Study On Development And Utilization Of Salicylic Acid Industrial Byproduct

Ultraviolet absorber is an optical stabilizer, which can absorb the ultraviolet part in sunlight and fluorescent light sources. UV absorbers are widely used not only in sunscreen cosmetics, and the anti-ultraviolet fabric, but also as a light stabilizer in polymer materials such as fiber, outdoor lumber, paint, varnish, plastic and rubber. It is possible to improve the materials' resistance to the sun, weather and aging.Salicylate is the first application of UV absorbers. Many kinds of the products are widely used. Salicylic acid-based ultraviolet absorber has relatively mild, stable, and more secure characteristics, especially very safe for the skin, but also has high compatibility in product system.In the paper, the salicylic acid industrial production byproduct, 4-hydroxy-1,3-dibenzoic acid, was used to synthesize nine kinds of 4-hydroxy-1,3-phthalate ester derivatives. The UV absorption spectra and fluorescence emission spectra of these compounds were researched. A UV absorption property of moderate-intensity was found in the wavelength near 310nm, which has potential applications. This paper is composed of the following sections: 1. Chloride reagent was used to synthesise 4-hydroxy-1,3-dimethyl-phthalate, 4-hydroxy-1,3-diethyl-phthalate,4-hydroxy-1,3-di-n-propyl-phthalate,4-hydroxy-1,3-diphen yl phthalate and the yields were respectively 92.7%,91.6%,90.3% and 90.8%;2. NaH was used as an alkali to synthesis 4-hydroxy-1,3-benzenedicarboxylic acid sodium salt, and then reacted with benzyl bromide to synthesis 4-hydroxy-1,3-dibenzoate di-benzyl ester. Temperature and material ratio was optimized, and the reaction yield was 88.9%;3. NaHSO4 was used as catalyst to synthesis 4-hydroxy-1,3-dibenzoate di-iso-octyl ester and 4-hydroxy-1,3-dibenzoate dioctyl phthalate, and the yields were respectively 93.7% and 92.5%;4. Nitrate was used as nitrating agent in the nitration reagent to synthesis 4-hydroxy-5-nitro-1,3-dimethyl phthalate, and then it was hydrolysised under basic conditions to synthesis 4-hydroxy-5-nitro-1,3-benzenedicarboxylic acid, the reaction yields were respectively 96.9% and 97.8%;5. The structures of the title compounds were conformed by H-NMR, and Their UV absorption spectra and fluorescence emission spectra were tested.The innovation of this paper is described as follows:This paper separated the major by-product,4-hydroxy-1,3-benzenedicarboxylic acid, from the waste of the salicylic acid industrial production. And then it used to synthesize nine kinds of 4-hydroxy-1,3-benzenedicarboxylic di-esters derived compounds. The preparation methods were not only simple, but also had high yields and low cost. Researches showed that these compounds have a UV absorption property of moderate-intensity in the wavelength near 310nm, which can be used as potential ultraviolet absorbers. Valuable ideas can be provided for the development and utilization of industrial byproducts salicylic.