Cresol production

Since before World War II, multimillion pound quantities of cresols have been produced annually in the United States (O Brochta 1949), and domestic production and sales of cresols have steadily increased in recent years. Approximately 57.3 (USITC 1986), 73.3 (USITC 1988), and 82.3 (USITC 1989) million pounds of cresols were produced annually in the United States in 1986, 1987, and 1988, respectively. Respective sales were 56.6 (USITC 1986), 66.8 (USITC 1988), and 72.1 (USITC 1989) million pounds. These production totals include data on the manufacture of cresylic acid and exclude information on cresol production by coke and gas-retort ovens. The commercial mixture of cresol isomers, in which the m-isomer predominates and contains less than 5% phenol, is sometimes referred to as cresylic acid (Windholz et al. 1983). However, cresylic acids generally are composed of cresols, phenols, and xylenols they are defined as those mixtures in which over 50% will boil at temperatures above 204 C (Sax and Lewis 1987). In 1987, the national capacity for producing cresylics was 208 million pounds per year (CMR 1987). Information regarding the production levels of individual isomers and specific mixtures was unavailable. 

The oldest cresol production method used in the United States is through the recovery of fractional distillates from coal tars. Most domestic cresols are formed via catalytic and thermal cracking of naphtha fractions during petroleum distillation. Since 1965, quantities of coal tar and petroleum isolates have been insufficient to meet the rising demand. Consequently, several processes for the manufacture of the various isomers have been developed. One General Electric facility produces o-cresol at an annual capacity of 10,000 tons by the methylation of phenol in the presence of catalysts. The Sherman-Williams Company uses the toluene sulfonation process and maintains an annual capacity for p-cresol of 15,000 tons. The Hercules Powder Company produced p-cresol until 1972 by the cymene- cresol process. 

The actual mechanism may not be as simple as implied by this equation, however. For example, Narita and Tezuka (1982) have shown that, in the solution phase oxidation at least, some of the cresol product contains an oxygen atom from the Oz. In addition, in the case of reaction of benzene, phenol may be formed by direct displacement of a hydrogen atom by OH (Bjergbakke et al., 1996 Koch, 1997 Pagsberg, 1997). 

Because of the high antioxidant value of the p-cresol products, the work was extended to study the alkylation with a-olefins of three other readily available phenols phenol, 2,4-xylenol, and 2,6-xylenol. The nominal products were 2,4,6-tri(sec-alkyl)phenols, 6-(sec-alkyl)-2,4-xylends and 4-(sec-alkyl)-2,6-xylenols, as shown in the following reactions. Remember that these structural designations are for convenience the actual products are complex mixtures. Again, yields of the desired alkylated phenol were very high. The trialykylated phenol products were... 

Two differences were observed between the dialkylated p-cresols and the trialkylated phenols. First, the sharp increase in activity always occurs at a somewhat higher molecular weight for the trialkylated phenols secondly, the p-cresol products are generally somewhat more effective throughout the entire range of molecular weights. The first may be... 

Synthetic cresols production from toluene feedstock will be discussed in some details in a subsequent chapter. A brief review of cresols or cresylic acid production from coal/lignite is presented here. 

Figure 2.2 Block diagram for p-cresol production (conventional) plant.

The process is continuous, very low in operating costs. Catalyst is regenerable. However, such plants are much more capital intensive and will call for much higher cresols production. These plants will be attractive only if a few downstream derivatives based on pure meto-cresol and para-cresol (if cresols are separated) apart from BHT are integrated with the mother plant. 

Because of somewhat lower boiling point compared to m-cresol andp-cresol, o-cresol is obtained as a co-product during fractionation of cresols from coal tar acids or during production of para-cresol based on sulfonation of toluene. Most of the p-cresol manufacturers such as PMC, INSPEC (now Laporte), Atul and others are producing o-cresol in the range of 600-1500 tpa depending on p-cresol production. 

Chinese company, Yanshen Petrochemicals Co., and the two Japanese companies, Sumitomo and Mitsui, using alkylation process are producing m-cresol and BHT though UOP/Kellog s process of cymenes and cresols production has been fully established. 

Meeting the need for a comprehensive source addressing every aspect of cresol production, analysis, and impact, this detailed reference offers the most up-to-date account of cresols and their downstream derivatives—written by an internationally renowned consultant in the fine chemicals industry. 

Last, but not the least important is pure o-cresol, which is obtained as a co-product during p-cresol production based on sulfonation of toluene. Pure o-cresol is also produced from phenol through a methylation process. o-Cresol has been conveniently used for manufacture of Coumarin, a vital fine chemical, and also epoxy resins and ECN resins. o-Cresol is also being used as a building block of agrochemicals. 

Operational results of the pilot plant and p-cresol production plant showed a good agreement with the calculated values. Differences were within a few percent. The reason for this agreement is attributed to the uniformity or the state inside the vessel. 

The p-cresol production plant completed a production run every 4.5 minutes through out the year obtaining a product of 99.5% purity from a p-,m-cresol mixture for almost the past ten years, even though its capacity was about ten times that of tne pilot plant. This cycle time may be shortened even even further in the near future. 

Furthermore, it is important to note that there is a world-class high pressure process and plant in operation for p-cresol production, running with a short cycle time throughout the year at pressures of over 150 MPa. Since the feasibility of the process has been satisfactorily certified, it is expected that this process will find applications in various fields of the industrial separation of chemicals. 

Pesticide Active Ingredient Production 4-Chlor-2-Methyl Acid Production 2,4 Salts Esters Production 4,6-dinitro-o-cresol Production Butadiene Furfural Cotrimer Captafol Production Captan Production Chloroneb Production Dacthal Production Sodium Pentachlorophenate Production TordonTM Acid Production 06/30/02... 

Aromatization of 1,4- and 1,2-cyclohexanediones leads to cresol products (eq 66) in over 90% yield. ... 

As a result of structure transformation of 5,7-di-teft-butylspiro(2,5) octa-4,7-diene-6-one in a solid phase at an ambient temperature, a single crystal 2-(3, 5-<7/-teA-t-6Mi /-4 -hydroxyphenyl)ethyloxy-/7-cresol is formed. However, that is simultaneous with reaction of formation 2-(3, 5 -<7/-tert-6wty/-4 -hydrox5 henyl)ethyloxy-p-cresol) products of reversible dimerization. Stmctures of compounds are based on the data of NMR and IR spectroscopy. 

These compounds absorb ultraviolet radiation which is present within the troposphere (see figure IX-L-2), and their photochemistry may be important. The primary process (I) has been suggested to explain the o-cresol product observed (Klotz et al., 1998b, 2000). Process (II) has been suggested to occur from the 2-methyloxepin form (Vogel and Gunther, 1967 Kaubisch et al., 1972) ... 

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