The present invention generally relates to organic chemistry and synthesis.
[002] More particularly, the present invention relates to Electrophilic & Nucleophilic substitution mechanisms for Halogenation. The introduction or replacement of substituent’s on aromatic rings by substitution reactions is one of the most fundamental transformations in organic electrophilic and nucleophilic substitution mechanisms.

BACKGROUND FOR THE INVENTION:
[003] The replacement of an atom, generally hydrogen, or a group attached to the carbon from the benzene ring by another group is known as aromatic substitution. The regioselectivity of these reactions depends upon the nature of the existing substituent and can be ortho, Meta or Para selective.
[004] By reference of US application no. US3957823A by BASF SE dated 1973-04-12, titled” Electrophilic substitution of nitrosamines” discloses a process for the electrophilic substitution of nitrosamines on the carbon atom in the a-position to the amino nitrogen by metalizing the nitrosamine of a secondary amine and then reacting it with an electrophilic reagent.
[005] By the reference of US application no. US6399835B1 by Bromine Compounds Ltd dated 2000-04-06, titled” Process for electrophilic aromatic substitution” discloses processes for the electrophilic substitution of aromatic compounds, such as alkylation, with the desired substituent are disclosed. The processes include contacting the aromatic compound, a precursor of the desired substituent, and an aqueous reagent containing zinc halide at elevated temperatures such as above 50° C.
[006] By the reference of CZ application no. CZ20001284A3 by Bromine Compounds Ltd. dated 1998-10-08, titled” Electrophilic substitution process of aromatic compounds” discloses a method of electrophilic substitution on an aromatic compound at wherein the aromatic compound, the precursor, is contacted the desired substituent and the aqueous reacting agent containing zinc halide at a temperature above 50 ° C. Preferred electrophilic aromatic substitution reactions are selected among halogenation, acylation reactions. If the reaction is alkylation, then the aqueous reagent contains zinc bromide, an alkali metal or alkaline metal bromide salt soils, preferably LiBr, and an acid. An important sign of the process is to use an aqueous reagent containing zinc halide as the primary medium for electrophilic aromatic substitution.
[007] By the reference of PCT application no. PCT/US1989/005315 by Exxon Chemical Patents Inc. dated 1989-11-22, titled” Functionalized copolymers of para-alkylstyrene /isoolefin prepared by nucleophilic substitution” discloses a functionalized polymer of an isoolefin having about 4 to about 7 carbon atoms and a para-alkylstyrene, wherein at least one type of a functional group is attached to the para-alkyl group of the para-alkyl styrene, said polymer having a substantially homogeneous compositional distribution.
[008] By the reference of CA application no. CA1177085A by Ethyl Corp dated 1982-10-15, titled” Nucleophilic substitution process” discloses Nitroarylacetic acid esters are prepared by reacting a nitroaromatic compound with an alpha,alpha-disubstituted acetic acid ester in a substantially anhydrous aprotic solvent and in the presence of a base so that the ester undergoes a nucleophilic substitution on an unsubstituted ring carbon of the nitroaromatic compound during which alpha-substituent functions as a leaving group. The nitro arylacetic acid esters formed by the process can be readily converted into derivatives, such as pharmaceuticals.
[009] By the reference of CA application no. CA1177086A by Ethyl Corp dated 1982-10-27, titled” Nucleophilic substitution process” discloses Nitroaralkyl cyanides are prepared by reacting a nitroaromatic compound with an alpha,alpha-disubstituted acetonitrile in a substantially anhydrous aprotic solvent and in the presence of a base so that the nitrile undergoes a nucleophilic substitution on an unsubstituted ring carbon of the halonitro aromatic compound during which an alpha-substituent functions as a leaving group. The nitroaralkyl cyanides formed by the process can be readily converted into derivatives, such as pharmaceuticals.
[010] By the reference of CA application no. CA1177087A by Ethyl Corp dated 1982-10-27, titled” Nucleophilic substitution process” discloses Nitroaralkyl cyanides are prepared by reacting a nitroaromatic compound with an alpha,alpha-disubstituted acetonitrile in a substantially anhydrous aprotic solvent and in the presence of a base so that the nitrile undergoes a nucleophilic substitution on an unsubstituted ring carbon of the halonitro aromatic compound during which an alpha-substituent functions as a leaving group. The nitroaralkyl cyanides formed by the process can be readily converted into derivatives, such as pharmaceuticals.
[011] By the reference of CA application no. CA1177084A by Ethyl Corp dated 1982-10-15, titled” Nucleophilic substitution process” discloses Nitroarylucetic acid esters are prepared by reacting a nitroaromatic compound with an alpha,alpha-disubstituted acetic acid ester in a substantially anhydrous aprotic solvent and in the presence of a base so that the ester undergoes a nucleophilic substitution on an unsubstituted ring carbon of the nitroaromatic compound during which alpha-substituent functions as a leaving group. The nitrourylacetic acid esters formed by the process can be readily converted into derivatives, such as pharmaceuticals.
[012] By the reference of EP application no. EP0751925A1 by the University of Leeds dated 1995-03-23, titled” Electrophilic substitution of triphenylene-based discotic liquid crystals” discloses a triphenylene such as Hexa-ß-substituted hexyloxy triphenylene is a-substituted by an electrophile in mixed polar cosolvents according to the reaction.
[013] The problem in the production of polymer and drugs is mostly related to Electrophilic & Nucleophilic substitution and Halogenation. So there is a need for an Electrophilic & Nucleophilic substitution mechanism for Halogenation.
[014] However, none of the above-discussed inventions provides such Electrophilic & Nucleophilic substitution consists of an electrophilic substitution reaction; a Nitration reaction; Nucleophilic Aromatic Substitution.

OBJECTS OF THE INVENTION:
[015] The main object of the present invention is to provide an Electrophilic & Nucleophilic substitution mechanism for Halogenation consisting of an electrophilic substitution reaction; a Nitration reaction; Nucleophilic Aromatic Substitution.
[016] Another object of the invention is to provide an electrophilic substitution.
[017] Another object of the invention is to provide a Nucleophilic substitution mechanism.
[018] Another object of the invention is to provide a s and p Complex in electrophilic substitution.
[019] Another object of the invention is to provide a Nitration Reaction.
[020] Another object of the invention is to provide a halogen onto aromatic rings by electrophilic substitution.
[021] Another object of the invention is to provide a bimolecular nucleophilic substitution reaction in which the substrate is attacked at a saturated carbon atom, the starting material has a tetrahedral structure, and the transition state has a trigonal bipyramidal structure.
[022] Another object of the invention is to provide Substitution by the addition-elimination mechanism
[023] Another object of the invention is to provide Substitution by the SRN1 mechanism

SUMMARY OF THE INVENTION:
[024] According to one aspect of our invention, an Electrophilic & Nucleophilic substitution mechanism for Halogenation consist of an electrophilic substitution reaction; a Nitration reaction; Nucleophilic Aromatic Substitution.
[025] In another aspect of the invention, an Electrophilic substitution reaction that comprises two steps: 1) In the first step, the electrophilic reagent attacks on the p electrons of the aromatic ring to form an intermediate which is known as aronium cation, the sigma complex, or the pentadienyl cation. 2) The second step of the reaction involves the elimination of a proton from the intermediate, by an anionic species, to form a substituted aromatic compound.
[026] In another aspect of the invention, Nitration reaction and it is carried out with a mixture of HNO3 and H2SO4 (nitrating agent) the reaction proceeds very slowly when HNO3 alone is used which indicate that H2SO4 converts the HNO3 into a form that is capable of reacting with benzene with great ease.
[027] In another aspect of the invention, Nucleophilic Aromatic Substitution, the replacement of hydrogen or substitution by a nucleophilic reagent is known as nucleophilic aromatic substitution wherein It doesn’t take place with the benzene itself but with its some substituted derivatives and with naphthalene. Synthetically important substitutions of aromatic compounds can also be done by nucleophilic reagents.
[028] In another aspect of the invention, Aryl diazonium ions as synthetic intermediates the first widely used intermediates for nucleophilic aromatic substitution were the aryl diazonium salts.

BRIEF DESCRIPTION OF DRAWINGS:
[029] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
[030] Figure 1: illustrates the addition of a nucleophile to an aromatic ring, followed by elimination of substituent results in nucleophilic substitution, as per an embodiment of the present invention
[031] Figure 2: illustrates vicarious nucleophilic aromatic substitution, as per an embodiment of the present invention.
[032] Figure 3: illustrates a Benzyne molecule that sideways overlaps pi sp2 orbitals a sigma bond out of the plane of the aromatic sigma-cloud, as per an embodiment of the present invention.
[033] Figure 4: illustrates an abstraction of hydrogen ion by the amide ion to form NH3 and Carbanion, as per an embodiment of the present invention.
[034] Figure 5: illustrates a Carbanion loss halide ion to form benzyne, as per an embodiment of the present invention.
[035] Figure 6: illustrates a reaction with Li-Hg or magnesium that results in the formation of transient organometallic compounds that decompose with the elimination of lithium halide, as per an embodiment of the present invention.
[036] Figure 7: illustrates a Diazotization of o-amino benzoic acid, as per an embodiment of the present invention.
[037] Figure 8: illustrates the Oxidation of 1-amino benzotriazole, as per an embodiment of the present invention.
[038] Figure 9: illustrates benzothiadiazide-1, 1-dioxide, as per an embodiment of the present invention.
[039] Figure 10: illustrates a dienes cycloaddition products are formed, as per an embodiment of the present invention.

BRIEF DESCRIPTION OF INVENTION:
[040] The present invention will now be described hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. While the following description details the preferred embodiments of the present invention is not limited in its application to the details of construction and arrangement of the parts illustrated in the accompanying drawings. With reference to the figures, the enclosed description and drawings are merely illustrative of preferred embodiments and represent several different ways of configuring the present invention. Although specific components, materials, configurations and uses of the present invention are illustrated and set forth in this disclosure, it should be understood that a number of variations to the components and to the configuration of those components described herein and in the accompanying figures can be made without changing the scope and function of the invention set forth herein.
[041] The present invention proposes an Electrophilic & Nucleophilic substitution mechanism for Halogenation consisting of an electrophilic substitution reaction; a Nitration reaction; Nucleophilic Aromatic Substitution.
[042] In another embodiment, Electrophilic Aromatic Substitution (EAS) reactions are important for synthetic purposes and are also among the most thoroughly studied classes of organic reactions from a mechanistic point of view.
[043] In another embodiment, a wide variety of electrophiles can affect aromatic substitution. Usually, it is a substitution of some other group for hydrogen that is of interest, but this is not always the case. For example, both silicon and mercury substituents can be replaced by electrophiles. The reactivity of a particular electrophile determines which aromatic compounds can be successfully substituted. Despite the wide range of electrophilic species and aromatic ring systems that can undergo substitution, a single broad mechanistic picture encompasses most EAS reactions.
[044] In another embodiment, the identity of the rate-determining step and the shape of the reaction energy profile is specific to individual reactions, but the sequence of steps and the nature of the intermediates are very similar across a wide range of reactivity.
[045] In another embodiment the invention provides an electrophilic substitution reaction that comprises two steps: 1) In the first step, the electrophilic reagent attacks on the p electrons of the aromatic ring to form an intermediate which is known as aronium cation, the sigma complex, or the pentadienyl cation. 2) The second step of the reaction involves the elimination of a proton from the intermediate, by an anionic species, to form a substituted aromatic compound.
[046] In another embodiment, the invention provides a reaction of the benzene nucleus in the product confers stability to the substituted product. Thus, the electrophilic aromatic substitution reactions are bimolecular since the rate-determining (first) step involves two-step mechanisms.
[047] In another embodiment, the invention provides the role of s and p Complex in Electrophilic Aromatic Substitution. Wherein formation of s complex follows the initial formation of a p complex in which electrophile is loosely held near the p-electron cloud of the aromatic ring, however, in most of the aromatic substitution, formation of a p-complex is found to be a reversible and rapid step which is followed by the slow (rate-determining) and irreversible step of s complex formation.
[048] In another embodiment, the invention provides a Nitration reaction and it is carried out with a mixture of HNO3 and H2SO4 (nitrating agent) the reaction proceeds very slowly when HNO3 alone is used which indicate that H2SO4 converts the HNO3 into a form that is capable of reacting with benzene with great ease. Evidence shows that H2SO4 helps in converting the HNO3 into nitronium ion which is the real nitrating agent. Like H2SO4 other strong acids (ex., BF3, HF) also serve the purpose.
Note:
? H2SO4 has no action on benzene itself under the conditions of nitration.
? Presence of NO + in the mixture has been confirmed by the Raman spectra.
? NO +is a powerful electrophile that attacks on the benzene ring.
? Each successive nitro group reduces the reactivity of the ring; it is easy to control conditions to obtain a mono nitration product, if poly nitration is desired more vigorous conditions are required.
[049] In another embodiment, the invention provides the effect of solvent. In CH3COOH and CH3NO2 formation of NO + is often the rate-controlling step. HNO3 in acetic anhydride (CH3CO)2O generates acetyl nitrate which gives high ortho: para ratios. A convenient procedure involves the reaction of the aromatic in chloroform or dichloromethane with a nitrate salt and trifluoroacetic anhydride. Presumably, trifluoroacety nitrate is generated under these conditions. (CH3CO)2O and (CF3CO)2O have been used in conjugation with HNO3 and zeolite-ß which gives excellent para selectivity. The improved selectivity is thought to occur as a result of nitration within the zeolite pores which may restrict access to the ortho-position.
[050] In another embodiment, Nitration can be catalyzed by lanthanide salts. For example, the nitration of benzene, toluene, and naphthalene by aqueous nitric acid proceeds in good yield in the presence of Yb(O3SCF3)3. The catalysis presumably results from an oxyphilic interaction of nitrate ion with the cation, which generates or transfers the NO + ion. This catalytic procedure uses a stoichiometric amount of nitric acid and avoids the excess strong acidity associated with conventional nitration conditions.
[051] In another embodiment, Catalysis results form an oxyphilic interaction of nitrate ion with the cation, which generates or transfers the NO + ion. This catalytic procedure uses a stoichiometric amount of nitric acid and avoids the excess strong acidity associated with the conventional nitration condition.
[052] In another embodiment, Salts containing the nitronium ion can be prepared and are reactive nitrating agents. The tetrafluroborate salt has been used most frequently, but the trifluromethane sulphonate can also be prepared readily, nitrogen heterocycles(pyridine, quinoline) form N-nitro salts on reaction with NO2BF4. These N-nitro heterocycles can act as nitrating reagents in a reaction called transfer nitration.
[053] In another embodiment, Compounds such as phenyl acetate esters and phenyl ethyl ethers, which have oxygen substituents that can serve as directing groups, show high ortho: para ratios under these conditions. These reactions are believed to involve coordination of the NO + at the substituent oxygen, followed by intramolecular transfer. Chlorine and bromine are reactive toward aromatic hydrocarbons, but Lewis acid catalysts are normally needed to achieve desirable rates. Elemental fluorine reacts very exothermically and careful control of conditions is required. Molecular iodine can effect substitution only on very reactive aromatics, but a number of more reactive iodination reagents have been developed. It takes place in the presence of a catalyst a halogen carrier such as iron powder, FeCl3, ZnCl2, AlBr3, iodine, pyridine etc. The function of the catalyst is to facilitate the formation of the electrophile, halonium ion Lewis Acid facilitates cleavage of halogen bond.
[054] In another embodiment, Rate studies show that chlorination is subject to acid catalysis, although the kinetics are frequently complex. It is much more rapid in polar than in non-polar solvents. N-Bromosuccinimide (NBS) and N-chlorosuccinimide (NCS) are alternate halogenating agents, both of which can halogenate moderately active aromatics in nonpolar solvents by using HCl or HClO4 as a catalyst. Halogenations are strongly catalysed by mercuric acetate or trifluroacetate which generate acylhypohalites which are the active halogenating agents. The trifluoroacetyl hypohalites are very reactive reagents. Even nitrobenzene, for example, is readily brominated by trifluoroacetyl hypobromite.
[055] In another embodiment the invention provides Halogenation. The halogens onto aromatic rings by electrophilic substitution is an important synthetic procedure is also a reactive brominating agent. Fluorination can be carried out using fluorine diluted with an inert gas. However, great care is necessary to avoid an uncontrolled reaction. Acetyl hypofluorite can be prepared in situ from fluorine and sodium acetate. It shows a strong preference for o-fluorination of alkoxy and acetamide-substituted rings. N-Fluoro-bis-(trifluoromethansulfonyl) amine (N-fluorotriflimide) display similar reactivity and can fluorinate benzene and activated aromatics.
[056] In another embodiment iodination,’s can be carried out by mixtures of iodine and various oxidants such as periodic acid, I2O5, NO2, and Ce(NH3)2(NO3)6. A mixture of cuprous iodide and a cupric salt can also affect iodination.
[057] In another embodiment, the invention provides iodination of moderately reactive aromatics that can be affected by mixtures of iodine and silver or mercuric salts. Hypoiodites are presumably the active iodinating species. Bis-(pyridine) iodonium salts can iodinate benzene and activated derivatives in the presence of strong acids such as HBF4 or CF3SO3H. Some representative Halogenations reactions.
[058] In another embodiment, the invention provides Friedel-Crafts Alkylation. Friedel-Crafts alkylation reactions are an important method for introducing carbon substituents on aromatic rings. The reactive electrophiles can be either discrete carbocation or polarized complexes that contain a reactive leaving group. Various combinations of reagents can be used to generate alkylating species. Alkylations usually involve alkyl halides and Lewis acids or reactions of alcohols or alkenes with strong acids.
[059] In another embodiment the invention provides owing to the involvement of carbonation’s, Friedel-Crafts alkylation’s can be accompanied by rearrangement of the alkylation group. For example, isopropyl groups are often introduced when n-propyl reactants.
[060] In another embodiment, Alkyl groups can also migrate from one position to another on the ring. Such migrations are also thermodynamically controlled and proceed in the direction of minimizing steric interactions between substitutions.
[061] In another embodiment, Methane sulfonate esters of secondary alcohols also give Friedel- crafts products in the presence of Sc(O3SCF3)3 or Cu(O3SCF3)2.
[062] In another embodiment, Friedel-crafts alkylation can occur intramolecular to form a fused ring. Intramolecular Friedel-Crafts reactions provide an important method for constructing polycyclic hydrocarbon frameworks. It is somewhat easier to form six-member than five-member rings in such reactions as depicted.
[063] In another embodiment, Friedel-Craft Acylation, it involves the reaction of acid-chlorides or anhydrides in presence of Lewis acids such as AlCl3, SbF5, or BF3. Bismuth (III) triflate is also a very active Acylation catalyst. For example, a combination of hafnium (IV) triflate and LiClO4 in nitromethane catalyzes acylation of moderately reactive aromatics by acetic-anhydride.
[064] In another embodiment, mixed anhydrides with trifluoroacetic acid are reactive acylating agents. The use of a mixed anhydride in the course of synthesis of the anticancer agent tamoxifen.
[065] In another embodiment, regioselectivity in Friedel-crafts acylation can be quite sensitive to reaction solvent. In general para, attack predominates for alkylbenzenes. The percentage of ortho attack increases with the electrophilicity of the acylium-ion. Moreover, by this method, no rearranged alkylated product (ex., Cumene) is formed.
[066] In another embodiment, Nucleophilic Aromatic Substitution, the replacement of hydrogen or substitution by a nucleophilic reagent is known as nucleophilic aromatic substitution. It doesn’t take place with the benzene itself but with its some substituted derivatives and with naphthalene. Synthetically important substitutions of aromatic compounds can also be done by nucleophilic reagents. There are several general mechanisms for substitution by nucleophiles. Unlike nucleophilic substitution at saturated carbon, aromatic nucleophilic substitution does not occur by a single-step mechanism. The broad mechanistic classes that can be recognized include addition-elimination, elimination-addition, and metal-catalyzed processes.
[067] In another embodiment, unimolecular nucleophilic substitution reactions proceed by a two-stage mechanism in which heterolysis precedes reaction with the nucleophileex, uncatalysed decomposition of aryl diazoniumcation. The unimolecular reaction is characterized experimentally by first-order kinetics-i.e., by a rate that depends only on the concentration of the substrate (and not the nucleophile), by the absence of effects of steric hindrance, by powerful facilitation of the reaction by the presence of electron-releasing groups attached to the reaction center, and by variable, and often diagnostic, stereochemistry.
[068] In another embodiment, bimolecular nucleophilic substitution reactions in which the substrate is attacked at a saturated carbon atom, the starting material has a tetrahedral structure, and the transition state has a trigonal bipyramidal structure. The mechanism of this reaction is characterized by the entry of the nucleophilic reagent from one side of the substrate molecule and the departure of the ion from the other side.
[069] The present invention as illustrated in Figure 1 provides another embodiment of the invention which includes a nucleophile to an aromatic ring, followed by elimination of substituent results in nucleophilic substitution. The addition of a nucleophile to an aromatic ring, followed by elimination of substituent results in nucleophilic substitution (Figure 1). The addition-elimination mechanism has been used for arylation of oxygen and nitrogen nucleophiles. The pyridine family of heteroaromatic nitrogen compounds is reactive toward nucleophile substitution at the C(2) and C(4) positions. The nitrogen atom serves to activate the ring towards nucleophilic attack by stabilizing the addition intermediate this kind of substitution reaction is especially important in the chemistry of pyrimidines.
[070] The present invention as illustrated in Figure 2 provides another embodiment of the invention which includes a vicarious nucleophilic aromatic substitution. A variation of the aromatic nucleophile substitution process in which the leaving group is front of the entering nucleophile has been developed and known as vicarious nucleophilic aromatic substitution (Figure 2).

Substitution by the elimination-addition mechanism:
[071] The present invention as illustrated in Figure 3 provides another embodiment of the invention which includes a Benzyne molecule that sideways overlaps pi sp2 orbitals a sigma bond out of the plane of the aromatic sigma-cloud. Figure 3: illustrates a Benzyne molecule that sideways overlaps pi sp2 orbitals a sigma bond out of the plane of the aromatic sigma-cloud, as per an embodiment of the present invention. In another embodiment, the elimination-addition mechanism involves a highly unstable intermediate called dehydrobenzene or benzyne.
[072] In another embodiment, a unique feature of this mechanism is that the entering nucleophile doesn't necessarily become bound to the carbon to which the leaving group was attached.
[073] In another embodiment, a new bond orbital lies along the side of the ring and has little interaction with the sigma cloud lying above and below the ring. The sideways overlap isn't very good, so the bond is weak and benzyne is highly reactive molecule.
[074] The present invention as illustrated in Figure 4 provides another embodiment of the invention which includes an abstraction of hydrogen ion by the amide ion to form NH3 and Carbanion. In another embodiment, Benzyne formation elimination step involves two steps:
(1) Abstraction of hydrogen ion by the amide ion to form NH3 and Carbanion (Figure 4).
(2) Carbanion loss halide ion to form benzyne (Figure 5).
[075] The present invention as illustrated in Figure 5 provides another embodiment of the invention which includes a Carbanion loss halide ion to form benzyne.
[076] In another embodiment, Addition steps also involve two steps:
(a) Attachment of amide ion to form carbanion.
(b) Carbanion abstracts a hydrogen ion form acid, NH3.
[077] The present invention as illustrated in Figure 6 provides another embodiment of the invention which includes a reaction with Li-Hg or magnesium that results in the formation of transient organometallic compounds that decompose with the elimination of lithium halide.
[078] The present invention as illustrated in Figure 7 provides another embodiment of the invention which includes a Diazotization of o-amino benzoic acid.
[079] The present invention as illustrated in Figure 8 provides another embodiment of the invention which includes an Oxidation of 1-amino benzotriazole.
[080] The present invention as illustrated in Figure 9 provides another embodiment of the invention which includes a benzothiadiazide-1, 1-dioxide.
[081] In another embodiment, there are several methods for Benzyne generation such as;
(1) Benzyne can also be generated from o-dihaloaromatic. Reaction with Li-Hg or magnesium results in the formation of transient organometallic compounds that decompose with the elimination of lithium halide (Figure 6).
(2) Diazotization of o-amino benzoic acid, (Figure 7).
(3) Oxidation of 1-aminobenzotriazole, (Figure 8).
(4) By benzothiadiazide-1, 1-dioxide, (Figure 9).
Reactions of benzyne,
(1) With dienes cycloaddition products are formed (Figure 10).
(2) Benzyne gives both cycloaddition and end reaction products with simple alkenes.
Substitution by the SRN1 mechanism
[082] In another embodiment, the distinctive feature of the SRN1 mechanism is an electron transfer between the nucleophile and the aryl-halide the overall reaction is mainly a chain process.
? Initiation.
? Propagation.
[083] The present invention as illustrated in Figure 8 provides another embodiment of the invention which includes an Oxidation of 1-amino benzotriazole.
[084] The present invention as illustrated in Figure 9 provides another embodiment of the invention which includes a benzothiadiazide-1, 1-dioxide.
[085] The present invention as illustrated in Figure 10 provides another embodiment of the invention which includes dienes cycloaddition products are formed; a Benzyne that gives both cycloaddition and ends reaction products with simple alkenes; an Initiation, propagation
[086] In another embodiment, a potential advantage of the SRN1mechanism is that it is not particularly sensitive to the nature of other aromatic ring substitution although EWG substitution favors the nucleophile addition step.
[087] In another embodiment, Nucleophile which shows SRN1 mechanism; ketone enolates, ester enolates, amide enolates, 2, 4 pentanediene dianion, pentadienyl and indenyl carbanion phenolates, phosphides, and thiolates.
[088] In another embodiment, the reactions are frequently initiated by light, which promotes the initial electron transfer. As for other radical chain processes, the reaction is sensitive to substances that can intercept the propagation intermediates.
[089] The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since the modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to the person skilled in the art, the invention should be construed to include everything within the scope of the disclosure and claims appended.

We Claims:

1. An Electrophilic & Nucleophilic substitution mechanism for Halogenation consist of an electrophilic substitution reaction; a Nitration reaction; Nucleophilic Aromatic Substitution.

2. The Electrophilic & Nucleophilic substitution mechanisms for Halogenation as claimed in claim 1, wherein electrophilic substitution reaction that comprises two steps: 1) In the first step, the electrophilic reagent attacks on the p electrons of the aromatic ring to form an intermediate which is known as aronium cation, the sigma complex, or the pentadienyl cation. 2) The second step of the reaction involves the elimination of a proton from the intermediate, by an anionic species, to form a substituted aromatic compound.

3. The Electrophilic & Nucleophilic substitution mechanisms for Halogenation as claimed in claim 1, wherein Nitration reaction and it is carried out with a mixture of HNO3 and H2SO4 (nitrating agent) the reaction proceeds very slowly when HNO3 alone is used which indicate that H2SO4 converts the HNO3 into a form that is capable of reacting with benzene with great ease.

4. The Electrophilic & Nucleophilic substitution mechanisms for Halogenation as claimed in claim 1, wherein Nucleophilic Aromatic Substitution, the replacement of hydrogen or substitution by a nucleophilic reagent is known as nucleophilic aromatic substitution wherein It doesn’t take place with the benzene itself but with its some substituted derivatives and with naphthalene. Synthetically important substitutions of aromatic compounds can also be done by nucleophilic reagents.

5. The Electrophilic & Nucleophilic substitution mechanisms for Halogenation as claimed in claim 1, wherein Aryl diazonium ions as synthetic intermediates the first widely used intermediates for nucleophilic aromatic substitution were the aryl diazonium salts.

6. The Electrophilic & Nucleophilic substitution mechanisms for Halogenation as claimed in claim 1, wherein Aryl diazonium ions are usually prepared by reaction of aniline with nitrous acid, which is generated in situ from a nitrite salt.

7. The Electrophilic & Nucleophilic substitution mechanisms for Halogenation as claimed in claim 1, wherein Unlike aliphatic diazonium ion, which decomposes very rapidly to molecular nitrogen and a carbocation, aryl diazonium ions are stable enough to exist in solution at room temperature and below.

8. The Electrophilic & Nucleophilic substitution mechanisms for Halogenation as claimed in claim 1, wherein the entering nucleophile doesn't necessarily become bound to the carbon to which the leaving group was attached.