add new variables conditional on another variable

Question

I have dataset1 with 11 variables like this

      id   e1   e1a  e2  e2a ... e5  e5a
       1   100   1   20   1  ... 15    2
       2   100   1   20   2  ... 40    1
       3   600   2   75   2  ... 300   2
       4   400   1   80   1  ... 20    2

I would like to add 5 new variables conditional on the value of variables e#a==2. Resulting in dataset2 with 16 variables:

      id   e1   e1a  e2  e2a ...e5  e5a  e1m  e2m...e5m
       1   100   1   20   1  ...15   2   NA   NA ...  15
       2   100   1   20   2  ... 40  1   NA   20 ...  NA
       3   600   2   75   2  ...300  2   600  75 ...  300
       4   400   1   80   1  ... 20  2   NA   NA ...  20

I've tried using a for loop as follows:

 Library(tidyverse)

 
 for(i in 1:5) { 
  mutate(dataset1, eim=ifelse(eia==2,ei,"NA" ))
  }

and it gives this error Error: Problem with mutate() column eim. ℹ eim = ifelse(eia == 2, ei, "NA"). x object 'eia' not found. Therefore I tried adding [] like this

 for(i in 1:5) { 
  mutate(dataset1, e[i]m=ifelse(e[i]a==2,e[i],"NA" ))
  }