## 2 Applications in Chemistry
### Hydrogenation Reaction
[PERSON] and co-workers recently published a new procedure for the conversion of cyclic carbonates **1** to diols **12** in overheated water, without an external catalyst or additive (Scheme 11) [44]. The reaction of ethylene carbonate proceeded smoothly to give the desired glycol in high yield (99%) along with CO\({}_{2}\) as a byproduct. The reaction was studied at different temperatures (100 \({}^{\circ}\)C to 250 \({}^{\circ}\)C) with water filling of 25% for 2 h. In general, a higher temperature was better in promoting the reaction and the methodology was extended to methyl- and ethyl-substituted ethylene carbonates. With these substrates, 10 h was needed to provide the corresponding diols with 59% and 62% yield, respectively. The same diols can be obtained from cyclic carbonates via a deprotection reaction. In this sense, the new heterogeneous zinc/imidazole catalyst was evaluated in various reactions such as transesterification and transcarbonation [45]. A small amount of the suitable zinc/imidazole catalyst immobilized on polystyrene resin proved effective to prepare 3-phenoxypropane-1,2-diol **12** from 4-(phenoxyymethyl)-1,3-dioxolan-2-one **1d** after 6 h in refluxing methanol (Scheme 11). An extension of the deprotection reaction was recently described by [PERSON] and co-workers [46], whereby 4-chalcogenomethyl-1,3-dioxolan-2-ones **1** were synthesized from GC **1a** (Section 2.4), then converted into diols **12** by using potassium carbonate in PEG-400 for 12 h at 25 \({}^{\circ}\)C (Scheme 12). Six vicinal diols bearing an arylsulfanyl or arylselenanyl moiety were obtained in excellent yields. [PERSON] and [PERSON] described the asymmetric hydroformylation of racemic 4-vinyl-1,3-dioxolan-2-one **1e** to prepare the aldehyde **1f** (Scheme 13) [47]. The authors reported the chemoselective and regiospecific formation of **1f** by using the \"pre-formed\" PtCl\({}_{2}\)(diphosphine) and tin(II) chloride catalyst and (25,45)-2,4-bis(diphenylphosphinopentane) [(5,5)-BDPP)]as an enantiopure diphosphine ligand. The platinum-containing catalytic systems provided nearly complete conversion of compound **1e** after 3, 19, and 72 h at 100, 60, and 40 \({}^{\circ}\)C, respectively. In addition, a hydrogenated product **1g** was formed, even under optimal conditions. In this work, the kinetic resolution of the aldehyde indicated that (S)-(**1f**) was preferably formed in the temperature range of 40-100 \({}^{\circ}\)C.  
[PERSON] and co-workers reported on the first use of an earth-abundant metal complex as a catalyst for the transfer hydrogenation of carbonate **14**, opening an indirect route for the reduction of CO2 to methanol (Scheme 14) [48]. An advantage of this method, according to the authors, is the use of isopropanol as a hydrogen source, avoiding the use of flammable hydrogen under high pressures. Using a metal-based catalyst, it was possible to perform the transfer hydrogenation of GC **1a** selectively, using the PNP pincer-type iron complex C17H38 BrFeNOP2 **15**. This reaction occurred at 140 \({}^{\circ}\)C over 6 to 24 h, obtaining the respective diols **12** and MeOH as products with 51-97% and 39-92% yield, respectively.