Nanoceria-promoted low Pd–Ni catalyst for the synthesis of secondary amines from aliphatic alcohols and ammonia

This paper describes the preparation of a series of bimetallic Pd–Ni catalysts supported over nanoceria with very low Ni and Pd loading (<0.5 wt%) for the direct amination of aliphatic alcohols with ammonia. Different metal impregnation methods were used for engineering the interaction between Pd, Ni and nanoceria. The as-prepared catalysts were characterized in detail by combining XRD, H2-TPR, H2-TPD, STEM-EDS-SDD and XPS. The sequence of impregnation of both metals and the Pd loading affected to an important extent the catalytic activity by conditioning the crystallite size and the Pd and Ni speciation, as well as the reducibility and reversible H2 storage properties. By optimizing the preparation protocols, a 0.5wt% Pd–0.5wt% Ni–Pd/CeO2 formulation prepared by sequential impregnation of the nickel and palladium precursors afforded 80% yield of dioctylamine at almost full conversion [TON = 1160 mmol per mmol (Ni + Pd)surface] in the direct amination reaction of 1-octanol with ammonia at 180 °C for 2 h. Metal leaching during the reaction could be completely avoided. The high catalytic performance of Pd–Ni induced by nanoceria places this catalyst among the best ever reported catalysts for the synthesis of secondary amines

Genotype-phenotype correlation in L1 associated diseases.

The neural cell adhesion molecule L1 (L1CAM) plays a key role during embryonic development of the nervous system and is involved in memory and learning. Mutations in the L1 gene are responsible for four X linked neurological conditions: X linked hydrocephalus (HSAS), MASA syndrome, complicated spastic paraplegia type 1 (SP-1), and X linked agenesis of the corpus callosum. As the clinical picture of these four L1 associated diseases shows considerable overlap and is characterised by Corpus callosum hypoplasia, mental Retardation, Adducted thumbs, Spastic paraplegia, and Hydrocephalus, these conditions have recently been lumped together into the CRASH syndrome. We investigate here whether a genotype-phenotype correlation exists in CRASH syndrome since its clinical spectrum is highly variable and numerous L1 mutations have been described. We found that (1) mutations in the extracellular part of L1 leading to truncation or absence of L1 cause a severe phenotype, (2) mutations in the cytoplasmic domain of L1 give rise to a milder phenotype than extracellular mutations, and (3) extracellular missense mutations affecting amino acids situated on the surface of a domain cause a milder phenotype than those affecting amino acids buried in the core of the domain