Functional groups, organic with triple bonds

Let us start out by a few comments about the terms used to describe carbon skeletons encountered in organic molecules. When considering a hydrocarbon (i.e., a compound consisting of only C and H) or a hydrocarbon group (i.e., a hydrocarbon substituent) in a molecule, the only possible functionalities are carbon-carbon double and triple bonds. A carbon skeleton is said to be saturated if it has no double or triple bond, and unsaturated if there is at least one such bond present. Hence, in a hydrocarbon, the term saturated indicates that the carbon skeleton contains the maximum number of hydrogen atoms compatible with the requirement that carbon always forms four bonds and hydrogen one. A saturated carbon atom is one that is singly bound to four other separate atoms. 

Skeletal formula The representation of an organic compound s carbon-to-carbon bonds by lines. A single line represents a single bond with double and triple lines for double and triple bonds, respectively. The carbon-to-hydrogen bonds are assumed but not shown apart from the outline, but other functional groups or elements use their conventional representation. 

A complete dichotomy between bond order and other functionality. This is in contrast to IUPAC s organic nomenclature, which uses morphemic suffixes to specify both degree of bond unsaturation (ane, -ene, and -yne), and also selected functional groups (-one, -al, etc.). In the proposed system, on the other hand, the individual chemical symbols for atoms alternate with bond descriptors (small integers or selected symbols). In particular, traditional single, double and triple bonds are... 

In Chapter 11 we continue our focus on organic molecules with electron-rich functional groups by examining alkynes, compounds that contain a carbon-carbon triple bond. Like alkenes, alkynes are nucleophiles with easily broken n bonds, and as such, they undergo addition reactions with electrophilic reagents. 

A polyfunctional organic molecule can contain many different kinds of functional groups, but for nomenclature purposes, we must choose just one suffix. It s not correct to use two sufhxes. Thus, keto ester 3 must be named either as a ketone with an -one. suffix or as an ester with an -oate suffix but can t be named as an -onoate. Similarly, amino alcohol 4 must be named either as an alcohol (-ol) or as an amine i-amine) but can t properly be named as an -olamine. The only exception to this rule is in naming compounds that have double or triple bonds. For example, the unsaturated acid H2C=CHCH2C00H is 3-butenoic acid, and the acetylenic alcohol HCSCCH2CH2CH2CH2OH is 5-hexyn-l-ol. 

One of die most popular reactions in organic chemistry is dissolving metal reductions [1-3], Two systems are frequently used - sodium dissolved in ammonia with alcohol and lithium dissolved in alkylamines [4]. Although calcium is seldom used, it has been successfully applied to the reduction of a variety of compounds and functional groups [5], including aromatic hydrocarbons, carbon-carbon double and triple bonds, benzyl ethers, allyl ethers, epoxides, esters, aliphatic nitriles, dithianes, als well as thiophenyl and sulfonyl groups. 

However, if we are to understand and classify the varied bonding models in metallo-organics, then the systematic analysis of crystallographic results for carefully chosen classes and subclasses of these compounds represents an essential starting point. Indeed, crystal structure analysis has underpinned the rapid developments in metallo-organic chemistry, particularly over the past 10-15 years, to the extent that some 48% of CSD entries now fall into this category. For these reasons, no modern review of triple-bonded functional groups would be complete without some consideration of their interaction with metal centres. 

The triple bonded organic functional groups considered in the present chapter are —CC—, —CN, —CNO (nitrile oxide), —OCN, —SCN and —N2. Some isomeric functions such as —NC, —NCO and —NCS, will also be included, as they sometimes occur together with their isomers. The general aspects and specific methods for the analysis of alkynes, nitriles, diazonium compounds, cyanates and thiocyanates, and other related functional groups were adequately described in previous books of the series The Chemistry of Functional Groups, Consideration was made there of detection and determination by means of chemical reactions and application of characteristic spectroscopic properties of the groups. 

Keep in mind that double and triple bonds between two carbon atoms are considered functional groups even though only carbon and hydrogen atoms are involved. By learning the properties associated with a given functional group, you can predict the properties of organic compounds for which you know the structure, even if you have never studied them. 

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