P-aminobenzyl

As with the other aminoplastics, the chemistry of resin formation is incompletely understood. It is, however, believed that under acid conditions at aniline-formaldehyde ratios of about 1 1.2, which are similar to those used in practice, the reaction proceeds via p-aminobenzyl alcohol with subsequent condensation between amino and hydroxyl groups (Figure 24.10). 

Aminoazo dyes, 9 249, 250 p-Aminobenzoic acid (PABA), 25 807 cosmetic uv absorber, 7 846t Aminobenzoisothiazoles, 9 290 2-Aminobenzothiazole dyes, 9 419 Aminobenzothiazoles, 9 289 4-(p-Aminobenzyl)cyclohexylamine,... 

There remain in this Section to be considered p-aminobenzyl-ideneaniline and />-aminoazobenzene and their derivatives. In these molecules two nitrogen basic centres are conjugated through a benzene ring, and the two systems are isoconjugate. 

The first known application of I AC was reported by Campbell et al. in 1951, where an antigen immobilized to p-aminobenzyl cellulose was used for antibody purification [9], Many current applications... 

The CCH of 2-(p-nitrobenzyl)-2-nitropropane (14) allowed the selective reduction of the nitroaiyl group, without reduction of the tertiary nitroalkyl group, giving 85-93% of 2-(p-aminobenzyl)-2-nitropropane (15) (Scheme 5). No diamino... 

CM cellulose (carboxymethyl) CM 22, 23 cellulose P cellulose (phosphate) SE cellulose (sulphoethyl) SM cellulose (sulphomethyl) DEAE cellulose (diethylaminoethyl) DE 22, 23 cellulose PAB cellulose (p-aminobenzyl) TEAE cellulose (triethylaminoethyl) ECTEOLA cellulose... 

Weak base ECTEOLA BD PAB Triethanolamine coupled to cellulose through glyceryl chains Benzoyl ated DEAE groups p-Aminobenzyl -o-ch2 -nh2... 

Melphalan and the racemic analog have been prepared by two general routes (Scheme I). In Approach (A) the amino acid function is protected, and the nitrogen mustard moiety is prepared by conventional methods from aromatic nitro-derivatives. Thus, the ethyl ester of N-phthaloyl-phenylalanine was nitrated and reduced catalytically to amine I. Compound I was reacted with ethylene oxide to form the corresponding bis(2-hydroxyethyl)amino derivative II, which was then treated with phosphorus oxychloride or thionyl chloride. The blocking groups were removed by acidic hydrolysis. Melphalan was precipitated by addition of sodium acetate and was recrystallized from methanol. No racemization was detected [10,28—30]. The hydrochloride was obtained in pure form from the final hydrolysis mixture by partial neutralization to pH 0.5 [31]. Variants of this approach, used for the preparation of the racemic compound, followed the same route via the a-acylamino-a-p-aminobenzyl malonic ester III [10,28—30,32,33] or the hydantoin IV [12]. 

These reactions are illustrated with the fragmentation of two isomeric aminoalco-hols and one aminodiol, which have been observed upon thioindigo sensitized irradiation in benzene solution [203]. Under these conditions, the (p-N,N-dimethyl-aminobenzyl) benzyl alcohol (24) suffers fragmentation with apparent internal disproportionation the benzyl alcohol function is oxidized, whereas the p-aminobenzyl function is reduced, giving rise to iVJV-dimethyl-p-toluidine and benzaldehyde. The acceptor is involved only as a sensitizer and, hence, remains unchanged. 

Alkyl Groups. As expected, all three toluidines give toluenearsonic acids in good yields (45-55%). From the o-, m-, and p-aminobenzyl alcohols the corresponding arsonic adds result in yields of 12-20%.2S When the reaction is applied to 2-hydroxy-4-mtro-5-alkylanilines,24 the yield of arsonic acid decreases as the length of the side chain is increased. o-Butylphenylarsonic acid is obtained by the Bart method in only a 12% yield.26 "... 

Attempts to purify the potato lectin on ovomucoid- and N,N -diacetylchitobiose-substituted Sepharose failed the lectin was so strongly bound that it could not be removed from the adsorbent by displacement with urea.483 To circumvent this difficulty, Delmotte and coworkers483 employed p-aminobenzyl 2-acetamido-2-deoxy-l-thio-/3-D-glucoside-substituted Sepharose, and eluted the lectin with 0.1 M acetic acid (yield 58 mg from 128 g of the protein in potato-tuber extract). 

Aminobenzonitrile is prepared by reduction of 3-nitrobenzonitrile by sodium disulfide in aqueous suspension (63%). This reagent causes some hydrolysis of the cyano group. A selective hydrogenation of the more reactive nitro group in the presence of the cyano group can also be done, e.g., in the preparation of p-aminobenzyl cyanide (7S>%). ... 

Ammonium salt, (NH4)[(NH3C6H4CH2P03)2MojO,5]-5H20 Sodium molybdate dihydrate (1.21 g, 5 mmol) and (p-aminobenzyl)phosphonic acid (0.37 g, 2 mmol) (Sigma) are dissolved in 70 mL of water. To this solution is added 2.0 mL of 3M HCl (6 mmol). The solution is boiled for 30 min and then filtered. When ammonium chloride (0.22 g, 4.2 mmol) dissolved in 2mL of water is added to the reaction solution, and the mixture is allowed to evaporate slowly at room temperature, a pale yellow crystalline powder is formed. It is collected, washed twice, quickly, with 1 mL of cold water, and then air dried. Yield 1.15g (94%). 

DEAE cellulose (diethylaminoethyl) DE 22, 23 cellulose PAB cellulose (p-aminobenzyl) TEAE cellulose (triethylaminoethyl) ECTEOLA cellulose... 

The recent data for kp(+) for A-ethyl-3-vinylcarbazole allows a further interesting correlation of absolute reactivity with structure. The cation derived from this monomer is a substituted p-aminobenzyl type and as such its reactivity might be expected to lie between that of the propagating cation from N-vinylcarbazole and those from isobutylvinyl ether and/7-methoxystyrene. Indeed this seems to be so as the value obtained, 2 x lO s S slots neatly between the figures of 5 x 10 s" and 5 x 10 M s as predicted. 

Figure 11.5. Prodrug of paclitaxel with two p-aminobenzyl alcohol moieties.

---