Carboxylic acid

About: Carboxylic acid is a research topic. Over the lifetime, 48544 publications have been published within this topic receiving 605696 citations.

Controlled Functionalization and Multistep Chemical Manipulation of Covalently Modified Si(111) Surfaces1

Abstract: A hydrogen-terminated Si(111) surface has been covalently modified by UV irradiation in the presence of ethyl undecylenate leading to a Si(111)-C10H20CO2Et surface. It is possible to carry out a diverse range of chemical manipulations of the ester group on the surface. For example, reduction with sodium borohydride provides a surface terminated with a primary alcohol. Reaction with an alkyl Grignard reagent gives a tertiary alcohol that can be acylated with acetyl chloride. Finally, hydrolysis of the ester leads to a carboxylic acid terminated surface that can be coupled to an amino acid using a standard solid phase amide coupling protocol. The surface density of the ester function can be controlled by dilution of the reacting ester with a long-chain alkene. This has the beneficial effects of minimizing the disruption of the alkyl chain packing in the monolayers and avoiding steric blocking of the ester group. It is expected that the ability to precisely control the average distance between large biomolec...

Non-peptide polyamino acid bioerodible polymers

Abstract: A novel bioerodible polymeric composition is provided comprising a plurality of monomer units of two or three amino acids which are polymerized via hydrolytically labile bonds at their respective side chains rather than at the amino or carboxylic acid terminals by amide bonds. Such polymers are useful for controlled release applications in vivo and in vitro for delivery of a wide variety of biologically and pharmacologically active ligands.

Role of water in formic acid decomposition

Abstract: Formic acid decomposes primarily to CO and H2 0 in the gas phase, but to CO, and H, in the aqueous phase. Ab-initio quantum chemical calculations were performed, using Hartree-Fock and density functional methods, to seek an explanation for this behavior. The effect of water on the two decomposition pathways and on the isomerization of formic acid was determined. The transition state structures were fully optimized and include up to two water molecules. In the absence of water, dehydration is more favorable than decarboxylation. The presence of water reduces the activation barriers for both decomposition pathways, but decarboxylation is consistently more favorable than dehydration. The water molecules actively participate in the bond-breaking and bondforming processes in the transition state. The reduction in the activation barriers with the addition of water indicates that water acts as a homogeneous catalyst for both dehydration and decarboxylation, whereas isomerization of formic acid occurs independently of water. Water has a strong effect on the relative stability of the formic acid isomers, acid - water complexes, and transition states. The relative stability of the transition states plays an important role in determining the faster decomposition pathway.