Sulfur groups catalyst

Two previous studies (Moser et al., 2007, 2006) explored the effects of synthetic compounds with hydrocarbon tail-group structures resembling those of FAME with attached bulky moieties on the CP and PP of SME. These studies examined novel fatty ethers made from the reaction of various alcohols (C2—Cm) with epoxidized alkyl oleates in the presence of sulfuric acid catalyst. Bulky esters (isopropyl and isobutyl) were chosen to further enhance the low temperature fluidity of the synthetic adducts produced. As the chain length of the ether moiety attached to the fatty backbone increased in length, a corresponding improvement in low temperature performance was noticed. Although the materials had improved low temperature properties over that of neat SME, none of the synthesized compounds demonstrated effectiveness in decreasing CP or PP when added to SME. 

An important general method for preparing indoles involves the catalytic elimination of ammonia from phenylhydrazones of carbonyl compounds having an a-roethylene group. Catalysts include zinc chloride, cuprous chloride, boron fluoride etherate, dilute sulfuric acid, alcoholic hydrochloric acid, and glacial acetic acid. ... 

In the manufacture of cellulose triacetate using sulfuric acid catalyst in the batch process, there is a stabilization step following the acetylation. The residual sulfate groups are hydrolyzed (called desulfation) at an elevated temperature by slow addition of dilute aqueous acetic acid solution containing magnesium or sodium acetate or other suitable base to neutralize the liberated sulfuric acid [26,27]. 

Cellulose-based natural fiber can be oxidized using oxidizing agent with acidic catalyst. Oxidation reactions applied to cellulose in fiber for chemical modifications [43]. Oxidation reactions occur on cellulose selectively at particular position. The reaction of sodium metaperiodate with cellulose in wood fiber in the presence of sulfuric acid catalyst at 120°C and 85 KPa pressure yielded the oxidized product. Sodium metaperiodate reacts with hydroxyl groups of cellulose and produce 2,3-dialdehyde cellulose which improved the physical and mechanical properties of polymer composites [44]. 

Water-soluble calix[4]resorcinols with sulfur group substituents function as catalysts in the amination (dehydration) of alcohols in aqueous medium (Scheme 4.25) [91]. 

Because the enamine functionality underwent a facile cyclizadon reacdon when the nitro group was reduced, the first step of this process was conversion of the enamine to the diethyl acetal 33 by treatment with ethanol containing sulfuric acid catalyst at reflux. The nitro group was reduced to an amine without significant concomitant cyclizadon and protected as its acetamide 34. The acetal protecting group was removed under ndld acidic condidons (pyridinium p-toluenesulfonate and... 

One of the new applications of K-carrageenan is in copolymeiization. One example is the copolymerization of K-carrageenan with acrylic acid with further acidification to convert the sulfate groups into sulfuric groups. This copolymer has been used as a catalyst during the hydrolysis of sucrose to glucose and fructose (El-Mohdy Rehim, 2008). 

Alternatively many thioether derivatives of cysteine and other thiols have been prepared by reaction of the thiol group with a cation generated from the corresponding alcohol, olefin, or halide. For example, treatment of iV-phthaloyl-L-cysteine (2) with isobutylene using a sulfuric acid catalyst provided a... 

Acetic anhydride adds to acetaldehyde in the presence of dilute acid to form ethyUdene diacetate [542-10-9], boron fluoride also catalyzes the reaction (78). Ethyfldene diacetate decomposes to the anhydride and aldehyde at temperatures of 220—268°C and initial pressures of 14.6—21.3 kPa (110—160 mm Hg) (79), or upon heating to 150°C in the presence of a zinc chloride catalyst (80). Acetone (qv) [67-64-1] has been prepared in 90% yield by heating an aqueous solution of acetaldehyde to 410°C in the presence of a catalyst (81). Active methylene groups condense acetaldehyde. The reaction of isobutfyene/715-11-7] and aqueous solutions of acetaldehyde in the presence of 1—2% sulfuric acid yields alkyl-y -dioxanes 2,4,4,6-tetramethyl-y -dioxane [5182-37-6] is produced in yields up to 90% (82). 

Esters. Most acryhc acid is used in the form of its methyl, ethyl, and butyl esters. Specialty monomeric esters with a hydroxyl, amino, or other functional group are used to provide adhesion, latent cross-linking capabihty, or different solubihty characteristics. The principal routes to esters are direct esterification with alcohols in the presence of a strong acid catalyst such as sulfuric acid, a soluble sulfonic acid, or sulfonic acid resins addition to alkylene oxides to give hydroxyalkyl acryhc esters and addition to the double bond of olefins in the presence of strong acid catalyst (19,20) to give ethyl or secondary alkyl acrylates. 

Suitable catalysts are /-butylphenylmethyl peracetate and phenylacetjdperoxide or redox catalyst systems consisting of an organic hydroperoxide and an oxidizable sulfoxy compound. One such redox initiator is cumene—hydroperoxide, sulfur dioxide, and a nucleophilic compound, such as water. Sulfoxy compounds are preferred because they incorporate dyeable end groups in the polymer by a chain-transfer mechanism. Common thermally activated initiators, such as BPO and AIBN, are too slow for use in this process. 

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