Acetic acid molecular weight

Name acetic acid Molecular formula C2H4O2 Molecular weight 60 pKa value 4.7... 

O-acetyl-a-D-mannopyranosyl unit. About half of the terminal P-D-mannopyranosyl units carry a pyruvic acid group as a 4,6-di-O-acetal. The molecular weight is probably on the order of 2 x 106 daltons, although much higher figures have been reported. 

Epoxide values were determined by a well established poten-tiometric titrimetric method using perchloric acid in acetic acid (3). Weight average molecular weights were measured in a SOFICA light scattering apparatus in diglyme. 

Xanthan (qv) is an extracellular bacterial polysaccharide produced by Xan-thomonas campestris. Xanthan is a branched polysaccharide with jS-1 4-d-glucopyranose units along the backbone. On every other nnit the oxygen at C-3 is substituted with a trisaccharide imit. Approximately half the fi-D mannose imits have a pyruvic acid group linked as an acetal derivative. Molecular weight has been estimated to be 2 x 10 . 

They are colourless liquids with characteristic odours, and are prepared by the condensation of ketones with alkyl orthoformates in the presence of alcohols, or by the reaction of acetylenes with alcohols in presence of HgO and BF3. In some cases trichloroethanoic acid is used as the catalyst. They lose alcohol when heated and form vinyl ethers. Exchange of alcohol groups occurs when the ketals of the lower alcohols are boiled with alcohols of greater molecular weight. See acetals. 

The excess of unchanged acetic anhydride is then hydrolysed by the addition of water, and the total free acetic acid estimated by titration with standard NaOH solution. Simultaneously a control experiment is performed identical with the above except that the alcohol is omitted. The difference in the volumes of NaOH solution required in the two experiments is equivalent to the difference in the amount of acetic add formed, i.e., to the acetic acid used in the actual acetylation. If the molecular weight of the alcohol is known, the number of hydroxyl groups can then be calculated. 

Heat the amine with one or two mols of redistilled benzaldehyde (according as to whether the base is a monamine or diamine) to 100° for 10 minutes if the molecular weight is unknown, use 1 g. of the base and 1 or 2 g. of benzaldehyde. Sometimes a solvent, such as alcohol (5 ml.) or acetic acid, may be used. Recrystallise from alcohol, dilute alcohol or benzene. 

Dissolve 0 01 mol (or 1 g. if the molecular weight is unknown) of the compound in 5 ml. of 3A sodium hydroxide solution, add 10-20 g. of crushed ice followed by 1-5 g. (1-5 ml.) of acetic anh3 dride. Shake the mixture vigorously for 30-60 seconds. The acetate separates in a practically pure condition either at once or after acidification by the addition of a mineral acid. Collect the acetyl derivative, and recrystallise it from hot water or from dilute alcohol. 

Esters can participate m hydrogen bonds with substances that contain hydroxyl groups (water alcohols carboxylic acids) This confers some measure of water solubil ity on low molecular weight esters methyl acetate for example dissolves m water to the extent of 33 g/100 mL Water solubility decreases as the carbon content of the ester increases Fats and oils the glycerol esters of long chain carboxylic acids are practically insoluble m water... 

Howardt describes a model system used to test the molecular weight distribution of a condensation polymer The polymer sample was an acetic acid-stabilized equilibrium nylon-6,6. Analysis showed it to have the following end group composition (in equivalents per 10 g) acetyl = 28.9,... 

The vapor density of acetic acid suggests a molecular weight much higher than the formula weight, 60.06. Indeed, the acid normally exists as a dimer (4), both in the vapor phase (5) and in solution (6). This vapor density anomaly has important consequences in engineering computations, particularly in distillations. 

The name naphthenic acid is derived from the early discovery of monobasic carboxyUc acids in petroleum, with these acids being based on a saturated single-ring stmcture. The low molecular weight naphthenic acids contain alkylated cyclopentane carboxyUc acids, with smaller amounts of cyclohexane derivatives occurring. The carboxyl group is usually attached to a side chain rather than direcdy attached to the cycloalkane. The simplest naphthenic acid is cyclopentane acetic acid [1123-00-8] (1, n = 1). 

Cyclic Peroxides. CycHc diperoxides (4) and triperoxides (5) are soHds and the low molecular weight compounds are shock-sensitive and explosive (151). The melting points of some characteristic compounds of this type are given in Table 5. They can be reduced to carbonyl compounds and alcohols with zinc and alkaH, zinc and acetic acid, aluminum amalgam, Grignard reagents, and warm acidified iodides (44,122). They are more difficult to analyze by titration with acidified iodides than the acycHc peroxides and have been sucessfuUy analyzed by gas chromatography (112). 

Acidolysis, Aminolysis, and Alcoholysis. When heated, polyamides react with monofunctional acids, amines, or alcohols, especially above the melt temperature, to undergo rapid loss of molecular weight (58,59), eg, as in acidolysis (eq. 3) with acetic acid [64-19-7] or aminolysis (eq. 4) with an ahphatic amine ... 

Carbon Cha.in Backbone Polymers. These polymers may be represented by (4) and considered derivatives of polyethylene, where n is the degree of polymeriza tion and R is (an alkyl group or) a functional group hydrogen (polyethylene), methyl (polypropylene), carboxyl (poly(acryhc acid)), chlorine (poly(vinyl chloride)), phenyl (polystyrene) hydroxyl (poly(vinyl alcohol)), ester (poly(vinyl acetate)), nitrile (polyacrylonitrile), vinyl (polybutadiene), etc. The functional groups and the molecular weight of the polymers, control thek properties which vary in hydrophobicity, solubiUty characteristics, glass-transition temperature, and crystallinity. 

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