18. give the product for the following reactions sequence. a) 3-pentanone b) 2-pentanone c) propanone d) 2-butanone e) methyl propanoate 19. give the product for the following reactions sequence. a) ch3ch2cocl b) ch3ch2cho c) ch3co2ch3 d) ch3ch2cooch3 e) ch3ch2ch2cl 20. give the product for the following reactions sequence. a) ch3ch2cocl b) ch3ch2conhch3 c) ch3conhch2ch3 d) ch3ch2cooch3 e) ch3ch2ch2cl