Priorities chains

When the first point of difference contains two or more identical atoms, proceed atom by atom down the highest priority chain to the next point of difference and apply rules 1,2 or 3 to determine the priority. 

In 47, the methyl and hydrogen are assigned the priorities (c) and (d). To determine the a and b priorities we must focus on the two arms that contain OCH. The highest priority chain is along C-O-C (the oxygen chain), but both groups are They are identical and we cannot use them to establish the priority. 

If the same alkyl group occurs more than once as a side chain, this is indicated by the prefixes di-, tri-, tetra-, etc. Side chains are cited in alphabetical order (before insertion of any multiplying prefix). The name of a complex radical (side chain) is considered to begin with the first letter of its complete name. Where names of complex radicals are composed of identical words, priority for citation is given to that radical which contains the lowest-numbered locant at the first cited point of difference in the radical. If two or more side chains are in equivalent positions, the one to be assigned the lowest-numbered locant is that cited first in the name. The complete expression for the side chain may be enclosed in parentheses for clarity or the carbon atoms in side chains may be indicated by primed locants. 

Unsaturated branched acyclic hydrocarbons are named as derivatives of the chain that contains the maximum number of double and/or triple bonds. When a choice exists, priority goes in sequence to (1) the chain with the greatest number of carbon atoms and (2) the chain containing the maximum number of double bonds. 

Should there be a choice for the fundamental straight chain of a radical, that chain is selected which contains (1) the maximum number of double and triple bonds, (2) the largest number of carbon atoms, and (3) the largest number of double bonds. These are in descending priority. 

Acyl Halides. Acyl halides, in which the hydroxyl portion of a carboxyl group is replaced by a halogen, are named by placing the name of the corresponding halide after that of the acyl radical. When another group is present that has priority for citation as principal group or when the acyl halide is attached to a side chain, the prefix haloformyl- is used as, for example, in fiuoro-formyl-. 

In the last three chapters we have examined the mechanical properties of bulk polymers. Although the structure of individual molecules has not been our primary concern, we have sought to understand the influence of molecular properties on the mechanical behavior of polymeric materials. We have seen, for example, how the viscosity of a liquid polymer depends on the substituents along the chain backbone, how the elasticity depends on crosslinking, and how the crystallinity depends on the stereoregularity of the polymer. In the preceding chapters we took the existence of these polymers for granted and focused attention on their bulk behavior. In the next three chapters these priorities are reversed Our main concern is some of the reactions which produce polymers and the structures of the products formed. 

Because the rules for organic nomenclature determine the priority of naming different carbon chains from their relative lengths, the systematic names for type AABB polyamides depend on the relative length of the carbon chains between the amide nitrogens and the two carbonyl functions of the polymer for aUphatic nylon-Ayy, when x < the lUPAC name is poly[imino-R imino(l2y-dioxo-R )]. When x > then the name is... 

The sulfur atom in the -CH2SH group of cysteine makes the side chain higher in priority than the -C02H group. 

The functional group has priority in numbering over hydrocarbon side chains. 

This is a modified form of the 1980 recommendations [4]. Priority is now given to naming cyclic forms, since in most cases branched-chain monosaccharides will form cyclic hemiacetals or hemiketals. 

First we need to find the functional group and make sure that the functional group is connected directly to the parent chain. Remember from the last section that if there are two functional groups, one of them gets priority. The functional group that gets priority is the one that needs to be connected to our parent chain. Of the three possibilities shown above, this rule eliminates the last possibility, because the functional group (OH) is not connected directly to the parent chain. 

Answer First we look for a functional group. This compound is a carboxylic acid, so we know the parent chain must include the carboxylic acid group. Next we look for a double bond. The parent chain should include that as weU. This gives us our answer. The triple bond will not be included in the parent chain, because the functional group and the double bond are a higher priority than a triple bond. 

Availability constraints the macroscopic limits on material resources and the availability or up-time of equipment. Availability of raw materials is an obvious constraint at scheduling. Obviously, no catalytic hydrogenation can be done if the catalyst is unavailable. Simultaneous operation of certain tasks is restricted by the limited availability of common utilities such as steam, electricity, or labour. The priority sequence in a product chain needs to be respected by ensuring that intermediate products are manufactured in time to be available when required by a batch of the consecutive product. 

Furthermore, the EU regularly produces and regularly updates the list of substances of high concern, i.e. the SVHC list. The identification of a substance as a SVHC and its inclusion in the candidate list is the first step of the authorization procedure. The European Chemical Agency in Helsinki identifies from the candidate list priority substances to be included in Annex XIV of REACH (the authorisation list). The substances on the candidate list will most probably be liable to stricter regulation in the future (authorisation/banning) which will stimulate the substitution of these chemicals. Currently in June 2012, there are 84 substances included in the candidate list. Examples of chemicals on the candidate list which may be relevant for the leather industry are phenolphthalein, boric acid, cobalt dichloride, dichromate (although not used by leather industry), phthalates (DEHP, DBP and BBP), acrylamide and short-chain chlorinated paraffins. 

The health of the population is closely related to the environmental situation in industrial areas. Heavy metals were the priority contaminators in large industrial centers of Ukraine for a long period of time [1]. They penetrated into the environment inside industrial wastes, and then circulate in trophic chains and reside in tissues of plants, animals, and humans. Our previous analyses showed that soil Zn deficiencies... 

The ring systems are treated as branched chains and phenyl group is treated for the purpose of determining its priority as though it had one of the Kekule s structures... 

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