Propyne, photolysis

With propyne or 1-hexyne, the mixture of the photolysis products consists of the... 

Photolysis of acyldisilanes at A > 360 nm (103,104) was shown, based on trapping experiments, to yield both silenes 22 and the isomeric siloxy-carbenes 23, but with polysilylacylsilanes only silenes 24 are formed, as shown by trapping experiments and NMR spectroscopy (104,122-124) (see Scheme 4). These silenes react conventionally with alcohols, 2,3-dimethylbutadiene (with one or two giving some evidence of minor amounts of ene-like products), and in a [2 + 2] manner with phenyl-propyne. Ketones, however, do not react cleanly. Perhaps the most unusual behavior of this family of silenes is their exclusive head-to-head dimerization as described in Section V. More recently it has been found that these silenes undergo thermal [2 + 2] reactions with butadiene itself (with minor amounts of the [2 + 4] adduct) and with styrene and vinyl-naphthalene. Also, it has been found that a dimethylsilylene precursor will... 

In 1972 a matrix-isolation study on the photolysis of diazopropyne (38) and some IR bands of propargylene (36) were reported in a doctoral thesis.65 In 1974, 36 was identified as one of the products of the vacuum UV irradiation of matrix-isolated propyne and allene.66... 

Preparation of alkenylcarbene metal complexes was reported by Le Bozec and Dixneuf et al. in 1991 by activation of propargylic alcohols in the presence of methanol [13[. Thus, photolysis of M(CO)6 (M = Cr, W) in the presence of 2-propyn-l-ol derivatives 30 in the presence of MeOH gave the corresponding... 

The ground state ofC3 is X I (linear). Both the absorption and the emission bands of C3 have been detected in the region 3400 to 4100 A with prominent bands at 4050 A. The transition is ascribed to AlUu <- X Y. +. D0(C2—C) = 7.31 0.02 eV. Sticf (934) suggests that C3 radicals observed in comets originate from the photolysis of propyne... 

Irradiation of [68] at room temperature results in low yields of acetylene, propyne, and butyne. Dimethyl-tetrahedrane is a speculative intermediate in this photolysis (63). 

A brief study of the direct photolysis of propyne at 2062 A has been made by Galli et The major gas-phase products are 1,5-hexadiyne, propene, hydrogen and acetylene, while smaller quantities of methane and compounds of the formulae C4H6, CgHg and CgHio were observed. The gas-phase products represented about... 

The photochemical decomposition of methanal in a solid Xe matrix has been studied. Work has also been reported dealing with the photodissociation dynamics of methanal, and ab initio calculations have been carried out on the photochemical decomposition of acetaldehyde into methane and CO. The photocatalytic decomposition of acetaldehyde to yield carbon dioxide has also been reported. The threshold for CC bond fission in propanal and the release of the CHO fragment has been shown to be at a wavelength of 326.26 nm. Chowdhury has reported the dissociation of propynal using multiphoton irradiation. Gas-phase photolysis of butyraldehyde in the 280-330 nm range has shown that the CHO radical is produced. ... 

Scheme 11-1 Formation of a single common species in the photolysis of 3-diazo-l-[- C]- and -[3- C]propynes.

Propargyl or allenyl HjC—C—C—H Photolysis of DTBP in propad iene or propyne/ Neat EPR/ 145 H(l) 1.262 H(3,3) 1.890 68Krul/ 71Voll, 77Hinl 247aj... 

Coupling of W(CO)(, butadiene, and ketones RiR C O at a Cp2Zr template results in the carbenes 39 containing a trans C=C double bond in the ring. This (teprottmates at the carbon a to the carbene atom and the resulting anion alkylates at the same posititm. Photolysis of M(CO)( (M = Or, W) in the presence of 2-propyn-l-ol derivatives HCsCCH(OH)[(CH=CH) ] and affoids... 

Photolysis (>270 nm) of oxazinone (70) at 7 K gives the -lactone (71), which undergoes further fragmentation to give MeCN, Bu CN, propyne, and t-butyl-acetylene. That such products can be isolated strongly suggests the intermediate formation of the azete (72), which undergoes spontaneous cycloreversion via the two modes indicated overleaf. ... 

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