Cresols, synthesis

I ovolac Synthesis and Properties. Novolac resins used in DNQ-based photoresists are the most complex, the best-studied, the most highly engineered, and the most widely used polymers in microlithography. Novolacs are condensation products of phenoHc monomers (typically cresols or other alkylated phenols) and formaldehyde, formed under acid catalysis. Figure 13 shows the polymerization chemistry and polymer stmcture formed in the step growth polymerization (31) of novolac resins. 

The synthesis of phenoxaphosphine-containing PODs by the cyclodehydration of polyhydra2ides obtained from 2,8-dichloroformyl-lO-phenylphenoxaphosphine-lO-oxide and aUphatic and aromatic dihydra2ides has been described (60). All polymers are soluble in formic acid, y -cresol, and cone H2SO4, but insoluble or partially soluble in ben2ene, chloroform, and hexamethylphosphoric triamide. 

The wide variety of ketomethylene and amino ketone monomers that could be synthesized, and the abiUty of the quinoline-forming reaction to generate high molar mass polymers under relatively mild conditions, allow the synthesis of a series of polyquinolines with a wide stmctural variety. Thus polyquinolines with a range of chain stiffness from a semirigid chain to rod-like macromolecules have been synthesized. Polyquinolines are most often prepared by solution polymerization of bis(i9-amino aryl ketone) and bis (ketomethylene) monomers, where R = H or C H, in y -cresol with di-y -cresyl phosphate at 135—140°C for a period of 24—48 h (92). 

Alkylated phenol derivatives are used as raw materials for the production of resins, novolaks (alcohol-soluble resins of the phenol—formaldehyde type), herbicides, insecticides, antioxidants, and other chemicals. The synthesis of 2,6-xylenol [576-26-1] h.a.s become commercially important since PPO resin, poly(2,6-dimethyl phenylene oxide), an engineering thermoplastic, was developed (114,115). The demand for (9-cresol and 2,6-xylenol (2,6-dimethylphenol) increased further in the 1980s along with the growing use of epoxy cresol novolak (ECN) in the electronics industries and poly(phenylene ether) resin in the automobile industries. The ECN is derived from o-cresol, and poly(phenylene ether) resin is derived from 2,6-xylenol. 

N HOAc, 90°, 40 h, high yield. This group has been used in a synthesis of 13-desoxydelphonine from o-cresol, a synthesis that required the group to be stable to many reagents. ... 

The same author has shown by repetition of the early experiments already referred to (p. 507) that when yohimbine hydrochloride is distilled with zinc dust there is formed in addition to harman (XVII), p-cresol, which must originate from ring E of the yohimbine formula (XIV) by inclusion of C as the methyl group. Witkop s formula for yobyrine (IV6) received prompt confirmation by Clemo and Swan s synthesis of this base by... 

The Phacm group is stable to the following conditions DIEA-CH2CI2, TFA-CH2CI2, piperidine-DMF, 0.1 M TBAF-DMF, and DBU-DMF for 24 h at It to HF-anisole or / -cresol (9 1) at 0° for 1 h and to TFA-scavengers (phenol, HSCH2CH2SH, p-cresol, anisole) for 2 h at 25°. It is partially stable (>80%) to TFMSA-TFA-/ -cresol for 2 h at 25°. These stability characteristics make the group compatible with BOC- or Fmoc-based peptide synthesis. ... 

The Doc group, introduced with the chloroformate and either DMAP or /-BuOK, is quite acid stable, but can be cleaved with TFMSA-thioanisole-EDT-TFA (10 min, rt) or with / -cresol-HF (1 h, 0°). The Doc group was found to be suitable for tryptophan protection in /-Bu-based peptide synthesis, since no /-butylation of tryptophan was observed during acid deprotection. 

The 4-nitrobenzyl group, used in the synthesis of phosphorylated serine, is introduced by the phosphoramidite method and can be cleaved with TFMSA/ MTB/m-cresol/l,2-ethanedithiol/TFA, 4 h, 0° to rt. 7V-Methylmorpholine at 80° also cleaves a 4-nitrobenzyl phosphate triester. 

The adaptation of the Bischler-Napieralski reaction to solid-phase synthesis has been described independently by two different groups. Meutermans reported the transformation of Merrifield resin-bound phenylalanine derivatives 32 to dihydroisoquinolines 33 in the presence of POCI3. The products 34 were liberated from the support using mixtures of HF/p-cresol. In contrast, Kunzer conducted solid-phase Bischler-Napieralski reactions on a 2-hydroxyethyl polystyrene support using the aromatic ring of the substrate 35 as a point of attachment to the resin. The cyclized products 36 were cleaved from the support by reaction with i-butylamine or n-pentylamine to afford 37. 

The first polyimine was reported by Adams and coworkers [182] from terephthalaldehyde and benzidine and dianisidine. Between 1950 and 1959 Marval and coworkers [174-176] reported a number of polyimines. Suematsu and coworkers [170] reported the first successful synthesis of high molecular weight fully aromatic polyimines by solution polycondensation method using w-cresol as reaction medium. 

Reductive ring opening of the [i-lactam 10 (X = O), obtained by [2 + 2] cycloaddition of chloro-sulfonyl isocyanate and tetraphenylcyclopentadiene followed by treatment with /7-cresol, with sodium hydride in anhydrous tetrahydrofuran yields 3,5,6,7-tetraphenyl-2//-azepin-2-one (11, X = O).41 Surprisingly, similar treatment of the reduced /Mactam 10 (X = H2) is reported to yield 3,5,6,7-letraphenyl-2//-azepine (11, X = H2), the first monocyclic 277-azepine to be isolated and characterized. Physical data for this compound, however, are inconclusive and attempts to reproduce this synthesis have failed.291... 

Synthesis in m-cresol. The dianhydride (1.35 mmol) is added to a stirred solution of 1.35 mmol of die diamine in die appropriate amount of m-cresol containing 6 drops of isoquinoline under N2 at room temperature. After 3 h, it is heated to reflux (ca. 200° C) and maintained at that temperature for 3 h. During this time, the water of imidization is distilled from die reaction mixture along with 1 to 3 mL of m-cresol. The m-cresol is continually replaced to keep the total volume of the solution constant. After die solution is allowed to cool to room temperature, it is diluted witii 20 mL of m-cresol and then slowly added to 1 L of vigorously stirred 95% ethanol. The precipitated polymer is collected by filtration, washed witii ethanol and ether and dried under reduced pressure at 125°C for 24 h. 

Figure 7.13 Synthesis of 2,6-dimethylphenol end-capped cresol novolac resin.

Synthesis of hydrolytically stable siloxane-urethanes by the melt reaction of organo-hydroxy terminated siloxane oligomers with various diisocyanates have been reported i97,i98) -yhg polymers obtained by this route are reported to be soluble in cresol and displayed rubber-like properties. However the molecular weights obtained were not very high. A later report56) described the use of hydroxybutyl terminated disiloxanes in the synthesis of poly(urethane-siloxanes). No data on the characterization of the copolymers have been given. However, from our independent kinetic and synthetic studies on the same system 199), unfortunately, it is clear that these types of materials do not result in well defined multiphase copolymers. The use of low molecular weight hydroxypropyl-terminated siloxanes in the synthesis of siloxane-urethane type structures has also been reported 198). 

The literature on basic- and acid-catalyzed alkylation of phenol and of its derivatives is wide [1,2], since this class of reactions finds industrial application for the synthesis of several intermediates 2-methylphenol as a monomer for the synthesis of epoxy cresol novolac resin 2,5-dimethylphenol as an intermediate for the synthesis of antiseptics, dyes and antioxidants 2,6-dimethylphenol used for the manufacture of polyphenylenoxide resins, and 2,3,6-trimethylphenol as a starting material for the synthesis of vitamin E. The nature of the products obtained in phenol methylation is affected by the surface characteristics of the catalyst, since catalysts having acid features address the electrophilic substitution in the ortho and para positions with respect to the hydroxy group (steric effects in confined environments may however affect the ortho/para-C-alkylation ratio), while with basic catalysts the ortho positions become the... 

With an effective strategy for construction of the diazofluorene established, we set out to prepare the coupling partners required for synthesis of (—)-kinamycin F (6). The synthesis of the enone 117 began with meta-cresol (128, Scheme 3.23). Silylation formed the silyl ether 119 in nearly quantitative yield. Birch reduction of the silyl ether 119 formed the cyclohexadiene derivative 129 in excellent yield. Asymmetric dihydroxylation [52] of 129 occurred regioselectively to afford the... 

Three additional circles have been added at the left of Figure 1 to represent the additional components involved in the production of synthesis gas. These involve the light gases H2 and CO, with N2, 02 and Ar as minor components water and ammonia with amines as minor components and cresols and other organic components. These three additional types of components produce a total of 15 combinations of interactions between the various types of components or 12 additional interactions. Thus the additional work to be done could be as much as four to five times the amount already done on oil and gas components. 

Cresol-Type Components. Large amounts of cresol-type components are produced in synthesis gas processes. 

The problems associated with new synthesis gas processes are far greater than problems associated with gas processing plants or refineries because of water, salt, sludge, ammonia, and cresols present in the process streams. This paper attempts to identify the magnitude of the problems and methods for solving these problems. The problem of predicting the thermodynamic properties of nonpolar-polar mixtures by means of equations of state is also identified as an area needing study. 

At the end of World War II, Fischer-Tropsch technology was under study in most industrial nations. Coal can be gasified to produce synthesis gas (syngas), which can be converted to paraffinic liquid fuels and chemicals by the Fischer-Tropsch synthesis. Liquid product mainly contains benzene, toluene, xylene (BTX), phenols, alkylphenols and cresol. The low cost and high availability of crude oil, however, led to a decline in interest in liquid fuels made from coal. 

Scheme 11.5. Synthesis of 7-mer-neo-conjugate N-Neo-C. (i) Deprotection with 4% trichloroacetic acid in CH2CI2, and coupling with 3 in the presence of 1/7-tetrazole followed by capping with acetic anhydride in pyridine/THF solution, and oxidation with I2 in THF/H20/pyridine solution (ii) p-elimination followed by deprotection from the solid support using cone. NH4OH (c) 1,4-dioxane solution containing 3% CF3CO2H and 1% m-cresol (v/v/v %). Reprinted with permission from Bioconj. Chem. 2007, 18, 160-169.

Synthesis of primidolol (65) can be carried out by a convergent scheme. One branch consists in application of the usual scheme to o-cresol (62) ring opening of the intermediate oxirane with ammonia leads to the primary amine (63). The side chain fragment (64) can be prepared by alkylation of pyrimidone (63) with ethylene dibromide to afford Alkylation of ami noalcohol with halide ... 

The fully functionalized chiral arylamine 814 with the required -configuration of the stereogenic center for the total synthesis of neocarazostatin B (268) was obtained from commercial guaiacol (815) over eight steps in 65% overall yield (613). The same racemic arylamine (+ )-814 was previously used for the racemic synthesis of neocarazostatin B and was available in 10 steps and 14% overall yield based on o-cresol, a different commercial starting material (614). 

Wu et al. reported the total synthesis of clausenaquinone A (112) using a palladium(ll)-mediated oxidative cyclization of the 2-arylamino-5-methoxy-l,4-benzoquinone 874 (107). This total synthesis was undertaken to establish the structure of natural clausenaquinone A (112). The key intermediate, 2-(3-hydroxy-4-methylanilino)-5-methoxy-l,4-benzoquinone (874), required for this synthesis, was obtained by the reaction of 5-amino-o-cresol (873) with 2-methoxy-l,4-benzoquinone (872) which was readily obtained by oxidation of methoxyhydroquinone (871). The palladium(ll)-mediated oxidative cyclization is non-regioselective. Thus, the cyclization of the 2-arylamino-5-methoxy-l,4-benzoquinone 874 with palladium(Il)... 

Timari et al. described a total synthesis of furostifoline (224) starting from commercial o-cresol (1133). The key steps in this approach are the Suzuki coupling to the o-nitrobiaryl 1139 and subsequent Cadogan s reductive cyclization via a nitrene intermediate (692). 

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