g, ca. 83% pure) was dissolved in 258 g of Escaid 110 at 60.degree. C. in 
a 2-liter round bottom flask. An aqueous solution of copper sulfate (500 g 
water; 85.6 g of CuSO.sub.4 -5H.sub.2 O) and concentrated ammonium 
hydroxide (72 g of 30% in water) were added to the flask. The solution was 
stirred for 2 hours at room temperature using an overhead stirrer. The 
phases were allowed to separate overnight. The organic layer was separated 
and washed twice with 50 mls water. The organic solution was placed on a 
rotoevaporator at 20 mbar/70.degree. C. for 2 hours to remove trace 
amounts of water. The loaded reagent in Escaid.RTM. 110 and the aqueous 
phase were analyzed for copper. 
Loaded reagent in Escaid.RTM. 110: 41,400 ug Cu/g 
Aqueous phase:363 ug Cu/g