I»-Toluidine

Cl Acid Gieen 25 [4403-90-1] (3) (Cl 61570) was also invented in 1894. This dye shows improved wetfastness, and is prepared from leucoquinizarin by reaction with 2 moles of i)-toluidine in a similat manner to the preparation of Cl Acid Violet 43 (134). Wetfastness and leveling properties may be altered by choosing the substituents of arylamines. The introduction of alkyl groups into aromatic amines improves the wetfastness and affinity in neutral or weekly acid baths. Examples ate Cl Acid Blue 80 [4474-24-27] (131) (Cl 61585) and Cl Acid Gieen 27 [6408-57-7] (132) (Cl 61580). 

Figure 16. Hydrogenation of i-toluidine on plane face surface Rh atoms (left) effect of metal crystallite size on TOF (right). (Reprinted from Reference [160], 2006, with permission from Elsevier).

A large number of azines were produced in the early decades of industrial dye manufacture. The synthesis was an all-in operation involving a sequence of oxidation reactions. Mauveine (3), for example, was prepared by oxidizing aniline containing o- and /i-toluidines with potassium dichromate in cold dilute sulfuric acid solution. 

The /i-toluidine salt of phenanthrene-2-sulfonic acid forms flat needles or plates melting at 282° (291° corr.) that of the 3-acid forms thick needles melting at 217° (222° corr.). 

Prepare o-tolunitrile, b.p. 94-96°/20 mm., from o-toluidine following the method given in Section IV,66 under i -Toluidine. Also prepare 600 g. of 75 per cent, sulphuric acid by adding 450 g. (245 ml.) of con-... 

From the sulfonyl chloride,/i-toluidine and aqueous sodium hydroxide For directions and examples see Vogel, p 553... 

From the sodium, potassium or ammonium salt with /i-toluidine or /i-toluidine hydrochloride in water See Shriner, p 269, Vogel, p 555,0 C Dermer and V H Dermer, y Org CAem, 7, 581 (1942), A D Barton and L Young, y Amer Chem 5oc, 65, 294 (1943)... 

From the sodium, potassium, ferric or barium salt (after boiling with sulfuric acid) with /i-toluidine and hydrochloric acid... 

From the acid chloride with i-toluidine in ether or benzene... 

Dimethyltocol A/,W-Dimethyl-o-toluidine N,W-Dimethyl- i-toluidine A/,W-Dimethyl-/)-toluidine 5-(3,3-Dimethyl-l-triazenyl)-lif-... 

What is the cause of the differences observed in the SwAr reaction with o- and /i-toluidines It seems that moving the methyl substituent from the para- to the or-t/zo-position affects the rate of decomposition of the Meisenheimer intermediate. The nucleophilic attack (A i) is more difficult in the case of o-toluidine and leads to a more congested Meisenheimer intermediate. Steric compression in the intermediate may be relieved by partial reversion to the reactants, enhancing h- and converting this route into a competitive alternative to the decomposition pathway. The rate expression for o-toluidine (Eq. 33.1) reflects that the two decomposition pathways of the intermediate (reversion to reactants k and formation of the reaction products ( 2 + A 3[aminej) have to be considered. 

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