methanol metabolism phosphate transition state molecule krebs cycle exothermic reaction correlation cesium atomic weights single step alcohols alcohol atoms ethers joules electron pair organic solvents heat flow chirality ketone amino acids diels alder reaction junior chemistry carbons isomer constituents intermediates catalytic hydrogenation molecules racemic mixture acetone reagents cis catalysts covalent bonds selectivity dehydration reaction activation energy highest energy temperatures cytosine organic chemistry catalyst chemical reactions concentration nucleophile reagent synthesis dehydration derivatives journal article electrons presence acyl water molecules solvent electron density byproducts oxidation room temperature equilibrium alkyne sodium pyruvate protons substrates organic reactions chemical reaction hydrogen gas electrophile hydrogen bonds esters reactants alkenes electron acceptor carbon atoms proteins atomic mass protons neutrons and electrons cell cycles chromosomes alkene dna molecule cells local anesthetic aspirin carbon dioxide hydrogen peroxide glucose living organisms atom ammonia thymine hydrogen Organic acids and bases chemistry salicylic acid chemicals