**2.2. Synthesis of di(n‐ and isoalkyl(C4–C9))cyclohexane‐1,2‐dicarboxylates**

Cyclohexanedicarboxylic esters are produced through the catalytic hydrogenation of corre‐ sponding phthalates or through the Diels‐Alder reaction of maleic acid esters with ethylene followed by hydrogenation using supported nickel catalyst [10].

Di(n‐ and isoalkyl(C4–C9)) phthalates were synthesized in the esterification reaction of phthalic anhydride with appropriate aliphatic alcohol using an optimized procedure [11, 12]. Hydro‐ genation of these esters, after their prior purification by distillation, were carried out in a high pressure reactor in the presence of the Ni catalyst on aluminosilicate support at 150°C for 3.0 h and under 9.0 MPa hydrogen pressure, according to the following scheme:

where R = alkyl (C4 – C9).

**1. Introduction**

chloride) (PVC) or epoxy resins.

**2.1. Di(alkyl)cyclohexane‐1,2‐dicarboxylates**

man health when compared to di(alkyl)phthalates.

**2. Plasticizers**

Di(n‐ and isononyl)cyclohexane‐1,2‐dicarboxylate (DINCH) isomers are considered to be relatively safe substitutes of the corresponding phthalates, especially when used in the manufacturing of various medical devices and toys. For this reason there is a great interest in

In this chapter, we present the results of the application of the different modern chromato‐ graphic and spectrometric analytical techniques, such as gas chromatography (GC), electro‐ spray‐mass spectrometry (ESI/MS), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), gas chromatography‐mass spectrometry (GC/MS), and others

They were obtained in the catalytic hydrogenation reactions in the presence of the Ni catalyst and used as plasticizers and cross‐linking agents to some polymers, such as poly(vinyl

Di(alkyl) esters of 1,2‐benzene dicarboxylic acid of higher molecular weight, such as di(2‐ ethylhexyl)phthalate (DEPH) or di(isononyl)phthalate (DINP), are widely used as plasticizers in the processing of various types of polymers, especially poly(vinyl chloride). These types of compounds are not chemically bound to the polymers, so they are gradually released from them by volatilization from the surface into the air, or by migration due to contact with a solid, or by extraction from the polymer into a liquid also due to direct contact [1]. These compounds are becoming challenging environmental pollutants with a strong impact on the human health. The toxicity effects of these compounds have been intensively investigated, and within the last decade some of those compounds have been classified as endocrine disruptors [2] and potential carcinogens [3–6]. The metabolism of DINP in animals [7] and in humans [8, 9] has been studied. In these studies, where deuterium‐labeled DINP was used, samples of animal and human urine were found to contain monoester of mono‐iso‐nonylphthalate and its oxidized isomers containing hydroxy, oxo, and carboxy functional groups as metabolites of DINP.

The new di(alkyl)cyclohexane 1,2 dicarboxylates (DINCH) plasticizers may be used to im‐ prove the flexibility of some polymers, mainly PVC. They also have less toxic effect on hu‐

Cyclohexanedicarboxylic esters are produced through the catalytic hydrogenation of corre‐ sponding phthalates or through the Diels‐Alder reaction of maleic acid esters with ethylene

**2.2. Synthesis of di(n‐ and isoalkyl(C4–C9))cyclohexane‐1,2‐dicarboxylates**

followed by hydrogenation using supported nickel catalyst [10].

the analysis of their isomers by different analytical methods.

228 New Advances in Hydrogenation Processes - Fundamentals and Applications

similar ones to the identification of the new generation additives.

During the hydrogenation reaction of di(alkyl)phthalates, *cis* and *trans* isomers of the di(alkyl(C4–C9))cyclohexane‐1,2‐dicarboxylates are formed as the main products with a yield of 98.0%.
