Novel pyrimidinyl ethers, their use as herbicides, herbicidal compositions comprising said pyrimidinyl ethers and processes for the preparation thereof

A compound of formula I, ##STR31## wherein either R.sub.1 is H or (C.sub.1-18)alkyl, (C.sub.1-18)alkyl substituted by up to 2 substituents selected from (C.sub.1-4)alkoxy or 2-tetrahydrofuryl;

• (C.sub.1-18)alkenyl;
• (C.sub.3-8)-cycloalkyl or (C.sub.3-8)cycloalkyl-(C.sub.1-5)alkyl, unsubstituted or substituted by up to 2 halogens selected from fluorine, chlorine and bromine;
• phenyl unsubstituted or substituted by up to 3 substituents selected from halogen of the group fluorine, chlorine and bromine (C.sub.1 -C.sub.4)alkyl and (C.sub.1 -C.sub.4)alkoxy;
• and R.sub.2 is H, (C.sub.1 -C.sub.5)alkyl,
• or R.sub.1 and R.sub.2 together are a (C.sub.4 -C.sub.6)alkylene chain,
• Y.sub.1 and Y.sub.2 independently are H or halogen selected from fluorine, chlorine or bromine,
• R.sub.3, R.sub.4 and R.sub.5 independently are H, (C.sub.1 -C.sub.5)alkyl unsubstituted or substituted by halogen selected from fluorine, chlorine or bromine,
• R.sub.6 is (C.sub.1 -C.sub.5)alkyl, and
• R.sub.7 is H or (C.sub.1 -C.sub.5)alkyl in free base or acid addition salt form.