Process for production of polymers by free-radical polymerization of acrylic acid wherein the polymer is a water-absorbing polymer obtainable by a process comprising the steps of: i) polymerizing the acrylic acid in the presence of a crosslinker to form a polymer gel; ii) optionally comminuting the polymer gel; iii) drying the optionally comminuted polymer gel to obtain water-absorbing polymer structures; and iv) optionally surface-aftertreating the water-absorbing polymer structures; wherein the acrylic acid was obtained by a method of synthesis comprising the step of: splitting an organic material by means of an enzyme or of at least one constituent of an enzyme, through fermentation or through enzymes isolated from cells and optionally immobilized on a substrate, or at least one constituent of enzymes, the organic material is at least 75 wt% based on a carbohydrate, wherein the organic material used comprises malt extract, oatmeal or milk powder, pure defined carbohydrates, in particular polysaccharides, such as raffinose, starch, cellulose, glycogen or dextrins, disaccharides, such as sucrose, lactose or maltose, and monosaccharides, preferably hexoses such as galactose, xylose, glucose, galactose or fructose, or else sugar alcohols, wherein the step of splitting the carbohydrate gives β-hydroxypropionic acid and wherein the method of synthesis for the acrylic acid, in addition to a step a) of enzymatically splitting the carbohydrate to obtain β-hydroxypropionic acid, comprises a step b) of: - catalytically dehydrating the β-hydroxy-propionic acid to obtain acrylic acid, wherein the catalyst used is a porous supporting body contacted with an inorganic acid and the porous supporting body is at least 90 wt% based on a silicon oxide and has a surface area in a range extending from 0.005 to 450 m 2 /g. i) polymerizing the acrylic acid in the presence of a crosslinker to form a polymer gel; ii) optionally comminuting the polymer gel; iii) drying the optionally comminuted polymer gel to obtain water-absorbing polymer structures; and iv) optionally surface-aftertreating the water-absorbing polymer structures; wherein the acrylic acid was obtained by a method of synthesis comprising the step of: splitting an organic material by means of an enzyme or of at least one constituent of an enzyme, through fermentation or through enzymes isolated from cells and optionally immobilized on a substrate, or at least one constituent of enzymes, the organic material is at least 75 wt% based on a carbohydrate, wherein the organic material used comprises malt extract, oatmeal or milk powder, pure defined carbohydrates, in particular polysaccharides, such as raffinose, starch, cellulose, glycogen or dextrins, disaccharides, such as sucrose, lactose or maltose, and monosaccharides, preferably hexoses such as galactose, xylose, glucose, galactose or fructose, or else sugar alcohols, wherein the step of splitting the carbohydrate gives β-hydroxypropionic acid and wherein the method of synthesis for the acrylic acid, in addition to a step a) of enzymatically splitting the carbohydrate to obtain β-hydroxypropionic acid, comprises a step b) of: - catalytically dehydrating the β-hydroxy-propionic acid to obtain acrylic acid, wherein the catalyst used is a porous supporting body contacted with an inorganic acid and the porous supporting body is at least 90 wt% based on a silicon oxide and has a surface area in a range extending from 0.005 to 450 m 2 /g. splitting an organic material by means of an enzyme or of at least one constituent of an enzyme, through fermentation or through enzymes isolated from cells and optionally immobilized on a substrate, or at least one constituent of enzymes, the organic material is at least 75 wt% based on a carbohydrate, wherein the organic material used comprises malt extract, oatmeal or milk powder, pure defined carbohydrates, in particular polysaccharides, such as raffinose, starch, cellulose, glycogen or dextrins, disaccharides, such as sucrose, lactose or maltose, and monosaccharides, preferably hexoses such as galactose, xylose, glucose, galactose or fructose, or else sugar alcohols, wherein the step of splitting the carbohydrate gives β-hydroxypropionic acid and wherein the method of synthesis for the acrylic acid, in addition to a step a) of enzymatically splitting the carbohydrate to obtain β-hydroxypropionic acid, comprises a step b) of: - catalytically dehydrating the β-hydroxy-propionic acid to obtain acrylic acid, - catalytically dehydrating the β-hydroxy-propionic acid to obtain acrylic acid, wherein the catalyst used is a porous supporting body contacted with an inorganic acid and the porous supporting body is at least 90 wt% based on a silicon oxide and has a surface area in a range extending from 0.005 to 450 m 2 /g.