Acetone acetylene , alkyne

DNA sequencing and. 1113 Electrospray ionization (ESI) mass spectrometry, 417-418 Electrostatic potential map, 37 acetaldehyde, 688 acetamide, 791,922 acetate ion. 43. 53, 56, 757 acetic acid. 53. 55 acetic acid dimer, 755 acetic anhydride, 791 acetone, 55, 56. 78 acetone anion, 56 acetyl azide, 830 acetyl chloride, 791 acetylene. 262 acetylide anion, 271 acid anhydride, 791 acid chloride, 791 acyl cation, 558 adenine, 1104 alanine, 1017 alanine zwitterion, 1017 alcohol. 75 alkene, 74, 147 alkyl halide, 75 alkyne. 74... 

No defined complexes could be isolated from reactions of complex 1 with acetone Me2C=0. Complexes 2a and 2b react with acetone to give the zirconafuranone 2c, which is an interesting zirconocene precursor in view of its extremely good solubility in hydrocarbon solvents and because of its ability to dissociate into the alkyne complex [2f], It is also possible to cleanly substitute the bis(trimethylsilyl)acetylene unit so as to obtain the complex 47, or, alternatively, to substitute the acetone with formation of the zirconafuranone 95 (Fig. 10.14) [2f],... 

Alkanes n-butene, isopentane, isooctane Cydoalkanes t dohezane, methylcyclopentane Olefins (sometimes called alkenes ) ethylene, propylene, butene Cydoolefins ( clohezene Alkynes acetylene Aromatics toluene, i ene CHLORINATED HYDROCARBONS ALDEHYDES, RCHO formaldehyde, acetaldehyde KETONES, RCX R " acetone, methylethylketone NITRIC OXIDE, NO ... 

As l,2,4-triazole-3,5-dione (PTAD) is a stronger dienophile than acetylenic esters, more facile formation of the Diels-Alder cycloadducts was expected. But because it cannot behave as a diene in a reaction with alkynes such as diethyl azodicarboxylate, the formation of dihydrooxadia-zines is excluded. In spite of these characteristics, no Diels-Alder adducts were obtained in the reaction of l-phenyl-4-vinylpyrazole with PTAD in acetone at -80°C and 2,2-dimethyl-4(l-phenylpyrazol-4-yl)-8-phenyl-l,6,8-triaza-3-oxabicyclo[4.3.0]nona-7,9-dione 277 was obtained as a major product. The isolation of the tetrahydrooxadiazine 277 indicates that the 1,4-dipole 278 was formed and trapped with acetone. 

On the other hand, the catalytic system CpRu(CH3CN)3PF6/SnBr4 in the presence of lithium bromide in a less polar solvent such as acetone led to the favored formation of (Z)-vinyl bromides. Interestingly, when alkynes with a quaternary propargylic carbon or aryl acetylenes were used, complete selectivity for the (Z) isomer was obtained [60] (Eq. 46). 

A 1 litre three-necked round-bottomed flask is equipped with a gas inlet tube, a mechanical stirrer, and an efficient reflux condenser (in the case of volatile acetylenes, a solid carbon dioxide-acetone cold finger condenser) with the top of the condenser connected to a cold trap, and furnished with an inert atmosphere. (CAUTION particularly in the case of volatile acetylenes, all connections, and the stirrer seal, must be gas-tight). The alkyne (0.5-0.6 mol) is introduced into a solution of ethylmagnesium bromide (approximately equimolar) in ether or THF, as a gas or from the dropping funnel, under the conditions summarized in Table 3.5 this table also specifies the conditions required to complete the metallation. 

Alkynes are readily hydrocyanated in the presence of a homogeneous catalyst, especially a nickel-based catalyst system. However, zerovalent palladium compounds are reported to catalyze the reaction as well, but are less efficient [60], The reaction gives an easy access to the synthetically valuable a,P-un-saturated nitriles. The use of acetone cyanohydrin as a synthetic equivalent for the difficult-to-handle HCN provides an efficient alternative, but the substrate/ catalyst ratio has to be increased in comparison with the reaction with HCN. The regioselectivity of the reaction is controlled by steric, electronic, and chelative effects. Investigations were predominantly performed by changing the substituent pattern on the acetylenic substrate [61]. 

However, hydration of alkynes by acid alone is less important than addition of water under the influence of mercury salts. For this purpose solutions of mercury(n) sulfate in sulfuric acid or of mercury(n) acetate in acetic acid are generally used. When the products are water-soluble, the hydration can be effected with aqueous catalyst solutions for water-insoluble acetylenes it is advisable to add solvents such as 70% methanol, 70% acetone, or acetic acid.83... 

Thiophenes from alkynes 48 The alkyne is dissolved in methanol, ethanol, or acetone and the solution is adjusted to pH 9-10 by adding N-sodium hydroxide solution in the proportion 9 1. Hydrogen sulfide is then led in at 20-80° until a sample of the mixture no longer shows acetylene bands in its UV spectrum (4-20 h). The mixture is then treated with water, and the product is taken up in ether, dried over sodium sulfate, freed from solvent, and distilled or recrystallized. Thus were prepared 2,5-dimethylthiophene, b.p. 134-136° (70%), 2,5-dlethyl-thiophene, b.p. 180-181° (65%), and 2,5-diphenylthiophene, m.p. 152-153° (85%). 

Acid-catalysed cyclization of the alcohol 581 yields the dihydro-y-pyrone 582, which is converted into the benzene derivatives 586 by sequential treatment with trimethylsilyl chloride and acetylenes 584 (R = H, Me or C02Me R = Bz or C02Me). The process involves formation of the pyran 583, Diels-Alder addition to the alkynes and extrusion of acetone from the adducts 585. ... 

The physical properties of alkynes (Table 9-1) are similar to those of alkanes and alkenes of similar molecular weights. Alkynes are relatively nonpolar and nearly insoluble in water. They are quite soluble in most organic solvents, including acetone, ether, methylene chloride, chloroform, and alcohols. Many alkynes have characteristic, mildly offensive odors. Acetylene, propyne, and the butynes are gases at room temperature, just like the coitesponding alkanes and alkenes. In fact, the boiling points of alkynes are nearly the same as those of alkanes and alkenes with similar carbon skeletons. 

The procedures presented in this chapter represent basic reactions of alkynes. That involving hydration of 2-methyl-3-butyn-2-ol through electrophilic addition of water to the tr-system is a reaction analogous to the conversion of acetylene to acetaldehyde, a precursor to acetic acid and acetone. In addition, the formation of an alkyne via an elimination reaction illustrates an alternate approach to forming a carbon-carbon triple bond, although one that is not nearly so easy experimentally as adding water to calcium carbide to make acetylene ... 

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