Unleaded aviation fuel

1. A lead-free aviation gasoline composition having a high motor octane number and low freezing temperature, the gasoline comprising:

(a) about forty-five percent (45%) to about sixty-five percent (65%) by weight of at least one unleaded gasoline base fuel having a motor octane number of between ninety-seven (97) and ninety-nine point nine (99.9);

(b) about ten percent (10%) to about thirty-five percent (35%) by weight of one or more alkylated benzenes;

(c) about six percent (6%) to about twelve percent (12%) by weight, collectively, of one or more of iso-pentane, n-butane, and iso-butane; and

(d) about four percent (4%) to about fifteen percent (15%) by weight aromatic-amines, said aromatic amines comprising N-methyl-p-toluidine in combination with at least one of N-methyl-m-toluidine and m-Toluidine, and a ratio of N-methyl-p-toluidine to the at least one of N-methyl-m-toluidine and m-Toluidine is about four to one (4:1) to twelve to one (12:1);

wherein the gasoline has a freezing point of −58° C. or lower.

2. The aviation gasoline as set forth in claim 1 , wherein the ratio is about four to one (4:1) to nine to one (9:1), by weight.

3. The aviation gasoline (a) as set forth in claim 1 , wherein the gasoline comprises about six percent (6%) to about fifteen percent (15%) by weight of the aromatic amines.

4. The aviation gasoline as set forth in claim 1 , wherein the aromatic amines further comprise N,N-dimethylated-p-toluidine.

5. The aviation gasoline as set forth in claim 4 , wherein the amount of N,N-dimethylated-p-toluidine does not exceed 5 wt. % of the aromatic amines.

6. The aviation gasoline as set forth in claim 1 , wherein the unleaded gasoline base fuel has a motor octane number of about ninety-eight (98).

7. A method for manufacture of the aviation fuel composition according to claim 1 , the method comprising blending together components (a), (b), (c), and (d).

8. A method for operating a spark ignition aircraft engine, the method comprising introducing the aviation gasoline composition according to claim 1 into a spark ignition aircraft engine and combusting the gasoline in the engine.

9. The aviation gasoline as set forth in claim 1 , wherein component (d) comprises about four percent (4%) to about fifteen percent (15%) by weight of N-methyl-p-toluidine in combination with both N-methyl-m-toluidine and m-toluidine.

10. The aviation gasoline as set forth in claim 1 , wherein component (d) comprises about four percent (4%) to about fifteen percent (15%) by weight of N-methyl-p-toluidine in combination with N-methyl-m-toluidine.

11. The aviation gasoline as set forth in claim 9 , wherein the ratio of N-methyl-p-toluidine to N-methyl-m-toluidine is 8:1 to 9:1.

12. The aviation gasoline as set forth in claim 1 , wherein component (d) comprises about four percent (4%) to about fifteen percent (15%) by weight of N-methyl-p-toluidine in combination with m-Toluidine.

13. The aviation gasoline as set forth in claim 12 , wherein the ratio of N-methyl-p-toluidine to m-toluidine is 4:1.

14. The aviation gasoline as set forth in claim 1 , wherein the alkylated benzenes comprise mono- di- or trialkylated benzenes, and the gasoline comprises about fifteen percent (15%) to about thirty percent (30%) by weight of the alkylated benzenes.

15. The aviation gasoline as set forth in claim 14 , wherein the alkylated benzenes are selected from the group consisting of xylenes, ethyl benzene, toluene, and 1,3,5-trimethylbenzene, and mixtures thereof.

16. The aviation gasoline as set forth in claim 15 , wherein:

component (a) has a motor octane number of 88 to 99.9;

component (b) is m-xylene or 1,3,5-trimethylbenzene or a mixture thereof; and

component (c) is isopentane.

17. The aviation gasoline as set forth in claim 16 , wherein the gasoline comprises about six percent (6%) to about fifteen percent (15%) by weight of component (d), and 0.01 wt % to 5 wt % of component (d) is N,N-dimethylated-p-toluidine.

18. The aviation gasoline as set forth in claim 17 , wherein component (d) comprises N-methyl-p-toluidine in combination with both N-methyl-m-toluidine and m-toluidine.

19. The aviation gasoline as set forth in claim 17 , wherein component (d) comprises N-methyl-p-toluidine in combination with N-methyl-m-toluidine.

20. The aviation gasoline as set forth in claim 17 , wherein component (d) comprises N-methyl-p-toluidine in combination with m-Toluidine.