| Name | Formula | Alpha Formula | Edge | Filename | Citation |
| Perfluorobutane | C4F10 | C4F10 | C 1s | fn-0cckk.os | RI&88 |
| Perfluorobutane | C4F10 | C4F10 | F 1s | fn-0ffkk.os | RI&88 |
| silyl triflate | Me3SiOSO2CF3 | C4F3H9O3SSi | C 1s | uh-0cckk.os | UH94a |
| silyl triflate | Me3SiOSO2CF3 | C4F3H9O3SSi | Si 2p | uh-0sill.os | UH94a |
| 1,3- Hexafluorobutadiene | CF2CF=CFCF2 | C4F6 | C 1s | fb-0cckk.os | RI&88 |
| 1,3- Hexafluorobutadiene | CF2CF=CFCF2 | C4F6 | F 1s | fb-0ffkk.os | RI&88 |
| Perfluoro-2-butyne (Matheson) | CF3CCCF3 | C4F6 | C 1s | fy-0cckk.os | HS&84 |
| Perfluoro-2-butyne (Matheson) | CF3CCCF3 | C4F6 | F 1s | fy-0ffkk.os | HS&84 |
| perfluoro-2-butene | CF3CF=CFCF3 | C4F8 | C 1s | ft-0cckk.os | RI&88 |
| perfluoro-2-butene | CF3CF=CFCF3 | C4F8 | F 1s | ft-0ffkk.os | RI&88 |
| per-Fluoro-Cyclobutane | c-C4F8 | C4F8 | C 1s | fc-0cckk.os | RI&88 |
| per-Fluoro-Cyclobutane | c-C4F8 | C4F8 | F 1s | fc-0ffkk.os | IM&88 |
| Isobutane | CH3CH(CH3)CH3 | C4H10 | C 1s | ib-0cckk.os | HI87 |
| n-Butane | C4H10 | C4H10 | C 1s | ba-0cckk.os | HI&87 |
| Diethylether | (C2H5)2O | C4H10O | C 1s | de-0cckk.os | UH&95b |
| Diethylether | (C2H5)2O | C4H10O | O 1s | de-0ookk.os | UH&95b |
| t-Butyl alcohol | C4H9OH | C4H10O | C 1s | tl-0cckk.os | MI&87 |
| t-Butyl alcohol | C4H9OH | C4H10O | O 1s | tl-0ookk.os | MI&87 |
| trimethylmethoxy silane | Me3SiOMe | C4H12OSi | C 1s | ua-0cckk.os | UT+97 |
| trimethylmethoxy silane | Me3SiOMe | C4H12OSi | O 1s | ua-0ookk.os | UT+97 |
| trimethylmethoxy silane | Me3SiOMe | C4H12OSi | Si 2p | ua-0sill.os | UT+97 |
| tetramethylsilane | Me4Si | C4H12Si | C 1s | ui-0cckk.os | UX+94 |
| tetramethylsilane | Me4Si | C4H12Si | Si 2p | ui-0sill.os | UX+94 |
| Thiophene(atl.code-`C4H4S',`THI') | c-C4H4S | C4H4S | C 1s | ta-0cckk.os | HN&86 |
| Thiophene(atl.code-`C4H4S',`THI') | c-C4H4S | C4H4S | S 1s | ta-0ssl3.os | HN&86 |
| Selenophene | c-SeC4H4 | C4H4Se | C 1s | se-0cckk.os | HTB89 |
| Selenophene | c-SeC4H4 | C4H4Se | Se 3d,3p | se-0sem5.os | HTB89 |
| Pyrrole | c-C4H5N | C4H5N | C 1s | po-0cckk.os | NIH86 |
| Pyrrole | c-C4H5N | C4H5N | N 1s | po-0nnkk.os | NIH86 |
| 2-Butyne | CH3C:::CCH3 | C4H6 | C 1s | by-0cckk.os | RI&88 |
| Acetic Anhydride | ME(CO)O(CO)ME | C4H6O3 | C1s | ko-0cckk.os | |
| Acetic Anhydride | ME(CO)O(CO)ME | C4H6O3 | O1s | ko-0ookk.os | |
| Dimethyl Pyrocarbonate | ME(O)CO(O)CO(O)ME | C4H6O5 | O1s | kl-0cckk.os | |
| dimethyl pyrocarbonate | MeO-CO-O-CO-OMe | C4H6O5 | C 1s | kl-0ookk.os | |
| Diacetimide | ME(CO)NH(CO)ME | C4H7N02 | C1s | kn-0cckk.os | |
| Diacetimide | ME(CO)NH(CO)ME | C4H7N02 | N1s | kn-0nnkk.os | |
| Diacetimide | ME(CO)NH(CO)ME | C4H7N02 | O1s | kn-0ookk.os | |
| Butadiene | CH2=CHCH=CH2 | C4H8 | C 1s | bt-0cckk.os | MC&87 |
| Cyclobutane | c-C4H8 | C4H8 | C 1s | cb-0cckk.os | HN&86 |
| Ethyl allophanate | NH2CONHCOOC2H5 | C4H8N2O3 | ep-0cckk.os | ||
| Ethyl allophanate | NH2CONHCOOC2H5 | C4H8N2O3 | N 1s | ep-0nnkk.os | |
| Ethyl allophanate | NH2CONHCOOC2H5 | C4H8N2O3 | ep-0ookk.os | ||
| Tetrahydrofuran | c-C4H8O | C4H8O | C 1s | tk-0cckk.os | NIH86 |
| Tetrahydrofuran | c-C4H8O | C4H8O | O 1s | tk-0ookk.os | NIH86 |
| Pyrrolidine | c-C4H9N | C4H9N | C 1s | pq-0cckk.os | NIH86 |
| Pyrrolidine | c-C4H9N | C4H9N | N 1s | pq-0nnkk.os | NIH86 |