Is there something wrong wth my 3 year old son?

since my son turned 2 he has been very uncontrolable and when i ask him to do something he ignores me. if i ask him to get something and its infront of him he pretends not to see it. when i ask him to behave he misbehaves more. when i tell him off he screams in my face, slams doors and baby gates, even hits out at me and others. i am finding it difficult to cope as i have another son who has just turned 1 and he is needing more attention and im afraid that if he keeps seeing this behaviour from his brother that he will pick up on it. im also afraid that my youngest son will become scared of my because he is seeing my shouting and crying and sometimes smacking his brother. i do dicipline my son but it does not seem to work i just feel like ive failed with him. any advice will be deeply appreciated because i dont think i can cope much longer!