Hydrolysis partial

The partial hydrolysis of polysaccharides by acids or enzymes, to give di-, tri-, and oligo-saccharides has been developed in the past ten years into one of the principal methods of polysaccharide structural chemistry. Elucidation of the structure of the oligosaccharides formed provides information, both about the main structural features and about minor details of the parent polysaccharide, that in many cases could not be obtained by other available methods. 

Acid hydrolysis is a reversible reaction and, if more concentrated solutions are used, there may be formed oligosaccharides that are not characteristic of the polysaccharide hydrolyzed. However, in dilute solutions (less than 1 %), the reverse reaction is unimportant and only insignificant amounts of artificial oligosaccharides are formed.  

Kuhni has developed a theoretical treatment of the results of the hydrolysis of linear, uniformly built polysaccharides this treatment gives good agreement with experimental results for the hydrolysis of cellulose. When a fraction, a, of the glycosidic linkages is split, the amount of oligosaccharide containing n monomer residues is na (l — a) . The maximum amount. 

A linear polysaccharide containing only one type of linkage gives, on 

Partial hydrolysis is also useful in the study of some problems connected with heteroglycans. Whistler and Durso hydrolyzed guaran to 79 % completion and isolated 4-0-/3-D-mannopyranosyl-D-mannose, 6-0-a-n-galacto-pyranosyl-D-mannose, and 6-0-a-D-galactopyranosyl-4-0- 3-D-mannopyran-osyl-D-mannose from the hydrolysate. This enabled an unambiguous 

Also suited for the specific enzymatic hydrolysis of peptide chains is the endoproteinase Glu-C from Staphylococcus aureus V8. It cleaves Glu-X bonds (ammonium carbonate buffer pH 7.8 or ammonium acetate buffer pH 4.0) as well as Glu-X plus Asp-X bonds (phosphate buffer pH 7.8). The most important chemical method for selective cleavage uses cyanogen bromide (BrCN) to attack Met-X-hnkages (Reaction 1.86). Hydrolysis of proteins with strong acids reveals a difference in the rates of hydrolysis of peptide bonds depending on the adjacent amino acid side chain. Bonds involving amino groups of serine and threonine are particularly susceptible to hydrolysis. This effect is due to 

N 0-acyl migration via the oxazoline and subsequent hydrolysis of the ester bond  

The fragmentation of the protein is performed by different enzymic and/or chemical techniques, at least by two enzymes of different specifity. The arrangement of the obtained peptides in the same order as they occur in the intact protein is accomplished with the aid of overlapping sequences. The principle of this method is illustrated for subtilisin BPN as an example in Fig. 1.11. 

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Prepared by the action of ammonia on benzoyl chloride or benzoic esters, or by partial hydrolysis of benzonitrile. 

Proteins consist of large numbers of amino-acids joined by the p>eptide link —CO —NH — into chains, as shown in the diagram, where R and R" are amino-acid residues. These chains are called peptides and may be broken into smaller chains by partial hydrolysis (see peptides). Proteins may contain more than one peptide chain thus insulin consists of... 

Higher chlorides, Si2Cle to Si6Cl,4 (highly branched - some cyclic) are formed from SiCU plus Si or a silicide or by amine catalysed disproportionations of Si2Cl,5, etc. Partial hydrolysis gives oxide chlorides, e.g. CUSiOSiCla. SiCU is used for preparation of silicones. 

Antimony Ill) fluoride is a readily hydrolysable solid which finds use as a fluorinaling agent. Antimony(lll) chloride is a soft solid, m.p. 347 K. It dissolves in water, but on dilution partial hydrolysis occurs and antimony chloride oxide SbOCl is precipitated ... 

Cannot be used for alcohols, phenols or amines, with all of which it combines. Not advisable for acidic liquids, as ordinary calcium chloride always contains some calcium hydroxide owing to partial hydrolysis during preparation. Usually used for alcohols (see p. 88). Cannot be used for acidic compounds, nor for esters, which it would hydrolyse. 

Dissolve a small portion of the sodium derivative in a few mi. of water in a test-tube, and add one drop of ferric chloride solution. A deep red coloration is produced, but rapidly disappears as the iron is precipitated as ferric hydroxide. The sodium (derivative (A) of the nitromethane wh dissolved in water undergoes partial hydrolysis,... 

The addition of the sulphuric acid first neutralises the sodium hydroxide, and then gives a weakly acidic and therefore colourless solution. The sodium derivative (A) then undergoes further partial hydrolysis in order to re-establish the original equilibrium, and the sodium hydroxide thus formed again produces the pink coloration, which increases in depth as the hydrolysis proceeds. 

Place 5 ml. of benzaldehyde in a wide-necked stout-walled bottle of about 100 ml. capacity (a conical flask is too fragile for this purpose) and add 50 ml. of concentrated dy 0 880) ammonia solution. Cork the bottle securely, shake vigorously, and then allow to stand for 24 hours, by which time the layer of benzaldehyde at the bottom of the bottle will have been converted into a hard mass of hydrobenzamide. (If after 24 hours the crude hydrobenzamide is still syrupy, shake the mixture vigorously and allow to stand for another hour, when the conversion will be complete.) Break up the solid pellet with a strong spatula, filter at the pump, wash with water and drain thoroughly. Recrystallise from ethanol methylated spirit should not be used, as it contains sufficient water to cause partial hydrolysis back to benzaldehyde and ammonia. Hydrobenzamide is obtained as colourless crystals, m.p. 101° (and not 110° as frequently quoted) yield, 4 g. 

The oxidation of higher alkenes in organic solvents proceeds under almost neutral conditions, and hence many functional groups such as ester or lac-tone[26,56-59], sulfonate[60], aldehyde[61-63], acetal[60], MOM ether[64], car-bobenzoxy[65], /-allylic alcohol[66], bromide[67,68], tertiary amine[69], and phenylselenide[70] can be tolerated. Partial hydrolysis of THP ether[71] and silyl ethers under certain conditions was reported. Alcohols are oxidized with Pd(II)[72-74] but the oxidation is slower than the oxidation of terminal alkenes and gives no problem when alcohols are used as solvents[75,76]. 

By-product acetic acid is obtained chiefly from partial hydrolysis of cellulose acetate [9004-35-7]. Lesser amounts are obtained through the reaction of acetic anhydride and cellulose. Acetylation of saHcyHc acid [69-72-7] produces one mole of acetic acid per mole of product and the oxidation of allyl alcohol using peracetic acid to yield glycerol furnishes by-product acid, but the net yield is low. 

Many of these reactions are reversible, and for the stronger nucleophiles they usually proceed the fastest. Typical examples are the addition of ammonia, amines, phosphines, and bisulfite. Alkaline conditions permit the addition of mercaptans, sulfides, ketones, nitroalkanes, and alcohols to acrylamide. Good examples of alcohol reactions are those involving polymeric alcohols such as poly(vinyl alcohol), cellulose, and starch. The alkaline conditions employed with these reactions result in partial hydrolysis of the amide, yielding mixed carbamojdethyl and carboxyethyl products. 

The reaction with sodium sulfite or bisulfite (5,11) to yield sodium-P-sulfopropionamide [19298-89-6] (C3H7N04S-Na) is very useful since it can be used as a scavenger for acrylamide monomer. The reaction proceeds very rapidly even at room temperature, and the product has low toxicity. Reactions with phosphines and phosphine oxides have been studied (12), and the products are potentially useful because of thek fire retardant properties. Reactions with sulfide and dithiocarbamates proceed readily but have no appHcations (5). However, the reaction with mercaptide ions has been used for analytical purposes (13)). Water reacts with the amide group (5) to form hydrolysis products, and other hydroxy compounds, such as alcohols and phenols, react readily to form ether compounds. Primary aUphatic alcohols are the most reactive and the reactions are compHcated by partial hydrolysis of the amide groups by any water present. 

Aluminum chloride hydroxide [1327-41 -9] also called polyaluminum chloride or PAG, is made by partial hydrolysis of aluminum chloride to form a mixture of polymeric species. It is more expensive than alum on a weight basis, but has advantages over alum such as not lowering the pH as much and better cost-effectiveness in some appHcations. Residual aluminum in the water is said to be lower and performance in cold water is better (6,7). It is sold as a solution (see Aluminum compounds, polyaluminum cm ORiDEs). 

Solid Superacids. Most large-scale petrochemical and chemical industrial processes ate preferably done, whenever possible, over soHd catalysts. SoHd acid systems have been developed with considerably higher acidity than those of acidic oxides. Graphite-intercalated AlCl is an effective sohd Friedel-Crafts catalyst but loses catalytic activity because of partial hydrolysis and leaching of the Lewis acid halide from the graphite. Aluminum chloride can also be complexed to sulfonate polystyrene resins but again the stabiUty of the catalyst is limited. 

Reportedly, simple alkyl isocyanates do not dimerize upon standing. They trimerize to isocyanurates under comparable reaction conditions (57). Aliphatic isocyanate dimers can, however, be synthesized via the phosgenation of A[,A[-disubstituted ureas to yield /V-(ch1orocarhony1)ch1oroformamidine iatermediates which are subsequendy converted by partial hydrolysis and base catalyzed cycUzation. This is also the method of choice for the synthesis of l-alkyl-3-aryl-l,3-diazetidiones (mixed dimers of aromatic and aUphatic isocyanates) (58). 

Properties and Reactions. Several methods of preparation are available for POCI3, including partial hydrolysis of PCl by heating in the presence of oxaflc or boric acid, chlorination and hydrolysis of PCl in the presence of H PO, ... 

Pentavalent phosphorus derivatives can be converted to phosphonyl halides or phosphine oxides by partial hydrolysis or by other oxygen donors. 

An alternative synthesis route for PES involves the partial hydrolysis of dichlorodiphenyl sulfone (2) with base to produce 4-chloro-4 -hydroxydiphenylsulfone [7402-67-7] (3) followed by the polycondensation of this difimctional monomer in the presence of potassium hydroxide or potassium carbonate (7). 

Partial hydrolysis of a metal alkoxide to form reactive monomers. 

Vinyl resins ie, copolymers of vinyl chloride and vinyl acetate which contain hydroxyl groups from the partial hydrolysis of vinyl acetate and/or carboxyl groups, eg, from copolymerized maleic anhydride, may be formulated with alkyd resins to improve their appHcation properties and adhesion. The blends are primarily used in making marine top-coat paints. 

Condensation catalysts include both acids and bases, as well as organic compounds of metals. Both tin(II) and tin(IV) complexes with carboxyhc acids ate extremely useful. It has been suggested that the tin catalyst is converted to its active form by partial hydrolysis followed by reaction with the hydrolyzable silane to yield a tin—sdanolate species (eqs. 22 and 23) (193,194). 

Succinic acid reacts with urea in aqeous solution to give a 2 1 compound having mp 141°C (116,117), which has low solubiUty in water. A method for the recovery of succinic acid from the wastes from adipic acid manufacture is based on this reaction (118,119). The monoamide succinamic acid [638-32-4] NH2COCH2CH2COOH, is obtained from ammonia and the anhydride or by partial hydrolysis of succinknide. The diamide succinamide [110-14-3], (CH2C0NH2)2, nip 268—270°C, is obtained from succinyl chloride and ammonia or by partial hydrolysis of succinonitrile. Heating succinknide with a primary amine gives A/-alkylsucckiknides (eq. 9). 

On partial hydrolysis, diorganotin halides and carboxylates may form basic salts having a rather comphcated stmcture ... 

High purity tetraalkyl titanates can be obtained by a process whereby the Hquid organic titanate esters are subjected to partial hydrolysis to form a sohd that can be separated from the reaction mass. The remaining Hquid is distilled to give a high purity product (4). For example, tetraisopropyl titanate purified in this manner contains ... 

Partial hydrolysis of TYZOR DC or the monoethylacetoacetate ester chelate, followed by removal of the isopropyl alcohol by-product, gives a dimeric )J.-oxo chelate (8), which also has improved cold-temperature-storage stabiUty (98). 

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