Formic acid nettle

H-COOH methanoic (formic) acid — nettle stings... 

Other living things besides animals also use acid to sting. The stinging nettle bush has sharp, hollow hairs that contain various chemicals, including formic acid, that irritate the skin of any animal that is unfortunate enough to rub up against it. 

We first met nettle stings on p. 253, where methanoic ( formic ) acid was identified as the active toxin causing the pain. Like its... 

Oocrmimee.—lke greater number of tbe aoids of this secies are met with ready formed in nature, some in the free state, as formic acid in ants and nettles, ralerio acid in the valerian root, pehu onio acid in the essential oil of the jPehrgonim roaem, and cerotio acid in bees>wax. 

Formic acid also occurs in the hairs of certain caterpillars, and in the sting of nettles. 

Formic acid (HCO2H) is an organic acid secreted by ants and stinging nettles. Calculate the pH and the concentrations of all species present (HCO2H, HCO2-, H3O+,andOH-)in0.20MHCO2H(Ka = 1.8 X 10 4). Also calculate the percent dissociation. 

Other chemicals may after repeated exposure cause more subtle effects on the skin such as allergic reactions. Skin sensitization can be caused by nickel in jewellery or the constituents of some washing powders. Sensitization of the skin leading to allergic, contact dermatitis can be very serious as well as disfiguring and is the most common industrial disease (see Chapter 7). Some natural toxicants, such as nettle sting (formic acid) and the very potent substances in the plant poison ivy, can be skin irritants. 

Occurrence.—The members of this series of acids are derived from the methane series of hydrocarbons and occur very commonly in nature. In a few cases they are found free as formic acid in ants and nettles and valeric acid in the root of Valeriana. In most cases the acids are combined with alcohols as esters and as such are found in ethereal oils, fats and waxes. This has given them the name fatty acids. 

Formic acid—HCO,OH—46—occurs in the acid secretion of red ants, in the stinging hairs of certain insects, in the blood, urine, bile, perspiration, and muscular fluid of man, in the stinging-nettle, and in the leaves of trees of the pine family. It is produced in a number of reactions by the oxidation of many organic substances sugar, starch, flbrin, gelatin, albumin, etc. by the action of potash upon chloroform and kindred bodies by the action of mineral acids in hydrocyanic acid during the fermentation of diabetic urine by the direct union of carbon mon-... 

Formic acid methanoic acid H —C —OH O II Stinging agents of certain ants and nettles used in food preservation... 

Formic acid and acetic acid are the two most important carboxylic acids. Formic acid is a source of irritation in the bites of ants and other insects or in the scratch of nettles. A liquid with a sharp, irritating odor, formic acid is used in manufacturing esters, salts, and plastics. Acetic acid is present in a concentration of about 5% in vinegar and is responsible for its odor and taste. Acetic acid is among the least expensive organic acids, and is therefore a raw material in many commercial processes that require a carboxylic acid. Sodium acetate is one of several common salts of carboxylic acids. It is used to control the acidity of chemical processes and in preparing soaps and pharmaceutical agents. 

The strongest carboxyhc acid is formic acid, H-COOH. Formic acid is released when red ants bite and when nettles are touched, and is the source of the strong irritation people feel. In fact, formic acid is so closely associated with ants that the Latin word for ant is the origin... 

As Table 19-1 indicates, even the simplest carboxylic acids are abundant in nature. Formic acid is present not only in ants, where it functions as an alarm pheromone and chemical weapon, but also in plants. For example, one reason why human skin hurts after it touches the stinging nettle is that formic acid is deposited in the wounds. 

Formic or methanoic acid (an aliphatic acid). Found in sweat, urine and stinging nettles. 

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