Organic carbamates are important raw materials and/or intermediates in the production of fine chemicals , such as pesticides, herbicides, pharmaceuticals and dyestuffs [2, 3], in addition to being employed as amine protecting groups in organic synthesis  and linkers in combinatorial synthesis [1, 4].
The conventional process for the production of organic carbamates is based mainly on the reaction between alcohols and toxic isocyanates . This approach is not environmentally friendly, because of the need to input high amounts of energy, the use of toxic phosgene as a raw material and also the formation of corrosive hydrochloric acid as a side product [2, 6]. Several phosgene-free processes for the production of organic carbamates, such as reductive carbonylation of nitro compounds , oxidative carbonylation of amines , and alcoholysis of substituted urea [9–11], have been explored. Before these processes acquire a real industrial application, much work has to be carried out in order to reduce the severity of the reaction conditions employed, which presently require high temperatures and pressures, and the use of expensive noble metal catalysts. Recently, an alternative route to organic carbamates via the alkoxycarbonylation of amines with alkyl carbonates [12–14] – especially dimethyl carbonate (DMC) – under relatively mild reaction conditions and using cheap catalysts, has been receiving considerable attention. This route appears promising, also given that DMC is presently produced on a large scale by the oxidative carbonylation of methanol . In addition, DMC is easy to handle, cheap, nontoxic and clean, with the methoxycarbonylation reaction yielding methanol as main byproduct. Thus, if the methoxycarbonylation reaction between amines and DMC is coupled with the oxidative carbonylation of alcohols, it is hoped that a green, "zero emission" process for the production of organic carbamates, with could be achieved.
Dialkyl carbamates are of significant importance in industry because their thermolysis results in diisocyanates, which are precursors of polyurethane . A few reports have dealt with the synthesis of dialkyl carbamates from the alkoxycarbonylation reaction between diamines and DMC using homogeneous catalysts [17, 18]. However, difficulties associated with homogeneous catalysis systems are well known, notably those relating to the separation and recycling of the catalyst that result in loss of the latter and also product contamination. These issues can be overcome easily if a heterogeneous, rather than homogeneous, catalyst is employed. Regarding the synthesis of dialkyl carbamates from the reaction between diamines and DMC, to the best of our knowledge, no heterogeneous catalyst has been hitherto reported.
Berlinite is the most stable and nonporous phase of all polymorphs of aluminophosphates . Its main potential application can be seen in the field of functional materials, such as high-performance sealants of corrosion- and wear-resistant coatings [20, 21], acoustic wave devices, memory glass  and piezoelectric materials . While porous aluminophosphates and their transition metal-incorporated derivatives were widely used as catalysts [24, 25], a catalytic application of berlinite was never found.
In this study, we address for the first time the preparation of a zinc-incorporated berlinite, namely ZnAlPO4 – using 1,6-hexanediamine (HDA) as a structural template – and its application as a heterogeneous catalyst in the production of dimethylhexane-1,6-dicarbamate via the methoxycarbonylation between HDA and DMC under mild conditions. Factors influencing the reaction were studied systematically, with a possible reaction mechanism also proposed.