NOVELTY - Sweetening a fluid or gas, involves treating the fluid or gas with a composition comprising at least one epoxide compound (I) or an alcohol/alpha- or beta-functionalized epoxide compound (II).    USE - For sweetening a fluid or gas used in the production, transportation, storage, and/or separation of crude oil or natural gas; and in a coal-fired process, waste-water process, farm, slaughter house, land-fill, municipality waste-water plant, coking coal process, or a biofuel process (all claimed).    ADVANTAGE - The composition scavenges hydrogen sulfide and/or mercaptans from the fluid or gas. The scavenging composition is particularly useful for the removal of hydrogen sulfide and/or mercaptans from crude oil based, natural gas based, and coal based products, processes, and refinery streams. The composition is applicable to both upstream and downstream processes; and is useful in a wide range of climates and under a wide range of process conditions. The composition removes hydrogen sulfide and/or mercaptans from fuels without hazing or clouding of the fuel. The composition is non-nitrogen based; pass all standard American Society for Testing and Materials (ASTM) and Universal Oil Products (UOP) tests for mercaptans; is non-aqueous based; and is small molecule with low volatility. Additionally, the scavenged product diols possess low volatility, easing sequestration and removal from treated fluids and gases. The compounds used are particularly useful for scavenging of hydrogen sulfide and/or mercaptans from liquids and gases found in the oil, gas, and/or coal industries.    DETAILED DESCRIPTION - Sweetening a fluid or gas, involves treating the fluid or gas with a composition comprising at least one epoxide compound of formula (I) or an alcohol/alpha- or beta-functionalized epoxide compound of formula (II).    X'=-OH, -SH, or -NHR3;    R3=H, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, cycloalkyl, or -C(O)R7;    R7=-OR15, -SR16, -NR17R18, H, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or cycloalkyl;    R15-R18=H, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or cycloalkyl;    R1a-R1g=H, halo, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or cycloalkyl;or    R1d+R1f together with the carbon atoms to which they are attached=an aryl or heteroaryl;    n=0 or 1;    R1=H or a moiety comprising an alpha - or beta -functionalized epoxide (where alpha - or beta -functionalization is selected from -OH, -SH, or -NHR23, and at least one R1 group is a moiety comprising alpha - or beta -functionalized epoxide);    R23=H, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, cycloalkyl, or -C(O)R27;    R27=-OR35, -SR36, -NR37R38, H, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or cycloalkyl;    A1=CR1sR1t;    R35-R38=H, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or cycloalkyl;    R', R'', R''', R1s, and R1t=H, halo, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or cycloalkyl;    y=0-6;    z=1-20.    Provided that R1e and R1g are absent when R1d and R1f together with the carbon atoms to which they are attached form an aryl or a heteroaryl. The alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, and cycloalkyl are each optionally substituted with at least one suitable substituent.