Sulfuric acid effect

Early studies by Musculus88 indicated that concentrated sulfuric acid effects polymerization of D-glucose. Nakamura10 found that optimal conditions for this polycondensation involve heating of D-glucose (20 g.) with concentrated sulfuric acid (1 ml.) at 95° for 10-20 min. Carbonization was conspicuous when 4 ml. of sulfuric acid was used. Under these optimal... 

Treatment of 2-benzoylbenzoic acid with concentrated sulfuric acid effects cyclodehydration to anthraquinone, a pale-yellow, high-melting compound of great stability. Because anthraquinone can be sulfonated only under forcing conditions, a high temperature can be used to shorten the reaction time without loss in yield of product the conditions are so adjusted that anthraquinone separates from the hot solution in crystalline form favoring rapid drying. 

Properties Pinkish-white to gray needles. Soluble in hot water but almost insoluble in cold water. Derivation (3-naphthol is nitrated to mtroso-ji-naphthol by reaction with nitrous acid and the product treated with sodium bisulfite. Upon acidification the free sulfurous acid effects simultaneous reduction and sulfonation. 

Add with a pipet a 0.2-mL aliquot of each of the filtrates into a clean, dry test tube, and at 30-s intervals add 1.00 mL enzyme reagent. Immediately place in a 37°C water bath. (Reactions may be run for 45 minutes at room temperature with some loss in sensitivity.) Run duplicate aliquots of the unknown filtrate. After exactly 30 minutes, remove the tubes one at a time (30-s intervals) and add 50 mL 3 M H2S04. The sulfuric acid effectively stops the enzyme reaction. 

This transition metal-free approach proceeded under very mild conditions and was typically regioselective for the formation of the meta-substituted product. It was noted that the amount of halogenation was dependent upon the acid used in the reaction. Changing from TFA to acetic acid resulted in sluggish reactivity, while sulfuric acid resulted in moderate conversion into the monobrominated product along with the formation of the dibrominated species (10%). In related work, the use of NBS in concentrated sulfuric acid effectively brominated a series of deactivated arenes [124]. One difference between the two approaches was that the latter was a bit more effective for the bromination of benzoic acid derivatives (Scheme 7.72). These approaches are complementary and are effective solutions for moderately deactivated systems, provided that the substrates do not contain functional groups that are sensitive to the acidic conditions. 

The use of potassium bichromate in sulfuric acid effects the oxidation of l-nitro-2-methyl-anthraquinone to the corresponding carboxylic acid. This reaction illustrates side-chain oxidation, an important route to carboxylic acids. 

Zelikoff JT, Schlesinger RB. Modulation of pulmonary immune defense mechanisms by sulfuric acid effects on macrophage-derived tumor necrosis factor and superoxide. Toxicology 1992 76 271-281. 

Catalytic gas-phase reactions play an important role in many bulk chemical processes, such as in the production of methanol, ammonia, sulfuric acid, and nitric acid. In most processes, the effective area of the catalyst is critically important. Since these reactions take place at surfaces through processes of adsorption and desorption, any alteration of surface area naturally causes a change in the rate of reaction. Industrial catalysts are usually supported on porous materials, since this results in a much larger active area per unit of reactor volume. 

The main justification for diesel fuel desulfurization is related to particulate emissions which are subject to very strict rules. Part of the sulfur is transformed first into SO3, then into hydrated sulfuric acid on the filter designed to collect the particulates. Figure 5.21 gives an estimate of the variation of the particulate weights as a function of sulfur content of diesel fuel for heavy vehicles. The effect is greater when the test cycle contains more high temperature operating phases which favor the transformation of SO2 to SO3. This is particularly noticeable in the standard cycle used in Europe (ECE R49). 

As mentioned in Section IX-2A, binary systems are more complicated since the composition of the nuclei differ from that of the bulk. In the case of sulfuric acid and water vapor mixtures only some 10 ° molecules of sulfuric acid are needed for water oplet nucleation that may occur at less than 100% relative humidity [38]. A rather different effect is that of passivation of water nuclei by long-chain alcohols [66] (which would inhibit condensation note Section IV-6). A recent theoretical treatment by Bar-Ziv and Safran [67] of the effect of surface active monolayers, such as alcohols, on surface nucleation of ice shows the link between the inhibition of subcooling (enhanced nucleation) and the strength of the interaction between the monolayer and water. 

Oxidation (Section 11 13) Oxidation of alkylben zenes occurs at the benzylic position of the alkyl group and gives a benzoic acid derivative Oxidiz mg agents include sodium or potassium dichro mate in aqueous sulfuric acid Potassium perman ganate (KMn04) is also an effective oxidant... 

When applied to the synthesis of ethers the reaction is effective only with primary alcohols Elimination to form alkenes predominates with secondary and tertiary alcohols Diethyl ether is prepared on an industrial scale by heating ethanol with sulfuric acid at 140°C At higher temperatures elimination predominates and ethylene is the major product A mechanism for the formation of diethyl ether is outlined m Figure 15 3 The individual steps of this mechanism are analogous to those seen earlier Nucleophilic attack on a protonated alcohol was encountered m the reaction of primary alcohols with hydrogen halides (Section 4 12) and the nucleophilic properties of alcohols were dis cussed m the context of solvolysis reactions (Section 8 7) Both the first and the last steps are proton transfer reactions between oxygens... 

Acid—Base Chemistry. Acetic acid dissociates in water, pK = 4.76 at 25°C. It is a mild acid which can be used for analysis of bases too weak to detect in water (26). It readily neutralizes the ordinary hydroxides of the alkaU metals and the alkaline earths to form the corresponding acetates. When the cmde material pyroligneous acid is neutralized with limestone or magnesia the commercial acetate of lime or acetate of magnesia is obtained (7). Acetic acid accepts protons only from the strongest acids such as nitric acid and sulfuric acid. Other acids exhibit very powerful, superacid properties in acetic acid solutions and are thus useful catalysts for esterifications of olefins and alcohols (27). Nitrations conducted in acetic acid solvent are effected because of the formation of the nitronium ion, NO Hexamethylenetetramine [100-97-0] may be nitrated in acetic acid solvent to yield the explosive cycl o trim ethyl en etrin itram in e [121 -82-4] also known as cyclonit or RDX. 

Dinitrogen tetroxide is an effective Eriedel-Crafts nitrating agent (152) for aromatics in the presence of aluminum chloride, ferric chloride, or sulfuric acid (153). Dinitrogen pentoxide is a powerhil nitrating agent, even in the absence of catalysts, preferably in sulfuric acid solution (154). SoHd dinitrogen pentoxide is known to be the nitronium nitrate, (N02) (N02). The use of BE as catalyst has been reported (155). 

SHica—alumina has been studied most extensively. Dehydrated sHica—alumina is inactive as isomerisation catalyst but addition of water increases activity until a maximum is reached additional water then decreases activity. The effect of water suggests that Brmnsted acidity is responsible for catalyst activity (207). SHica—alumina is quantitatively at least as acidic as 90% sulfuric acid (208). 

Starting from Benzene. In the direct oxidation of benzene [71-43-2] to phenol, formation of hydroquinone and catechol is observed (64). Ways to favor the formation of dihydroxybenzenes have been explored, hence CuCl in aqueous sulfuric acid medium catalyzes the hydroxylation of benzene to phenol (24%) and hydroquinone (8%) (65). The same effect can also be observed with Cu(II)—Cu(0) as a catalytic system (66). Efforts are now directed toward the use of Pd° on a support and Cu in aqueous acid and in the presence of a reducing agent such as CO, H2, or ethylene (67). Aromatic... 

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