Abstract
According to green chemistry recommendations, avoiding usage of solvents during chemical reactions was considered as a modern approach in research worldwide. Usage of solvents usually associated with environmental impacts and chemical contamination besides the economical factor. So, it is highly recommended to undergo the chemical reaction without using solvents. Accordingly, our present study aimed to prepare carboxylate salts under solvent-free conditions. In this study, twelve salts like salicylate, oxalate, tartrate, and citrate have been prepared successfully in the form of sodium, potassium, and calcium salts using grindstone neutralization reactions between reactants in solid phase. Reactions under investigations were examined and evaluated in terms of initiating grinding time, practical percentage yield (%), and the released reaction temperature as-well-as the violence of the reaction. The reaction was affected greatly by acidity, basicity, and aromaticity of the reactants. It was found that sodium, potassium, and calcium salts of oxalate, tartrate, and citrate easily prepared within shorter time period (~1-4min.) with relatively high practical percentage yield (~ 60-85%). The violence of the reactions was monitored by recording the maximum elevated temperature which reached to 103°C after 2min. for the reaction of tartaric acid with NaOH. Aluminum salts of salicylate, oxalate, tartrate, and citrate were excluded from the grindstone neutralization reactions due to insufficient chemical reactivity of aluminum hydroxide towards carboxylic acids. It was found that salicylic acid is the lowest reactive compound due to its aromatic property, and therefore salicylate salts show the lowest percentage yield (~50-70%). Acidity and basicity are the main operational factors affecting on the chemical structure of the final product and its amount. The rate of changing temperature with grinding time (Δ∅,°C/min.) was calculated for the investigated reactions, and the reaction of citric acid with NaOH has the highest Δ∅ value. Finally, the proposed chemical reaction is considered as good new water resources as-well-as simple preparation method for carboxylate salts. Grindstone neutralization reactions were characterized by simplicity, workability, applicability, efficiently in addition to shorter life time for the preparation of various salts of organic acids.