JUNE 2022 CHEMISTRY 19CCH4A 19CCH6A 19CCH6B 19CCH6C 19CCH6D 19CPCH4A 19CPCH4B 19NCH4A. 19SCH4A 19SCH6A 21CACH2A 21CAPH2A 21CCH2A 21CPCH2B 21CPCH2C 21CPCH2D