Triple bonds carbon-nitrogen

Lewis s concept of shared electron parr bonds allows for four electron double bonds and SIX electron triple bonds Carbon dioxide (CO2) has two carbon-oxygen double bonds and the octet rule is satisfied for both carbon and oxygen Similarly the most stable Lewis structure for hydrogen cyanide (HCN) has a carbon-nitrogen triple bond... 

Nucleophiles other than water can also add to the carbon-nitrogen triple bond of nitriles In the following section we will see a synthetic application of such a nude ophilic addition... 

The carbon-nitrogen triple bond of nitriles is much less reactive toward nucleophilic addition than is the carbon-oxygen double bond of aldehydes and ketones Strongly basic nucleophiles such as Gngnard reagents however do react with nitriles in a reaction that IS of synthetic value... 

In presence of one carbon-nitrogen triple bond —C—C=N In compounds with tendency to dipole formation, e.g., C=C—C=0 In aromatic compounds... 

Reductions of Nitriles. In the reduction of nitriles, hydrogen is added progressively across the carbon—nitrogen triple bond, forming first the imine and then the amine. 

In the above examples the polymerisation takes place by the opening of a carbon-carbon double bond. It is also possible to open carbonyl carbon-oxygen double bonds and nitrile carbon-nitrogen triple bonds. An example of the former is the polymerisation of formaldehyde to give polyformaldehyde (also known as polyoxymethylene and polyacetal) (Figure 2.3). 

Nitriles are susceptible to nucleophilic addition. In their hydrolysis, water adds to the carbon-nitrogen triple bond. In a series of proton-transfer steps, an anide is produced ... 

Draw an electron-dot structure for acetonitrile, C2H3N, which contains a carbon-nitrogen triple bond. How many electrons does the nitrogen atom have in its outer shell How many are bonding, and how many are non-bonding ... 

Angell (1) has investigated the Raman spectra of acetonitrile, propylene, and acrolein on a number of zeolites and found that physical adsorption occurred. There are sufficient differences between the spectrum of the liquid and of the adsorbed species (e.g. the carbon-carbon double bond stretching in the case of propylene and the carbon-nitrogen triple bond stretching in the case of acetonitrile) to make it quite clear that it was not merely a case of condensation in the pores of the solid adsorbent. 

These enzymes catalyze the addition of the elements of water to carbon-carbon double bonds (C=C), carbon-carbon triple bonds (C C), carbon-nitrogen double bonds (C=N), or carbon-nitrogen triple bonds (C N). These reactions are completely different from oxidoreductases since no redox reactions are involved. Illustrative examples include the following ... 

Oinuma K-I, Y Hashimoto, K Konishi, M Goda, T Noguchi, H Higashibata, M Kobayashi (2003) Novel aldox-ime dehydratase involved in carbon-nitrogen triple bond synthesis of Pseudomonas chlororaphis B23. J Biol Chem 278 29600-29608. 

Here is a list of all dangerous reactions that are related to nitrile functional group behaviour. By active polymerisation is meant the polymerisation that affects the carbon-nitrogen triple bond. Polymerisations that are related to an ethylene double bond will be dealt with on p.336. So far as stability is concerned, it is difficult to say whether certain spontaneous reactions of certain nitriles are... 

Mixing trichlorosilane, acetonitrile and diphenylsulphoxide, carried out at 10°C, detonated. This accident was put down to the exothermic addition reaction of the silicon-hydrogen bond on the carbon-nitrogen triple bond of nitrile. Other interpretations are possible for instance, the effect of traces of hydrogen chloride formed by the hydrolysis of chlorosilane on acetonitrile. 

The carbon-nitrogen triple bond of aryl thiocyanates acts as a dipolarophile in 1,3-dipolar cycloadditions. Reactions with nitrile oxides yield 5-arylthio-1,2,4-oxadiazoles 227 (X = O Y = S). Aryl selenocyanates behave similarly forming 5-arylseleno-l,2,4-oxadiazoles 227 (X = 0 Y = Se). Reactions of 5-aryl-... 

There are four single bonds (three C — H and one C — C) in the molecule. Those bonds are o bonds. But, the molecule contains six o bonds in total because both carbon - carbon double and carbon nitrogen triple bonds contain one o bond. 

The molecule contains three n bonds one in the carbon-carbon double bond and two in the carbon nitrogen triple bond. 

The anion radical species also adds to a carbon nitrogen triple bond and affords cyclic ketones (Scheme 37) [79, 80]. 

Only the most reactive organolithium compound, e.g. f-BuLi, is able to attack the carbon-nitrogen triple bond at temperatures below —20°C. For the other less reactive species, namely PhLi and n-BuLi, higher temperatures in ordinary solvents like pentane would be more appropriate to synthesize their lithiated Schiff bases. Flowever, for their detection IR spectroscopy seems to be unsuitable, since the relevant C=N stretching mode will be hidden by strong CH deformation modes of the solvent. 

Though not as common as double bonds, both carbon-carbon triple bonds (alkynes) and carbon-nitrogen triple bonds (nitriles) are important. Both occur in the 2,600-2,100 cm region of the spectrum. They are usually very sharp. The carbon-nitrogen triple bond tends to give a more intense peak than the alkyne peak. 

Structure H—C=N, a linear molecule with a carbon-nitrogen triple bond. Synonyms hydrocyanic acid prussic acid formonitrile... 

An analogue of the above transformations is the ring closure depicted in 3.33., which involves the formal addition of the phenylpalladium complex formed in the opening step of the catalytic cycle onto the carbon-nitrogen triple bond. In the above process o-methylamino-benzonitrile is also formed as by-product in 38% yield, indicating the presence of competing pathways.41... 

Of course, in all cases each carbon has a full octet of electrons. Carbon also forms double and triple bonds with several other elements that can exhibit a covalence of two or three. The carbon-oxygen (or carbonyl) double bond appears in carbon dioxide and many important organic compounds such as methanal (formaldehyde) and ethanoic acid (acetic acid). Similarly, a carbon-nitrogen triple bond appears in methanenitrile (hydrogen cyanide) and eth-anenitrile (acetonitrile). 

Exercise 11-6 a. Would you expect a carbon-nitrogen triple bond to be hydrogenated more, or less, easily than a carbon-carbon triple bond b. Why is it difficult to hydrogenate a tetrasubstituted alkene such as 2,3-dimethyl-2-butene ... 

Nitriles absorb with variable strength in the infrared in the region 2000 cm-1 to 2300 cm-1, due to stretching vibrations of the carbon-nitrogen triple bond. 

First, connect the carbon and nitrogen atoms. The only way the carbon can form four bonds and the nitrogen can form three bonds is if there is a carbon-nitrogen triple bond. 

The nitrile group in cyanopyridine can participate in intramolecular reactions. The presence in chalcone 118 of an ortho-hydroxyl substituent can lead to its addition to a carbon-nitrogen triple bond, with the formation of the 2/7-pyran-2-iminic moiety (compound 119) [126, 127] (Scheme 3.36). 

Carbon-nitrogen multiple bonds, Grignard additions, 9, 64 Carbon-nitrogen triple bonds... 

The carbon-nitrogen triple bond can also undergo ortho photocycloaddition to derivatives of benzene. Al-Jalal et al. [86] found that irradiation of 4-cyanoanisole in acrylonitrile produced three 1 1 adducts. Two of these were formed by the addition of the carbon-carbon double bond of acrylonitrile to positions 1,2 and 3,4, respectively, of 4-cyanoanisole. The third product was an aza-cyclooctatetraene, apparently formed by the addition of the carbon-nitrogen triple bond to the arene, followed by ring opening [87],... 

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