N-Cresol

The cresols occur in cresylic acid, a mixture of the three cresols together with some xylenols and neutral oils, obtained from coal tar distillates. Only the /n-cresol has the three reactive positions necessary to give cross-linked resins and so this is normally the desired material. The o-isomer is easily removed by distillation but separation of the close-boiling m- and p-isomers is difficult and so mixtures of these two isomers are used in practice. 

Chlorocresol, see y Chloro-ro-cresol p-Chlorocresol, see y Chloro-ro-cresol 4-Chloro-ro-cresol, see />Chloro-/n-cresol 6-Chloro-ro-cresol, see / Chloro /n-cresol Chlorodane, see Chlordane Chloroden, see 1,2-Dichlorobenzene Chlorodibromomethane, see Dibromochloromethane l-Chloro-2,3-dibromopropane, see l,2-Dibromo-3-chlor-... 

Preventol CMK, see p-Chloro-/n-cresol Preventol I, see 2,4,5-Trichlorophenol Priltox, see Pentachlorophenol Primary amyl acetate, see Amyl acetate Primary isoamyl alcohol, see Isoamyl alcohol Primary isobutyl alcohol, see Isoamyl alcohol Prioderm, see Malathion Prist, see Methyl cellosolve Profume A, see Chloropicrin Profume R 40B1, see Methyl bromide Prokarbol, see 4,6-Dinitro-o-cresol... 

Os(NH3)5(/n-cresol)]2+ exist primarily as the 2,5-cyclohexadien-l-one tautomers under equilibrium conditions in methanol (178). 

The protected human GIP (50 mg, 73.9 pmol) was treated with IM TfOH/thioanisole in TEA (3mL) in the presence of /n-cresol (108 pL, 140 equiv) and EDT (43 pL, 70 equiv) in an ice bath for 180 min, then dry Et20 was added. The resulting powder was collected by centrifugation, dried over KOH pellets in vacuo for 2h, and dissolved in H2O (5mL). The pH of the ice-chilled soln was adjusted to 8.0 with 5% NH4OH and after 30 min, to 5.0 with 1M AcOH. P-ME (207 pL, 400 equiv) was added and the soln, after being incubated for 20 h, was applied to a column of Sephadex G-50 (2.3 x 142 cm, 1M AcOH). The fractions (6 mL each, monitored at 280 nm) corresponding to the front main peak (tubes 41-64) were combined and the solvent was removed by lyophilization to give a powder yield 36 mg (98%). This crude product was further purified with CM-cellulose and RP-HPLC. The overall yield from the protected human GIP was 10%. 

Fig. 32.6 Influence of column length on analysis time. Analysis of phenols under isothermal conditions 1. phenol 2. o-cresol 3. 2,6-xylenol 4. p-cresol 5. n-cresol 6. o-ethylphenol 7. 2,4-xylenol 8. 2,5-xylenol 9. 2,3-xylenol 10. p-ethylphenol 11. m-ethylphenol 12. 3,5-xylenol 13. 3,4-xylenol.

Numerous studies have probed how novolac microstmcture influences resist lithographic properties. In one example, a series of resists were formulated from novolacs prepared with varying feed ratios of para-/meta-ct %dissolution rate decreased, and the resist contrast increased, as thepara-jmeta-cieso feed ratio increased (33). Condensation can only occur at the ortho position of n -cresol, but can occur at both the ortho- and i ra-positions of meta-cieso. It is believed that increased steric factors and chain rigidity that accompany increasedpara-cms(A content modify the polymer solubility. 

Figure 11.12 Shear viscosity and first normal stress difference versus shear rate for 17% PBLG (molecular weight 350,000) in /n-cresol. The circled triangles are negative N values. (From Kiss and Porter, reprinted with permission fromMol. Cryst. Liq. Cryst. 60 267, Copyright 1980, Gordon and Breach Publishers.)...

A part of the evidence for the mechanisms given in equations (40) and (42) is provided by the work of Lowry and co-workers (Lowry and Richards, 113 Lowry and Faulkner, 24) on the mutarotation of tetra methylglucose. In water the reaction proceeds at a measurable rate, and it is clearly catalyzed by both acids and bases. In aqueous solution pyridine is a powerful catalyst but in pure dry pyridine no reaction occurs, and likewise in pure dry re-cresol there is no reaction. Upon investigating the reaction in a mixture of pyridine and n-cresol, Lowry and Faulkner (24) found it to take place very rapidly. From these experiments Lowry drew the important conclusion that a proton cannot by itself wander from one part of the molecule to another. The transformation can occur only if the medium in which the molecule is placed has both acidic and basic properties, so that a proton can be removed from the molecule at one place and a proton added to the molecule at another place. Now these experiments furnish strong support to the mechanism of reactions (40) and (42) whereby both members of the conjugate acid-base pair play a part in the reaction. Instead of representing this mutual dependence by means of consecutive bimolecular reactions, Lowry chose to represent it by means of one trimolecular reaction... 

Fig. 1. Left Birefringent fluid liquid crystalline solution of poly-y-benzyl-L-glutamate in /n-cresol. Right Birefringent solid film of poly-y-benzyl-L-glutamate plasticized by 3,3 -dimethyl bisphenyl. Retardation lines characteristic of a helicoidal supramolecular structure are observed in the photomicrographs of both the liquid and solid states of this synthetic polypeptide.

The permeabihty coeffidraits at 25°C of phenol, /n-cresol, methylparaben, 1 la-hydroxyprogesterone, and corticosterone were taken from Table II. The 37 C permeabihty eoefficiraits of ethylparaben, propylparabrai, butylparaben, phenol, benzoic acid,/7-hydroxybenzoic add, /n-cresol, m II5A1 (/n-hydroxybenzyl alcohol), and m-hydroxyphenyl acetic add were taken from Table HI. The 37°C permeabihty coef-fident of methylparaben was not taken from Table HI, but from Table VI (in which the values reported in Table III arc averaged with several additional values). 

FIGURE 3.3 Effect of chain transfer to various solvents on the degree of polymerization of polystyrene at 333 K. 1, Benzene 2, -heptane 3,. rec-butyl benzene 4, /n-cresol 5, CC34 6, CBr4 7, n-butyl mercaptan. 

Combo reactors can be of two types, separation oriented and reaction oriented. In the first, reaction is used to achieve efficient separation, such as in the separation of />-cresol from its mixture with /n-cresol. This method need not necessarily be restricted to separation, for it can also be attractive from the reaction point of view in the following scenario the required product from a process comes out with a byproduct of low value in a very difficultly separable mixture of the two. If the byproduct can be converted to a useful coproduct in an easily separable mixture with the primary product, then we would have an attractive process. Alternatively, there can be two unimportant by-products in a difficultly separable mixture which can be converted to an easily separable mixture of useful products. An interesting example of this is illustrated later in this chapter. 

Room-temperature solution polycondensation is used for the preparation of hexafluoroisopropylidene-unit-containing poly(azomethine)s. At the end of the reaction, the water liberated by the reaction is thoroughly taken off as an azeotrope by vacuum distillation to allow the reaction to go to completion. Among DMF, DMSO, HMPA, NMP, and /n-cresol used as reaction solvents, m-cresol yields a polymer with higher reduced viscosity in higher yield. The reaction proceeds rapidly and is essentially completed in 30 min. 

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