Functional class

The lUPAC rules permit alkyl halides to be named m two different ways called func twnal class nomenclature and substitutive nomenclature In functional class nomencla ture the alkyl group and the halide (fluoride chloride bromide or iodide) are desig nated as separate words The alkyl group is named on the basis of its longest continuous chain beginning at the carbon to which the halogen is attached... 

Substitutive names are preferred but functional class names are sometimes more convenient or more familiar and are frequently encountered m organic chemistry... 

Functional class names of alcohols are derived by naming the alkyl group that bears the hydroxyl substituent (—OH) and then adding alcohol as a separate word The chain IS always numbered beginning at the carbon to which the hydroxyl group is attached... 

Functional class names are part of the lUPAC system they are not common names... 

Write structural formulas or build molecular models and give the functional class and substitutive names of all the isomeric alcohols that have the molecular formula C4H10O... 

Substitutive name 2 Bromohexane Functional class name 1 Methylpentyl bromide... 

The substitutive names of alcohols are derived by replacing the e end mg of an alkane with ol The longest chain containing the OH group becomes the basis for the name Functional class names of alcohols begin with the name of the alkyl group and end m the word alcohol... 

Handbooks are notorious for listing compounds according to their common names One gives the name sec isoamyl alcohol for a compound which could be called 1 2 dimethylpropyl alcohol according to the lUPAC functional class rules The best name for this compound is the substitutive lUPAC name What is it" ... 

Wnte structural formulas or build molecular models for all the constitutionally isomenc alcohols of molecular formula C5H12O Assign a substitutive and a functional class name to each one and specify whether it is a pnmary secondary or tertiary alcohol... 

The group H2C=CHCH2 — IS known as allyT which IS both a common name and a permissible lUPAC name It is most often encountered m functionally substituted deriv atives and compounds containing this group are much better known by their functional class lUPAC names than by their substitutive ones... 

Ethers are named m substitutive lUPAC nomenclature as alkoxy derivatives of alkanes Functional class lUPAC names of ethers are derived by listing the two alkyl groups m the general structure ROR m alphabetical order as separate words and then adding the word ether at the end When both alkyl groups are the same the prefix di precedes the name of the alkyl group... 

Substitutive lUPAC name Functional class lUPAC name... 

Section 16 1 Ethers are compounds that contain a C—O—C linkage In substitutive lUPAC nomenclature they are named as al/coxy derivatives of alkanes In functional class lUPAC nomenclature we name each alkyl group as a separate word (m alphabetical order) followed by the word ether... 

Substitutive lUPAC name 1 Methoxyhexane Functional class name Hexyl methyl ether... 

Sulfides are sulfur analogs of ethers they contain the C—S—C func tional group They are named as al/cylthw derivatives of alkanes m sub stitutive lUPAC nomenclature The functional class lUPAC names of sul tides are derived m the same manner as those of ethers but the concluding word is sulfide... 

Although substitutive names of the type just described are preferred the lUPAC rules also permit ketones to be named by functional class nomenclature The groups attached to the carbonyl group are named as separate words followed by the word ketone The groups are listed alphabetically... 

There are no functional class names for aldehydes in the lUPAC system... 

Convert each of the following functional class lUPAC names to a substitutive name... 

Ketones may also be named using functional class lUPAC nomenclature by citing the two groups attached to the carbonyl m alphabetical order followed by the word ketone Thus 3 methyl 2 butanone (substitutive) becomes isopropyl methyl ketone (functional class)... 

Substitutive lUPAC names for nitriles add the suffix nitrile fo fhe name of fhe parenf hydrocarbon chain fhaf includes fhe carbon of fhe cyano group Nifriles may also be named by replacing the ic acid or oic acid ending of the corresponding carboxylic acid with omtrile Alternatively they are sometimes given functional class lUPAC names as alkyl cyanides... 

Substitutive name Functional class names 1 Chlorobutane n Butyl chloride or butyl chloride 2 Chlorobutane sec Butyl chloride or 1 methylpropyl chloride... 

Substitutive name Functional class names 1 Butanol n Butyl alcohol or butyl alcohol 2 Butanol sec Butyl alcohol or 1 methylpropyl alcohol... 

Frosts circle (Section 11 19) A mnemonic that gives the Huckel TT MOs for cyclic conjugated molecules and 10ns Functional class nomenclature (Section 4 2) Type of lUPAC nomenclature in which compounds are named according to functional group families The last word in the name... 

Table 1.9 Functional Class Names Used in Radicofunctional Nomenclature 1.22...

In order of decreasing priority for citation of a functional class name, and the prefix for substitutive nomenclature, are the following related compounds ... 

Table 4. Comparison of Performance of Materials by Functional Class...

It is possible to regard radicofunctional nomenclature, in which the functional class narrie of a compound (c.g. alcohol, ketone, etc.) is cited after the names of the attached radicals, as involving an additive procedure (example 146). This type of nomenclature is gradually falling out of use in favor of the substitutive equivalent [for 146 the substitutive name would be l-(3-pyridyl)propan-l-one]. 

Eortunately, a 3D model does not have to be absolutely perfect to be helpful in biology, as demonstrated by the applications listed above. However, the type of question that can be addressed with a particular model does depend on the model s accuracy. At the low end of the accuracy spectrum, there are models that are based on less than 25% sequence identity and have sometimes less than 50% of their atoms within 3.5 A of their correct positions. However, such models still have the correct fold, and even knowing only the fold of a protein is frequently sufficient to predict its approximate biochemical function. More specifically, only nine out of 80 fold families known in 1994 contained proteins (domains) that were not in the same functional class, although 32% of all protein structures belonged to one of the nine superfolds [229]. Models in this low range of accuracy combined with model evaluation can be used for confirming or rejecting a match between remotely related proteins [9,58]. 

Proteins are usually separated into two distinct functional classes passive structural materials, which are built up from long fibers, and active components of cellular machinery in which the protein chains are arranged in small compact domains, as we have discussed in earlier chapters. In spite of their differences in structure and function, both these classes of proteins contain a helices and/or p sheets separated by regions of irregular structure. In most cases the fibrous proteins contain specific repetitive amino acid sequences that are necessary for their specific three-dimensional structure. 

The basic structure of all immunoglobulin (Ig) molecules comprises two identical light chains and two identical heavy chains linked together by disulfide bonds (Figure IS.2a). There are two different classes, or isotypes, of light chains, X and k, but there is no known functional distinction between them. Heavy chains, by contrast, have five different isotypes that divide the immunoglobulins into different functional classes IgG, IgM, IgA, IgD, and IgE, each with different effector properties in the elimination of antigen... 

Substitutive names are prefened, but functional class nanes are sometimes more convenient or more ffflniliar and are frequently encountered in organic chemistry. 

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