Acetylene derivs 2 molecules

Monosubstituted acetylenes add formaldehyde in the presence of copper, silver, and mercury acetyUde catalysts to give acetylenic alcohols (58) (Reppe reaction). Acetylene itself adds two molecules (see Acetylene-DERIVED chemicals). 

Hydrogen cyanide adds to an olefinic double bond most readily when an adjacent activating group is present in the molecule, eg, carbonyl or cyano groups. In these cases, a Michael addition proceeds readily under basic catalysis, as with acrylonitrile (qv) to yield succinonitnle [110-61-2], C4H4N2, iu high yield (13). Formation of acrylonitrile by addition across the acetylenic bond can be accompHshed under catalytic conditions (see Acetylene-DERIVED chemicals). 

Note Trichothecenes and valepotriates only react when there is an epoxy group present in the molecule their detection limits are in the range 25—200 ng substance per chromatogram zone [1]. The detection limits for acetylene derivatives are 100— 800 ng substance per chromatogram zone, but not all give a positive reaction [8]. 

This observation may well explain the considerable difference between metal-olefin and metal-acetylene chemistry observed for the trinuclear metal carbonyl compounds of this group. As with iron, ruthenium and osmium have an extensive and rich chemistry, with acetylenic complexes involving in many instances polymerization reactions, and, as noted above for both ruthenium and osmium trinuclear carbonyl derivatives, olefin addition normally occurs with interaction at one olefin center. The main metal-ligand framework is often the same for both acetylene and olefin adducts, and differs in that, for the olefin complexes, two metal-hydrogen bonds are formed by transfer of hydrogen from the olefin. The steric requirements of these two edgebridging hydrogen atoms appear to be considerable and may reduce the tendency for the addition of the second olefin molecule to the metal cluster unit and hence restrict the equivalent chemistry to that observed for the acetylene derivatives. 

The system A -bromoacetamide-hydrogen fluoride adds bromine monofluoride to acetylene derivatives.32 Hex-1-yne. hex-3-yne, 1.4-dichlorobut-2-yne, and phenylacetylene give the corresponding bromofiuoroalkenes, in no case is the addition of a second molecule of bromine monofluoride observed. Hex-1 -yne (3) produces 95% of the (E)- and 5% of the (Z)-isomcr 4. 

Many unsaturated compounds found in nature contain one or more acetylenic bonds, and these are predominantly produced by further desaturation of olefinic systems in fatty acid-derived molecules. They are surprisingly widespread in nature, and are found in many organisms, but are especially common in plants of the Compositae/Asteraceae, the Umbelliferae/Apiaceae, and fungi of the group... 

Linnett o gives a discussion of the use of valence force fieid with the addition ol selected cross terms. One method of reducing the number of constants to Tdc determined from the frequencies is to carry over from molecule to molecule certain force constants for squared terms and even for cross terms. Linnett mentions in this connection the work of Crawford and Brinkley who studied acetylene, ethane, methylacetylene, dimethylacetylene, hydrogen cyanide, methyl cyanide and the methyl halides in this way, and were able, for all the molecules, to account for 84 frequencies with 31 constants. Linnetttreated some of these compounds using a different force field. He was able to account satisfactorily for 25 frequencies using 11 force constants. From our point of view the trouble with these results is that Linnett obtained a value for the C - C force constant in these acetylene derivatives which was different from that obtained by Crawford and Brinkley. For C - C in methyl cyanide for example, Linnett obtained... 

In this class of reactions the side methylene bridge is introduced to the molecule by bonding it to the two bridgehead carbons. Naturally, a reaction in which a carbenoid is inserted into a cyclopropene system is most commonly employed. In fact, in many cases, carbene is inserted first into an acetylenic derivative and then again into its product yielding finally the bicyclobutane framework (equations 34, 35). This method was successfully employed in the synthesis of highly strained derivatives of bicyclobutane (equations 36, 37). 

RuCo3(CO)ii(NO)] (see Table 12) reacts with acetylene derivatives to give butterfly clusters [RuCo3(CO)9(NO)( i4-T 2-RC CR )]. Table 14 reports Co NMR data of such species [93]. In that case, Co NMR is a practical tool for the identification of the molecules and for the analysis of the ratio of the different isomers in the mixture. 

The helical conformation of polyacetylene derivatives bearing chiral side chains was first pointed out by Ciardelli in 197 4 24 and later extended and more clearly demonstrated by Grubbs in 199 1 25 and by Yashima and Okamoto in 1994.26a For poly(phenyl-acetylene) derivatives bearing no chiral side groups, Yashima and Okamoto showed that a helical conformation can be induced by interaction with added chiral small molecules.260 Apart from optical activity, a helical conformation of cis-cisoidal poly(phenyl-acetylene) in the solid state was pointed out by Simionescu and Percec.27... 

Subsequent interaction with electrophilic reagents in general yields a mixture of the allenic and the acetylenic derivative trimethylsilylation and alkylation, however, seem to afford the y-functionalized allenic ether [99]. Under strongly polar conditions, i.e. if lithium is replaced by potassium (by addition of t-BuOK) and HMPT is added as co-solvent, the y-metallated allenic ethers rearrange into the a-metallic derivatives [100]. This remarkable isomerization may take place via a head-to-tail arrangement of two metallated molecules ... 

Sanders and coworkers have developed syntheses of rather rigid cyclic oligoporphyrins (porphyrin-linker), (n = 2 4) by catalytic-coupling reactions of acetylene derivatives with copper salts. In particular, incorporation of metal ions into cyclic porphyrin oligomers provides the multi-interaction sites necessary to tightly bind heterocyclic compounds in the inner cavity (see section IV).Rigidity of host molecules is controlled by the structure of the linkage moieties. 

Pyrolysis of pyridine derivatives is a method for allylic and benzylic deamination the preparation of nitriles from aldehydes, and the preparation of isocyanates from acid chlorides or hydrazides Flash vacuum pyrolysis continues to yield interesting reactions and products. Recently, it has been reported that quite sensitive acetylene derivatives can be obtained by this method from 4-alkylideneisoxazol-5(4H)-ones by ring degradation. On the other hand, 2 carbamyl azide molecules cyclize under these conditions to form l,2,4-triazolidine-3,5-dione 1,2-ylids . 2H-Cyclohepta[b]furan-2-ones have been obtained by ring expansion of phenyl propiolates... 

When manganacycle 39 is allowed to remain in ether solution in the dark at atmospheric pressure, a single diastereomer of butenolide 49(configuration unknown) is produced in excellent yield(20j. Presumably, the butenolide results from formation of manganacycle 48 by loss of phenyl sulfinic acid, protonation of 48, migratory insertion of an additional molecule of CO producing ketene 51, enolization, and ring formation. We have previously demonstrated that this mechanism is operative in reactions of acetylene derivatives(75). 

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