Acetylenes monoalkyl

In a polluted or urban atmosphere, O formation by the CH oxidation mechanism is overshadowed by the oxidation of other VOCs. Seed OH can be produced from reactions 4 and 5, but the photodisassociation of carbonyls and nitrous acid [7782-77-6] HNO2, (formed from the reaction of OH + NO and other reactions) are also important sources of OH ia polluted environments. An imperfect, but useful, measure of the rate of O formation by VOC oxidation is the rate of the initial OH-VOC reaction, shown ia Table 4 relative to the OH-CH rate for some commonly occurring VOCs. Also given are the median VOC concentrations. Shown for comparison are the relative reaction rates for two VOC species that are emitted by vegetation isoprene and a-piuene. In general, internally bonded olefins are the most reactive, followed ia decreasiag order by terminally bonded olefins, multi alkyl aromatics, monoalkyl aromatics, C and higher paraffins, C2—C paraffins, benzene, acetylene, and ethane. 

Nucleophilic addition to acetylenic sulfoxides provides a,/ -ethylenic sulfoxides. Treatment of 181 with monoalkyl-copper afforded nearly quantitatively /J-alkylated a, / -ethylenic sulfoxides 182 through cis-addition to the triple bond. The reaction with lithium dimethylcuprate also afforded a similar adduct however, the reaction with lithium di-n-butylcuprate was found to give a small amount of ethyl n-butyl sulfoxide 183 besides the... 

Trichloromethyl lithium (generated from BrCCl3 and CH3Li at —100 °C) adds to dialkyl acetylenes and to monoalkyl acetylenes23, thus monoalkyl cyclopropenones became accessible which could not be obtained from terminal acetylenes by reaction with the above carbene sources. The 3,3-dihaIogeno-A1,2-cycIopropenes formed as primary products in the dihalocarbene reactions are usually not isolated, but are hydrolyzed directly to cyclopropenones. 

Rutledge, T. F. Sodium acetylide. II. Reactions of sodium acetylide in organic diluents. Preparation of monoalkyl acetylenes./. Org. Chem. 1959, 24, 840-842. 

Most of the simple monoalkyl- and arylisothiazoles may be prepared by direct ring synthesis either by the olefin route (Section I,C) or Wille s acetylenic route (Section I,D). 5-Alkylisothiazoles are accessible from isothiazolyllithium derivatives, and 3-alkyl- and arylisothiazoles are conveniently prepared by deamination of the readily available 5-aminoisothiazoles.37, 70,95 Arylisothiazoles have also been prepared from aminoisothiazoles by the Gomberg-Hey route.107... 

Phenylethynylcopper and phenacyl bromide afford intractable tars upon long reflux in DMF. However, at higher temperatures ( 240°C) a-haloketones can be converted in one step to furan derivatives [Eqs. (68a), (68b)] uncyclized acetylenic ketones are not isolated. The cycliza-tion is catalyzed by copper(I) through the copper-coordinated enol 128). Reaction of a,a -dibromoketones with an excess of a diorganocuprate is a new method for the a-alkylation of a ketone 231a). Only the monoalkyl derivative is isolated. The evidence points to the formation of a cyclopropanone intermediate which reacts with more of the cuprate to give an a-alkylated metal enolate. 

A special type of alkene metathesis is the reaction of an alkene with an alkyne to give a diene. Thus, a reaction between a monoalkylated acetylene and a mono-alkylated ethylene leads to a 1,3-diene bearing a methyhdene and a mixture of (Z)-and ( )-alkene residues [213]. If both unsaturated residues are structurally confined, as in a propargyl-allylamide, cychzation to a vinyl pyrrohne occurs [236]. This reaction has become a useful tool in the generation of sohd support-bound dienes for [2 -i- 4]-cycloadditions [237]. 

The hydride complex (CXLVIII) can be used for monoalkylation of acetylenic derivatives as well. The reaction course consists of cis addition of the rhodium hydride across the carbon-carbon triple bond, oxidative addition of alkyl iodide, and reductive elimination of the organic moiety (Schwartz et al 1972). 

The C=C stretching vibration absorbs weakly but clearly in monoalkyl acetylenes near 2120 cm in the infrared. This region is usually relatively free of interfering bands. Conjugation with a carbonyl increases the IR intensity of this band. In the Raman spectra the C=C stretch band is always very strong. 

The allenic dianion (219) is obtained from the acetylene (220) by treatment with two moles of butyl-lithium. Alkylation can be carried out successively using two different reagents to yield the tetrasubstituted allenes (221) hydrolysis of the monoalkylated products yields a -unsaturated aldehydes (222),... 

C = C- stretch Monoalkyl acetylenes Strong scattering in the Raman... 

Monohydric alcohols other than methanol react with monoalkyl-acetylenes to afford polymers. However, the use of trichloroacetic acid causes the reaction to proceed smoothly to 2,2-dialkoxyalkanes. 

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