A. Herstellung (V)

Nitroalkynes: A Unique Class of Energetic Materials

“…The first operational nitration of alkyne derivatives was published in 1975 by Jäger, Motte, and Viehe, who produced nitroalkynes from trialkylstannylalkynes and either nitronium tetrafluoroborate or dinitrogen pentoxide (Scheme 19). 12,53 This method, notable in view of some of its failures (e.g., with NO 2 Cl, R = Ph; section 4.1.1), afforded reasonable yields of alkylnitroalkynes. The nitronium salt proved to be a better nitrating agent than dinitrogen pentoxide, and trimethylstannyl was superior to triethylstannyl.…”

“…Of these, 1, 5 2, 8,9,11 3, 2,12,15 4, 12 6, 9 7, 17,19 8, 9 9, 12 10, 9 and 11 9 have been described in the refereed literature, and only 2, 6-11 3, 2,12-14 4, 12,13 5, 13 6, 9,10 7, 17,19,20 10, 9,10 and 11 9,10 were isolated in the pure state. Alkynes 12-15 have been made by Zhang and Eaton and are as yet unpublished.…”

“…Only a few years later, Motte and Jäger did succeed in oxidizing these compounds to the corresponding nitroalkynes (section 4.2.1). 12,15 Motte, in his 1974 dissertation, 53 tried to effect nitrations of lithiated (e.g., 25), trialkylstannyl- (26), and trialkylsilylalkynes (27)(28)(29)(30)(31) in his attempts to make 3-5, 7, and 32, respectively. Many of these experiments failed, as summarized for nitronium chloride in Scheme 4.…”

“…2 The nitro group has an electronegativity of 3.42, 3 surpassed by few groups or elements, 3,4 and, when attached to an alkynyl sp-hybridized carbon with an electronegativity of 3.07, 3 produces a highly reactive moiety. This leads to difficult preparation and purification, and is likely the reason why only fifteen nitroalkynes have been generated ( Figure 1): 1-nitroethyne (nitroacetylene) (1), 5 1-(trimethylsilyl)-2-nitroethyne (TMSnitroacetylene) (2), [6][7][8][9][10][11] 3,3-dimethyl-1-nitrobut-1-yne (tert-butylnitroacetylene) (3), 2,12-15 3-methyl-1-nitrobut-1-yne (isopropylnitroacetylene) (4), 12,13 1-nitropent-1-yne (propylnitroacetylene) (5), 13 1-tris(isopropylsilyl)-2-nitroethyne (TIPSnitroacetylene) (6), 9,10 (nitroethynyl)benzene (phenylnitroacetylene) (7), 13,[16][17][18][19][20] 1-nitroprop-1-yne (methylnitroacetylene) (8), 9,10 1-nitrohex-1-yne (butylnitroacetylene) (9), 12,13 1-[dimethyl(isopropyl)silyl]-2-nitroethyne (10), 9,10 1-(dimethyl-tert-butylsilyl)-2-nitroethyne (11), 9,10 1-iodo-2nitroacetylene (iodonitroacetylene) (12), 21…”

Synthesis and Utilization of Nitroalkyne Equivalents in Batch and Continuous Flow

“…Reports on the preparation of nitroalkynes are sparse, with the first successful synthesis being achieved in 1969 by Viehe and co‐workers, when 1 was prepared by an addition‐elimination sequence (Figure ) . The nitration of alkynyl stannanes with nitronium tetrafluoroborate (NO 2 BF 4 ) and hexafluorophosphate (NO 2 PF 6 ) can be used to access alkyl‐substituted nitroalkynes 2 – 4 in moderate yields, though they are noted to rapidly decompose . Physical data has been recorded for 1‐nitro‐2‐phenylacetylene 5 , but a yield for its preparation (4.5 %) has only been recorded once by Kashin et al .…”