1,3,5,7-Octatetrayne → HCID 15510876, compound

HRID 2226367Notes

Reaction equation

HRID 2226367 reaction equation
[Si:1]([C:8]#[C:9][C:10]#[C:11][C:12]#[C:13][C:14]#[C:15][Si:16]([CH2:21][CH3:22])([CH2:19][CH3:20])[CH2:17][CH3:18])([CH2:6][CH3:7])([CH2:4][CH3:5])[CH2:2][CH3:3].[CH:23]#[C:24][C:25]#[C:26][C:27]#[C:28][C:29]#[CH:30]>>[Si:1]([C:8]#[C:9][C:10]#[C:11][C:12]#[C:13][C:14]#[CH:15])([CH2:6][CH3:7])([CH2:4][CH3:5])[CH2:2][CH3:3].[Si:1]([C:23]#[C:24][C:25]#[C:26][C:27]#[C:28][C:29]#[C:30][C:8]#[C:9][C:10]#[C:11][C:12]#[C:13][C:14]#[C:15][Si:16]([CH2:17][CH3:18])([CH2:19][CH3:20])[CH2:21][CH3:22])([CH2:6][CH3:7])([CH2:4][CH3:5])[CH2:2][CH3:3]

Participants

4

Reactant 2

HCID 1386801,3,5,7-OctatetrayneHCID 12416634Triethyl(8-triethylsilylocta-1,3,5,7-tetraynyl)silane

Product 2

HCID 15510876HCID 15510876, compoundHCID 131718670HCID 131718670, compound

Procedure

Thus, by forming the appropriate alkynyl salt, the length of the alkynyl moiety, represented by the value of n, incorporated into the polymer formed in step 2 can be controlled. Typically, the value of n can be varied from 1 to 12. Acetylenic derivatives having the general formula H(C≡C)nH can be readily converted into the dilithio salts by reacting with n-butyllithium. The respective dilithio salts, with values of n varying from 1 to 12, can then be incorporated into the backbone of polymers (2) as shown in the aforementioned step 2. The value of n can be varied, typically, from 1 to 12, more often from 1 to 10 and 1 to 8, most often from 1 to 6 and, in particular, from 1 to 3 and 1 to 2. Acetylenic derivatives having the general formula H(C≡C)nH can be readily formed by the synthesis given by Eastmond et al. in Silylation as a Protective Method for Terminal Alkynes in Oxidative Couplings--A General Synthesis of the Parent Polyynes, 28 TETRAHEDRON 4601 (1972). Laboratory synthesis of the lower polyyne series H(C≡C)nH (n=2,3,4 and 5) is based upon low temperature sodamide dehydrohalogenation of α,ω-bis (chloromethyl)alkynes, ClCH2 (C≡C)n-1CH2Cl in liquid ammonia, a technique which provided a convenient route to diacetylene but which proved increasingly troublesome for tri- and for tetra-acetylene. Pentaacetylene, the highest member of the series was obtained in ca 1% yield from the precursor, ClCH2 (C≡C)4CH2Cl. Polyynes in the series H(C≡C)nH (n=4,5,6,7,8,9,10 and 12) have been prepared in solution by sequences involving Cu-catalyses oxidative couplings (Hay technique) of silyl-protected terminal alkynes, partial cleavage (desilylation) of the products by alkali, recoupling and complete desilylation. Thus using conditions established in a model coupling Et3SiC≡CH (I)→Et3Si(C≡C)2SiEt3 (II), coupling of the silyldiyne Et3Si(C≡C)2H (III) gives Et3Si(C≡C)4SiEt3 (IV) which upon controlled cleavage yields a chromatographically separable mixture of Et3Si(C≡ C)4SiEt3 (IV) , Et3Si(C=-C)4H (V) and H(C≡C)4H (VI). Coupling of Et3Si(C≡C)4H (V) in turn gives Et3Si(C≡C)8SiEt3 (VII) which upon cleavage yields Et3Si(C≡C)8H (VIII) and H(C≡C)8H (IX) and coupling of Et3Si(C≡C)8H (VIII) gives the bissilylhexadecaacetylene Et3Si (C≡C)16SiEt3 (X) .

Workup

  1. customyields

Sources & evidence

ORD record
ord-d2ed27f5471c44b9a6b7c38b1f8749a7
Source dataset
uspto-grants-1994_09
Patent number
US05348917

Reaction notes

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