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