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United States Patent Office Patented Dec 3,484,315 United States Patent Office Patented Dec. 16, 1969 1. 2 a compound selected from the group consisting of BH6, 3,484,315 Be(BH4)2 and B4H10. In general, the reaction of the REACTION PRODUCTS OF ALANE TERMINATED boron compound with the alane liquid should take place ERYLLIUM HYDRIDE WITH BH, Be(BH), OR above about -80 C. and below about --100° C. Am RossV410 I. Wagner, 4943 Queen Victoria Road, Woodland bient temperature is preferred. The reaction should take Hills, Calif. 91364; Louis R. Grant, Jr., 2278 Ronda place for between about 10 minutes and about 48 hours. Vista Drive, Los Angeles, Calif. 90027; and Frank The reactants should be present in molar ratios of boron C. Gunderloy, Jr., 376 N. Divernon Ave., Santa compound to alane terminated beryllium hydride liquid Susana, Calif. 93063 of about 0.1:1 to 10:1. Ratios of about 0.5:1 to 3:1 are No Drawing. Filed Dec. 7, 1967, Ser. No. 690,705 10 preferred. Int, C. C06b 15/10, C07f 5/02, C06d 5/08 It should be noted that another common boron hydride, U.S. C. 149-22 3 Claims pentaborane-9, will not work in the process of the instant invention. It is hypothesized that this is due to the relative difficulty of forming the highly reactive moiety BH by ABSTRACT OF THE DISCLOSURE 5 cleaving the B5Hg molecule, while this moiety is relatively Mobile liquid borane terminated beryllium hydride easily formed by cleavage of B2H6, Be(BH) and B.H. compounds are produced by reacting alane terminated At least 80 percent of the aluminum in the ATBH liquids beryllium hydride liquids with a compound selected from is replaced in this process by boron to form the new the group consisting of B2H6, Be(BH4)2, and B. Ho. BTBH liquids. This provess may be generalized by the These compounds are useful as rocket fuels and can be 20 equation: burned with H2O2. Cross-references to related applications where X represents the beryllium-containing portion of 25 the ATBH or BTBH liquid. In this general example, it This invention is related to co-pending application Ser. may be seen that the HAl(CH3)2 (an alane terminator) No. 607,132 filed Dec. 28, 1966, in the names of E. F. C. is replaced by BH3 (a borane terminator) while CH Cain et al., having a common assignee. groups and aluminum are displaced as the volatile com Background of the invention pound (CH3)2AlBH4. 30 This incorporation of boron and hydrogen in place of It is well known that beryllium is of great interest as aluminum and CH3 groups is highly advantageous to a a propellant fuel component since it is an extremely rocket fuel, since it is known that the highest specific energetic element and serves to increase the performance impulses are obtained when combusting fuels of the of the fuels. Usually, the beryllium is combined with highest possible hydrogen contents combined with ele hydrogen in the form of beryllium hydride. The beryllium ments of the lowest possible atomic weight, such other compounds can be incorporated into solid propellant elements being capable of high heat release during com formulations or used in liquid propellant applications. bustion. In the instant invention, it would be preferred to Prior art" combust the BTBH liquids with an oxygen oxidizer such Co-pending application Ser. No. 607,132, with a com 40 as H2O2, in order to obtain high heat release by virtue mon inventor and assignee, discloses the reaction of di of forming beryllium and boron oxides. methyl- or trimethyl-alane and Beh2 to produce a stable An example of a preparation of the starting alane ter non-volatile mobile liquid beryllium hydride compound minated beryllium hydride liquid of the instant inven which is terminated by aluminum alkyl (alane) groups. tion would be as follows: The specific alane terminated beryllium hydride (ATBH) 45 Example I liquid achieved from this reaction is a function of tem perature, reaction time, the ratio of reactants, and start A mixture of Al(CH3)3 (104 mmoles) and BeH (45.4 ing alane. Generally, the reaction takes place between mmoles) was heated at 120° C. for 16 hours. The filtered about 110° C. and 200° C. The reaction of BeH with the solution was used as the standard ATBH liquid for the aluminum compound should take place between about 2 hydriding reactions. An aliquot (2 milliliters) of the and 100 hours. The reactants should be present in molar filtrate was taken and the excess Al(CH3) was removed ratios of BeH2 to aluminum compound of from 0.1 to until constant weight (0.120--0.002 gram) was achieved. 100. Ratios of about 2 to 10 are preferred. The reaction Analysis of the viscous residue gave the Al:Be:H:CH must be performed either in a vacuum or in an inert gas ratio of 0.24:1.0:1.0:1.85 from which data the approxi blanket. 5 5 mate empirical formula (CHBeH)8(Al(CH3)32 can As revealed in the referenced application, ATBH liquids be calculated. Therefore, 0.120 gram of this ATBH liquid do have superior properties when used as liquid rocket is approximately one-third of a mole. fuels. However, these properties could be improved upon Using this alane terminated beryllium hydride liquid if the ATBH liquids were to be converted to boron alkyl and diborane, a mobile liquid borane terminated beryl (borane) terminated beryllium hydride (BTBH) liquids. 60 lium liquid was synthesized according to the following ex The improvement in impulse is attributable to the lower ample: molecular weight of boron and its combustion products. Example II It is an object of this invention to provide new borane terminated beryllium hydride derivatives, and a method A 2-milliliter aliquot of the standard ATBH material for their preparation. 65 was pumped to constant weight (0.1185 gram) and sub It is a further object of this invention to provide new sequently treated with B2H6 (0.455 mmole) at ambient liquid fuel compositions, and methods for their prepara temperature. The mixture became quite mobile within a tion. few minutes after reaching ambient temperatures. The Other and more specific advantages of this invention volatile components (0.0588 gram) were fractionated to will become apparent from the following description. 70 obtain B(CH3)3 (0.06 mmole) and an aluminum-contain The objects of this invention are accomplished by re ing liquid. Analysis of the non-volatile viscous material acting alane terminated beryllium hydride liquids with revealed the Be:H:CH3 ratio of 1:1.5:0.93. The amount 3,484,315 3 4. of aluminum (14.9 milligrams) found in the volatile Example VI fraction corresponded to a 80 percent displacement. Once again using the alane terminated beryllium hy In substantially the same synthesis as Example IV, dride liquid whose synthesis was described in Example I, 0.120 gram of ATBH liquid is treated with 1 mmole of a borane terminated beryllium hydride liquid was made Be(BHA). A mobile BTBH liquid is obtained. with beryllium borohydride according to the following 5 Example VII example: In substantially the same synthesis as Example III, Example III 0.120 gram of ATBH liquid is treated with 3 mmoles of Be(BH)2. A mobile BTBH liquid is obtained. A sample (0.1204 gram) of the ATBH material, as ob O It can be seen that all of the borane terminated beryl tained above for the previous reaction, was treated with lium hydride liquids have a lower CH group content and Be(BH) (0.0175 gram, 0.452 mmole) at ambient tem a higher hydrogen content than the alane terminated perature. The viscous ATBH material became quite mo beryllium hydride liquid from which they were derived. bile and contained only a small quantity of solid after 1 Since it is obvious that many changes and modifications hour; all but a trace of this material dissolved after stirring can be made in the above described details without de overnight. Fractional condensation yielded an aluminum parting from the nature and spirit of the invention, it is containing compound but no alkyl-boron derivatives. to be understood that the invention is not to be limited Analyses of the non-volatile viscous material revealed the thereto except as set forth in the appended claims. Be:H:CH ratio of 1:1.8:0.92, while the volatile fraction We claim: contained 82 percent of the aluminum. 20 1. The product produced from the process of reacting Again, using the alane terminated beryllium hydride an alane terminated beryllium hydride liquid with a com liquid of the Example I, this time using tetraborane as . pound selected from the group consisting of B2H6, the other reactant produced a borane terminated hydride Be(BH4)2 and B4H10, thereby producing a mobile borane liquid according to the following synthesis. terminated beryllium hydride liquid. Example IV 2. The product of claim 1 in which the boron com pound to alane terminated beryllium hydride liquid molar A third sample (0.1213 gram) of the prepared ATBH ratio is between about 0.1:1 and about 10:1. liquid was treated with BH-1 (0.429 mmole) at ambient 3. The product of claim 2 in which the ratio is between temperature. The liquid required approximately 1 hour to about 0.5:1 and about 3:1. become mobile. After stirring the mixture for 16 hours, 30 the liquid products were separated into volatile and non References Cited volatile fractions which were subsequently analyzed.
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