Sulfuric acid as solvent

The present procedure describes conditions, which allow for the formation of 5-bromoisoquinoline in good yield and high purity using easily available and inexpensive starting materials. In order to obtain the desired product, it is important to ensure careful temperature control to suppress the formation of 8-bromoisoquinoline, which is difficult to remove. By choosing sulfuric acid as solvent for the bromination, a convenient one-pot procedure to prepare 5-bromo-8-nitroisoquinoline, without prior isolation of 5-bromoisoquinoline, has been developed. Finally, the method can easily be scaled up from grams to kilograms of the title compounds. 

The reaction conditions necessary to obtain a good yield of the title compound (a difficult isomer), and to avoid hazards during the nitration of resorcinol, are critical and strict adherence to those specified is essential. The necessary 80% white fuming nitric acid must be completely free from oxides of nitrogen and nitrous acid, and procedures for this are detailed. Then the temperature dining addition of the diacetate must be kept between -10 and 0°C by regulating the rate of addition. The alternative use of 80% sulfuric acid as solvent for the 80% nitric acid (5 equiv.) is preferred as more reliable, but both methods have led to violent exothermic decomposition, accompanied by fume-off, after an induction period. In any event, the explosive 2,4,6-trinitroresorcinol ( styphnic acid ) is produced as a by-product. 

The fluorination of quinoline was performed in a microstructured reactor operated in the annular-flow regime, which contained one microchannel with two consecutive feeds for gas and liquid [311,312]. The role of the solvent was large. The reaction was totally unselective in acetonitrile and gave only tarlike products. With formic acid, a mixture of mono- and polyfluorinated products besides tar was formed. No tar formation was observed with concentrated sulfuric acid as solvent at 0-5 °C. In this way, a high selectivity of about 91% at medium conversion was achieved. Substitution was effective only in the electron-rich benzenoid core and not in the electron-poor pyridine-type core. The reactivity at the various positions in the quinoline molecule is 5 > 8 > 6 and thus driven by the vicinity to the heteroatom nitrogen that corresponds to the electrophilic reactivity known from proton/deuterium exchange studies in strong acid media. 

Shilov chemistry, developed from 1970, employs [Pt(II)CLt] salts to oxidize alkanes RH to ROH or RCl with modest efficiency. Pt(IV) is an efficient (but economically impractical) primary oxidant that makes the process catalytic. This discovery strongly contributed to the continuing activity in CH activation. Periana developed a related and much more efficient system for methane oxidation to methanol using 2,2 -bipyrimidine ligands and sulfuric acid as solvent. In this case, the sulfuric acid is the primary oxidant and the methanol formed is protected by being converted in situ to MeOSOsH, an ester that strongly resists further oxidation. This area is more fully described under the entry Alkane Carbon-Hydrogen Bond Activation. 

These results emphasize the fact that ions produced by self-ionization of the solvent, e.g., HsO and 0H in water, ROHt and R0 in alcohols, and NHi" and NHJ in liquid ammonia, do not of necessity possess abnormal conductance, although they frequently do so. It is seen from Table XIX that the conductance of the hydrogen ion in liquid ammonia, i.e., NHi", is normal the same is true for the NHi" ion. The anilinium and pyridinium ions also have normal conductances in the corresponding solvents. The conductance of the HSOr ion in sulfuric acid as solvent is, however, abnormally high it is probable that a Grotthuss type of... 

Hammett and Lowenheim [J. Am. Chem. Soc., 56, 2620 (1934)] electrolyzed, with inert electrodes, a solution of Ba(HS04)2 in sulfuric acid as solvent 1 g. of this solution contained 0.02503 g. BaS04 before electrolysis. After the passage of 4956 coulombs, 41 cc. of the anode solution and 39 cc. of the cathode solution, each having a density of 1.9, were run off they were found on analysis to contain 0.02411 and 0.02621 g. of BaS04 per gram of solution, respectively. Calculate the transference number of the cation. 

Interest in sulfuric acid-water mixtures and anhydrous sulfuric acid as solvents has considerably intensified in recent years following the pioneer work of Hantzsch (53, 54), mainly in the period 1907-1911, and the work of Hammett (55, 56, 57, 84) in the 1930 s. It is perhaps surprising that the chemical and physical properties of anhydrous sulfuric acid have been comparatively little investigated until recent years considering that sulfuric acid is probably the most widely used of inorganic chemicals and is available in an excellent state of purity. 

Interestingly, carbonylation can also proceed in the absence of CO, although in only 10% yield, using PdS04 as the catalyst in concentrated sulfuric acid as solvent and oxidant ... 

Polyamides can also be made by the reaction of amines with acyl halides, where the condensate is hydrochloric acid. This process is used to make aromatic polyamides, notably Kevlar and Nomex (Scheme 1.7). The reaction of p-phenylenediamine with terephthaloyl chloride results in the high performance p-aramid Kevlar. While Kevlar is expensive because processing requires the use of anhydrous sulfuric acid as solvent, its outstanding mechanical and thermal properties led to its use in demanding applications, including personal armor, bicycle tires, and racing sails. 

Most cellulose acetate is manufactured by a solution process, ie, the cellulose acetate dissolves as it is produced. The cellulose is acetylated with acetic anhydride acetic acid is the solvent and sulfuric acid the catalyst. The latter can be present at 10—15 wt % based on cellulose (high catalyst process) or at ca 7 wt % (low catalyst process). In the second most common process, the solvent process, methylene chloride replaces the acetic acid as solvent, and perchloric acid is frequentiy the catalyst. There is also a seldom used heterogeneous process that employs an organic solvent as the medium, and the cellulose acetate produced never dissolves. More detailed information on these processes can be found in Reference 28. 

Various processes involve acetic acid or hydrocarbons as solvents for either acetylation or washing. Normal operation involves the recovery or recycle of acetic acid, any solvent, and the mother Hquor. Other methods of preparing aspirin, which are not of commercial significance, involve acetyl chloride and saHcyHc acid, saHcyHc acid and acetic anhydride with sulfuric acid as the catalyst, reaction of saHcyHc acid and ketene, and the reaction of sodium saHcylate with acetyl chloride or acetic anhydride. 

Cellulose acetate [9004-35-7] is the most important organic ester because of its broad appHcation in fibers and plastics it is prepared in multi-ton quantities with degrees of substitution (DS) ranging from that of hydrolyzed, water-soluble monoacetates to those of fully substituted triacetate (Table 1). Soluble cellulose acetate was first prepared in 1865 by heating cotton and acetic anhydride at 180°C (1). Using sulfuric acid as a catalyst permitted preparation at lower temperatures (2), and later, partial hydrolysis of the triacetate gave an acetone-soluble cellulose acetate (3). The solubiUty of partially hydrolyzed (secondary) cellulose acetate in less expensive and less toxic solvents such as acetone aided substantially in its subsequent commercial development. 

The Prins reaction often yields stereospecifically the and-addition product this observation is not rationalized by the above mechanism. Investigations of the sulfuric acid-catalyzed reaction of cyclohexene 8 with formaldehyde in acetic acid as solvent suggest that the carbenium ion species 7 is stabilized by a neighboring-group effect as shown in 9. The further reaction then proceeds from the face opposite to the coordinating OH-group " ... 

Proton Transfers in Various Solvents. The Autoprotolysis of Methanol. Formic Acid as Solvent. The Sulfate Ion. Autoprotolysis of Formic Add. The Urea Molecule. Sulfuric Add and Liquid Ammonia as Solvents. 

Nitro-2-(3-nitrophenyl)-propanediol-1,3-dinitrate (2-Nitro-2-(m-nitrophenyl)-propane-l, 3-diol-dinitrate). (02N)C6H4. C(N02) (CH20N02)2, mw 332, N 16 %, OB to C02 -57.8%, pale yel acicular prisms, mp 71—73.6°. Can be prepd by nitrating 2-nitro-2-(3 r-nitrophenyl)-propanediol-1, 3 with mixed nitric-sulfuric acid, as described in Ref 2, p 23. Sol in most common organic solvents... 

C2Hs.C02.CH2.CH2,N02 mw 147,15 N 9.52% OB to C02 -114.15% colorl mobile liq mp, when distd above 150° the compd deton bp 106.0 to 108.2° at 10mm d 1.1727g/cc RI 1.4336. Prepn is by reacting at a boil 2-nitro-ethylalcohol with propionic acid in benz solvent, with coned sulfuric acid as the coupling reagent. The prod is recovered by vac distn Ref Beil 2, 524 ... 

In concluding this section, we should touch upon phase boundary concentration data for poly(p-benzamide) dimethylacetamide + 4% LiCl [89], poly(p-phenylene terephthalamide) (PPTA Kevlar)-sulfuric acid [90], and (hydroxy-propyl)cellulose-dichloroacetic acid solutions [91]. Although not included in Figs. 7 and 8, they show appreciable downward deviations from the prediction by the scaled particle theory for the wormlike hard spherocylinder. Arpin and Strazielle [30] found a negative concentration dependence of the reduced viscosity for PPTA in dilute Solution of sulfuric acid, as often reported on polyelectrolyte systems. Therefore, the deviation of the Ci data for PPTA in sulfuric acid from the scaled particle theory may be attributed to the electrostatic interaction. For the other two systems too, the low C] values may be due to the protonation of the polymer, because the solvents of these systems are very polar. 

Kraft Lignin. A softwood kraft lignin (KL) was isolated from a partly evaporated, industrial kraft black liquor by precipitation through the addition of dilute sulfuric acid as described elsewhere (7). The lignin was thereafter fractionated by successive extraction with organic solvents (7). The KL fraction used in the present investigation was the second of five fractions obtained (propanol soluble - methylene chloride insoluble). 

Dioxacyclohexanes can be produced in excellent yields from aliphatic or aryl-substituted alkenes.64 Dilute sulfuric acid at or above room temperature with paraformaldehyde appears to give the best results. Dioxane-water or acetic acid as solvent was found to afford increased yields in the Prins reaction of arylalkenes. 

Tests for carboxylic acids were made by paper chromatography using 95% ethanol (100 ml.) and concentrated ammonium hydroxide (1 ml.) as solvent and aqueous bromothymol blue as indicator (1). Tests for pyridines were made on their hydrochlorides using butanol-.acetic acid water (4 1 5) as solvent and ammoniacal iron chloride or cysteine-sulfuric acid as indicators. Phenol tests were made using the same solvent and ammoniacal silver nitrate as indicator. Preliminary separations by gas chromatography were attempted using a 15-foot silicone gum column and a hydrogen flame attachment. 

---