Zur Kenntnis des o-Oxyphenylacetylens

Transition‐Metal‐Free Synthesis of 4‐Alkynylquinazolines

“…After successfully obtaining 4‐alkynylquinazoline precursors ( 3 a – d ), we conducted an optimization study for their ring opening using 4‐(benzofuran‐2‐yl)quinazoline ( 3 a ) as a model substrate (Table 2). First, we tried the reaction in pyridine in the presence of sodium (Table 2, Entry 1), but there was no 4 a in the resulting complex mixture [15] . We observed no conversion in the reactions using sodium amide in THF or NH 3 (Table 2, Entry 2 and 3).…”

Vapor Pressures and Gibbs Energies of Formation of the Three Hydroxybenzaldehydes

“…But the normal ( p = 1 × 10 5 Pa) boiling temperature of this liquid has been determined by several authors. So, we used the mean of the values reported in the literature − together with the ( p , T ) data measured in this work to fit all these values of vapor pressures by the Clarke and Glew equation, eq , over the wide range of temperatures T = (266.5 to 470) K. In this equation p o is the standard pressure ( p o = 1 × 10 5 Pa), p is the vapor pressure at the temperature T , θ is a reference temperature, R is the molar gas constant, and the thermodynamic properties of sublimation or vaporization Δ cr,1 g G m o (θ), Δ cr,1 g H m o (θ), and Δ cr,1 g C p ,m o (θ), are adjusted by the fitting. Because of the large temperature interval, it was possible to derive the variation of Δ 1 g C p ,m o (θ) with the temperature represented by the equation Δ 1 g C p , m o (θ)/J·K –1 ·mol –1 = [−(105 ± 6) + (0.081 ± 0.011).θ], assuming a linear variation of Δ 1 g C p ,m o (θ) with the temperature, accordingly to the fourth term of eq . The thermodynamic properties of sublimation of o -HBAD could not be accurately derived due to the narrow temperature range and to the scarce number of the sublimation vapor pressures that were possible to measure for its crystalline phase.…”

“…The vapor presssures at different temperatures of the liquid and crystalline phases of o -HBAD are represented in Figure together with the mean value, T = (470 ± 1) K, of the normal ( p = 1 × 10 5 Pa) boiling temperatures reported in the literature. − Other literature boiling temperatures, T = 366 K at p = 3.3 × 10 3 Pa, T = 368 K at p = 4.7 × 10 3 Pa, T = 360 K at p = 1.7 × 10 3 Pa, and T = 309 K at p = 5.3 × 10 2 Pa are also presented in this figure. As may be observed, the literature value at T = 366 K is well within the fitting curve, but the other three literature results are clearly out.…”

“…Phase diagram of o- hydroxybenzaldehyde: ○, vaporization; ◇, vaporization (supercooled liquid); □, sublimation; ▲, mean value of normal ( p = 1 × 10 5 Pa) boiling temperature reported in literature; − ●, boiling temperature, T = 366 K at p = 3.3 × 10 3 Pa; ×, boiling temperature, T = 368 K at p = 4.7 × 10 3 Pa; ★, boiling temperature, T = 360 K at p = 1.7 × 10 3 Pa; ■, boiling temperature, T = 309 K at p = 5.3 × 10 2 Pa . Triple point data determined in this work: T = 272.8 K; p = 9.1 Pa.…”

Chemistry and biology of vitamin B6. 33. General method for modifying the 2-methyl group of pyridoxol. Synthesis and biological activity of 2-vinyl- and 2-ethynylpyridoxols and related compounds

“…2-(/3-Chlorovinyl)-2-norpyridoxol (1, R2 = CH=CHC1) Hydrochloride. The blocking groups in 19 were hydrolyzed as described for 16: yield 73%; mp 177-179°d ec; nmr (D20) 4.87 and 5.02 (4-and 5-CH2), 6.70-7.83 (CH=CHC\), 8.47 3-0-Benzyl-a4,a5-0-isopropylidene-2-ethynyl-2-norpyridoxol (18). Fresh NaNH2 was prepared according to the method of Vaughn, et al, 22 from Na (69 mg), liquid NH3 (10 ml), and Fe(N03)2 (0.6 mg).…”