Diazonium Salt Treatment

The physico-mechanical properties of o-hydroxybenzene diazonium salt-treated coir-reinforced polypropylene (PP) composites been investigated by Islam et al. [26]. 

Coir fiber was chemically treated with o-hydroxybenzene diazonium salt to improve mechanical properties of the composites. The mechanical properties of the composites prepared from chemically treated coir were found to be much better compared to those of untreated ones. The surface morphologies of the fractured surfaces of the composites were also found to be changed. 

---

In view of the instability of aminoindolizines, they have not been used to prepare diazonium salts. Treatment of 1-nitroindolizines, however, with dry nitric oxide gave diazonium nitrates in high yield (67CC424). 

Reductive deamination of primary arylamines The ammo substituent of an arylamine can be replaced by hydrogen by treatment of its de rived diazonium salt with ethanol or with hypophosphorous acid... 

The alternative approach is to pad the fabric with the alkaline naphthol and dry, foUowed by printing directly onto this prepared fabric diazonium salts or stabilized diazonium salts. Coupling is instant and the only further treatment needed is to remove aU the uncoupled naphthol and surface azo pigment in a subsequent washing treatment. Because the choice of colors is limited from one naphthol component, other shades are obtained by using other classes of dye alongside the azoic colors, eg, reactives. This approach is widely used in the production of African prints. 

Diazotization of a primary arylamine followed by treatment of the diazonium salt with copper(l) bromide or copper(l) chloride yields the corresponding aryl bromide or aryl chloride. 

Aniline 77 was converted into its diazonium salt with nitrous acid and this was followed by reduction with stannous chloride to afford the corresponding arylhydrazine 78. Condensation of 78 with 3-cyanopropanal dimethylacetal 79 gave the arylhydrazone 80. Treatment of 80 with PPE resulted in cyclization to indole 81. The nitrile group was then reduced to the primary amine by catalytic hydrogenation. Reaction of the amine with excess formalin and sodium borohydride resulted in Imitrex (82). 

Elimination of the hydroxyaminomethyl moiety from nitro oxime 15 by treatment with a diazonium salt gave hydrazone 43 (75LA1029) (Scheme 15). The same product was obtained by coupling the diazonium salt with the compound 16. On heating in aniline, oxime 15 was transformed into Schiff base 42. Acylation of the oxime 15 with benzoyl chloride in pyridine led to a mixture of furazan 44 and dinitrile 45. 

Treatment of the diazonium salts with sodium azide yields azido derivatives (93HAC521, 93IZV1949, 93RCB1865, 94HAC441, 96ROC734, 96ZOR766). 

Dilution of a solution of diazonium salts in sulfuric acid with water affords triazene derivatives (95IZV1315,95RCB1269). Treatment of a bridged bis(amino) furazans 200 with nitrous acid in acetic or hydrochloric acid gives macrocyclic triazene 201 (Scheme 132) (95MI4). 

Ciprofibrate (48), a more potent lipid-lowering agent clofibrate, is prepared from Simmons-Smith product by Sandmeyer replacement of the amino group by a hydroxyl via the diazonium salt. Phenol undergoes the Reimer-Thiemann like process common to these agents upon alkaline treatment with acetone and chloroform to complete the synthesis of ci profib-rate (48). 

Replacement of chlorine on the pendant benzoyl group by azide is apparently consistent with antiinflammatory activity. Acylation of indomethacin intermediate with p-nitrobenzoyl chloride leads to the corresponding amide (7). Saponification ( ) followed by reduction of the nitro group gives the amine 9. The diazonium salt (10) obtained on treatment with nitrous acid is then reacted with sodium azide there is thus obtained zidomethacin (11). 

Nucleophilic processes that generate chloroindoles are largely confined to the displacements of oxy functions and Sandmeyer reactions of diazo-nium salts [81 H( 15)547]. A low yield of 2-chloroindole was obtained by a reaction sequence that involved treatment of oxindole with phosphoryl chloride, and then treatment of the Vilsmeier salt with sodium bicarbonate [66JOC2627 86H(24)2879]. It is, however, much better to prepare this compound from 2-lithioindole (92JOC2495). With phosphoryl chloride and dimethylformamide ethyl l-hydroxyindole-2-carboxylate failed to give the expected 3-formyl derivative. Instead there was a 50% yield of the 3-chloro derivative (84CPB3678). Diazonium salts have been used as precursors in... 

Sandmeyer reactions used have included the preparation of the 5-iodo compound from the diazonium salt of 5-amino-8-isoquinolinol further reaction with iodine monochloride gave 5,7-diiodo-8-isoquinolinol (66JMC46). Treatment of 1-chloroisoquinoline with iodide gave the 1-iodo analogue (47%) (67YZ1342). 

MNN is obtained in 3—5% yield by the nitration of naphthalene and is present at this level in coml MNN. It is best prepd by indirect methods for example, by the removal of an amino group from an appropriately substituted nitro-naphthylamine. The amine is treated with Na nitrite and acid to form the diazonium salt which is replaced with a H atom by redn with EtOH (Ref 7). It may also be prepd by treatment of 6-nitro-l, 2,3,4-tetrahydronaphthalene with Br to form a dibromo compn (probably the 1,4-isomer), followed by removal of two moles of H bromide by distn in the presence of base (Ref 10). 2-Naphthalenediazonium fluoroborate... 

Dinitronaphthalene (1,4-DNN). Long yel needles from MeOH, mp 134° (Refs 6 34) CA Registry No 6921-26-2. It is prepd by the diazotization of 4-nitro-l-naphthylamine followed by treatment of the diazonium salt with powd Cu and Na nitrite (Ref 45)... 

Dinitronaphthalene (Delta-dinitronaphtha-lenet 1,6-DNN). Crysts from acet ac, mp 166-67°, bp at 10mm 235°, 360° with decompn (Refs 2 31) CA Registry No 60746-5. It is prepd by the nitration of 2-nitronaphtha- ene with nitric ac/sulfuric ac in hot acet ac (Ref 21) by diazotization of 5-nitro-2-naphthyl-amine followed by treatment of the diazonium salt with Na cobaltinitrite, yield 40% (Ref 36) or by removal of the amino group from 1,6-dinitro-2-naphthylamine by diazotization followed by redn (Ref 17). The temp of expin is 492°(Refl7)... 

CA Registry No 24824-26-8. It is prepd by the diazotization of 6-nitro-2-naphthylamine followed by treatment of the diazonium salt with... 

---